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The current understanding of the health effects of eggs is nuanced and context-dependent. Eggs are a nutrient-dense food, providing high-quality protein, choline, folate, vitamin D, and B vitamins.[1] However, eggs are also a major source of dietary cholesterol, which has been the focus of ongoing debate regarding cardiovascular risk.
Recent large-scale meta-analyses and cohort studies indicate that higher egg consumption (typically ≥1 egg/day) is associated with a modestly increased risk of cardiovascular disease (CVD) and all-cause mortality, particularly in US and older populations.[2-6] The risk appears to be largely mediated by dietary cholesterol intake, with each additional 300 mg of cholesterol per day (roughly equivalent to 1.5 eggs) associated with increased CVD and mortality risk.[4-6] However, after adjusting for dietary cholesterol, the association between egg consumption and adverse outcomes is attenuated.[4]
Conversely, several umbrella reviews and multinational studies report no significant association between moderate egg intake and CVD or mortality in the general population, and some suggest possible benefits for satiety, muscle protein synthesis, and child growth.[1][7-10] The evidence is inconsistent, with substantial heterogeneity and critically low quality in many meta-analyses.[8-9]
In summary, moderate egg consumption (up to 1 egg/day) can be part of a healthy diet for most individuals, but higher intake may confer modest risk, especially in populations with elevated baseline risk or high dietary cholesterol intake. Clinical decisions should be individualized, considering patient risk factors and overall dietary patterns.[1-10]

1.
Eggs: Healthy or Risky? A Review of Evidence From High Quality Studies on Hen's Eggs.

Myers M, Ruxton CHS.

Nutrients. 2023;15(12):2657. doi:10.3390/nu15122657.

Hen's eggs (from ) provide choline, folate, vitamin D, iodine, B vitamins and high-quality protein and are no longer viewed by national bodies as a risk factor for hypercholesterolaemia and cardiovascular disease (CVD). Yet, questions remain about the benefits and risks of eating eggs regularly. This review evaluates recent high-quality evidence from randomised controlled trials (RCT) and meta-analyses of observational studies and considers new areas of interest, such as weight management, protein metabolism, allergy risk and sustainability. In several RCT, eggs increased muscle protein synthesis and lowered fat mass, which could support optimal body composition. Eggs within a meal improved satiety, which could translate into lower energy intakes, although more RCT are needed. In observational studies, higher egg consumption was associated with a null effect or a modest reduced risk of CVD. For type 2 diabetes (T2D) incidence and risk of CVD in people with T2D, there were inconsistencies between observational and RCT data, with the former noting positive associations and the latter seeing no effect of higher egg intake on markers of T2D and CVD. Sustainability metrics suggest that eggs have the lowest planetary impact amongst animal proteins. To lower allergy risk, earlier introduction of eggs into weaning diets is warranted. In conclusion, the balance of evidence points to eggs being a nutritious food suggesting there are broad health benefits from including eggs in the diet at intakes higher than that currently consumed by European populations.

2.
Associations of Dietary Cholesterol, Serum Cholesterol, and Egg Consumption With Overall and Cause-Specific Mortality: Systematic Review and Updated Meta-Analysis.

Zhao B, Gan L, Graubard BI, et al.

Circulation. 2022;145(20):1506-1520. doi:10.1161/CIRCULATIONAHA.121.057642.

Leading Journal

Background: Despite substantial research highlighting the importance of exogenous dietary cholesterol intake and endogenous serum cholesterol level in human health, a thorough evaluation of the associations is lacking. Our study objective was to examine overall and cause-specific mortality in relation to dietary and serum cholesterol, as well as egg consumption, and conduct an updated meta-regression analysis of cohort studies.

Methods: We conducted a prospective analysis of 27 078 men in the ATBC Study (Alpha-Tocopherol, Beta-Carotene Cancer Prevention). Multivariable-controlled cause-specific Cox proportional hazards regression models were used to calculate hazard ratios and 31-year absolute mortality risk differences. A systematic review and meta-analysis of cohort studies was also performed (PROSPERO [

Url: https://www.crd.york.ac.uk/prospero/; Unique identifier: CRD42021272756]).

Results: Based on 482 316 person-years of follow-up, we identified 22 035 deaths, including 9110 deaths from cardiovascular disease (CVD). Greater dietary cholesterol and egg consumption were associated with increased risk of overall and CVD-related mortality. Hazard ratios for each additional 300 mg cholesterol intake per day were 1.10 and 1.13 for overall and CVD-related mortality, respectively; for each additional 50-g egg consumed daily, hazard ratios were 1.06 and 1.09, respectively, for overall and CVD-related mortality (all P values<0.0001). After multivariable adjustment, higher serum total cholesterol concentrations were associated with increased risk of CVD-related mortality (hazard ratios per 1 SD increment, 1.14; P<0.0001). The observed associations were generally similar across cohort subgroups. The updated meta-analysis of cohort studies on the basis of 49 risk estimates, 3 601 401 participants, and 255 479 events showed consumption of 1 additional 50-g egg daily was associated with significantly increased CVD risk (pooled relative risk, 1.04 [95% CI, 1.00-1.08]; I2=80.1%). In the subgroup analysis of geographic regions (Pinteraction=0.02), an increase of 50-g egg consumed daily was associated with a higher risk of CVD in US cohorts (pooled relative risk, 1.08 [95% CI, 1.02-1.14]) and appeared related to a higher CVD risk in European cohorts with borderline significance (pooled relative risk, 1.05), but was not associated with CVD risk in Asian cohorts.

Conclusions: In this prospective cohort study and updated meta-analysis, greater dietary cholesterol and egg consumption were associated with increased risk of overall and CVD-related mortality. Our findings support restricted consumption of dietary cholesterol as a means to improve long-term health and longevity.

3.

Background: Recent studies have reported conflicting associations between egg consumption and the risk of all-cause or cardiovascular disease (CVD) mortality, including ischemic heart disease (IHD) mortality and stroke mortality. With accumulating evidence, up-to-date evidence about the association should be synthesized.

Objectives: We aimed to assess the association of the risk of all-cause and CVD mortality with egg consumption.

Methods: We searched the PubMed, Embase, and Web of Science databases through 3 November, 2021 for observational studies conducted in participants ≥18 y of age and which provided ORs, RRs, or HRs and 95% CIs for ≥3 egg consumption categories or for increased intake of egg addressing the associations of interest. A random-effects model was used to pool the reported risk estimates. Restricted cubic splines were used to examine the dose-response association.

Results: Twenty-four articles with 48 reports (25 for all-cause mortality, 11 for CVD mortality, 6 for IHD mortality, and 6 for stroke mortality) involving 11,890,695 participants were included. Intake of each 1-egg/d increment was associated with increased risk of all-cause mortality (

Rr: 1.06; 95%

Ci: 1.02, 1.10; P = 0.008), but the association was restricted to women, Americans, and studies with adjustments for hyperlipidemia. Egg consumption was linearly associated with CVD mortality only in participants >60 y of age, Americans, studies with follow-up duration ≥15 y, and studies with adjustments for hyperlipidemia (P ≤ 0.018). No significant association was found between egg consumption and IHD or stroke mortality (P ≥ 0.080).

Conclusions: Egg consumption was linearly associated with a modestly increased risk of all-cause mortality and, in older participants, Americans, and studies with longer follow-up or adjustments for hyperlipidemia, CVD mortality. These findings suggest that it may be prudent to avoid high egg consumption.

4.
Associations of Dietary Cholesterol or Egg Consumption With Incident Cardiovascular Disease and Mortality.

Zhong VW, Van Horn L, Cornelis MC, et al.

JAMA logoJAMA. 2019;321(11):1081-1095. doi:10.1001/jama.2019.1572.

Leading Journal
Abstract

Importance 
Cholesterol is a common nutrient in the human diet and eggs are a major source of dietary cholesterol. Whether dietary cholesterol or egg consumption is associated with cardiovascular disease (CVD) and mortality remains controversial.
Objective 
To determine the associations of dietary cholesterol or egg consumption with incident CVD and all-cause mortality.
Design, Setting, and Participants 
Individual participant data were pooled from 6 prospective US cohorts using data collected between March 25, 1985, and August 31, 2016. Self-reported diet data were harmonized using a standardized protocol.
Exposures 
Dietary cholesterol (mg/day) or egg consumption (number/day).
Main Outcomes and Measures 
Hazard ratio (HR) and absolute risk difference (ARD) over the entire follow-up for incident CVD (composite of fatal and nonfatal coronary heart disease, stroke, heart failure, and other CVD deaths) and all-cause mortality, adjusting for demographic, socioeconomic, and behavioral factors.
Results 
This analysis included 29 615 participants (mean [SD] age, 51.6 [13.5] years at baseline) of whom 13 299 (44.9%) were men and 9204 (31.1%) were black. During a median follow-up of 17.5 years (interquartile range, 13.0-21.7; maximum, 31.3), there were 5400 incident CVD events and 6132 all-cause deaths. The associations of dietary cholesterol or egg consumption with incident CVD and all-cause mortality were monotonic (all P values for nonlinear terms, .19-.83). Each additional 300 mg of dietary cholesterol consumed per day was significantly associated with higher risk of incident CVD (adjusted HR, 1.17 [95% CI, 1.09-1.26]; adjusted ARD, 3.24% [95% CI, 1.39%-5.08%]) and all-cause mortality (adjusted HR, 1.18 [95% CI, 1.10-1.26]; adjusted ARD, 4.43% [95% CI, 2.51%-6.36%]). Each additional half an egg consumed per day was significantly associated with higher risk of incident CVD (adjusted HR, 1.06 [95% CI, 1.03-1.10]; adjusted ARD, 1.11% [95% CI, 0.32%-1.89%]) and all-cause mortality (adjusted HR, 1.08 [95% CI, 1.04-1.11]; adjusted ARD, 1.93% [95% CI, 1.10%-2.76%]). The associations between egg consumption and incident CVD (adjusted HR, 0.99 [95% CI, 0.93-1.05]; adjusted ARD, −0.47% [95% CI, −1.83% to 0.88%]) and all-cause mortality (adjusted HR, 1.03 [95% CI, 0.97-1.09]; adjusted ARD, 0.71% [95% CI, −0.85% to 2.28%]) were no longer significant after adjusting for dietary cholesterol consumption.
Conclusions and Relevance 
Among US adults, higher consumption of dietary cholesterol or eggs was significantly associated with higher risk of incident CVD and all-cause mortality in a dose-response manner. These results should be considered in the development of dietary guidelines and updates.

5.
Egg and Cholesterol Consumption and Mortality From Cardiovascular and Different Causes in the United States: A Population-Based Cohort Study.

Zhuang P, Wu F, Mao L, et al.

PLoS Medicine. 2021;18(2):e1003508. doi:10.1371/journal.pmed.1003508.

Leading Journal

Background: Whether consumption of egg and cholesterol is detrimental to cardiovascular health and longevity is highly debated. Data from large-scale cohort studies are scarce. This study aimed to examine the associations of egg and cholesterol intakes with mortality from all causes, cardiovascular disease (CVD), and other causes in a US population.

Methods And Findings: Overall, 521,120 participants (aged 50-71 years, mean age = 62.2 years, 41.2% women, and 91.8% non-Hispanic white) were recruited from 6 states and 2 additional cities in the US between 1995 and 1996 and prospectively followed up until the end of 2011. Intakes of whole eggs, egg whites/substitutes, and cholesterol were assessed by a validated food frequency questionnaire. Cause-specific hazard models considering competing risks were used, with the lowest quintile of energy-adjusted intake (per 2,000 kcal per day) as the reference. There were 129,328 deaths including 38,747 deaths from CVD during a median follow-up of 16 years. Whole egg and cholesterol intakes were both positively associated with all-cause, CVD, and cancer mortality. In multivariable-adjusted models, the hazard ratios (95% confidence intervals) associated with each intake of an additional half of a whole egg per day were 1.07 (1.06-1.08) for all-cause mortality, 1.07 (1.06-1.09) for CVD mortality, and 1.07 (1.06-1.09) for cancer mortality. Each intake of an additional 300 mg of dietary cholesterol per day was associated with 19%, 16%, and 24% higher all-cause, CVD, and cancer mortality, respectively. Mediation models estimated that cholesterol intake contributed to 63.2% (95% CI 49.6%-75.0%), 62.3% (95% CI 39.5%-80.7%), and 49.6% (95% CI 31.9%-67.4%) of all-cause, CVD, and cancer mortality associated with whole egg consumption, respectively. Egg white/substitute consumers had lower all-cause mortality and mortality from stroke, cancer, respiratory disease, and Alzheimer disease compared with non-consumers. Hypothetically, replacing half a whole egg with equivalent amounts of egg whites/substitutes, poultry, fish, dairy products, or nuts/legumes was related to lower all-cause, CVD, cancer, and respiratory disease mortality. Study limitations include its observational nature, reliance on participant self-report, and residual confounding despite extensive adjustment for acknowledged dietary and lifestyle risk factors.

Conclusions: In this study, intakes of eggs and cholesterol were associated with higher all-cause, CVD, and cancer mortality. The increased mortality associated with egg consumption was largely influenced by cholesterol intake. Our findings suggest limiting cholesterol intake and replacing whole eggs with egg whites/substitutes or other alternative protein sources for facilitating cardiovascular health and long-term survival.

Trial Registration: ClinicalTrials.gov NCT00340015.

6.
Dietary Cholesterol and Egg Intake in Relation to Incident Cardiovascular Disease and All-Cause and Cause-Specific Mortality in Postmenopausal Women.

Chen GC, Chen LH, Mossavar-Rahmani Y, et al.

The American Journal of Clinical Nutrition. 2021;113(4):948-959. doi:10.1093/ajcn/nqaa353.

Background: The potential cardiovascular impact of dietary cholesterol intake has been actively debated for decades.

Objectives: We aimed to evaluate associations of dietary cholesterol and egg intakes with incident cardiovascular disease (CVD) and all-cause and cause-specific mortality.

Methods: We included 96,831 US postmenopausal women aged 50-79 y without known CVD or cancer during baseline enrollment (1993-1998) of the Women's Health Initiative. Dietary information was collected using a validated FFQ. Incident CVD [i.e., ischemic heart disease (IHD) and stroke] and all-cause and cause-specific mortality were ascertained and adjudicated through February 2018.

Results: A total of 9808 incident CVD cases and 19,508 all-cause deaths occurred during a median follow-up of 17.8 y and 18.9 y, respectively. After multivariable adjustment for traditional risk factors and key dietary nutrients including dietary saturated fat, there were modest associations of dietary cholesterol intake with incident CVD (HRQ5versusQ1: 1.12; 95%

Ci: 1.03, 1.21; P-trend < 0.001) and all-cause mortality (HRQ5versusQ1: 1.09; 95%

Ci: 1.02, 1.15; P-trend < 0.001). Significant positive associations were also observed between dietary cholesterol and incident IHD (P-trend = 0.007), incident ischemic stroke (P-trend = 0.002), and CVD mortality (P-trend = 0.002), whereas there was an inverse association for incident hemorrhagic stroke (P-trend = 0.037) and no association for mortality from cancer, Alzheimer disease/dementia, respiratory diseases, or other causes (P-trend > 0.05). Higher egg consumption was also associated with modestly higher risk of incident CVD (P-trend = 0.004) and all-cause mortality (P-trend < 0.001), with HRs of 1.14 (95%

Ci: 1.04, 1.25) and 1.14 (95%

Ci: 1.07, 1.22), respectively, when comparing ≥1 egg/d with <1 egg/wk.

Conclusions: Both higher dietary cholesterol intake and higher egg consumption appeared to be associated with modestly elevated risk of incident CVD and all-cause mortality in US postmenopausal women.

7.
Association of Egg Intake With Blood Lipids, Cardiovascular Disease, and Mortality in 177,000 People in 50 Countries.

Dehghan M, Mente A, Rangarajan S, et al.

The American Journal of Clinical Nutrition. 2020;111(4):795-803. doi:10.1093/ajcn/nqz348.

Background: Eggs are a rich source of essential nutrients, but they are also a source of dietary cholesterol. Therefore, some guidelines recommend limiting egg consumption. However, there is contradictory evidence on the impact of eggs on diseases, largely based on studies conducted in high-income countries.

Objectives: Our aim was to assess the association of egg consumption with blood lipids, cardiovascular disease (CVD), and mortality in large global studies involving populations from low-, middle-, and high-income countries.

Methods: We studied 146,011 individuals from 21 countries in the Prospective Urban Rural Epidemiology (PURE) study. Egg consumption was recorded using country-specific validated FFQs. We also studied 31,544 patients with vascular disease in 2 multinational prospective studies: ONTARGET (Ongoing Telmisartan Alone and in Combination with Ramipril Global End Point Trial) and TRANSCEND (Telmisartan Randomized Assessment Study in ACEI Intolerant Subjects with Cardiovascular Disease). We calculated HRs using multivariable Cox frailty models with random intercepts to account for clustering by study center separately within each study.

Results: In the PURE study, we recorded 14,700 composite events (8932 deaths and 8477 CVD events). In the PURE study, after excluding those with history of CVD, higher intake of egg (≥7 egg/wk compared with <1 egg/wk intake) was not significantly associated with blood lipids, composite outcome (

Hr: 0.96; 95%

Ci: 0.89, 1.04; P-trend = 0.74), total mortality (

Hr: 1.04; 95%

Ci: 0.94, 1.15; P-trend = 0.38), or major CVD (

Hr: 0.92; 95%

Ci: 0.83, 1.01; P-trend = 0.20). Similar results were observed in ONTARGET/TRANSCEND studies for composite outcome (HR 0.97; 95%

Ci: 0.76, 1.25; P-trend = 0.09), total mortality (

Hr: 0.88; 95%

Ci: 0.62, 1.24; P-trend = 0.55), and major CVD (

Hr: 0.97; 95%

Ci: 0.73, 1.29; P-trend = 0.12).

Conclusions: In 3 large international prospective studies including ∼177,000 individuals, 12,701 deaths, and 13,658 CVD events from 50 countries in 6 continents, we did not find significant associations between egg intake and blood lipids, mortality, or major CVD events. The ONTARGET and TRANSCEND trials were registered at clinicaltrials.gov as NCT00153101. The PURE trial was registered at clinicaltrials.gov as NCT03225586.

8.
Effect of Egg Consumption on Health Outcomes: An Updated Umbrella Review of Systematic Reviews and Meta-Analysis of Observational and Intervention Studies.

Formisano E, Lopes Neri LC, Caffa I, et al.

Nutrition, Metabolism, and Cardiovascular Diseases : NMCD. 2025;35(5):103849. doi:10.1016/j.numecd.2025.103849.

New Research

Aims: To evaluate the effect of egg consumption on health outcomes.

Data Synthesis: A systematic search in PubMed, Scopus, Lilacs, and Web of Science was developed using terms ("egg consumption" or "egg intake") and ("health" or "chronic diseases" or "diabetes" or "cancer" or "cholesterol" or "dyslipidemia"), and meta-analyses of observational or interventional studies published since January 2020 were included. The studies' quality was evaluated through AMSTAR-2 and NutriGrade, and the strength of evidence according to sample size, heterogeneity, and quality of articles. Fourteen meta-analyses were included (10 observational, 4 interventional studies). The wide range of outcomes, with substantial variability and high heterogeneity, indicated a lack of robust evidence. The overall quality of studies was critically low. The level of evidence was very weak for all the significant associations: risk of heart failure (RR 1.15; 95%

Ci: 1.02-1.30), cancer mortality (RR 1.13; 95%CI 1.06-1.20), higher levels of LDL cholesterol (WMD 7.39; 95%CI 5.82-8.95), total cholesterol (WMD 9.12; 95%CI 7.35-10.89), and apolipoprotein B-100 (WMD 0.06; 95%CI 0.03-0.08). Conversely, egg intake has been weakly associated with improvements in HDL cholesterol (WMD 1.37; 95%CI 0.49-2.25), apolipoprotein A1 (WMD 0.03; 95%CI 0.01-0.05), and growth parameters in children (WMD 0.47; 95%CI 0.13-0.80). No evidence of association was found among all cardiovascular outcomes and all-cause mortality risk between high vs. low egg consumption.

Conclusion: Due to the critically low strength of studies, insufficient evidence is available to discourage egg consumption, suggesting eggs can be part of a healthy diet.

9.
The Effect of Egg Consumption on Cardiometabolic Health Outcomes: An Umbrella Review.

Mah E, Chen CO, Liska DJ.

Public Health Nutrition. 2020;23(5):935-955. doi:10.1017/S1368980019002441.

Objective: This umbrella review provides an overview of the consistency and gaps in the evidence base on eggs and cardiometabolic health.

Design: PubMed, Web of Science, Cochrane Library, the Nutrition Evidence Systematic Review and Agency for Healthcare Research and Quality databases were screened for evidence-based reviews in English that assessed human studies on egg consumption and cardiometabolic outcomes.

Results: Seven systematic reviews and fifteen meta-analyses were identified, with eighteen of these published since 2015. Overall, the systematic reviews were of low quality, while meta-analyses were of moderate- to high-quality. No association of increased egg intake and risks of heart disease or stroke in the general population were found in the meta-analyses. Increased risk of heart failure was noted in two meta-analyses that analysed the same three cohort studies. Five recent meta-analyses reported no increased risk of type 2 diabetes mellitus (T2DM) in the general population, although increased risk in US-based populations only has been reported. Older (<2013) meta-analyses reported increased risks of cardiovascular disease (CVD) or heart disease in T2DM populations, and no recent evidence-based reviews were identified. Finally, only one meta-analysis reported intervention studies specifically on eggs and biomarkers (i.e. lipids), and the results contradicted those from observation studies.

Conclusions: Recent evidence-based reviews conclude that increased egg consumption is not associated with CVD risk in the general population. More research is needed on the positive associations between egg consumption and heart failure and T2DM risk, as well as CVD risk in diabetics, before firm conclusions can be made.

10.
Egg Consumption and Human Health: An Umbrella Review of Observational Studies.

Marventano S, Godos J, Tieri M, et al.

International Journal of Food Sciences and Nutrition. 2020;71(3):325-331. doi:10.1080/09637486.2019.1648388.

Egg consumption has been an area of controversy regarding its impact on human health largely due to the content in cholesterol and its potential role in cardio-metabolic outcomes. This study aimed to summarise the level of evidence of egg consumption on various health outcomes. A systematic search for meta-analyses was performed: study design, dose-response relationship, heterogeneity and agreement of results over time, and identification of potential confounding factors were considered to assess the level of evidence. Results from this umbrella review showed a substantial no association between egg consumption and a number of health outcomes, including cancer, cardiovascular and metabolic disorders. In contrast, evidence of possible beneficial effects toward stroke risk has been found. In conclusions, egg may be part of a healthy diet; however, additional studies exploring confounding factors are needed to ascertain the potential detrimental effects.

Finished thinking

Analyzing query
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Egg whites are healthier than whole eggs for individuals seeking to reduce dietary cholesterol intake and cardiovascular risk. Egg whites provide high-quality protein with minimal calories, virtually no fat, and negligible cholesterol, whereas whole eggs contain significant cholesterol (∼186 mg per large egg, almost entirely in the yolk) and additional fat.[1-3]
Large cohort studies and meta-analyses demonstrate that higher whole egg and dietary cholesterol intake are associated with increased all-cause and cardiovascular mortality, and that replacing whole eggs with egg whites or substitutes is associated with lower mortality and improved cardiovascular outcomes.[1][4] Randomized trials and animal studies further show that egg white consumption does not raise plasma or liver cholesterol, and may even lower plasma cholesterol and body fat accumulation, while whole eggs and yolks can increase blood pressure and liver lipid accumulation.[5-6]
Egg whites also possess bioactive proteins with antioxidant and anti-inflammatory properties, and have demonstrated benefits for muscle mass, strength, and metabolic health without the adverse lipid effects seen with whole eggs.[3][7] For patients with established cardiovascular risk factors, diabetes, or hyperlipidemia, egg whites are preferred over whole eggs as a protein source.[1-2][4]
However, whole eggs provide additional micronutrients (e.g., choline, vitamin D, B vitamins) and may improve HDL profiles in some populations, so the choice should be individualized based on overall dietary patterns and risk profile.[8-9] For most patients prioritizing cardiovascular health, egg whites are the healthier option.

1.
Egg and Cholesterol Consumption and Mortality From Cardiovascular and Different Causes in the United States: A Population-Based Cohort Study.

Zhuang P, Wu F, Mao L, et al.

PLoS Medicine. 2021;18(2):e1003508. doi:10.1371/journal.pmed.1003508.

Leading Journal

Background: Whether consumption of egg and cholesterol is detrimental to cardiovascular health and longevity is highly debated. Data from large-scale cohort studies are scarce. This study aimed to examine the associations of egg and cholesterol intakes with mortality from all causes, cardiovascular disease (CVD), and other causes in a US population.

Methods And Findings: Overall, 521,120 participants (aged 50-71 years, mean age = 62.2 years, 41.2% women, and 91.8% non-Hispanic white) were recruited from 6 states and 2 additional cities in the US between 1995 and 1996 and prospectively followed up until the end of 2011. Intakes of whole eggs, egg whites/substitutes, and cholesterol were assessed by a validated food frequency questionnaire. Cause-specific hazard models considering competing risks were used, with the lowest quintile of energy-adjusted intake (per 2,000 kcal per day) as the reference. There were 129,328 deaths including 38,747 deaths from CVD during a median follow-up of 16 years. Whole egg and cholesterol intakes were both positively associated with all-cause, CVD, and cancer mortality. In multivariable-adjusted models, the hazard ratios (95% confidence intervals) associated with each intake of an additional half of a whole egg per day were 1.07 (1.06-1.08) for all-cause mortality, 1.07 (1.06-1.09) for CVD mortality, and 1.07 (1.06-1.09) for cancer mortality. Each intake of an additional 300 mg of dietary cholesterol per day was associated with 19%, 16%, and 24% higher all-cause, CVD, and cancer mortality, respectively. Mediation models estimated that cholesterol intake contributed to 63.2% (95% CI 49.6%-75.0%), 62.3% (95% CI 39.5%-80.7%), and 49.6% (95% CI 31.9%-67.4%) of all-cause, CVD, and cancer mortality associated with whole egg consumption, respectively. Egg white/substitute consumers had lower all-cause mortality and mortality from stroke, cancer, respiratory disease, and Alzheimer disease compared with non-consumers. Hypothetically, replacing half a whole egg with equivalent amounts of egg whites/substitutes, poultry, fish, dairy products, or nuts/legumes was related to lower all-cause, CVD, cancer, and respiratory disease mortality. Study limitations include its observational nature, reliance on participant self-report, and residual confounding despite extensive adjustment for acknowledged dietary and lifestyle risk factors.

Conclusions: In this study, intakes of eggs and cholesterol were associated with higher all-cause, CVD, and cancer mortality. The increased mortality associated with egg consumption was largely influenced by cholesterol intake. Our findings suggest limiting cholesterol intake and replacing whole eggs with egg whites/substitutes or other alternative protein sources for facilitating cardiovascular health and long-term survival.

Trial Registration: ClinicalTrials.gov NCT00340015.

2.
Impact of Whole Egg Intake on Blood Pressure, Lipids and Lipoproteins in Middle-Aged and Older Population: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Wang MX, Wong CH, Kim JE.

Nutrition, Metabolism, and Cardiovascular Diseases : NMCD. 2019;29(7):653-664. doi:10.1016/j.numecd.2019.04.004.

Background And Aim: Effects of whole egg consumption on cardiovascular diseases (CVD) risk in the middle-aged and older population remain unclear due to inconsistent findings from observational and randomized controlled trials (RCTs). This meta-analysis aimed to assess the impacts of whole egg and egg category (whole eggs versus egg substitutes) intake quantity on CVD risk factors from systematically searched RCTs. Egg substitutes were hypothesized to have minimal effects of the blood lipid and lipoprotein profile as they are void of dietary cholesterol.

Methods And Results: As many as 434 studies identified from PubMed, Cochrane Library, CINAHL and Medline (Ovid) databases were screened and data were extracted from 8 selected RCTs. Quality of the selected studies were assessed and the overall effect sizes of weighted mean differences (WMD) were calculated using a random effects model. Non-differential effects in blood pressures, lipids and lipoproteins were observed when >4 whole eggs/week compared to ≤4 whole eggs/week were consumed. Intake of >4 whole eggs/week compared to equivalent amounts of egg substitutes caused greater elevations in blood total cholesterol (

Wmd: 0.198 mmol/L; 95% CIs: 0.056, 0.339), HDL cholesterol (

Wmd: 0.068 mmol/L; 95% CIs: 0.006, 0.130) and LDL cholesterol (

Wmd: 0.171 mmol/L; 95% CIs: 0.028, 0.315) but did not differentially affect triglycerides concentration.

Conclusion: Overall, the results support the notion that quantity of whole egg intake does not affect CVD risk factors and consuming egg substitutes may also be beneficial compared to whole eggs on lowering CVD risk in the middle-aged and older population.

3.
Health Functions of Egg Protein.

Matsuoka R, Sugano M.

Foods (Basel, Switzerland). 2022;11(15):2309. doi:10.3390/foods11152309.

Egg protein is a remarkably abundant source of protein, with an amino acid score of 100 and the highest net protein utilization rate. However, there have been relatively fewer studies investigating the health benefits of egg protein. In this review, we have summarized the available information regarding the health benefits of egg proteins based on human studies. In particular, studies conducted on the characteristics of egg whites, as they are high in pure protein, have reported their various health functions, such as increases in muscle mass and strength enhancement, lowering of cholesterol, and visceral fat reduction. Moreover, to facilitate and encourage the use of egg white protein in future, we also discuss its health functions. These benefits were determined by developing an egg white hydrolysate and lactic-fermented egg whites, with the latter treatment simultaneously improving the egg flavor. The health benefits of the protein hydrolysates from the egg yolk (bone growth effect) and eggshell membrane (knee join pain-lowering effect) have been limited in animal studies. Therefore, the consumption of egg protein may contribute to the prevention of physical frailty and metabolic syndromes.

4.
Associations of Dietary Cholesterol, Serum Cholesterol, and Egg Consumption With Overall and Cause-Specific Mortality: Systematic Review and Updated Meta-Analysis.

Zhao B, Gan L, Graubard BI, et al.

Circulation. 2022;145(20):1506-1520. doi:10.1161/CIRCULATIONAHA.121.057642.

Leading Journal

Background: Despite substantial research highlighting the importance of exogenous dietary cholesterol intake and endogenous serum cholesterol level in human health, a thorough evaluation of the associations is lacking. Our study objective was to examine overall and cause-specific mortality in relation to dietary and serum cholesterol, as well as egg consumption, and conduct an updated meta-regression analysis of cohort studies.

Methods: We conducted a prospective analysis of 27 078 men in the ATBC Study (Alpha-Tocopherol, Beta-Carotene Cancer Prevention). Multivariable-controlled cause-specific Cox proportional hazards regression models were used to calculate hazard ratios and 31-year absolute mortality risk differences. A systematic review and meta-analysis of cohort studies was also performed (PROSPERO [

Url: https://www.crd.york.ac.uk/prospero/; Unique identifier: CRD42021272756]).

Results: Based on 482 316 person-years of follow-up, we identified 22 035 deaths, including 9110 deaths from cardiovascular disease (CVD). Greater dietary cholesterol and egg consumption were associated with increased risk of overall and CVD-related mortality. Hazard ratios for each additional 300 mg cholesterol intake per day were 1.10 and 1.13 for overall and CVD-related mortality, respectively; for each additional 50-g egg consumed daily, hazard ratios were 1.06 and 1.09, respectively, for overall and CVD-related mortality (all P values<0.0001). After multivariable adjustment, higher serum total cholesterol concentrations were associated with increased risk of CVD-related mortality (hazard ratios per 1 SD increment, 1.14; P<0.0001). The observed associations were generally similar across cohort subgroups. The updated meta-analysis of cohort studies on the basis of 49 risk estimates, 3 601 401 participants, and 255 479 events showed consumption of 1 additional 50-g egg daily was associated with significantly increased CVD risk (pooled relative risk, 1.04 [95% CI, 1.00-1.08]; I2=80.1%). In the subgroup analysis of geographic regions (Pinteraction=0.02), an increase of 50-g egg consumed daily was associated with a higher risk of CVD in US cohorts (pooled relative risk, 1.08 [95% CI, 1.02-1.14]) and appeared related to a higher CVD risk in European cohorts with borderline significance (pooled relative risk, 1.05), but was not associated with CVD risk in Asian cohorts.

Conclusions: In this prospective cohort study and updated meta-analysis, greater dietary cholesterol and egg consumption were associated with increased risk of overall and CVD-related mortality. Our findings support restricted consumption of dietary cholesterol as a means to improve long-term health and longevity.

5.

The dose-dependent effect of egg consumption on plasma cholesterol in humans remains inconclusive. It is unknown if egg white consumed in a normal amount can reduce plasma cholesterol. We used hamsters as a model to (i) investigate the dose-dependent effect of consuming zero to five whole eggs on plasma total cholesterol (TC) and (ii) examine if egg white, equivalent to one to five eggs, possessed any reducing effects on plasma TC. In experiment 1, hamsters were divided into six groups ( n = 8 each) and fed either a control diet or one of five experimental diets supplemented with whole-egg powder equivalent to one to five eggs per 2000 kcal. Results showed that supplementation with one egg increased plasma TC by 25% compared with that of the control (226 ± 16 versus 282 ± 56 mg/dL, p < 0.05), whereas supplementation with two to five eggs did not significantly produce any additional effects on plasma cholesterol. However, supplementation with one to five eggs in diets caused a dose-dependent accumulation of cholesterol in the liver from 21.5 ± 4.4 to 71.3 ± 7.3 mg/g ( p < 0.01). In the second experiment, hamsters were divided into six groups and fed either a high-cholesterol control diet or one of five experimental diets supplemented with egg-white powder from one to five eggs. Results showed that egg-white powder affected neither plasma nor liver cholesterol levels. The egg-white powder did not affect fecal sterol excretion, suggesting it had no effect on cholesterol absorption. It was therefore concluded that consumption of two to five eggs did not significantly produce any additional effects on plasma cholesterol, whereas egg white did not possess a plasma-cholesterol-lowering activity if it was consumed at amounts similar to those in a normal human diet.

6.
Effect of Consumption of Whole Egg and Egg Fractions on Cardiovascular Disease Factors in Adult Rats.

Chairuk P, Zaman RU, Naphatthalung J, Jansakul C.

Journal of the Science of Food and Agriculture. 2021;101(9):3942-3951. doi:10.1002/jsfa.11034.

Background: While eggs are a low-cost source of protein, rich in macro- and micronutrients, the association of egg intake and cardiovascular disease (CVD) remains controversial. This study investigated the effect of egg consumption on CVD parameters. Eggs were boiled, separated into four fractions (whole egg, 50% yolk-reduced whole egg, egg yolk and egg white) and then freeze-dried. The different egg fractions or distilled water (control) were orally gavaged to adult male Wistar rats at 1 g kg rat body weight, each day for 8 weeks, following which basal blood pressure, heart rate, complete blood cell count, blood biochemistry, body fat and liver cell lipid accumulation were determined. The vascular functions of isolated thoracic aorta were studied using classical pharmacological techniques.

Results: In comparison to the control group, none of the egg fractions affected body weight, food intake, plasma glucose or lipid profile. The yolk group experienced increased plasma alkaline phosphatase and creatinine levels, while egg white caused decreased plasma cholesterol and blood urea nitrogen. Whole egg and egg yolk increased blood pressure and mean hemoglobin concentration and the yolk increased liver lipid accumulation. Egg white decreased the white blood cell count and body fat lipids. No changes were found in basal heart rate or vascular functions in any of the groups.

Conclusions: Consumption of whole egg or egg yolk at the dosage given caused hypertension, with impairment of liver and kidney functions following the intake of yolk alone. However, egg white is beneficial for the cardiovascular system as it decreased plasma cholesterol and body fat accumulation. © 2020 Society of Chemical Industry.

7.
Antioxidant Stress and Anti-Inflammatory Activities of Egg White Proteins and Their Derived Peptides: A Review.

Zhou N, Zhao Y, Yao Y, et al.

Journal of Agricultural and Food Chemistry. 2022;70(1):5-20. doi:10.1021/acs.jafc.1c04742.

Oxidative stress and chronic inflammation are the common pathological bases of chronic diseases such as atherosclerosis, cancer, and cardiovascular diseases, but most of the treatment drugs for chronic diseases have side effects. There is an increasing interest to identify food-derived bioactive compounds that can mitigate the pathological pathways associated with oxidative stress and chronic inflammation. Egg white contain a variety of biologically active proteins, many of which have antioxidant and anti-inflammatory activities and usually show better activity after enzymatic hydrolysis. This review covers the antioxidative stress and anti-inflammatory activities of egg white proteins and their derived peptides and clarifies their mechanism of action and . In addition, the link between oxidative stress and inflammation as well as their markers are reviewed. It suggests the potential application of egg white proteins and their derived peptides and puts forward further research prospects.

8.
Consumption of Different Egg-Based Diets Alters Clinical Metabolic and Hematological Parameters in Young, Healthy Men and Women.

Andersen CJ, Huang L, Zhai F, et al.

Nutrients. 2023;15(17):3747. doi:10.3390/nu15173747.

Eggs-particularly egg yolks-are a rich source of bioactive nutrients and dietary compounds that influence metabolic health, lipid metabolism, immune function, and hematopoiesis. We investigated the effects of consuming an egg-free diet, three egg whites per day, and three whole eggs per day for 4 weeks on comprehensive clinical metabolic, immune, and hematologic profiles in young, healthy adults (18-35 y, BMI < 30 kg/m2 or <30% body fat for men and <40% body fat for women, n = 26) in a 16-week randomized, crossover intervention trial. We observed that average daily macro- and micronutrient intake significantly differed across egg diet periods, including greater intake of choline during the whole egg diet period, which corresponded to increased serum choline and betaine without altering trimethylamine N-oxide. Egg white and whole egg intake increased serum isoleucine while whole egg intake reduced serum glycine-markers of increased and decreased risk of insulin resistance, respectively-without altering other markers of glucose sensitivity or inflammation. Whole egg intake increased a subset of large HDL particles (H6P, 10.8 nm) and decreased the total cholesterol:HDL-cholesterol ratio and % monocytes in female participants using combined oral contraceptive (COC) medication (n = 11) as compared to female non-users (n = 10). Whole egg intake further increased blood hematocrit whereas egg white and whole egg intake reduced blood platelet counts. Changes in clinical immune cell counts between egg white and whole egg diet periods were negatively correlated with several HDL parameters yet positively correlated with measures of triglyceride-rich lipoproteins and insulin sensitivity. Overall, the intake of whole eggs led to greater overall improvements in micronutrient diet quality, choline status, and HDL and hematologic profiles while minimally-yet potentially less adversely-affecting markers of insulin resistance as compared to egg whites.

9.
Eggs: Healthy or Risky? A Review of Evidence From High Quality Studies on Hen's Eggs.

Myers M, Ruxton CHS.

Nutrients. 2023;15(12):2657. doi:10.3390/nu15122657.

Hen's eggs (from ) provide choline, folate, vitamin D, iodine, B vitamins and high-quality protein and are no longer viewed by national bodies as a risk factor for hypercholesterolaemia and cardiovascular disease (CVD). Yet, questions remain about the benefits and risks of eating eggs regularly. This review evaluates recent high-quality evidence from randomised controlled trials (RCT) and meta-analyses of observational studies and considers new areas of interest, such as weight management, protein metabolism, allergy risk and sustainability. In several RCT, eggs increased muscle protein synthesis and lowered fat mass, which could support optimal body composition. Eggs within a meal improved satiety, which could translate into lower energy intakes, although more RCT are needed. In observational studies, higher egg consumption was associated with a null effect or a modest reduced risk of CVD. For type 2 diabetes (T2D) incidence and risk of CVD in people with T2D, there were inconsistencies between observational and RCT data, with the former noting positive associations and the latter seeing no effect of higher egg intake on markers of T2D and CVD. Sustainability metrics suggest that eggs have the lowest planetary impact amongst animal proteins. To lower allergy risk, earlier introduction of eggs into weaning diets is warranted. In conclusion, the balance of evidence points to eggs being a nutritious food suggesting there are broad health benefits from including eggs in the diet at intakes higher than that currently consumed by European populations.

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There is no established recommended daily limit for egg white consumption in current US dietary guidelines; egg whites are low in cholesterol and can be consumed more freely than whole eggs.[1-2] The American Heart Association and other major guidelines focus on limiting dietary cholesterol, which is concentrated in the yolk, not the white.
Replacing whole eggs with egg whites or egg substitutes is associated with lower all-cause and cardiovascular mortality, supporting their use for individuals concerned about cholesterol intake.[3-4] Egg whites provide high-quality protein and have demonstrated benefits for muscle mass and metabolic health, with no adverse effects on plasma or liver cholesterol at typical consumption levels in both human and animal studies.[5-6]
Most clinical studies and dietary guidelines address upper limits for whole eggs or dietary cholesterol, not egg whites specifically. There is no evidence in the medical literature to suggest harm from typical egg white consumption in healthy adults, though extremely high protein intake from any source may warrant caution in individuals with renal impairment or other specific conditions.[1][7]
In summary, egg whites do not have a specific recommended daily limit in the context of cardiovascular health, and can be consumed liberally as a protein source in place of whole eggs for most individuals. Further research may be needed to define upper intake limits for egg whites in special populations, but current consensus supports their safety and utility in heart-healthy dietary patterns.[1-7]

1.
2021 Dietary Guidance to Improve Cardiovascular Health: A Scientific Statement From the American Heart Association.

Lichtenstein AH, Appel LJ, Vadiveloo M, et al.

Circulation. 2021;144(23):e472-e487. doi:10.1161/CIR.0000000000001031.

Leading Journal

Guidance for reducing CVD risk and LDL cholesterol concentrations have historically included recommendations to limit dietary cholesterol, although more recently numerical limits have not been explicit. 131 A positive relation between dietary cholesterol and LDL cholesterol concentrations has been documented; still, the current US intake is similar to the historical 300 mg/d upper level. 132 Consistent with these findings, the 2020 Dietary Guidelines Advisory Committee report noted that current intakes should not be increased. 9 Assessing the independent effect of dietary cholesterol on CVD risk is complicated by the lack of evidence at plausible, rather than extremely high intakes, and the difficulty in isolating the effects of eggs from those of frequently paired foods such as bacon and sausage. Adhering to a dietary pattern consistent with the guidance in this document will result in relatively low dietary cholesterol intakes. An in-depth analysis of the topic can be found in the AHA scientific statement on dietary cholesterol and cardiovascular risk. 132

2.
Egg Consumption and Heart Health: A Review.

Clayton ZS, Fusco E, Kern M.

Nutrition (Burbank, Los Angeles County, Calif.). 2017;37:79-85. doi:10.1016/j.nut.2016.12.014.

Cardiovascular disease is the leading cause of death in the United States. Until recently, reducing dietary cholesterol has been a part of the American Heart Association (AHA) and American College of Cardiology (ACC) guidelines on lifestyle management, despite inconclusive evidence to support the recommendation. Considering eggs are a rich source of dietary cholesterol (typically containing 141-234 mg per egg), individuals with increased risk for CVD are advised not to consume eggs. Furthermore, based on the 2012 AHA/ACC guidelines, individuals with lower risk for CVD have previously been advised to avoid consuming eggs due to the high content of dietary cholesterol. Rather than strictly limiting cholesterol intake, the AHA and ACC guidelines now recommend dietary patterns that emphasize fruits, vegetables, whole grains, low-fat dairy products, poultry, fish, and nuts as an approach to favorably alter blood lipid levels. Of note, the 2015-2020 Dietary Guidelines for Americans have removed the recommendation of limiting cholesterol intake to no more than 300 mg per day; however, the guidelines advise that individuals should eat as little dietary cholesterol as possible while consuming a healthy eating pattern. The purpose of this review is to summarize the documented health risks of egg consumption in individuals with low and high risk for CVD and determine whether current recommendations are warranted based on the available literature. We also aim to provide guidance for future studies that will help further elucidate the health modulating effect of eggs.

3.
Egg and Cholesterol Consumption and Mortality From Cardiovascular and Different Causes in the United States: A Population-Based Cohort Study.

Zhuang P, Wu F, Mao L, et al.

PLoS Medicine. 2021;18(2):e1003508. doi:10.1371/journal.pmed.1003508.

Leading Journal

Background: Whether consumption of egg and cholesterol is detrimental to cardiovascular health and longevity is highly debated. Data from large-scale cohort studies are scarce. This study aimed to examine the associations of egg and cholesterol intakes with mortality from all causes, cardiovascular disease (CVD), and other causes in a US population.

Methods And Findings: Overall, 521,120 participants (aged 50-71 years, mean age = 62.2 years, 41.2% women, and 91.8% non-Hispanic white) were recruited from 6 states and 2 additional cities in the US between 1995 and 1996 and prospectively followed up until the end of 2011. Intakes of whole eggs, egg whites/substitutes, and cholesterol were assessed by a validated food frequency questionnaire. Cause-specific hazard models considering competing risks were used, with the lowest quintile of energy-adjusted intake (per 2,000 kcal per day) as the reference. There were 129,328 deaths including 38,747 deaths from CVD during a median follow-up of 16 years. Whole egg and cholesterol intakes were both positively associated with all-cause, CVD, and cancer mortality. In multivariable-adjusted models, the hazard ratios (95% confidence intervals) associated with each intake of an additional half of a whole egg per day were 1.07 (1.06-1.08) for all-cause mortality, 1.07 (1.06-1.09) for CVD mortality, and 1.07 (1.06-1.09) for cancer mortality. Each intake of an additional 300 mg of dietary cholesterol per day was associated with 19%, 16%, and 24% higher all-cause, CVD, and cancer mortality, respectively. Mediation models estimated that cholesterol intake contributed to 63.2% (95% CI 49.6%-75.0%), 62.3% (95% CI 39.5%-80.7%), and 49.6% (95% CI 31.9%-67.4%) of all-cause, CVD, and cancer mortality associated with whole egg consumption, respectively. Egg white/substitute consumers had lower all-cause mortality and mortality from stroke, cancer, respiratory disease, and Alzheimer disease compared with non-consumers. Hypothetically, replacing half a whole egg with equivalent amounts of egg whites/substitutes, poultry, fish, dairy products, or nuts/legumes was related to lower all-cause, CVD, cancer, and respiratory disease mortality. Study limitations include its observational nature, reliance on participant self-report, and residual confounding despite extensive adjustment for acknowledged dietary and lifestyle risk factors.

Conclusions: In this study, intakes of eggs and cholesterol were associated with higher all-cause, CVD, and cancer mortality. The increased mortality associated with egg consumption was largely influenced by cholesterol intake. Our findings suggest limiting cholesterol intake and replacing whole eggs with egg whites/substitutes or other alternative protein sources for facilitating cardiovascular health and long-term survival.

Trial Registration: ClinicalTrials.gov NCT00340015.

4.
Impact of Whole Egg Intake on Blood Pressure, Lipids and Lipoproteins in Middle-Aged and Older Population: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Wang MX, Wong CH, Kim JE.

Nutrition, Metabolism, and Cardiovascular Diseases : NMCD. 2019;29(7):653-664. doi:10.1016/j.numecd.2019.04.004.

Background And Aim: Effects of whole egg consumption on cardiovascular diseases (CVD) risk in the middle-aged and older population remain unclear due to inconsistent findings from observational and randomized controlled trials (RCTs). This meta-analysis aimed to assess the impacts of whole egg and egg category (whole eggs versus egg substitutes) intake quantity on CVD risk factors from systematically searched RCTs. Egg substitutes were hypothesized to have minimal effects of the blood lipid and lipoprotein profile as they are void of dietary cholesterol.

Methods And Results: As many as 434 studies identified from PubMed, Cochrane Library, CINAHL and Medline (Ovid) databases were screened and data were extracted from 8 selected RCTs. Quality of the selected studies were assessed and the overall effect sizes of weighted mean differences (WMD) were calculated using a random effects model. Non-differential effects in blood pressures, lipids and lipoproteins were observed when >4 whole eggs/week compared to ≤4 whole eggs/week were consumed. Intake of >4 whole eggs/week compared to equivalent amounts of egg substitutes caused greater elevations in blood total cholesterol (

Wmd: 0.198 mmol/L; 95% CIs: 0.056, 0.339), HDL cholesterol (

Wmd: 0.068 mmol/L; 95% CIs: 0.006, 0.130) and LDL cholesterol (

Wmd: 0.171 mmol/L; 95% CIs: 0.028, 0.315) but did not differentially affect triglycerides concentration.

Conclusion: Overall, the results support the notion that quantity of whole egg intake does not affect CVD risk factors and consuming egg substitutes may also be beneficial compared to whole eggs on lowering CVD risk in the middle-aged and older population.

5.

The dose-dependent effect of egg consumption on plasma cholesterol in humans remains inconclusive. It is unknown if egg white consumed in a normal amount can reduce plasma cholesterol. We used hamsters as a model to (i) investigate the dose-dependent effect of consuming zero to five whole eggs on plasma total cholesterol (TC) and (ii) examine if egg white, equivalent to one to five eggs, possessed any reducing effects on plasma TC. In experiment 1, hamsters were divided into six groups ( n = 8 each) and fed either a control diet or one of five experimental diets supplemented with whole-egg powder equivalent to one to five eggs per 2000 kcal. Results showed that supplementation with one egg increased plasma TC by 25% compared with that of the control (226 ± 16 versus 282 ± 56 mg/dL, p < 0.05), whereas supplementation with two to five eggs did not significantly produce any additional effects on plasma cholesterol. However, supplementation with one to five eggs in diets caused a dose-dependent accumulation of cholesterol in the liver from 21.5 ± 4.4 to 71.3 ± 7.3 mg/g ( p < 0.01). In the second experiment, hamsters were divided into six groups and fed either a high-cholesterol control diet or one of five experimental diets supplemented with egg-white powder from one to five eggs. Results showed that egg-white powder affected neither plasma nor liver cholesterol levels. The egg-white powder did not affect fecal sterol excretion, suggesting it had no effect on cholesterol absorption. It was therefore concluded that consumption of two to five eggs did not significantly produce any additional effects on plasma cholesterol, whereas egg white did not possess a plasma-cholesterol-lowering activity if it was consumed at amounts similar to those in a normal human diet.

6.
Health Functions of Egg Protein.

Matsuoka R, Sugano M.

Foods (Basel, Switzerland). 2022;11(15):2309. doi:10.3390/foods11152309.

Egg protein is a remarkably abundant source of protein, with an amino acid score of 100 and the highest net protein utilization rate. However, there have been relatively fewer studies investigating the health benefits of egg protein. In this review, we have summarized the available information regarding the health benefits of egg proteins based on human studies. In particular, studies conducted on the characteristics of egg whites, as they are high in pure protein, have reported their various health functions, such as increases in muscle mass and strength enhancement, lowering of cholesterol, and visceral fat reduction. Moreover, to facilitate and encourage the use of egg white protein in future, we also discuss its health functions. These benefits were determined by developing an egg white hydrolysate and lactic-fermented egg whites, with the latter treatment simultaneously improving the egg flavor. The health benefits of the protein hydrolysates from the egg yolk (bone growth effect) and eggshell membrane (knee join pain-lowering effect) have been limited in animal studies. Therefore, the consumption of egg protein may contribute to the prevention of physical frailty and metabolic syndromes.

7.
Associations of Dietary Cholesterol or Egg Consumption With Incident Cardiovascular Disease and Mortality.

Zhong VW, Van Horn L, Cornelis MC, et al.

JAMA logoJAMA. 2019;321(11):1081-1095. doi:10.1001/jama.2019.1572.

Leading Journal
Introduction

The associations between dietary cholesterol consumption and cardiovascular disease (CVD) and mortality remain controversial despite decades of research. The debate has intensified recently due to the inclusion of 2 seemingly contradictory statements in the 2015-2020 Dietary Guidelines for Americans: (1) “Cholesterol is not a nutrient of concern for overconsumption”; and (2) “Individuals should eat as little dietary cholesterol as possible while consuming a healthy eating pattern.” The most recent meta-analysis of prospective cohort studies could not draw meaningful conclusions about the association between dietary cholesterol consumption and CVD, primarily due to sparse data, between-study heterogeneity, and lack of methodologic rigor of the reviewed studies.

Quiz Ref ID Cholesterol, saturated fat, and animal protein often coexist in foods. The interaction and independence between dietary cholesterol and these nutrients in relation to CVD and mortality remain uncertain. Further, it is unclear whether eating an overall high-quality diet attenuates the associations of dietary cholesterol consumption with CVD and mortality or if the food source of cholesterol (eg, eggs, red meat, poultry, fish, and dairy products) is important. Eggs, specially the yolk, are a major source of dietary cholesterol; a large egg (≈50 g) contains approximately 186 mg of cholesterol. Reported associations of egg consumption with CVD and mortality have been inconsistent overall and by subtypes of these events.

Individual participant data were pooled from 6 cohorts from the Lifetime Risk Pooling Project to address the aforementioned gaps. The primary objective was to determine the associations of dietary cholesterol or egg consumption with incident CVD and all-cause mortality.

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Many proponents of plant-based diets claim that the protein found in egg whites is as unhealthy as the protein found in processed meats because both are animal-derived proteins, and epidemiologic evidence consistently shows that replacing animal protein—including egg protein—with plant protein is associated with lower all-cause and cardiovascular mortality. This claim is grounded in large cohort studies and substitution analyses demonstrating that the source of protein, not just the amount, is critical for long-term health outcomes.
The medical literature shows that animal protein intake (from eggs, processed meats, and red meats) is associated with higher risk of cardiovascular disease and mortality, while plant protein intake is associated with lower risk. Substitution analyses specifically indicate that replacing 3% of energy from egg protein or processed meat protein with plant protein results in a significant reduction in mortality risk (hazard ratios for all-cause mortality: 0.81 for egg protein, 0.66 for processed red meat protein).[1-2] The adverse associations are thought to be due to the "protein package"—animal proteins are often accompanied by cholesterol, saturated fat, and other pro-inflammatory components, whereas plant proteins come with beneficial nutrients and bioactive compounds.[3-4]
However, it is important to note that the risk associated with egg whites is likely lower than that of processed meats, as egg whites are devoid of cholesterol and saturated fat, and the literature does not show the same magnitude of risk for egg whites as for processed meats. The claim by plant-based diet proponents is therefore an oversimplification; while plant protein is consistently associated with better outcomes, the health risks of egg white protein are not equivalent to those of processed meat protein.
Table 3 from Song et al. illustrates how the health effects of animal versus plant protein intake are modified by lifestyle factors, and highlights the importance of protein source in risk stratification.
Table 3. Age- and Sex-Standardized Characteristics of Study Participants According to Percentage of Energy From Animal and Plant Protein Intake in the Healthy- and Unhealthy-Lifestyle Groups

Content used under license from the JAMA Network® © American Medical Association

1.
Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality.

Song M, Fung TT, Hu FB, et al.

JAMA logoJAMA Internal Medicine. 2016;176(10):1453-1463. doi:10.1001/jamainternmed.2016.4182.

Abstract

Plant protein was associated with lower all-cause mortality (HR, 0.90 per 3% energy increment; 95% CI, 0.86-0.95; P for trend < .001) and cardiovascular mortality (HR, 0.88 per 3% energy increment; 95% CI, 0.80-0.97; P for trend = .007). These associations were confined to participants with at least 1 unhealthy lifestyle factor based on smoking, heavy alcohol intake, overweight or obesity, and physical inactivity, but not evident among those without any of these risk factors. Replacing animal protein of various origins with plant protein was associated with lower mortality. In particular, the HRs for all-cause mortality were 0.66 (95% CI, 0.59-0.75) when 3% of energy from plant protein was substituted for an equivalent amount of protein from processed red meat, 0.88 (95% CI, 0.84-0.92) from unprocessed red meat, and 0.81 (95% CI, 0.75-0.88) from egg.

Conclusions and Relevance High animal protein intake was positively associated with cardiovascular mortality and high plant protein intake was inversely associated with all-cause and cardiovascular mortality, especially among individuals with at least 1 lifestyle risk factor. Substitution of plant protein for animal protein, especially that from processed red meat, was associated with lower mortality, suggesting the importance of protein source.

Discussion

Indeed, unlike animal protein, plant protein has not been associated with increased insulinlike growth factor 1 levels and has been linked to lower blood pressure, reduced low-density lipoprotein levels, and improved insulin sensitivity. Substitution of plant protein for animal protein has been related to a lower incidence of CVD and type 2 diabetes. Moreover, although a high intake of red meat, particularly processed red meat, has been associated with increased mortality in a recent meta-analysis of 13 cohort studies, high consumption of nuts, a major contributor to plant protein, has been associated lower CVD and all-cause mortality. These results underscore the importance of protein sources for risk assessment and suggest that other components in protein-rich foods (eg, sodium, nitrates, and nitrites in processed red meat), in addition to protein per se, may have a critical health effect.

Interestingly, in this study, we found that the association of animal and plant protein with mortality varied by lifestyle factors, and any statistically significant protein-mortality associations were restricted to participants with at least 1 of the unhealthy behaviors, including smoking, heavy alcohol intake, overweight or obesity, and physical inactivity. Several reasons may explain these findings. First, given the remaining variation of health behaviors across protein intake categories in the unhealthy-lifestyle group, residual confounding from lifestyle factors may contribute to the observed protein-mortality associations. However, our results are robust to adjustment for a wide spectrum of potential confounders and the propensity score. Second, our results suggest that the adverse effects of high animal protein intake and beneficial effects of plant protein may be enhanced by other unhealthy lifestyle choices and become evident among the subgroup of individuals with these behaviors who may already have had some underlying inflammatory or metabolic disorders. Finally, as shown in Table 3, participants with a similar intake and with and without a healthy lifestyle demonstrated distinct profiles of protein sources. Those with unhealthy lifestyles consumed more processed and unprocessed red meat, whereas the healthy-lifestyle group consumed more fish and chicken as animal protein sources, suggesting that different protein sources, at least in part, contributed to the observed variation in the protein-mortality associations according to lifestyle factors. This hypothesis is supported by our substitution analysis results.

Table 3:
Caption: Age- and Sex-Standardized Characteristics of Study Participants According to Percentage of Energy From Animal and Plant Protein Intake in the Healthy- and Unhealthy-Lifestyle Groups

2.
Association Between Plant and Animal Protein Intake and Overall and Cause-Specific Mortality.

Huang J, Liao LM, Weinstein SJ, et al.

JAMA logoJAMA Internal Medicine. 2020;180(9):1173-1184. doi:10.1001/jamainternmed.2020.2790.

Discussion

Our findings of more pronounced inverse plant protein associations in women who were younger than 60 years, and in both men and women with a favorable BMI, suggest that those health effects can be overshadowed by, for example, metabolic impairment-associated oxidative stress and systemic chronic inflammation.

Our observation of stronger inverse mortality associations for plant protein from bread, cereal, and pasta substitution of red meat protein and egg protein do not stand alone in the literature. Higher red and processed meat consumption have been consistently associated with increased premature death, possibly owing to systemic oxidative stress, inflammation, heme iron, and endogenous formation of N-nitroso compounds. Grains and cereal foods have high contents of bioactive substances, including phenolic compounds, antioxidants, vitamins, minerals, and phytoestrogens, and increased whole grain consumption has been favorably associated with reduced cardiovascular disease risk factors, including hypertension, total cholesterol and low-density lipoprotein cholesterol. Moreover, a meta-analysis of 17 prospective cohorts that included 150 328 deaths found greater consumption of total red meat and processed meat was associated with excess risk of overall, CVD, and cancer mortality, and lower total mortality risk and cause-specific mortality risk in persons having greater consumption of plant protein–rich whole grains and cereal fiber. Consistent with our findings, it has been shown that replacement of 3% energy from egg protein with plant protein was associated with decreased risk of overall mortality, with mortality risk reductions of 19% and 18% in US cohorts and a Japanese cohort, respectively. In addition, an analysis of 6 prospective US cohorts, showed that higher egg consumption was associated with increased risk of incident CVD and all-cause mortality in a dose-response manner.

There are several strengths of our study. The large cohort sample size and number of events as well as long-term follow-up afforded substantial power to detect moderate associations between substitution of plant protein for animal protein and mortality risk and to assess effect modification by other risk factors. The large number of deaths permitted a robust examination of cause-specific mortality. Of note, approximately 40% of daily dietary protein was from plant sources and 60% was animal protein (including 19% dairy protein), which are similar to the plant and animal protein intakes of the US population.

3.
Animal and Plant Protein Sources and Cardiometabolic Health.

Mariotti F.

Advances in Nutrition (Bethesda, Md.). 2019;10(Suppl_4):S351-S366. doi:10.1093/advances/nmy110.

Leading Journal

The sources or types of protein in the diet have long been overlooked regarding their link to cardiometabolic health. The picture is complicated by the fact that animal and plant proteins are consumed along with other nutrients and substances which make up the "protein package" so plant and animal protein come with clear nutrient clusters. This review aimed at deciphering the relation between plant and animal protein and cardiometabolic health by examining different nutritional levels (such as amino acids, protein type, protein foods, protein patterns, and associated overall dietary and nutrient patterns) and varying levels of scientific evidence [basic science, randomized controlled trials (RCTs), observational data]. Plant protein in Western countries is a robust marker of nutrient adequacy of the diet, whereas the contribution of animal protein is highly heterogeneous. Yet recent data from large cohorts have confirmed that total and animal proteins are associated with the risk of cardiovascular disease and diabetes, even when fully adjusting for lifestyle and dietary or nutritional factors. Here again, there is marked variability depending on the type of animal protein. Protein from processed red meat and total red meat on the one hand, and from legumes, nuts, and seeds on the other, are often reported at the extremes of the risk range. RCTs using purified proteins have contributed little to the topic to date, inasmuch as the findings cannot readily be extrapolated to current or near-future diets, but RCTs studying whole protein foods have shown a beneficial effect of pulses. Despite the fact that many of the benefits of plant protein reported in observational or interventional studies may stem from the protein package that they convey and the nutrients that they displace, there are also important indications that protein per se may affect cardiometabolic health via the many amino acids that are present in typically contrasting levels in plant compared with animal proteins.

4.
The Impact of Type of Dietary Protein, Animal Versus Vegetable, in Modifying Cardiometabolic Risk Factors: A Position Paper From the International Lipid Expert Panel (ILEP).

Zhubi-Bakija F, Bajraktari G, Bytyçi I, et al.

Clinical Nutrition (Edinburgh, Scotland). 2021;40(1):255-276. doi:10.1016/j.clnu.2020.05.017.

Proteins play a crucial role in metabolism, in maintaining fluid and acid-base balance and antibody synthesis. Dietary proteins are important nutrients and are classified into: 1) animal proteins (meat, fish, poultry, eggs and dairy), and, 2) plant proteins (legumes, nuts and soy). Dietary modification is one of the most important lifestyle changes that has been shown to significantly decrease the risk of cardiovascular (CV) disease (CVD) by attenuating related risk factors. The CVD burden is reduced by optimum diet through replacement of unprocessed meat with low saturated fat, animal proteins and plant proteins. In view of the available evidence, it has become acceptable to emphasize the role of optimum nutrition to maintain arterial and CV health. Such healthy diets are thought to increase satiety, facilitate weight loss, and improve CV risk. Different studies have compared the benefits of omnivorous and vegetarian diets. Animal protein related risk has been suggested to be greater with red or processed meat over and above poultry, fish and nuts, which carry a lower risk for CVD. In contrast, others have shown no association of red meat intake with CVD. The aim of this expert opinion recommendation was to elucidate the different impact of animal vs vegetable protein on modifying cardiometabolic risk factors. Many observational and interventional studies confirmed that increasing protein intake, especially plant-based proteins and certain animal-based proteins (poultry, fish, unprocessed red meat low in saturated fats and low-fat dairy products) have a positive effect in modifying cardiometabolic risk factors. Red meat intake correlates with increased CVD risk, mainly because of its non-protein ingredients (saturated fats). However, the way red meat is cooked and preserved matters. Thus, it is recommended to substitute red meat with poultry or fish in order to lower CVD risk. Specific amino acids have favourable results in modifying major risk factors for CVD, such as hypertension. Apart from meat, other animal-source proteins, like those found in dairy products (especially whey protein) are inversely correlated to hypertension, obesity and insulin resistance.

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Approximately 60% of the total protein content in an egg comes from the egg white, and about 40% comes from the yolk.[1] This distribution is consistent across standard large eggs, though minor variations may occur depending on hen breed, age, and diet.[2-3] The egg white contains primarily albumin proteins, while the yolk contains a mix of lipoproteins and other protein fractions.[4]

1.
The Effect of Whole Egg Intake on Muscle Mass: Are the Yolk and Its Nutrients Important?.

Santos HO, Gomes GK, Schoenfeld BJ, de Oliveira EP.

International Journal of Sport Nutrition and Exercise Metabolism. 2021;31(6):514-521. doi:10.1123/ijsnem.2021-0086.

Whole egg may have potential benefits for enhancing muscle mass, independent of its protein content. The yolk comprises ∼40% of the total protein in an egg, as well as containing several nonprotein nutrients that could possess anabolic properties (e.g., microRNAs, vitamins, minerals, lipids, phosphatidic acid and other phospholipids). Therefore, the purpose of this narrative review is to discuss the current evidence as to the possible effects of egg yolk compounds on skeletal muscle accretion beyond those of egg whites alone. The intake of whole egg seems to promote greater myofibrillar protein synthesis than egg white intake in young men. However, limited evidence shows no difference in muscle hypertrophy when comparing the consumption of whole egg versus an isonitrogenous quantity of egg white in young men performing resistance training. Although egg yolk intake seems to promote additional acute increases on myofibrillar protein synthesis, it does not seem to further enhance muscle mass when compared to egg whites when consumed as part of a high-protein dietary patterns, at least in young men. This conclusion is based on very limited evidence and more studies are needed to evaluate the effects of egg yolk (or whole eggs) intake on muscle mass not only in young men, but also in other populations such as women, older adults, and individuals with muscle wasting diseases.

2.
Modification of the Protein Amino Acid Content in Hen Eggs as a Consequence of Different Concentrations of Lupine and Soy in Feed.

Tomczak A, Zielińska-Dawidziak M, Klimowicz P, et al.

Molecules (Basel, Switzerland). 2024;29(16):3727. doi:10.3390/molecules29163727.

The effect of the diet modification (soybean and lupine addition) on the content of protein and amino acids (AA) in eggs was studied. Both the sampling day and the diet influenced the total protein content. In albumen, the lowest protein content (10.6%) was noted after administering a diet containing 25% lupine; in the same egg the yolk contained the most proteins (16.7%). In the content of nonessential AA (NAA) in egg yolks, differences were noted only for cysteine, with its the highest content in the yolks of the control group. The stable content of essential yolk amino acids (EAA) was observed only for isoleucine, leucine, tryptophan and phenylalanine. The highest contents of EAA and NAA were recorded in the yolks of the control group (~47 and ~53 g/100 g of protein, respectively) and in the group with 25% additions of lupine (~42 and ~51 g/100 g of protein, respectively). AA with constant content in the tested albumens were methionine, tryptophan and alanine. The highest content of EAA (>~42 g/100 g of protein) and NAA (>~62 g/100 g of protein) were determined in albumen of eggs determined in the group with at least 20% additions of lupine. The highest content of EAA for humans delivered eggs from groups 4-6 (with the addition of soy into the diet ≤5%). The protein sources used in the hen diet significantly influenced the content of protein and individual AA in the produced eggs.

3.
Comparative Analysis of Nutrient Content and Energy of Eggs From Different Chicken Genotypes.

Antova GA, Gerzilov VT, Petkova ZY, et al.

Journal of the Science of Food and Agriculture. 2019;99(13):5890-5898. doi:10.1002/jsfa.9863.

Background: Eggs are important foods in the daily diet of humans and have great biological activity and a high digestibility. Egg yolk is a good source of biologically active substances such as fatty acids, phospholipids, sterols and tocopherols. The eggs of seven chicken genotypes were analyzed for their chemical composition, and a detailed study of the lipids in egg yolk was conducted.

Results: Energy composition of the egg yolk and egg albumen was 29.06-30.51 MJ kg and 19.77-20.93 MJ kg respectively. Regarding their chemical composition: water ranged from 471.7 to 515.4 g kg and 878.3-885.9 g kg ; fat content in dry matter ranged from 607 to 647 g kg and 6.7-11.6 g kg ; protein varied from 302 to 331.7 g kg and 823.6-892.5 g kg ; ash ranged from 33.7 to 37.7 g kg and 63.8-74.0 g kg ; and nitrogen-free extracts ranged from 12.7 to 36.5 g kg and 35.0-96.2 g kg . The sterols and phospholipids in the yolk lipids were 16-26 g kg and 59-127 g kg . The main fatty acids in the lipids were oleic (39.1-47.3%) and palmitic (26.0-35.5%) acids. Cholesterol in the yolk lipids ranged from 15.9 to 25.9 g kg . Phosphatidylcholine (389-573 g kg ), phosphatidylethanolamine (219-355 g kg ) and phosphatidylinositol (112-284 g kg ) were the main phospholipids. The content of saturated fatty acids in the phospholipids was significantly higher than that in triacylglycerols.

Conclusion: Small variations in the chemical composition of eggs from seven different genotypes were observed. Significant differences in the fatty acid compositions of the main classes of phospholipids and the triacylglycerol fraction were established. © 2019 Society of Chemical Industry.

4.
Egg Proteins: Fractionation, Bioactive Peptides and Allergenicity.

Chang C, Lahti T, Tanaka T, Nickerson MT.

Journal of the Science of Food and Agriculture. 2018;98(15):5547-5558. doi:10.1002/jsfa.9150.

Eggs are an important source of macro and micronutrients within the diet, comprised of proteins, lipids, vitamins, and minerals. They are constituted by a shell, the white (containing 110 g kg proteins: ovalbumin, ovotransferrin, ovomucoid, lysozyme and ovomucin), and the yolk (containing 150-170 g kg proteins: lipovitellins, phosvitin, livetins, and low-density lipoproteins). Owing to their nutritional value and biological characteristics, both the egg white and yolk proteins are extensively fractionated using different techniques (e.g., liquid chromatography, ultrafiltration, electrophoresis, and chemical precipitation), in which liquid chromatography is the most commonly used technique to obtain individual proteins with high protein recovery and purity to develop novel food products. However, concerns over allergenic responses induced by certain egg proteins (e.g., ovomucoid, ovalbumin, ovotransferrin, lysozyme, α-livetin, and lipoprotein YGP42) limit their widespread use. As such, processing technologies (e.g., thermal processing, enzymatic hydrolysis, and high-pressure treatment) are investigated to reduce the allergenicity by conformational changes. In addition, biological activities (e.g., antioxidant, antimicrobial, antihypertensive, and anticancer activities) associated with egg peptides have received more attention, in which enzyme hydrolysis is demonstrated as a promising way to break polypeptides sequences and produce bioactive peptides to provide nutritional and therapeutic benefits for human health. © 2018 Society of Chemical Industry.

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Dioxins, mercury, and other harmful substances can accumulate in egg whites, although the extent and pattern of accumulation may differ from the yolk depending on the contaminant.
Dioxins and dioxin-like compounds (such as PCDD/Fs and PCBs) are lipophilic and preferentially accumulate in fatty tissues, so the yolk—being rich in fat—typically contains higher concentrations than the white. However, measurable levels of dioxins and related compounds have been detected in both egg whites and yolks, and the presence in egg whites is well documented in the context of environmental contamination, especially in eggs from free-range hens exposed to contaminated soil or feed.[1-4]
Mercury, including both inorganic and methylmercury forms, can also be deposited in eggs. Experimental studies demonstrate that egg whites can accumulate significant levels of mercury, sometimes even exceeding those in the yolk, particularly following acute or high-level exposure. Egg whites may serve as a sensitive bioindicator for environmental mercury exposure in poultry, and thus can contribute to human dietary mercury intake.[5-7]
Other contaminants, such as mycotoxins (e.g., deoxynivalenol, ochratoxin A), can also be found in egg whites, sometimes at higher concentrations than in yolks, depending on the specific toxin and exposure scenario.[8]
In summary, egg whites are not immune to the accumulation of dioxins, mercury, or other harmful substances, and their contamination reflects environmental and husbandry factors affecting the entire egg.[2][5][7-8]

1.
Poultry Eggs as a Source of PCDD/­Fs, PCBs, PBDEs and PBDD/­Fs.

Pajurek M, Pietron W, Maszewski S, Mikolajczyk S, Piskorska-Pliszczynska J.

Chemosphere. 2019;223:651-658. doi:10.1016/j.chemosphere.2019.02.023.

Leading Journal

Regardless of the country or region of the world, poultry eggs are one of the most important components of the human diet. Nutritional value is derived from them, but chicken eggs can be contaminated with POPs. The aim of the study was to compare the impact of different types of chicken husbandry system on bioaccumulation of selected POPs. The HRGC/HRMS method was used for determination of 58 congeners of chlorinated and brominated halogenated aromatic hydrocarbons. The influence of the farm rearing system on concentration and congener profile was seen for most groups of tested contaminants, of which the eggs were a source. Human exposure to dioxins and dioxin-like compounds as a result of consumption of contaminated eggs should be a subject of concern. The occurrence of PCDD/Fs, PCBs, PBDEs, and PBDD/Fs in commonly consumed foodstuffs such as eggs supports the need for further research on environmental pollutants and for determination of exposure as the result of their occurrence in different food categories.

2.
Leading Journal

Some types of poultry bedding made from recycled materials have been reported to contain environmental contaminants such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs, dioxins), polychlorinated biphenyls (PCBs) brominated flame retardants (BFRs) polychlorinated naphthalenes (PCNs), polybrominated dioxins (PBDD/Fs), perfluoroalkyl substances (PFAS), etc. In one of the first studies of its kind, the uptake of these contaminants by chicken muscle tissue, liver, and eggs from three types of recycled, commercially available bedding material was simultaneously investigated using conventional husbandry to raise day old chickens to maturity. A weight of evidence analysis showed that PCBs, polybrominated diphenylethers (PBDEs), PCDD/Fs, PCNs and PFAS displayed the highest potential for uptake which varied depending on the type of bedding material used. During the first three to four months of laying, an increasing trend was observed in the concentrations of ΣTEQ (summed toxic equivalence of PCDD/Fs, PCBs, PBDD/Fs, PCNs and polybrominated biphenyls), NDL-PCBs and PBDEs in the eggs of chickens raised on shredded cardboard. Further analysis using bio-transfer factors (BTFs) when egg production reached a steady state, revealed that some PCB congeners (PCBs 28, 81, 138, 153 and 180) irrespective of molecular configuration or chlorine number, showed the highest tendency for uptake. Conversely, BTFs for PBDEs showed good correlation with bromine number, increasing to a maximum value for BDE-209. This relationship was reversed for PCDFs (and to some extent for PCDDs) with tetra- and penta- chlorinated congeners showing a greater tendency for selective uptake. The overall patterns were consistent, although some variability in BTF values was observed between tested materials which may relate to differences in bioavailability. The results indicate a potentially overlooked source of food chain contamination as other livestock products (cow's milk, lamb, beef, duck, etc.) could be similarly impacted.

3.
Reevaluation on Accumulation and Depletion of Dioxin-Like Compounds in Eggs of Laying Hens: Quantification on Dietary Risk From Feed to Egg.

Wang C, Dong S, Wang P, et al.

The Science of the Total Environment. 2021;801:149690. doi:10.1016/j.scitotenv.2021.149690.

Leading Journal

Updated assessment on transfer of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) from feed to food is essential for understanding human exposure risk. A controlled feeding experiment was conducted for laying hens to reevaluate the transfer characteristics of dioxin-like compounds from feed to egg. Two fortified diets (1.17 and 5.13 pg TEQ g dry weight), made by blending with fly ash, were fed to laying hens for 14 days, followed by 28-days depletion. Levels of ∑TEQ in eggs rapidly increased once exposure started, reaching at 1.98 and 6.86 pg TEQ g lw at the end of exposure for low- and high-exposure groups, respectively, and dropped to under the European legislation (maximum levels: 5.0 pg TEQ g lw) after 28-days depletion. The quantitative depletions showed that the half-lives (T) of ∑TEQ in eggs were 23 and 14 days for low- and high-exposure groups, respectively. The depletion and accumulation rates of PCDD/Fs were in the range of 0.026-0.151 and 0.005-0.016 day, respectively, representing that the T of PCDD/Fs in eggs ranged from 5 to 27 days. The depletion kinetics of DL-PCBs was not significant in egg. The hens with higher laying rates exhibited shorter T of PCDD/Fs, implying that increasing laying rate could expedite the depletion of PCDD/Fs in egg. The T of PCDD/Fs in egg were negatively correlated with the chlorine number, indicating that lower chlorinated congeners tended to be retained in the egg. Transfer rates of PCDD/Fs were in the range of 4-19%, which were lower than the previous results. These results were attributed to short exposure time and low bioavailability of PCDD/Fs in fly ash. Estimations of dietary intake highlighted the dietary risk of PCDD/Fs from feed to egg, which would pose limited adverse effects on human health.

4.
Bioaccumulation of PCDD/­Fs and PCBs in Free-Range Hens: Congener Fingerprints and Biotransfer Factors.

Lambiase S, Fiorito F, Serpe FP, et al.

Chemosphere. 2022;309(Pt 1):136602. doi:10.1016/j.chemosphere.2022.136602.

Leading Journal

The bioaccumulation of lipophilic environmental contaminants in farm animals is an important issue to control and prevent human exposure to toxic pollutants. Free-range hens were used as a model to assess the transfer and the bioaccumulation of PCDD/Fs, DL-PCBs and NDL-PCBs from the soil to eggs in an area in the Campania region particularly affected by pollution, the "Land of Fires". We determined the following ranges of concentrations in eggs: 0.90-5.51 pg WHO-TEQ g fat for PCDD/Fs; 1.63-4.24 pg WHO-TEQ g fat for DL-PCBs; 2.77-9.75 pg WHO-TEQ g fat for the sum of PCDD/Fs and DL-PCBs and 12.53-30.94 ng g fat for NDL-PCBs. Higher contamination levels were observed in the eggs from free-range hens, compared to those of the control group, that is hens raised indoors; this indicates that soil remains a major source of contamination. Livers showed low levels of contamination for both outdoor and indoor reared hens. Biotransfer factors (BTFs) were calculated for each of the 35 PCDD/F and PCB congeners analysed. The BTFs highlighted that the transfer and bioaccumulation depend on chlorination degree and substitution pattern, in particular they increase with increasing chlorination degree up to the hexa-chlorinated congeners and then decrease. An exception to these finding was observed for 2,3,7,8 TCDD and 2,3,7,8 TCDF, which showed very high BTFs. These results demonstrate the importance of promoting studies on the environmental contaminants bioaccumulation as they provide an effective support for the risk assessment and management of exposure to toxic chemicals.

5.
Metabolisms of Both Inorganic and Methyl-Mercury in Hens Reveal Eggs as an Effective Bioindicator for Environmental Hg Pollution.

Wang Z, Liao J, Gai P, et al.

Journal of Hazardous Materials. 2024;465:133191. doi:10.1016/j.jhazmat.2023.133191.

Leading Journal

Mercury (Hg) is a globally distributed toxic metal and could pose serious harm to birds, which may ultimately threaten human health through poultry consumption. However, the avian Hg metabolism remains unclear. Poultry, like chickens, are more accessible human dietary sources than wild birds and are ideal proxies to study Hg metabolism in birds. In this study, the avian Hg metabolism is carefully investigated with hens fed by Hg-spiked (both inorganic mercury IHg and methylmercury MeHg) foods. Our results demonstrate that feces and eggs are the main removal pathways of Hg from hens, rather than feathers. Eggs show particularly rapid responses towards Hg exposures, thus could be more sensitive to environmental Hg pollution than feathers, feces or internal organs (and tissues). Egg yolk (with THg peak of 55.92 ng/g on Day 6) and egg white (THg peak of 1195.03 ng/g on Day 4) react as an effective bioindicator for IHg and MeHg exposure, respectively. In 90-day-single-dose exposure, IHg is almost completely excreted, while approximately 11% of MeHg remains in internal organs. Our study provides new insight into the metabolism and lifetime of IHg and MeHg in birds, advancing the understanding of the dynamics for human exposure to Hg through poultry products.

6.
Mercury Level in Worldwide Poultry Food Products: A Systematic Review.

Alves ACN, de Almeida Santos AN, Dos Santos SM, et al.

Biological Trace Element Research. 2025;:10.1007/s12011-025-04659-1. doi:10.1007/s12011-025-04659-1.

New Research

Mercury is a metal known for its toxic effects on environmental, animal and human health. The presence of Hg in poultry and its potential impact on food safety still need to be explored, especially considering that poultry is the most consumed source of protein in the global population. This study aimed to systematically review mercury and methylmercury levels in poultry meat and eggs worldwide. The searches were conducted in the Web of Science, PubMed, and Scopus databases, resulting in 123 studies, of which only 30 were deemed suitable. Studies were found across sixteen countries: India, Thailand, Malaysia, China, Poland, Egypt, Ghana, Nigeria, Bangladesh, Iran, USA, Italy, Colombia, Romania, Tanzania, Algeria, and Saudi Arabia. Five poultry species were reported, with chicken being the most recorded species in 16 countries. Among biological samples, eggs and liver were the most used for measuring mercury and methylmercury levels. Levels above those permitted by regulatory organizations such as the United States Department of Agriculture (USDA), China's National Health Commission (NHC), and Thailand's Ministry of Public Health - set at 0.05, 0.05, and 0.02 mg.kg-1 respectively - were observed in 12 of the 17 countries, with the highest concentrations detected in chicken eggs from Colombia. Therefore, poultry production is not Hg-free and contamination by this metal must be monitored.

7.
Total Mercury in Different Egg Tissues Provides Insights to Mercury Metabolisms in Bird Bodies.

Wang Z, Liao J, Guo X, Li X, Kwon SY.

Ecotoxicology and Environmental Safety. 2023;249:114336. doi:10.1016/j.ecoenv.2022.114336.

Leading Journal

Mercury (Hg) pollution in birds has been widely reported, but the metabolism of Hg in bird bodies remains unclear. Measurement of Hg concentrations in bird tissues (muscles and organs) could provide insights into the metabolism of Hg in bird bodies, however, this approach is often invasive. To avoid invasive procedures, we conducted feeding experiments using chickens and used eggs as a proxy for understanding Hg metabolism in chicken bodies. For the control group, various THg concentrations were observed in egg whites, egg yolks, and eggshells, but the THg concentration trends for different egg tissues were not statistically different (P > 0.05). For the Hg feeding group (0.3 mg/kg body weight, feeding once), Hg peaks were observed in egg yolks and egg whites at different time periods, suggesting different response time to dietary Hg in chicken body tissues. Mercury in egg yolks peaked at Day 6, suggesting their quick response to dietary Hg. Egg whites reached Hg peak at Day 20, exhibiting a slower response to dietary Hg. Eggshells did not show a Hg peak, perhaps due to their predominant inorganic components that do not trigger Hg bioaccumulation. We measured THg/THg ratios in various chicken eggs purchased from three areas in Guizhou, SW China. The THg/THg ratios for Huaxi, Hezhang and Wuchuan were 1.33 (0.57-2.41), 7.89 (4.27-19.47) and 2.64 (1.68-4.22), respectively, to suggest different exposure history for chickens. This study provides new insights into the metabolism and lifetime of Hg in bird bodies.

8.

Mycotoxins, such as aflatoxins (AFs), deoxynivalenol (DON), zearalenone (ZEN), and ochratoxin A (OTA), present significant health risks due to their carcinogenic and toxic properties. This study conducted a systematic review and meta-analysis to assess the global prevalence, concentration, and associated health risks of mycotoxins in domestic bird eggs. Following the PRISMA guideline, a comprehensive search was performed across PubMed, Scopus, and Web of Science (2005-2024). Thirteen studies, encompassing 8,410 egg samples, were analyzed. The pooled prevalence and concentration of mycotoxins were estimated using random-effects models, while probabilistic risk assessment was performed via Monte Carlo simulation, calculating the Margin of Exposure (MOEs) and Hazard Quotient (HQ). The prevalence ranking of aflatoxins (AFs) in eggs was as follows: AFB1 (19%) > AFB2 (12%) > AFG1 (10%) ≈ AFG2 (10%). In terms of mean pooled concentration, mycotoxins followed this order: DON (83.93 µg/kg) > ZEN (6.00 µg/kg) > AFs (5.604 µg/kg) > OTA (2.52 µg/kg). Concentrations of DON and OTA were higher in egg white than in yolk, whereas ZEN levels were higher in yolk. From a public health perspective, risk assessment revealed alarming exposure levels, particularly in China, Egypt, and Jordan, where MOEs values for AFB1 were significantly below the safety threshold (MOEs < 10,000). Children were found to be at heightened risk due to their lower body weight and developing physiological systems, with MOEs as low as 3 in China. Additionally, HQ analyses indicated non-negligible risks from DON, OTA, and ZEN, particularly in China and Poland, where dietary exposure may contribute to chronic toxicity or endocrine disruption.

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Egg white consumption is considered healthy, especially in the context of concerns about dietary cholesterol and cardiovascular risk. Egg whites are a high-quality protein source with minimal fat and virtually no cholesterol, and their intake is associated with lower all-cause and cardiovascular mortality compared to whole eggs, as demonstrated in large US cohort studies.[1] Substitution analyses show that replacing whole eggs with egg whites or egg substitutes is linked to improved long-term survival and reduced risk of stroke, cancer, respiratory disease, and Alzheimer’s disease.[1]
Egg white protein is highly digestible, supports muscle mass, and may lower cholesterol and visceral fat, with additional antioxidant and anti-inflammatory properties.[2-3] Experimental data indicate that egg white consumption can decrease plasma cholesterol and body fat accumulation, and does not adversely affect metabolic or cardiovascular parameters in healthy adults.[4]
There is no established upper limit for egg white intake in current US dietary guidelines, and egg whites can be consumed liberally as a protein source for most individuals, except those with specific contraindications such as severe renal impairment.[1-2] While environmental contaminants such as dioxins and mercury can accumulate in egg whites, the risk is primarily determined by local husbandry and environmental factors, not by the intrinsic properties of egg whites themselves.
In summary, egg whites are a healthy protein source and are preferable to whole eggs for individuals seeking to minimize dietary cholesterol and cardiovascular risk.[1-2][4]

1.
Egg and Cholesterol Consumption and Mortality From Cardiovascular and Different Causes in the United States: A Population-Based Cohort Study.

Zhuang P, Wu F, Mao L, et al.

PLoS Medicine. 2021;18(2):e1003508. doi:10.1371/journal.pmed.1003508.

Leading Journal

Background: Whether consumption of egg and cholesterol is detrimental to cardiovascular health and longevity is highly debated. Data from large-scale cohort studies are scarce. This study aimed to examine the associations of egg and cholesterol intakes with mortality from all causes, cardiovascular disease (CVD), and other causes in a US population.

Methods And Findings: Overall, 521,120 participants (aged 50-71 years, mean age = 62.2 years, 41.2% women, and 91.8% non-Hispanic white) were recruited from 6 states and 2 additional cities in the US between 1995 and 1996 and prospectively followed up until the end of 2011. Intakes of whole eggs, egg whites/substitutes, and cholesterol were assessed by a validated food frequency questionnaire. Cause-specific hazard models considering competing risks were used, with the lowest quintile of energy-adjusted intake (per 2,000 kcal per day) as the reference. There were 129,328 deaths including 38,747 deaths from CVD during a median follow-up of 16 years. Whole egg and cholesterol intakes were both positively associated with all-cause, CVD, and cancer mortality. In multivariable-adjusted models, the hazard ratios (95% confidence intervals) associated with each intake of an additional half of a whole egg per day were 1.07 (1.06-1.08) for all-cause mortality, 1.07 (1.06-1.09) for CVD mortality, and 1.07 (1.06-1.09) for cancer mortality. Each intake of an additional 300 mg of dietary cholesterol per day was associated with 19%, 16%, and 24% higher all-cause, CVD, and cancer mortality, respectively. Mediation models estimated that cholesterol intake contributed to 63.2% (95% CI 49.6%-75.0%), 62.3% (95% CI 39.5%-80.7%), and 49.6% (95% CI 31.9%-67.4%) of all-cause, CVD, and cancer mortality associated with whole egg consumption, respectively. Egg white/substitute consumers had lower all-cause mortality and mortality from stroke, cancer, respiratory disease, and Alzheimer disease compared with non-consumers. Hypothetically, replacing half a whole egg with equivalent amounts of egg whites/substitutes, poultry, fish, dairy products, or nuts/legumes was related to lower all-cause, CVD, cancer, and respiratory disease mortality. Study limitations include its observational nature, reliance on participant self-report, and residual confounding despite extensive adjustment for acknowledged dietary and lifestyle risk factors.

Conclusions: In this study, intakes of eggs and cholesterol were associated with higher all-cause, CVD, and cancer mortality. The increased mortality associated with egg consumption was largely influenced by cholesterol intake. Our findings suggest limiting cholesterol intake and replacing whole eggs with egg whites/substitutes or other alternative protein sources for facilitating cardiovascular health and long-term survival.

Trial Registration: ClinicalTrials.gov NCT00340015.

2.
Health Functions of Egg Protein.

Matsuoka R, Sugano M.

Foods (Basel, Switzerland). 2022;11(15):2309. doi:10.3390/foods11152309.

Egg protein is a remarkably abundant source of protein, with an amino acid score of 100 and the highest net protein utilization rate. However, there have been relatively fewer studies investigating the health benefits of egg protein. In this review, we have summarized the available information regarding the health benefits of egg proteins based on human studies. In particular, studies conducted on the characteristics of egg whites, as they are high in pure protein, have reported their various health functions, such as increases in muscle mass and strength enhancement, lowering of cholesterol, and visceral fat reduction. Moreover, to facilitate and encourage the use of egg white protein in future, we also discuss its health functions. These benefits were determined by developing an egg white hydrolysate and lactic-fermented egg whites, with the latter treatment simultaneously improving the egg flavor. The health benefits of the protein hydrolysates from the egg yolk (bone growth effect) and eggshell membrane (knee join pain-lowering effect) have been limited in animal studies. Therefore, the consumption of egg protein may contribute to the prevention of physical frailty and metabolic syndromes.

3.
Antioxidant Stress and Anti-Inflammatory Activities of Egg White Proteins and Their Derived Peptides: A Review.

Zhou N, Zhao Y, Yao Y, et al.

Journal of Agricultural and Food Chemistry. 2022;70(1):5-20. doi:10.1021/acs.jafc.1c04742.

Oxidative stress and chronic inflammation are the common pathological bases of chronic diseases such as atherosclerosis, cancer, and cardiovascular diseases, but most of the treatment drugs for chronic diseases have side effects. There is an increasing interest to identify food-derived bioactive compounds that can mitigate the pathological pathways associated with oxidative stress and chronic inflammation. Egg white contain a variety of biologically active proteins, many of which have antioxidant and anti-inflammatory activities and usually show better activity after enzymatic hydrolysis. This review covers the antioxidative stress and anti-inflammatory activities of egg white proteins and their derived peptides and clarifies their mechanism of action and . In addition, the link between oxidative stress and inflammation as well as their markers are reviewed. It suggests the potential application of egg white proteins and their derived peptides and puts forward further research prospects.

4.
Effect of Consumption of Whole Egg and Egg Fractions on Cardiovascular Disease Factors in Adult Rats.

Chairuk P, Zaman RU, Naphatthalung J, Jansakul C.

Journal of the Science of Food and Agriculture. 2021;101(9):3942-3951. doi:10.1002/jsfa.11034.

Background: While eggs are a low-cost source of protein, rich in macro- and micronutrients, the association of egg intake and cardiovascular disease (CVD) remains controversial. This study investigated the effect of egg consumption on CVD parameters. Eggs were boiled, separated into four fractions (whole egg, 50% yolk-reduced whole egg, egg yolk and egg white) and then freeze-dried. The different egg fractions or distilled water (control) were orally gavaged to adult male Wistar rats at 1 g kg rat body weight, each day for 8 weeks, following which basal blood pressure, heart rate, complete blood cell count, blood biochemistry, body fat and liver cell lipid accumulation were determined. The vascular functions of isolated thoracic aorta were studied using classical pharmacological techniques.

Results: In comparison to the control group, none of the egg fractions affected body weight, food intake, plasma glucose or lipid profile. The yolk group experienced increased plasma alkaline phosphatase and creatinine levels, while egg white caused decreased plasma cholesterol and blood urea nitrogen. Whole egg and egg yolk increased blood pressure and mean hemoglobin concentration and the yolk increased liver lipid accumulation. Egg white decreased the white blood cell count and body fat lipids. No changes were found in basal heart rate or vascular functions in any of the groups.

Conclusions: Consumption of whole egg or egg yolk at the dosage given caused hypertension, with impairment of liver and kidney functions following the intake of yolk alone. However, egg white is beneficial for the cardiovascular system as it decreased plasma cholesterol and body fat accumulation. © 2020 Society of Chemical Industry.

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There is no practical way for a consumer to directly determine whether the eggs they are purchasing are free from contamination by harmful substances such as dioxins, mercury, or other environmental toxins. Routine testing for these contaminants is not performed at the point of sale, and contamination can occur regardless of production type (conventional, organic, free-range) or region, as demonstrated in multiple studies.[1-3]
Contaminant levels in eggs are primarily influenced by environmental factors such as local soil, feed, and proximity to industrial pollution sources, rather than by labeling or husbandry system alone.[1][4-6] Eggs from free-range hens foraging on contaminated soil or exposed to polluted bedding materials are at particular risk for elevated dioxin and PCB levels.[4-7] However, contamination exceeding regulatory limits is rare in commercial eggs, and most eggs in monitored regions are below established safety thresholds.[1][8-9]
Regulatory agencies in the US, EU, and other regions set maximum allowable levels for dioxins, PCBs, and other persistent organic pollutants in eggs, and conduct periodic surveillance to identify and remove contaminated products from the market.[10] Consumers relying on eggs from small-scale or backyard producers in areas with known environmental contamination may face higher risk, but commercial eggs from large producers are generally subject to more rigorous quality control.
In summary, the only reliable assurance of contaminant-free eggs is through regulatory monitoring and laboratory analysis, not through consumer-level inspection or label claims.[1][9-10]

1.
Leading Journal

Chicken eggs from five different production types (conventional, omega-3 enriched, free range, organic and free run) were collected, when available, from three regions (west, central and east) of Canada to determine persistent organic pollutant (POP) concentrations. Total polychlorinated biphenyl (PCB) concentrations (∑37 congeners) in yolks from the eggs ranged from 0.162 ng g(-1) lipid to 24.8 ng g(-1) lipid (median 1.25 ng g(-1) lipid) while the concentration of the sum of the 6 indicator PCBs ranged from 0.100 ng g(-1) lipid to 9.33 ng g(-1) lipid (median 0.495 ng g(-1) lipid). Total polychlorinated dibenzo-p-dioxin/dibenzofuran (PCDD/F) concentrations ranged from 2.37 pg g(-1) lipid to 382 pg g(-1) lipid (median 9.53 pg g(-1) lipid). The 2005 WHO toxic equivalency (TEQ) ranged from 0.089 pg TEQ(PCDD/F+dioxin-like[DL]-PCB) g(-1) lipid to 12.8 pg TEQ(PCDD/F+DL-PCB) g(-1) lipid (median 0.342 pg TEQ(PCDD/F+DL-PCB) g(-1) lipid). PCB and PCDD/F concentrations were significantly different (p<0.001) in egg yolks from different regions of collection. In contrast to observations in Europe, PCB and PCDD/F concentrations in Canadian egg yolks were not impacted solely by the production type (e.g., conventional, free range, organic, etc.) used to maintain the laying chickens. Additionally, only one Canadian free range yolk from western Canada (12.8 pg TEQ(PCDD/F+DL-PCB) g(-1) lipid) exceeded the European toxic equivalent concentration limits for eggs (5 pg TEQ(PCDD/F+DL-PCB) g(-1) lipid). This differs from observations in Europe where free range/home produced eggs frequently have higher POP concentrations than eggs from other production types. Median PCB dietary intake estimates based on consumption of eggs were less than 10 ng d(-1) while median PCDD/F intakes were less than 45 pg d(-1).

2.
Determination of Selected Endocrine Disruptors in Organic, Free-Range, and Battery-Produced Hen Eggs and Risk Assessment.

Kuzukiran O, Yurdakok-Dikmen B, Sevin S, et al.

Environmental Science and Pollution Research International. 2018;25(35):35376-35386. doi:10.1007/s11356-018-3400-5.

An increasing amount of evidence suggests that phthalic acid esters (PAE), polychlorinated biphenyls (PCB), polybrominated diphenyl ethers (PBDE), and organochlorine pesticides (OCP) are related to mutagenic, carcinogenic, and endocrine disruptor effects (EDCs). These lipophilic compounds are highly resistant to breakdown processes, and consequently remain in the environment, followed by uptake into the food chain. Human exposure to lipophilic compounds results from the consumption of food containing EDCs, mainly foodstuffs of animal origin with a high fat content, since these contaminants accumulate in fatty tissues. Foodstuffs in which EDCs can accumulate include meat, fish, eggs, and milk. We investigated the contamination in edible eggs to determine whether relative differences in the contaminants' residue levels appeared in three types of egg production (i.e., battery, free-range, and organic). The results showed that PAEs, especially dimethyl phthalate contamination, was the most abundant in the battery eggs, and the PCBs, PBDEs, and OCPs were the most abundant in the free-range eggs. The eggs were contaminated by more than one chemical, and as many as five contaminants (PCB180, PBDE47, dimethyl phthalate, diethyl phthalate, and di-n-butyl phthalate in battery eggs, and PCB138, PCB153, PCB180, diethyl phthalate, and di-2-ethylhexyl phthalate in organic eggs) were detected in the same egg. However, none of the chemicals detected were at the maximum limit of acceptable risk.

3.
Influence of the Method of Production of Eggs on the Daily Intake of Polycyclic Aromatic Hydrocarbons and Organochlorine Contaminants: An Independent Study in the Canary Islands (Spain).

Luzardo OP, Rodríguez-Hernández A, Quesada-Tacoronte Y, et al.

Food and Chemical Toxicology : An International Journal Published for the British Industrial Biological Research Association. 2013;60:455-62. doi:10.1016/j.fct.2013.08.003.

Analysis of 16 polycyclic aromatic hydrocarbons (PAHs), 20 organochlorine pesticides (OCPs) and 18 polychlorinated biphenyls (PCBs) were performed on eggs from three different production types (conventional, free-run and organic) collected from the markets of the Canary Islands (Spain). Unlike other studies we did not found differences in the content of PCBs or OCPs of eggs in relation to its production type. Median ∑OCPs content was 3.87 ng g⁻¹ fat, being dieldrin, dicofol, hexachlorobenzene, p,p'-DDE and p,p'-DDT the most frequently detected. Median ∑PCBs value was 3.93 ng g⁻¹ fat, with 79.9% of this amount coming from the marker PCBs. Two samples, one free-run and one organic, greatly exceeded the current European Commission (EC) limit of 2.5 pg TEQ(PCDD/F) g⁻¹ lipid, but the rest were well below of this limit. The concentrations of PAHs in conventionally produced eggs were almost 4 times higher than in free-run or organic eggs. Mean dietary intake estimates of the organochlorine contaminants based on consumption of eggs, regardless of the type chosen, is negligible for the Canary Islands' population. However, the median dietary intake estimates of PAHs greatly depend on the type of eggs chosen, being much lower when free-run and organic eggs are consumed.

4.

PCDD/Fs and PCBs are environmentally persistent substances that have been associated with adverse effects on human health. Contamination of soils, animal feed and pastures leads to their bioaccumulation of in food products of animal origin, which are considered the major source of intake of these contaminants in humans. We analyzed eggs from free-range hens, sampled from small farms, located within a distance of 4.5 km from a secondary aluminum smelter in Northern Italy. The concentrations of PCDD/Fs, DL-PCBs and NDL-PCBs were higher in eggs from locations close to the plant, and strongly exceeded the limits set by EU Regulation 1259/2011 (2.5 pg WHO TEQ fat g(-1) for PCDD/Fs, 5.0 pg WHO TEQ g(-1) for PCDD/Fs and DL-PCBs L, 40 ng g(-1) for NDL-PCBs). Without the prompt and immediately applied control strategies, the consumption of contaminated eggs may have posed [corrected] a risk for human health, especially for children (≤9 years) and infants (≤3 years), due to the 2-fold excess of the current exposure limits.

5.
Leading Journal

Some types of poultry bedding made from recycled materials have been reported to contain environmental contaminants such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs, dioxins), polychlorinated biphenyls (PCBs) brominated flame retardants (BFRs) polychlorinated naphthalenes (PCNs), polybrominated dioxins (PBDD/Fs), perfluoroalkyl substances (PFAS), etc. In one of the first studies of its kind, the uptake of these contaminants by chicken muscle tissue, liver, and eggs from three types of recycled, commercially available bedding material was simultaneously investigated using conventional husbandry to raise day old chickens to maturity. A weight of evidence analysis showed that PCBs, polybrominated diphenylethers (PBDEs), PCDD/Fs, PCNs and PFAS displayed the highest potential for uptake which varied depending on the type of bedding material used. During the first three to four months of laying, an increasing trend was observed in the concentrations of ΣTEQ (summed toxic equivalence of PCDD/Fs, PCBs, PBDD/Fs, PCNs and polybrominated biphenyls), NDL-PCBs and PBDEs in the eggs of chickens raised on shredded cardboard. Further analysis using bio-transfer factors (BTFs) when egg production reached a steady state, revealed that some PCB congeners (PCBs 28, 81, 138, 153 and 180) irrespective of molecular configuration or chlorine number, showed the highest tendency for uptake. Conversely, BTFs for PBDEs showed good correlation with bromine number, increasing to a maximum value for BDE-209. This relationship was reversed for PCDFs (and to some extent for PCDDs) with tetra- and penta- chlorinated congeners showing a greater tendency for selective uptake. The overall patterns were consistent, although some variability in BTF values was observed between tested materials which may relate to differences in bioavailability. The results indicate a potentially overlooked source of food chain contamination as other livestock products (cow's milk, lamb, beef, duck, etc.) could be similarly impacted.

6.
Soil as a Source of Dioxin Contamination in Eggs From Free-Range Hens on a Polish Farm.

Piskorska-Pliszczynska J, Mikolajczyk S, Warenik-Bany M, Maszewski S, Strucinski P.

The Science of the Total Environment. 2014;466-467:447-54. doi:10.1016/j.scitotenv.2013.07.061.

Leading Journal

The transfer of dioxins from contaminated soil into the food chain has recently become an up-and-coming topic in the environmental policy and health-related consumer protection. Within the framework of the 2011 National Food Survey that monitored the levels of PCDD/Fs and PCBs in foods of animal origin, the sum of the WHO-PCDD/F/PCB-TEQ concentrations exceeding two-fold the European Union's maximum level was detected in eggs from a free-range farm (12.55 ± 2.37 pg WHOPCDD/F/PCB-TEQ/g fat). Investigations have revealed that the source of egg contamination was the backyard soil on which the hens were foraging. A follow-up study of laying hens from this farm has demonstrated the transfer of dioxins into all tested tissues (breast and leg muscles, abdominal fat), liver and ovarian follicles. The bioaccumulation of dioxins was found to be congener and tissue-dependent. The highest concentration was found in the liver, followed by the ovarian follicles, and the adipose tissue. The PCDD/F levels in the liver often were approximately two times higher from those in other materials from the same hen. The potential dioxin intakes with eggs were expressed as the percent of the Tolerable Weekly Intake (TWI), and the Provisional Tolerable Monthly Intake (PTMI). The weekly intake of dioxins would be 3.5 pg WHO-TEQ/kg b.w. (24.9% TWI) for an adult and 20.3 pg WHO-TEQ/kg b.w. (145.2% TWI) for a 3-year old child. Considering a monthly consumption of such contaminated eggs, intake of dioxins would be slightly lower, but still over 100% of the PTMI for a child. The obtained results complement the knowledge on possible dioxin sources in food and are important for risk management authorities.

7.
Bioaccumulation of PCDD/­Fs and PCBs in Free-Range Hens: Congener Fingerprints and Biotransfer Factors.

Lambiase S, Fiorito F, Serpe FP, et al.

Chemosphere. 2022;309(Pt 1):136602. doi:10.1016/j.chemosphere.2022.136602.

Leading Journal

The bioaccumulation of lipophilic environmental contaminants in farm animals is an important issue to control and prevent human exposure to toxic pollutants. Free-range hens were used as a model to assess the transfer and the bioaccumulation of PCDD/Fs, DL-PCBs and NDL-PCBs from the soil to eggs in an area in the Campania region particularly affected by pollution, the "Land of Fires". We determined the following ranges of concentrations in eggs: 0.90-5.51 pg WHO-TEQ g fat for PCDD/Fs; 1.63-4.24 pg WHO-TEQ g fat for DL-PCBs; 2.77-9.75 pg WHO-TEQ g fat for the sum of PCDD/Fs and DL-PCBs and 12.53-30.94 ng g fat for NDL-PCBs. Higher contamination levels were observed in the eggs from free-range hens, compared to those of the control group, that is hens raised indoors; this indicates that soil remains a major source of contamination. Livers showed low levels of contamination for both outdoor and indoor reared hens. Biotransfer factors (BTFs) were calculated for each of the 35 PCDD/F and PCB congeners analysed. The BTFs highlighted that the transfer and bioaccumulation depend on chlorination degree and substitution pattern, in particular they increase with increasing chlorination degree up to the hexa-chlorinated congeners and then decrease. An exception to these finding was observed for 2,3,7,8 TCDD and 2,3,7,8 TCDF, which showed very high BTFs. These results demonstrate the importance of promoting studies on the environmental contaminants bioaccumulation as they provide an effective support for the risk assessment and management of exposure to toxic chemicals.

8.
Levels of PCDD/­Fs, PCBs, Metals and Rare Earth Elements in Eggs and Vegetables From Areas With Different Environmental Contamination Impacts in the Campania Region (Southern Italy).

Lambiase S, Fiorito F, Trifuoggi M, Gallo P, Esposito M.

Environmental Science and Pollution Research International. 2024;31(43):55695-55707. doi:10.1007/s11356-024-34880-9.

Studying the links between environmental pollution and the levels of contamination in food is an important challenge to ensure human health. Matched samples of eggs from free-range hens and vegetables were analysed to investigate the bioaccumulation of PCDD/Fs, PCBs, metals and rare earth elements. Only two egg samples resulted above the limit fixed for PCDD/Fs and the action level set for DL-PCBs. The highest concentrations were found in the eggs from an area situated in a big city affected by strong urbanisation. Although eggs and vegetables were subjected to the same environmental pollution, the PCDD/F and PCB bioaccumulation that occurred in the eggs was much higher than those in vegetables (p < 0.01). In vegetables, the highest PCDD/F and PCB concentrations were found in lettuce and potatoes grown on contaminated soil. Higher bioaccumulation of Fe and Zn occurred in eggs compared to vegetables; La, Pr, Nd, Sm and Eu were found only in lettuce samples. The results of this study may provide important data useful in the risk assessment of human exposure through diet in accidents involving dangerous chemicals. Furthermore, the estimated weekly intakes calculated for PCDD/Fs and PCBs highlighted that, although vegetables accumulate very low concentrations of these contaminants, they contribute more than eggs to human exposure.

9.
Depletion Study of PCDD/­Fs and Dioxin-Like PCBs Concentrations in Contaminated Home-Produced Eggs: Preliminary Study.

Menotta S, D'antonio M, Diegoli G, et al.

Analytica Chimica Acta. 2010;672(1-2):50-4. doi:10.1016/j.aca.2010.04.043.

Dioxins (PCDD/Fs) and polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants. The contamination of food products with dioxins and PCBs is a well studied issue, because food is generally considered the major source of dioxin intake for humans. In Italy, the Regional Monitoring Plan (part of the national residue monitoring plan) used in the field for 2009 has also included the control of environmental pollutants in small egg producers. Following an irregular result, 12 laying hens were transferred into a laboratory controlled environment. Eggs were collected for 60 days and they were weekly analysed for the evaluation of dioxins, dioxin-like PCBs (DL-PCBs), and non-dioxin-like PCBs (NDL-PCBs, six congeners) levels. The dioxins and PCBs contents were determined, according to EPA methods, by gas chromatography ic determination coupled with high resolution mass spectrometry (HRGC-HRMS). The content of PCDD/Fs, DL-PCBs and NDL-PCBs was evaluated weekly by mean from week to week. The concentration of dioxins was lower than DL-PCBs (2.5 pg TEQ g(-1) of fat against 4.5 pg TEQ g(-1) of fat), but we observed the same depletion trend for both pollutants. On the opposite, NDL-PCBs had a different course: we noted there was an increase between weeks 6 and 7, but the mean levels remained very low (about 20 ng g(-1) of fat). The dioxins, and sum of dioxin and DL-PCBs concentration were below the fixed European limits (i.e. 3 pg TEQ g(-1) of fat for dioxins and 6 pg TEQ g(-1) of fat for sum of dioxins and DL-PCBs), beginning from the 3rd week of trial.

10.
Dioxins and PCBs in Feed and Food--Review From European Perspective.

Malisch R, Kotz A.

The Science of the Total Environment. 2014;491-492:2-10. doi:10.1016/j.scitotenv.2014.03.022.

Leading Journal

During the 1990s, a number of adverse contamination incidents focussed the attention of the media and the general public on food safety. This led to the evaluation of safety measures with regard to dioxin intake from food. Important aspects regarding dioxins and PCBs in the food chain are reviewed here, allowing a contextual understanding of the present situation through its chronological developments. About 90-98% of the average exposure of humans to dioxins and PCBs results from dietary intake, with food of animal origin being the predominant source. Therefore, animal feed contributes considerably to the presence of these compounds in food. The detection of the "real" source of a contamination event in the food chain is a complex scientific problem and requires specific knowledge on production processes and changes of patterns during bioaccumulation. This is demonstrated by complex investigations performed in three studies on two continents to identify the source (e.g. from contamination of cow's milk in Germany, to citrus pulp pellets from Brazil as an ingredient in feed, then to contaminated lime for neutralization and finally to a landfill with residues of vinyl chloride monomer production). This example shows also the substantial economic losses resulting from incidents in the food chain and the consequences to global trade. In 2001, the EU Scientific Committee on Food established a group tolerable weekly intake (TWI) of 14 pg WHO-TEQ/kg body weight and concluded that a considerable proportion of the European population would exceed this TWI. On the global level, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) provides scientific advice to the Codex Alimentarius Commission and therefore contributes to harmonized international food standards. In its evaluation of 2001, JECFA derived a provisional tolerable monthly intake (PTMI) of 70 pg TEQ/kg body weight. The sum of the median intake of PCDD/F-TEQ and PCB-TEQ exceeded the PTMI in Western European countries, was in the PTMI range in North America, but lower in Japan and New Zealand. The 90th percentile of PCDD/F-TEQ exceeded the PTMI in Western European countries and North America, the 90th percentile of coplanar PCBs in Western European countries. Therefore, in 2001 the EU Commission developed a strategy to reduce the presence of dioxins and PCBs in the environment and in the food chain. The legislative measures comprised maximum levels and action levels for feed and food, and a Rapid Alert System for detected incidents was introduced. The network of the EU Reference Laboratory and National Reference Laboratories contributes to harmonization within the EU Member States and developed analytical criteria for screening and confirmatory methods for control of feed and food. After all these efforts it is of general interest to see whether these measures had an effect. The 2012 evaluation of the European Food Safety Authority (EFSA) based on comprehensive monitoring data of 26 European countries shows a general decrease in dietary exposure of dioxins and DL-PCBs between 2002-2004 and 2008-2010, estimated to be between 16.6% and 79.3% for the different population groups. A smaller decrease was observed for NDL-PCBs. The percentage of individuals exposed above the TWI of 14 pg TEQ/kg b.w. was estimated to be between 1.0 and 52.9%. Toddlers and other children were the most exposed groups (being at the upper end of these ranges). Fish, meat and dairy products appeared to be the highest contributing food groups to dietary exposure.

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The likelihood that contaminants such as dioxins, mercury, or other harmful substances will accumulate over time and lead to disease from consuming one egg per day is very low in most settings, provided the eggs are commercially produced and not from highly contaminated environments.[1-3]
Dioxins and related persistent organic pollutants (POPs) are present in eggs, but regulatory monitoring in North America and Europe has led to a substantial reduction in dietary exposure, and most commercial eggs contain levels well below established safety thresholds.[1-2] The majority of dietary dioxin exposure comes from animal-derived foods, with eggs contributing a small fraction (about 5%) of total intake in adults.[4] For an average adult, consuming one egg per day from commercial sources typically results in dioxin and PCB intake well below the tolerable weekly or monthly intake set by the European Food Safety Authority and the Joint FAO/WHO Expert Committee on Food Additives.[1-3]
However, eggs from free-range or backyard hens exposed to contaminated soil, feed, or building materials can contain much higher levels of dioxins and PCBs, sometimes exceeding regulatory limits and posing a risk for chronic accumulation and adverse health effects, especially in children or high consumers.[5-9] Mercury and other contaminants are less commonly found at harmful levels in eggs, but can be present in regions with significant environmental pollution.[10]
In summary, for most individuals consuming one commercially produced egg per day, the risk of disease from contaminant accumulation is minimal. The risk increases if eggs are sourced from environments with known contamination, but this is uncommon in regulated commercial production.[1-2][4]

1.
Dioxins and PCBs in Feed and Food--Review From European Perspective.

Malisch R, Kotz A.

The Science of the Total Environment. 2014;491-492:2-10. doi:10.1016/j.scitotenv.2014.03.022.

Leading Journal

During the 1990s, a number of adverse contamination incidents focussed the attention of the media and the general public on food safety. This led to the evaluation of safety measures with regard to dioxin intake from food. Important aspects regarding dioxins and PCBs in the food chain are reviewed here, allowing a contextual understanding of the present situation through its chronological developments. About 90-98% of the average exposure of humans to dioxins and PCBs results from dietary intake, with food of animal origin being the predominant source. Therefore, animal feed contributes considerably to the presence of these compounds in food. The detection of the "real" source of a contamination event in the food chain is a complex scientific problem and requires specific knowledge on production processes and changes of patterns during bioaccumulation. This is demonstrated by complex investigations performed in three studies on two continents to identify the source (e.g. from contamination of cow's milk in Germany, to citrus pulp pellets from Brazil as an ingredient in feed, then to contaminated lime for neutralization and finally to a landfill with residues of vinyl chloride monomer production). This example shows also the substantial economic losses resulting from incidents in the food chain and the consequences to global trade. In 2001, the EU Scientific Committee on Food established a group tolerable weekly intake (TWI) of 14 pg WHO-TEQ/kg body weight and concluded that a considerable proportion of the European population would exceed this TWI. On the global level, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) provides scientific advice to the Codex Alimentarius Commission and therefore contributes to harmonized international food standards. In its evaluation of 2001, JECFA derived a provisional tolerable monthly intake (PTMI) of 70 pg TEQ/kg body weight. The sum of the median intake of PCDD/F-TEQ and PCB-TEQ exceeded the PTMI in Western European countries, was in the PTMI range in North America, but lower in Japan and New Zealand. The 90th percentile of PCDD/F-TEQ exceeded the PTMI in Western European countries and North America, the 90th percentile of coplanar PCBs in Western European countries. Therefore, in 2001 the EU Commission developed a strategy to reduce the presence of dioxins and PCBs in the environment and in the food chain. The legislative measures comprised maximum levels and action levels for feed and food, and a Rapid Alert System for detected incidents was introduced. The network of the EU Reference Laboratory and National Reference Laboratories contributes to harmonization within the EU Member States and developed analytical criteria for screening and confirmatory methods for control of feed and food. After all these efforts it is of general interest to see whether these measures had an effect. The 2012 evaluation of the European Food Safety Authority (EFSA) based on comprehensive monitoring data of 26 European countries shows a general decrease in dietary exposure of dioxins and DL-PCBs between 2002-2004 and 2008-2010, estimated to be between 16.6% and 79.3% for the different population groups. A smaller decrease was observed for NDL-PCBs. The percentage of individuals exposed above the TWI of 14 pg TEQ/kg b.w. was estimated to be between 1.0 and 52.9%. Toddlers and other children were the most exposed groups (being at the upper end of these ranges). Fish, meat and dairy products appeared to be the highest contributing food groups to dietary exposure.

2.
Polychlorinated Dioxins, Furans (PCDD/­Fs), Dioxin-Like Polychlorinated Biphenyls (Dl-PCBs) and Indicator PCBs (Ind-PCBs) in Egg and Egg Products in Turkey.

Olanca B, Cakirogullari GC, Ucar Y, Kirisik D, Kilic D.

Chemosphere. 2014;94:13-9. doi:10.1016/j.chemosphere.2013.08.056.

Leading Journal

The aim of the study is to determine concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dioxin-like polychlorinated biphenyls (dl-PCBs) and indicator PCBs (ind-PCBs) in eggs from cage hens without soil contact, pasteurized egg samples and imported egg yolk powder samples in Turkey. Concentrations of PCDD/Fs, PCDD/Fs and dl-PCBs, and ind-PCBs in eggs and pasteurized egg samples are in the range of 0.247-1.527 pg WHO-TEQ(2005)g(-1) fat, 0.282-1.762 pg WHO-TEQ(2005)g(-1) fat and 202-1,235 pg g(-1) fat, respectively. For egg yolk powder samples, concentrations of PCDD/Fs, PCDD/Fs and dl-PCBs, and ind-PCBs are in the range of 0.122-0.494 pg WHO-TEQ(2005)g(-1) fat, 0.214-0.640 pg WHO-TEQ(2005)g(-1) fat and 217-1,498 pg g(-1) fat, respectively. All results for PCDD/Fs, PCDD/Fs and dl-PCBs, and ind-PCBs are below the values of 2.5 pg WHO-TEQ(2005)g(-1) fat, 5.0 pg WHO-TEQ(2005)g(-1) fat and 40 ng g(-1) fat imposed in Turkish Regulation for eggs and egg products, respectively. In all samples 2,3,4,7,8-PeCDF, 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD and PCB126 are the most prominent congeners. Mean estimated daily exposure to PCDD/Fs and dl-PCBs for Turkish population from egg is 0.011 pg WHO-TEQ(2005)d(-1)kg body weight (bw)(-1). Although the exposure levels are below the TDI of 2 pg WHO-TEQ(1998)kg bw(-1), the results were based only on consumption of egg. In order to estimate total dietary intake for Turkish population, various food items should be investigated.

3.
Reevaluation on Accumulation and Depletion of Dioxin-Like Compounds in Eggs of Laying Hens: Quantification on Dietary Risk From Feed to Egg.

Wang C, Dong S, Wang P, et al.

The Science of the Total Environment. 2021;801:149690. doi:10.1016/j.scitotenv.2021.149690.

Leading Journal

Updated assessment on transfer of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) from feed to food is essential for understanding human exposure risk. A controlled feeding experiment was conducted for laying hens to reevaluate the transfer characteristics of dioxin-like compounds from feed to egg. Two fortified diets (1.17 and 5.13 pg TEQ g dry weight), made by blending with fly ash, were fed to laying hens for 14 days, followed by 28-days depletion. Levels of ∑TEQ in eggs rapidly increased once exposure started, reaching at 1.98 and 6.86 pg TEQ g lw at the end of exposure for low- and high-exposure groups, respectively, and dropped to under the European legislation (maximum levels: 5.0 pg TEQ g lw) after 28-days depletion. The quantitative depletions showed that the half-lives (T) of ∑TEQ in eggs were 23 and 14 days for low- and high-exposure groups, respectively. The depletion and accumulation rates of PCDD/Fs were in the range of 0.026-0.151 and 0.005-0.016 day, respectively, representing that the T of PCDD/Fs in eggs ranged from 5 to 27 days. The depletion kinetics of DL-PCBs was not significant in egg. The hens with higher laying rates exhibited shorter T of PCDD/Fs, implying that increasing laying rate could expedite the depletion of PCDD/Fs in egg. The T of PCDD/Fs in egg were negatively correlated with the chlorine number, indicating that lower chlorinated congeners tended to be retained in the egg. Transfer rates of PCDD/Fs were in the range of 4-19%, which were lower than the previous results. These results were attributed to short exposure time and low bioavailability of PCDD/Fs in fly ash. Estimations of dietary intake highlighted the dietary risk of PCDD/Fs from feed to egg, which would pose limited adverse effects on human health.

4.
Fish Intake, Contaminants, and Human Health: Evaluating the Risks and the Benefits.

Mozaffarian D, Rimm EB.

JAMA logoJAMA. 2006;296(15):1885-99. doi:10.1001/jama.296.15.1885.

Leading Journal
Evidence Synthesis > Risks of PCBs and Dioxins

PCBs are synthetic organochlorine compounds previously used in industrial and commercial processes. Dioxins—commonly referring to dibenzodioxins and dibenzofurans—are organochlorine by-products of waste incineration, paper bleaching, pesticide production, and production of polyvinyl chloride plastics. Manufacture and processing of PCBs was prohibited in 1977, and regulatory and industry efforts have reduced dioxin emissions by more than 90% since 1987. Nevertheless, these contaminants persist for long periods in the environment, and thus while levels are steadily declining, PCBs and dioxins continue to be present in low concentrations in many foods (Table 2).

Cancer Risks . Animal experiments and some evidence in humans indicate that PCBs and dioxins are carcinogenic, possibly related to effects on the aryl hydrocarbon receptor, a transcription factor affecting gene expression. Multiple congeners (structural variants) of PCBs and dioxins exist. Potential toxicities of foods are calculated using toxic equivalence (TEQ): the sum of each congener's level in the food multiplied by that congener's toxic equivalency factor (standardized against 2,3,7,8-tetrachlorodibenzo-p-dioxin). In the United States, PCBs comprise 28% and dioxins 72% of total TEQ exposure. Among adults, major dietary sources of PCBs and dioxins are beef, chicken, and pork (34% of total TEQ); dairy products (30%); vegetables (22%); fish and shellfish (9%); and eggs (5%). Dietary sources are similar for children.

Although major sources of exposure to PCBs and dioxins are meats, dairy products, and vegetables, considerable attention has been given to fish sources (Table 2). When PCBs and dioxins were measured in farmed and wild salmon, levels were similar to those in several other foods (Table 2).

5.

PCDD/Fs and PCBs are environmentally persistent substances that have been associated with adverse effects on human health. Contamination of soils, animal feed and pastures leads to their bioaccumulation of in food products of animal origin, which are considered the major source of intake of these contaminants in humans. We analyzed eggs from free-range hens, sampled from small farms, located within a distance of 4.5 km from a secondary aluminum smelter in Northern Italy. The concentrations of PCDD/Fs, DL-PCBs and NDL-PCBs were higher in eggs from locations close to the plant, and strongly exceeded the limits set by EU Regulation 1259/2011 (2.5 pg WHO TEQ fat g(-1) for PCDD/Fs, 5.0 pg WHO TEQ g(-1) for PCDD/Fs and DL-PCBs L, 40 ng g(-1) for NDL-PCBs). Without the prompt and immediately applied control strategies, the consumption of contaminated eggs may have posed [corrected] a risk for human health, especially for children (≤9 years) and infants (≤3 years), due to the 2-fold excess of the current exposure limits.

6.
Pentachlorophenol From an Old Henhouse as a Dioxin Source in Eggs and Related Human Exposure.

Piskorska-Pliszczynska J, Strucinski P, Mikolajczyk S, et al.

Environmental Pollution (Barking, Essex : 1987). 2016;208(Pt B):404-12. doi:10.1016/j.envpol.2015.10.007.

Leading Journal

High levels of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were detected in free-range eggs, and these levels reached a concentration of 29.84 ± 7.45 pg of WHO-TEQ/g of fat. This value exceeded the EU maximum permitted level of 2.5 pg of WHO-TEQ/g of fat for PCDD/F congeners by twelve-fold. A chemical analysis (HRGC-HRMS) revealed elevated amounts of OCDD, OCDF, HxCDD, HpCDD and HpCDF. During the investigation, samples of feed, soil, wall scrapings, wooden ceiling of the henhouse and tissues from laying hens were examined for dioxin contents (30 samples altogether). The long and complicated investigation found that the source of dioxins in the poultry farm was pentachlorophenol-treated wood, which was used as structural components in the 40-year-old farm building adapted to a henhouse. The wooden building material contained PCDD/Fs at a concentration of 3922.60 ± 560.93 pg of WHO-TEQ/g and 11.0 ± 2.8 μg/kg of PCP. The potential risk associated with dioxin intake was characterized by comparing the theoretically calculated weekly and monthly intakes with the toxicological reference values (TRVs), namely the Tolerable Weekly Intake (TWI) and Provisional Tolerable Monthly Intake (PTMI) values of 14 pg of WHO-TEQ/kg of bw and 70 pg of WHO-TEQ/kg of bw, respectively. The intake of dioxins estimated for high egg consumers (approximately 5-6 eggs/week) exceeded the TWI and PTMI values, which may pose a risk of delayed adverse health effects. The estimated dose of PCDD/Fs and DL-PCBs for children consuming 5 eggs per week exceeded the TWI by as much as 450% because of their nearly 5-fold-lower body weight. Although the dioxin intake estimated for the average consumption of eggs in the general population did not exceed any of the TRVs applied (58.7% TWI and 51.1% PTMI), such a situation should be considered unacceptable from a public health perspective because eggs are not the only source of these contaminants.

7.
Soil as a Source of Dioxin Contamination in Eggs From Free-Range Hens on a Polish Farm.

Piskorska-Pliszczynska J, Mikolajczyk S, Warenik-Bany M, Maszewski S, Strucinski P.

The Science of the Total Environment. 2014;466-467:447-54. doi:10.1016/j.scitotenv.2013.07.061.

Leading Journal

The transfer of dioxins from contaminated soil into the food chain has recently become an up-and-coming topic in the environmental policy and health-related consumer protection. Within the framework of the 2011 National Food Survey that monitored the levels of PCDD/Fs and PCBs in foods of animal origin, the sum of the WHO-PCDD/F/PCB-TEQ concentrations exceeding two-fold the European Union's maximum level was detected in eggs from a free-range farm (12.55 ± 2.37 pg WHOPCDD/F/PCB-TEQ/g fat). Investigations have revealed that the source of egg contamination was the backyard soil on which the hens were foraging. A follow-up study of laying hens from this farm has demonstrated the transfer of dioxins into all tested tissues (breast and leg muscles, abdominal fat), liver and ovarian follicles. The bioaccumulation of dioxins was found to be congener and tissue-dependent. The highest concentration was found in the liver, followed by the ovarian follicles, and the adipose tissue. The PCDD/F levels in the liver often were approximately two times higher from those in other materials from the same hen. The potential dioxin intakes with eggs were expressed as the percent of the Tolerable Weekly Intake (TWI), and the Provisional Tolerable Monthly Intake (PTMI). The weekly intake of dioxins would be 3.5 pg WHO-TEQ/kg b.w. (24.9% TWI) for an adult and 20.3 pg WHO-TEQ/kg b.w. (145.2% TWI) for a 3-year old child. Considering a monthly consumption of such contaminated eggs, intake of dioxins would be slightly lower, but still over 100% of the PTMI for a child. The obtained results complement the knowledge on possible dioxin sources in food and are important for risk management authorities.

8.
PCDD/­Fs and Dioxin-Like PCBs in Home-Produced Eggs From Belgium: Levels, Contamination Sources and Health Risks.

Van Overmeire I, Waegeneers N, Sioen I, et al.

The Science of the Total Environment. 2009;407(15):4419-29. doi:10.1016/j.scitotenv.2008.11.058.

Leading Journal

This paper discusses the dioxin TEQ levels as determined by the chemically activated luciferase gene expression assay (CALUX) and by HRGC-HRMS in eggs, soils, faeces and kitchen waste samples obtained in the CONTEGG study. The samples were collected in each Belgian province at private homes and in small gardens where chickens are held. The CALUX levels for eggs sampled in autumn were higher than the levels in eggs obtained at the same locations in spring (median values of 5.86 and 4.08 pg CALUX TEQ/g fat, respectively). The total WHO-TEQ levels in eggs, determined by HRGC-HRMS, ranged from 3.29 to 95.35 pg TEQ/g fat in autumn and from 1.50 to 64.79 pg TEQ/g fat in spring. In the soils on which the chickens forage, levels of 2.51-11.35 pg I-TEQ/g in autumn and 2.00-7.86 pg I-TEQ/g in spring were found. The congener pattern of PCDD/Fs in the eggs, soils and faeces was dominated by OCDD, in addition to 1,2,3,4,6,7,8-HeptaCDD, OCDF and 1,2,3,4,6,7,8-HeptaCDF. The predominant dioxin-like PCBs were PCB118, PCB 105 and PCB 156. The dioxin-like PCBs contributed on average 47%, 14% and 20% to the total WHO-TEQ in eggs, soils and faeces, respectively. Kitchen waste samples were very low-contaminated with dioxin-like compounds. The present results showed a good agreement between egg and soil TEQ levels for PCDD/Fs but not for dioxin-like PCBs. This study showed that current soil levels found in some private gardens do not lead to egg levels below the current EU maximal level of 6 pg total TEQ/g fat for dioxins and dioxin-like PCBs. The consumers of the analysed eggs attained 5-79% of the tolerable weekly intake (TWI) of 14 pg TEQ/kg bw for dioxins and dioxin-like PCBs by exposure to their home-produced eggs only.

9.
Polychlorinated Dibenzo-P-Dioxins and Dibenzofurans (PCDD/­Fs) and Biphenyls (PCBs) in Home-Produced Eggs.

Hoogenboom RLAP, Ten Dam G, van Bruggen M, et al.

Chemosphere. 2016;150:311-319. doi:10.1016/j.chemosphere.2016.02.034.

Leading Journal

Home produced eggs from 62 addresses in the Netherlands were investigated for the levels of polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/Fs) and biphenyls (PCBs), both dioxin-like (dl) and non-dioxin-like (ndl). Compared to commercial eggs, levels were relatively high with a median of 4.6 pg TEQ g(-1) fat for the sum of PCDD/Fs and dl-PCBs, and a highest level of 18.9 pg TEQ g(-1) fat. A number of samples showed clearly elevated ndl-PCB levels with a median of 13 ng g(-1) fat and a highest level of 80 ng g(-1) fat. There were no clear regional differences, even though part of the samples were derived from the rather industrial Rotterdam/Rijnmond area. Based on the congener patterns, former backyard burning of waste seems the most likely source for most eggs, with two exceptions where other sources contributed to the contamination. Similar is true for the ndl-PCBs. The study shows that average levels are about ten-fold higher than commercial eggs and may substantially contribute to the intake of PCDD/Fs and dl-PCBs by consumers. Intervention measures to reduce the intake of these contaminants by laying hens are advised.

10.
Poultry Eggs as a Source of PCDD/­Fs, PCBs, PBDEs and PBDD/­Fs.

Pajurek M, Pietron W, Maszewski S, Mikolajczyk S, Piskorska-Pliszczynska J.

Chemosphere. 2019;223:651-658. doi:10.1016/j.chemosphere.2019.02.023.

Leading Journal

Regardless of the country or region of the world, poultry eggs are one of the most important components of the human diet. Nutritional value is derived from them, but chicken eggs can be contaminated with POPs. The aim of the study was to compare the impact of different types of chicken husbandry system on bioaccumulation of selected POPs. The HRGC/HRMS method was used for determination of 58 congeners of chlorinated and brominated halogenated aromatic hydrocarbons. The influence of the farm rearing system on concentration and congener profile was seen for most groups of tested contaminants, of which the eggs were a source. Human exposure to dioxins and dioxin-like compounds as a result of consumption of contaminated eggs should be a subject of concern. The occurrence of PCDD/Fs, PCBs, PBDEs, and PBDD/Fs in commonly consumed foodstuffs such as eggs supports the need for further research on environmental pollutants and for determination of exposure as the result of their occurrence in different food categories.

Finished thinking

Analyzing query
Searching published medical literature, guidelines, FDA, CDC, and more
Synthesizing relevant information
The health benefits of eating one egg per day generally outweigh the potential harms related to dietary cholesterol and environmental contaminants for most individuals in the general population. Eggs provide high-quality protein, choline, folate, vitamin D, and B vitamins, and are associated with improved satiety, muscle protein synthesis, and favorable body composition in randomized trials.[1] Large multinational cohort studies and meta-analyses consistently show that moderate egg consumption (up to one egg per day) is not associated with increased risk of cardiovascular disease or mortality after adjusting for overall dietary patterns and cholesterol intake.[2-6]
Some US-based studies report a modestly increased risk of cardiovascular disease and all-cause mortality with higher egg or dietary cholesterol consumption, but these associations are attenuated or become non-significant after adjusting for dietary cholesterol or other confounders.[7-9] The increased risk is most relevant for individuals with elevated baseline risk, such as older adults, Americans, or those with hyperlipidemia, and is primarily mediated by dietary cholesterol rather than egg consumption per se.[9]
Replacing whole eggs with egg whites or substitutes may further reduce mortality risk, particularly from cardiovascular and cancer causes, and is recommended for individuals at higher risk.[10] The risk from environmental contaminants in commercially produced eggs is low and not a major concern in the general US population based on current evidence; most studies focus on dietary cholesterol rather than contaminants.[1][3][7] Data on long-term health effects of low-level environmental contaminants in eggs are limited and may warrant further research.
In summary, one egg per day is considered safe and beneficial for most adults, with the balance of evidence supporting inclusion in a healthy dietary pattern.

1.
Eggs: Healthy or Risky? A Review of Evidence From High Quality Studies on Hen's Eggs.

Myers M, Ruxton CHS.

Nutrients. 2023;15(12):2657. doi:10.3390/nu15122657.

Hen's eggs (from ) provide choline, folate, vitamin D, iodine, B vitamins and high-quality protein and are no longer viewed by national bodies as a risk factor for hypercholesterolaemia and cardiovascular disease (CVD). Yet, questions remain about the benefits and risks of eating eggs regularly. This review evaluates recent high-quality evidence from randomised controlled trials (RCT) and meta-analyses of observational studies and considers new areas of interest, such as weight management, protein metabolism, allergy risk and sustainability. In several RCT, eggs increased muscle protein synthesis and lowered fat mass, which could support optimal body composition. Eggs within a meal improved satiety, which could translate into lower energy intakes, although more RCT are needed. In observational studies, higher egg consumption was associated with a null effect or a modest reduced risk of CVD. For type 2 diabetes (T2D) incidence and risk of CVD in people with T2D, there were inconsistencies between observational and RCT data, with the former noting positive associations and the latter seeing no effect of higher egg intake on markers of T2D and CVD. Sustainability metrics suggest that eggs have the lowest planetary impact amongst animal proteins. To lower allergy risk, earlier introduction of eggs into weaning diets is warranted. In conclusion, the balance of evidence points to eggs being a nutritious food suggesting there are broad health benefits from including eggs in the diet at intakes higher than that currently consumed by European populations.

2.
Association of Egg Intake With Blood Lipids, Cardiovascular Disease, and Mortality in 177,000 People in 50 Countries.

Dehghan M, Mente A, Rangarajan S, et al.

The American Journal of Clinical Nutrition. 2020;111(4):795-803. doi:10.1093/ajcn/nqz348.

Background: Eggs are a rich source of essential nutrients, but they are also a source of dietary cholesterol. Therefore, some guidelines recommend limiting egg consumption. However, there is contradictory evidence on the impact of eggs on diseases, largely based on studies conducted in high-income countries.

Objectives: Our aim was to assess the association of egg consumption with blood lipids, cardiovascular disease (CVD), and mortality in large global studies involving populations from low-, middle-, and high-income countries.

Methods: We studied 146,011 individuals from 21 countries in the Prospective Urban Rural Epidemiology (PURE) study. Egg consumption was recorded using country-specific validated FFQs. We also studied 31,544 patients with vascular disease in 2 multinational prospective studies: ONTARGET (Ongoing Telmisartan Alone and in Combination with Ramipril Global End Point Trial) and TRANSCEND (Telmisartan Randomized Assessment Study in ACEI Intolerant Subjects with Cardiovascular Disease). We calculated HRs using multivariable Cox frailty models with random intercepts to account for clustering by study center separately within each study.

Results: In the PURE study, we recorded 14,700 composite events (8932 deaths and 8477 CVD events). In the PURE study, after excluding those with history of CVD, higher intake of egg (≥7 egg/wk compared with <1 egg/wk intake) was not significantly associated with blood lipids, composite outcome (

Hr: 0.96; 95%

Ci: 0.89, 1.04; P-trend = 0.74), total mortality (

Hr: 1.04; 95%

Ci: 0.94, 1.15; P-trend = 0.38), or major CVD (

Hr: 0.92; 95%

Ci: 0.83, 1.01; P-trend = 0.20). Similar results were observed in ONTARGET/TRANSCEND studies for composite outcome (HR 0.97; 95%

Ci: 0.76, 1.25; P-trend = 0.09), total mortality (

Hr: 0.88; 95%

Ci: 0.62, 1.24; P-trend = 0.55), and major CVD (

Hr: 0.97; 95%

Ci: 0.73, 1.29; P-trend = 0.12).

Conclusions: In 3 large international prospective studies including ∼177,000 individuals, 12,701 deaths, and 13,658 CVD events from 50 countries in 6 continents, we did not find significant associations between egg intake and blood lipids, mortality, or major CVD events. The ONTARGET and TRANSCEND trials were registered at clinicaltrials.gov as NCT00153101. The PURE trial was registered at clinicaltrials.gov as NCT03225586.

3.
Effect of Egg Consumption on Health Outcomes: An Updated Umbrella Review of Systematic Reviews and Meta-Analysis of Observational and Intervention Studies.

Formisano E, Lopes Neri LC, Caffa I, et al.

Nutrition, Metabolism, and Cardiovascular Diseases : NMCD. 2025;35(5):103849. doi:10.1016/j.numecd.2025.103849.

New Research

Aims: To evaluate the effect of egg consumption on health outcomes.

Data Synthesis: A systematic search in PubMed, Scopus, Lilacs, and Web of Science was developed using terms ("egg consumption" or "egg intake") and ("health" or "chronic diseases" or "diabetes" or "cancer" or "cholesterol" or "dyslipidemia"), and meta-analyses of observational or interventional studies published since January 2020 were included. The studies' quality was evaluated through AMSTAR-2 and NutriGrade, and the strength of evidence according to sample size, heterogeneity, and quality of articles. Fourteen meta-analyses were included (10 observational, 4 interventional studies). The wide range of outcomes, with substantial variability and high heterogeneity, indicated a lack of robust evidence. The overall quality of studies was critically low. The level of evidence was very weak for all the significant associations: risk of heart failure (RR 1.15; 95%

Ci: 1.02-1.30), cancer mortality (RR 1.13; 95%CI 1.06-1.20), higher levels of LDL cholesterol (WMD 7.39; 95%CI 5.82-8.95), total cholesterol (WMD 9.12; 95%CI 7.35-10.89), and apolipoprotein B-100 (WMD 0.06; 95%CI 0.03-0.08). Conversely, egg intake has been weakly associated with improvements in HDL cholesterol (WMD 1.37; 95%CI 0.49-2.25), apolipoprotein A1 (WMD 0.03; 95%CI 0.01-0.05), and growth parameters in children (WMD 0.47; 95%CI 0.13-0.80). No evidence of association was found among all cardiovascular outcomes and all-cause mortality risk between high vs. low egg consumption.

Conclusion: Due to the critically low strength of studies, insufficient evidence is available to discourage egg consumption, suggesting eggs can be part of a healthy diet.

4.
Egg Consumption and Risk of Cardiovascular Disease: Three Large Prospective US Cohort Studies, Systematic Review, and Updated Meta-Analysis.

Drouin-Chartier JP, Chen S, Li Y, et al.

BMJ (Clinical Research Ed.). 2020;368:m513. doi:10.1136/bmj.m513.

Leading Journal

Objective: To evaluate the association between egg intake and cardiovascular disease risk among women and men in the United States, and to conduct a meta-analysis of prospective cohort studies.

Design: Prospective cohort study, and a systematic review and meta-analysis of prospective cohort studies.

Setting: Nurses' Health Study (NHS, 1980-2012), NHS II (1991-2013), Health Professionals' Follow-Up Study (HPFS, 1986-2012).

Participants: Cohort analyses included 83 349 women from NHS, 90 214 women from NHS II, and 42 055 men from HPFS who were free of cardiovascular disease, type 2 diabetes, and cancer at baseline.

Main Outcome Measures: Incident cardiovascular disease, which included non-fatal myocardial infarction, fatal coronary heart disease, and stroke.

Results: Over up to 32 years of follow-up (>5.54 million person years), 14 806 participants with incident cardiovascular disease were identified in the three cohorts. Participants with a higher egg intake had a higher body mass index, were less likely to be treated with statins, and consumed more red meats. Most people consumed between one and less than five eggs per week. In the pooled multivariable analysis, consumption of at least one egg per day was not associated with incident cardiovascular disease risk after adjustment for updated lifestyle and dietary factors associated with egg intake (hazard ratio for at least one egg per day less than one egg per month 0.93, 95% confidence interval 0.82 to 1.05). In the updated meta-analysis of prospective cohort studies (33 risk estimates, 1 720 108 participants, 139 195 cardiovascular disease events), an increase of one egg per day was not associated with cardiovascular disease risk (pooled relative risk 0.98, 95% confidence interval 0.93 to 1.03, I=62.3%). Results were similar for coronary heart disease (21 risk estimates, 1 411 261 participants, 59 713 coronary heart disease events; 0.96, 0.91 to 1.03, I=38.2%), and stroke (22 risk estimates, 1 059 315 participants, 53 617 stroke events; 0.99, 0.91 to 1.07, I=71.5%). In analyses stratified by geographical location (P for interaction=0.07), no association was found between egg consumption and cardiovascular disease risk among US cohorts (1.01, 0.96 to 1.06, I=30.8%) or European cohorts (1.05, 0.92 to 1.19, I=64.7%), but an inverse association was seen in Asian cohorts (0.92, 0.85 to 0.99, I=44.8%).

Conclusions: Results from the three cohorts and from the updated meta-analysis show that moderate egg consumption (up to one egg per day) is not associated with cardiovascular disease risk overall, and is associated with potentially lower cardiovascular disease risk in Asian populations.

Systematic Review Registration: PROSPERO CRD42019129650.

5.
Egg Consumption and Blood Lipid Parameters According to the Presence of Chronic Metabolic Disorders: The EVIDENT II Study.

Mesas AE, Garrido-Miguel M, Fernández-Rodríguez R, et al.

The Journal of Clinical Endocrinology and Metabolism. 2022;107(3):e963-e972. doi:10.1210/clinem/dgab802.

Context: Egg consumption is one of the main dietary sources of cholesterol, but whether individuals who eat more eggs have a worse blood lipid profile remains controversial.

Objective: We examined the relationship between egg consumption and lipid parameters and explored whether this relationship changes according to the presence of chronic metabolic disorders.

Methods: A multicenter cross-sectional study was conducted with adult participants in the EVIDENT II trial. Adjusted linear regression models were stratified by the main chronic metabolic disorders.

Results: Among the 728 participants (61.9% women, mean age 52.1 ± 11.9 years), the mean egg consumption was equivalent to 5 to 6 eggs per week for a 70-kg individual. In the fully adjusted analysis, no association was found of egg consumption with total and high-density lipoprotein cholesterol (HDL-c), and triglyceride levels. Furthermore, compared with the first quartile of consumption, the fourth quartile was associated with lower low-density lipoprotein cholesterol (LDL-c) levels (coefficient -7.01; 95% CI -13.39, -0.62) and a lower LDL-c/HDL-c ratio (coefficient -0.24, 95% CI -0.41, -0.06). In the analyses stratified by chronic metabolic diseases, higher egg consumption was not associated with lipid profile in those with obesity, hypertension, type 2 diabetes, dyslipidemia, or treated with hypolipidemic drugs, and was associated with a better lipid profile in participants without these conditions.

Conclusion: Higher egg consumption was not associated with blood lipids in individuals with chronic metabolic disorders. In individuals without such conditions, the lipid profile was better among those who consumed more eggs. Our findings support current guidelines recommending eggs as part of a healthy diet.

6.
The Effect of Egg Consumption on Cardiometabolic Health Outcomes: An Umbrella Review.

Mah E, Chen CO, Liska DJ.

Public Health Nutrition. 2020;23(5):935-955. doi:10.1017/S1368980019002441.

Objective: This umbrella review provides an overview of the consistency and gaps in the evidence base on eggs and cardiometabolic health.

Design: PubMed, Web of Science, Cochrane Library, the Nutrition Evidence Systematic Review and Agency for Healthcare Research and Quality databases were screened for evidence-based reviews in English that assessed human studies on egg consumption and cardiometabolic outcomes.

Results: Seven systematic reviews and fifteen meta-analyses were identified, with eighteen of these published since 2015. Overall, the systematic reviews were of low quality, while meta-analyses were of moderate- to high-quality. No association of increased egg intake and risks of heart disease or stroke in the general population were found in the meta-analyses. Increased risk of heart failure was noted in two meta-analyses that analysed the same three cohort studies. Five recent meta-analyses reported no increased risk of type 2 diabetes mellitus (T2DM) in the general population, although increased risk in US-based populations only has been reported. Older (<2013) meta-analyses reported increased risks of cardiovascular disease (CVD) or heart disease in T2DM populations, and no recent evidence-based reviews were identified. Finally, only one meta-analysis reported intervention studies specifically on eggs and biomarkers (i.e. lipids), and the results contradicted those from observation studies.

Conclusions: Recent evidence-based reviews conclude that increased egg consumption is not associated with CVD risk in the general population. More research is needed on the positive associations between egg consumption and heart failure and T2DM risk, as well as CVD risk in diabetics, before firm conclusions can be made.

7.
Associations of Dietary Cholesterol, Serum Cholesterol, and Egg Consumption With Overall and Cause-Specific Mortality: Systematic Review and Updated Meta-Analysis.

Zhao B, Gan L, Graubard BI, et al.

Circulation. 2022;145(20):1506-1520. doi:10.1161/CIRCULATIONAHA.121.057642.

Leading Journal

Background: Despite substantial research highlighting the importance of exogenous dietary cholesterol intake and endogenous serum cholesterol level in human health, a thorough evaluation of the associations is lacking. Our study objective was to examine overall and cause-specific mortality in relation to dietary and serum cholesterol, as well as egg consumption, and conduct an updated meta-regression analysis of cohort studies.

Methods: We conducted a prospective analysis of 27 078 men in the ATBC Study (Alpha-Tocopherol, Beta-Carotene Cancer Prevention). Multivariable-controlled cause-specific Cox proportional hazards regression models were used to calculate hazard ratios and 31-year absolute mortality risk differences. A systematic review and meta-analysis of cohort studies was also performed (PROSPERO [

Url: https://www.crd.york.ac.uk/prospero/; Unique identifier: CRD42021272756]).

Results: Based on 482 316 person-years of follow-up, we identified 22 035 deaths, including 9110 deaths from cardiovascular disease (CVD). Greater dietary cholesterol and egg consumption were associated with increased risk of overall and CVD-related mortality. Hazard ratios for each additional 300 mg cholesterol intake per day were 1.10 and 1.13 for overall and CVD-related mortality, respectively; for each additional 50-g egg consumed daily, hazard ratios were 1.06 and 1.09, respectively, for overall and CVD-related mortality (all P values<0.0001). After multivariable adjustment, higher serum total cholesterol concentrations were associated with increased risk of CVD-related mortality (hazard ratios per 1 SD increment, 1.14; P<0.0001). The observed associations were generally similar across cohort subgroups. The updated meta-analysis of cohort studies on the basis of 49 risk estimates, 3 601 401 participants, and 255 479 events showed consumption of 1 additional 50-g egg daily was associated with significantly increased CVD risk (pooled relative risk, 1.04 [95% CI, 1.00-1.08]; I2=80.1%). In the subgroup analysis of geographic regions (Pinteraction=0.02), an increase of 50-g egg consumed daily was associated with a higher risk of CVD in US cohorts (pooled relative risk, 1.08 [95% CI, 1.02-1.14]) and appeared related to a higher CVD risk in European cohorts with borderline significance (pooled relative risk, 1.05), but was not associated with CVD risk in Asian cohorts.

Conclusions: In this prospective cohort study and updated meta-analysis, greater dietary cholesterol and egg consumption were associated with increased risk of overall and CVD-related mortality. Our findings support restricted consumption of dietary cholesterol as a means to improve long-term health and longevity.

8.
Associations of Dietary Cholesterol or Egg Consumption With Incident Cardiovascular Disease and Mortality.

Zhong VW, Van Horn L, Cornelis MC, et al.

JAMA logoJAMA. 2019;321(11):1081-1095. doi:10.1001/jama.2019.1572.

Leading Journal
Abstract

Importance 
Cholesterol is a common nutrient in the human diet and eggs are a major source of dietary cholesterol. Whether dietary cholesterol or egg consumption is associated with cardiovascular disease (CVD) and mortality remains controversial.
Objective 
To determine the associations of dietary cholesterol or egg consumption with incident CVD and all-cause mortality.
Design, Setting, and Participants 
Individual participant data were pooled from 6 prospective US cohorts using data collected between March 25, 1985, and August 31, 2016. Self-reported diet data were harmonized using a standardized protocol.
Exposures 
Dietary cholesterol (mg/day) or egg consumption (number/day).
Main Outcomes and Measures 
Hazard ratio (HR) and absolute risk difference (ARD) over the entire follow-up for incident CVD (composite of fatal and nonfatal coronary heart disease, stroke, heart failure, and other CVD deaths) and all-cause mortality, adjusting for demographic, socioeconomic, and behavioral factors.
Results 
This analysis included 29 615 participants (mean [SD] age, 51.6 [13.5] years at baseline) of whom 13 299 (44.9%) were men and 9204 (31.1%) were black. During a median follow-up of 17.5 years (interquartile range, 13.0-21.7; maximum, 31.3), there were 5400 incident CVD events and 6132 all-cause deaths. The associations of dietary cholesterol or egg consumption with incident CVD and all-cause mortality were monotonic (all P values for nonlinear terms, .19-.83). Each additional 300 mg of dietary cholesterol consumed per day was significantly associated with higher risk of incident CVD (adjusted HR, 1.17 [95% CI, 1.09-1.26]; adjusted ARD, 3.24% [95% CI, 1.39%-5.08%]) and all-cause mortality (adjusted HR, 1.18 [95% CI, 1.10-1.26]; adjusted ARD, 4.43% [95% CI, 2.51%-6.36%]). Each additional half an egg consumed per day was significantly associated with higher risk of incident CVD (adjusted HR, 1.06 [95% CI, 1.03-1.10]; adjusted ARD, 1.11% [95% CI, 0.32%-1.89%]) and all-cause mortality (adjusted HR, 1.08 [95% CI, 1.04-1.11]; adjusted ARD, 1.93% [95% CI, 1.10%-2.76%]). The associations between egg consumption and incident CVD (adjusted HR, 0.99 [95% CI, 0.93-1.05]; adjusted ARD, −0.47% [95% CI, −1.83% to 0.88%]) and all-cause mortality (adjusted HR, 1.03 [95% CI, 0.97-1.09]; adjusted ARD, 0.71% [95% CI, −0.85% to 2.28%]) were no longer significant after adjusting for dietary cholesterol consumption.
Conclusions and Relevance 
Among US adults, higher consumption of dietary cholesterol or eggs was significantly associated with higher risk of incident CVD and all-cause mortality in a dose-response manner. These results should be considered in the development of dietary guidelines and updates.

9.

Background: Recent studies have reported conflicting associations between egg consumption and the risk of all-cause or cardiovascular disease (CVD) mortality, including ischemic heart disease (IHD) mortality and stroke mortality. With accumulating evidence, up-to-date evidence about the association should be synthesized.

Objectives: We aimed to assess the association of the risk of all-cause and CVD mortality with egg consumption.

Methods: We searched the PubMed, Embase, and Web of Science databases through 3 November, 2021 for observational studies conducted in participants ≥18 y of age and which provided ORs, RRs, or HRs and 95% CIs for ≥3 egg consumption categories or for increased intake of egg addressing the associations of interest. A random-effects model was used to pool the reported risk estimates. Restricted cubic splines were used to examine the dose-response association.

Results: Twenty-four articles with 48 reports (25 for all-cause mortality, 11 for CVD mortality, 6 for IHD mortality, and 6 for stroke mortality) involving 11,890,695 participants were included. Intake of each 1-egg/d increment was associated with increased risk of all-cause mortality (

Rr: 1.06; 95%

Ci: 1.02, 1.10; P = 0.008), but the association was restricted to women, Americans, and studies with adjustments for hyperlipidemia. Egg consumption was linearly associated with CVD mortality only in participants >60 y of age, Americans, studies with follow-up duration ≥15 y, and studies with adjustments for hyperlipidemia (P ≤ 0.018). No significant association was found between egg consumption and IHD or stroke mortality (P ≥ 0.080).

Conclusions: Egg consumption was linearly associated with a modestly increased risk of all-cause mortality and, in older participants, Americans, and studies with longer follow-up or adjustments for hyperlipidemia, CVD mortality. These findings suggest that it may be prudent to avoid high egg consumption.

10.
Egg and Cholesterol Consumption and Mortality From Cardiovascular and Different Causes in the United States: A Population-Based Cohort Study.

Zhuang P, Wu F, Mao L, et al.

PLoS Medicine. 2021;18(2):e1003508. doi:10.1371/journal.pmed.1003508.

Leading Journal

Background: Whether consumption of egg and cholesterol is detrimental to cardiovascular health and longevity is highly debated. Data from large-scale cohort studies are scarce. This study aimed to examine the associations of egg and cholesterol intakes with mortality from all causes, cardiovascular disease (CVD), and other causes in a US population.

Methods And Findings: Overall, 521,120 participants (aged 50-71 years, mean age = 62.2 years, 41.2% women, and 91.8% non-Hispanic white) were recruited from 6 states and 2 additional cities in the US between 1995 and 1996 and prospectively followed up until the end of 2011. Intakes of whole eggs, egg whites/substitutes, and cholesterol were assessed by a validated food frequency questionnaire. Cause-specific hazard models considering competing risks were used, with the lowest quintile of energy-adjusted intake (per 2,000 kcal per day) as the reference. There were 129,328 deaths including 38,747 deaths from CVD during a median follow-up of 16 years. Whole egg and cholesterol intakes were both positively associated with all-cause, CVD, and cancer mortality. In multivariable-adjusted models, the hazard ratios (95% confidence intervals) associated with each intake of an additional half of a whole egg per day were 1.07 (1.06-1.08) for all-cause mortality, 1.07 (1.06-1.09) for CVD mortality, and 1.07 (1.06-1.09) for cancer mortality. Each intake of an additional 300 mg of dietary cholesterol per day was associated with 19%, 16%, and 24% higher all-cause, CVD, and cancer mortality, respectively. Mediation models estimated that cholesterol intake contributed to 63.2% (95% CI 49.6%-75.0%), 62.3% (95% CI 39.5%-80.7%), and 49.6% (95% CI 31.9%-67.4%) of all-cause, CVD, and cancer mortality associated with whole egg consumption, respectively. Egg white/substitute consumers had lower all-cause mortality and mortality from stroke, cancer, respiratory disease, and Alzheimer disease compared with non-consumers. Hypothetically, replacing half a whole egg with equivalent amounts of egg whites/substitutes, poultry, fish, dairy products, or nuts/legumes was related to lower all-cause, CVD, cancer, and respiratory disease mortality. Study limitations include its observational nature, reliance on participant self-report, and residual confounding despite extensive adjustment for acknowledged dietary and lifestyle risk factors.

Conclusions: In this study, intakes of eggs and cholesterol were associated with higher all-cause, CVD, and cancer mortality. The increased mortality associated with egg consumption was largely influenced by cholesterol intake. Our findings suggest limiting cholesterol intake and replacing whole eggs with egg whites/substitutes or other alternative protein sources for facilitating cardiovascular health and long-term survival.

Trial Registration: ClinicalTrials.gov NCT00340015.

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The cholesterol found in egg yolks is not considered beneficial for health, particularly in the context of eating one egg per day. Egg yolks are a major source of dietary cholesterol (∼186 mg per large egg), and higher dietary cholesterol intake is associated with increased risk of cardiovascular disease and all-cause mortality in large US cohort studies and meta-analyses.[1-2] The American Heart Association recommends limiting dietary cholesterol as part of heart-healthy dietary patterns.[3]
However, the impact of one egg per day on blood lipids and cardiovascular risk is modest for most healthy individuals, and several multinational studies and meta-analyses report no significant association between moderate egg consumption and adverse outcomes, especially outside the US or in populations with otherwise healthy diets.[4-7] Individual response to dietary cholesterol varies, and compensatory mechanisms may mitigate its effect in many people.[8]
In summary, egg yolk cholesterol is not considered beneficial, and its intake should be limited in individuals at elevated cardiovascular risk, but one egg per day is unlikely to cause harm in most healthy adults when consumed as part of a balanced diet.[1-3]

1.
Associations of Dietary Cholesterol, Serum Cholesterol, and Egg Consumption With Overall and Cause-Specific Mortality: Systematic Review and Updated Meta-Analysis.

Zhao B, Gan L, Graubard BI, et al.

Circulation. 2022;145(20):1506-1520. doi:10.1161/CIRCULATIONAHA.121.057642.

Leading Journal

Background: Despite substantial research highlighting the importance of exogenous dietary cholesterol intake and endogenous serum cholesterol level in human health, a thorough evaluation of the associations is lacking. Our study objective was to examine overall and cause-specific mortality in relation to dietary and serum cholesterol, as well as egg consumption, and conduct an updated meta-regression analysis of cohort studies.

Methods: We conducted a prospective analysis of 27 078 men in the ATBC Study (Alpha-Tocopherol, Beta-Carotene Cancer Prevention). Multivariable-controlled cause-specific Cox proportional hazards regression models were used to calculate hazard ratios and 31-year absolute mortality risk differences. A systematic review and meta-analysis of cohort studies was also performed (PROSPERO [

Url: https://www.crd.york.ac.uk/prospero/; Unique identifier: CRD42021272756]).

Results: Based on 482 316 person-years of follow-up, we identified 22 035 deaths, including 9110 deaths from cardiovascular disease (CVD). Greater dietary cholesterol and egg consumption were associated with increased risk of overall and CVD-related mortality. Hazard ratios for each additional 300 mg cholesterol intake per day were 1.10 and 1.13 for overall and CVD-related mortality, respectively; for each additional 50-g egg consumed daily, hazard ratios were 1.06 and 1.09, respectively, for overall and CVD-related mortality (all P values<0.0001). After multivariable adjustment, higher serum total cholesterol concentrations were associated with increased risk of CVD-related mortality (hazard ratios per 1 SD increment, 1.14; P<0.0001). The observed associations were generally similar across cohort subgroups. The updated meta-analysis of cohort studies on the basis of 49 risk estimates, 3 601 401 participants, and 255 479 events showed consumption of 1 additional 50-g egg daily was associated with significantly increased CVD risk (pooled relative risk, 1.04 [95% CI, 1.00-1.08]; I2=80.1%). In the subgroup analysis of geographic regions (Pinteraction=0.02), an increase of 50-g egg consumed daily was associated with a higher risk of CVD in US cohorts (pooled relative risk, 1.08 [95% CI, 1.02-1.14]) and appeared related to a higher CVD risk in European cohorts with borderline significance (pooled relative risk, 1.05), but was not associated with CVD risk in Asian cohorts.

Conclusions: In this prospective cohort study and updated meta-analysis, greater dietary cholesterol and egg consumption were associated with increased risk of overall and CVD-related mortality. Our findings support restricted consumption of dietary cholesterol as a means to improve long-term health and longevity.

2.
Associations of Dietary Cholesterol or Egg Consumption With Incident Cardiovascular Disease and Mortality.

Zhong VW, Van Horn L, Cornelis MC, et al.

JAMA logoJAMA. 2019;321(11):1081-1095. doi:10.1001/jama.2019.1572.

Leading Journal
Abstract

Importance 
Cholesterol is a common nutrient in the human diet and eggs are a major source of dietary cholesterol. Whether dietary cholesterol or egg consumption is associated with cardiovascular disease (CVD) and mortality remains controversial.
Objective 
To determine the associations of dietary cholesterol or egg consumption with incident CVD and all-cause mortality.
Design, Setting, and Participants 
Individual participant data were pooled from 6 prospective US cohorts using data collected between March 25, 1985, and August 31, 2016. Self-reported diet data were harmonized using a standardized protocol.
Exposures 
Dietary cholesterol (mg/day) or egg consumption (number/day).
Main Outcomes and Measures 
Hazard ratio (HR) and absolute risk difference (ARD) over the entire follow-up for incident CVD (composite of fatal and nonfatal coronary heart disease, stroke, heart failure, and other CVD deaths) and all-cause mortality, adjusting for demographic, socioeconomic, and behavioral factors.
Results 
This analysis included 29 615 participants (mean [SD] age, 51.6 [13.5] years at baseline) of whom 13 299 (44.9%) were men and 9204 (31.1%) were black. During a median follow-up of 17.5 years (interquartile range, 13.0-21.7; maximum, 31.3), there were 5400 incident CVD events and 6132 all-cause deaths. The associations of dietary cholesterol or egg consumption with incident CVD and all-cause mortality were monotonic (all P values for nonlinear terms, .19-.83). Each additional 300 mg of dietary cholesterol consumed per day was significantly associated with higher risk of incident CVD (adjusted HR, 1.17 [95% CI, 1.09-1.26]; adjusted ARD, 3.24% [95% CI, 1.39%-5.08%]) and all-cause mortality (adjusted HR, 1.18 [95% CI, 1.10-1.26]; adjusted ARD, 4.43% [95% CI, 2.51%-6.36%]). Each additional half an egg consumed per day was significantly associated with higher risk of incident CVD (adjusted HR, 1.06 [95% CI, 1.03-1.10]; adjusted ARD, 1.11% [95% CI, 0.32%-1.89%]) and all-cause mortality (adjusted HR, 1.08 [95% CI, 1.04-1.11]; adjusted ARD, 1.93% [95% CI, 1.10%-2.76%]). The associations between egg consumption and incident CVD (adjusted HR, 0.99 [95% CI, 0.93-1.05]; adjusted ARD, −0.47% [95% CI, −1.83% to 0.88%]) and all-cause mortality (adjusted HR, 1.03 [95% CI, 0.97-1.09]; adjusted ARD, 0.71% [95% CI, −0.85% to 2.28%]) were no longer significant after adjusting for dietary cholesterol consumption.
Conclusions and Relevance 
Among US adults, higher consumption of dietary cholesterol or eggs was significantly associated with higher risk of incident CVD and all-cause mortality in a dose-response manner. These results should be considered in the development of dietary guidelines and updates.

Key Points

Question Is consuming dietary cholesterol or eggs associated with incident cardiovascular disease (CVD) and all-cause mortality?

Findings Among 29 615 adults pooled from 6 prospective cohort studies in the United States with a median follow-up of 17.5 years, each additional 300 mg of dietary cholesterol consumed per day was significantly associated with higher risk of incident CVD (adjusted hazard ratio [HR], 1.17; adjusted absolute risk difference [ARD], 3.24%) and all-cause mortality (adjusted HR, 1.18; adjusted ARD, 4.43%), and each additional half an egg consumed per day was significantly associated with higher risk of incident CVD (adjusted HR, 1.06; adjusted ARD, 1.11%) and all-cause mortality (adjusted HR, 1.08; adjusted ARD, 1.93%).

Meaning Among US adults, higher consumption of dietary cholesterol or eggs was significantly associated with higher risk of incident CVD and all-cause mortality in a dose-response manner.

3.
2021 Dietary Guidance to Improve Cardiovascular Health: A Scientific Statement From the American Heart Association.

Lichtenstein AH, Appel LJ, Vadiveloo M, et al.

Circulation. 2021;144(23):e472-e487. doi:10.1161/CIR.0000000000001031.

Leading Journal

Guidance for reducing CVD risk and LDL cholesterol concentrations have historically included recommendations to limit dietary cholesterol, although more recently numerical limits have not been explicit. 131 A positive relation between dietary cholesterol and LDL cholesterol concentrations has been documented; still, the current US intake is similar to the historical 300 mg/d upper level. 132 Consistent with these findings, the 2020 Dietary Guidelines Advisory Committee report noted that current intakes should not be increased. 9 Assessing the independent effect of dietary cholesterol on CVD risk is complicated by the lack of evidence at plausible, rather than extremely high intakes, and the difficulty in isolating the effects of eggs from those of frequently paired foods such as bacon and sausage. Adhering to a dietary pattern consistent with the guidance in this document will result in relatively low dietary cholesterol intakes. An in-depth analysis of the topic can be found in the AHA scientific statement on dietary cholesterol and cardiovascular risk. 132

4.
Association of Egg Intake With Blood Lipids, Cardiovascular Disease, and Mortality in 177,000 People in 50 Countries.

Dehghan M, Mente A, Rangarajan S, et al.

The American Journal of Clinical Nutrition. 2020;111(4):795-803. doi:10.1093/ajcn/nqz348.

Background: Eggs are a rich source of essential nutrients, but they are also a source of dietary cholesterol. Therefore, some guidelines recommend limiting egg consumption. However, there is contradictory evidence on the impact of eggs on diseases, largely based on studies conducted in high-income countries.

Objectives: Our aim was to assess the association of egg consumption with blood lipids, cardiovascular disease (CVD), and mortality in large global studies involving populations from low-, middle-, and high-income countries.

Methods: We studied 146,011 individuals from 21 countries in the Prospective Urban Rural Epidemiology (PURE) study. Egg consumption was recorded using country-specific validated FFQs. We also studied 31,544 patients with vascular disease in 2 multinational prospective studies: ONTARGET (Ongoing Telmisartan Alone and in Combination with Ramipril Global End Point Trial) and TRANSCEND (Telmisartan Randomized Assessment Study in ACEI Intolerant Subjects with Cardiovascular Disease). We calculated HRs using multivariable Cox frailty models with random intercepts to account for clustering by study center separately within each study.

Results: In the PURE study, we recorded 14,700 composite events (8932 deaths and 8477 CVD events). In the PURE study, after excluding those with history of CVD, higher intake of egg (≥7 egg/wk compared with <1 egg/wk intake) was not significantly associated with blood lipids, composite outcome (

Hr: 0.96; 95%

Ci: 0.89, 1.04; P-trend = 0.74), total mortality (

Hr: 1.04; 95%

Ci: 0.94, 1.15; P-trend = 0.38), or major CVD (

Hr: 0.92; 95%

Ci: 0.83, 1.01; P-trend = 0.20). Similar results were observed in ONTARGET/TRANSCEND studies for composite outcome (HR 0.97; 95%

Ci: 0.76, 1.25; P-trend = 0.09), total mortality (

Hr: 0.88; 95%

Ci: 0.62, 1.24; P-trend = 0.55), and major CVD (

Hr: 0.97; 95%

Ci: 0.73, 1.29; P-trend = 0.12).

Conclusions: In 3 large international prospective studies including ∼177,000 individuals, 12,701 deaths, and 13,658 CVD events from 50 countries in 6 continents, we did not find significant associations between egg intake and blood lipids, mortality, or major CVD events. The ONTARGET and TRANSCEND trials were registered at clinicaltrials.gov as NCT00153101. The PURE trial was registered at clinicaltrials.gov as NCT03225586.

5.
Eggs: Healthy or Risky? A Review of Evidence From High Quality Studies on Hen's Eggs.

Myers M, Ruxton CHS.

Nutrients. 2023;15(12):2657. doi:10.3390/nu15122657.

Hen's eggs (from ) provide choline, folate, vitamin D, iodine, B vitamins and high-quality protein and are no longer viewed by national bodies as a risk factor for hypercholesterolaemia and cardiovascular disease (CVD). Yet, questions remain about the benefits and risks of eating eggs regularly. This review evaluates recent high-quality evidence from randomised controlled trials (RCT) and meta-analyses of observational studies and considers new areas of interest, such as weight management, protein metabolism, allergy risk and sustainability. In several RCT, eggs increased muscle protein synthesis and lowered fat mass, which could support optimal body composition. Eggs within a meal improved satiety, which could translate into lower energy intakes, although more RCT are needed. In observational studies, higher egg consumption was associated with a null effect or a modest reduced risk of CVD. For type 2 diabetes (T2D) incidence and risk of CVD in people with T2D, there were inconsistencies between observational and RCT data, with the former noting positive associations and the latter seeing no effect of higher egg intake on markers of T2D and CVD. Sustainability metrics suggest that eggs have the lowest planetary impact amongst animal proteins. To lower allergy risk, earlier introduction of eggs into weaning diets is warranted. In conclusion, the balance of evidence points to eggs being a nutritious food suggesting there are broad health benefits from including eggs in the diet at intakes higher than that currently consumed by European populations.

6.
Nutritional Viewpoints on Eggs and Cholesterol.

Sugano M, Matsuoka R.

Foods (Basel, Switzerland). 2021;10(3):494. doi:10.3390/foods10030494.

Although most current epidemiologic studies indicate no significant association between consuming one egg daily and blood cholesterol levels and cardiovascular risk, arguments still persist with a positive association. Since the diet is one of the most influential factors for this association, we illustrate characteristic features in Japanese people whose dietary pattern is distinct from that, for example, the US (United States) population. Available epidemiologic studies in healthy Japanese people show no association between consumption of one egg daily and blood cholesterol level, consistent with those observed in the US population. However, when consumption of major nutrients and food sources of cholesterol are compared to the US population, Japanese people may have an extra-reserve against the influence of eggs on cardiovascular risk markers, despite consuming relatively more eggs. Further discussion on the influence of nutrients contained in the egg and dietary pattern, including interaction with gut microbes, is necessary. In addition, special consideration at the personalized level is needed for judgment regarding dietary cholesterol not only for hypercholesterolemic patients but for hyper-responsive healthy persons. Although randomized controlled trials with long-term follow-up are required to evaluate the association between consumption of eggs and human health, available information, at least from the nutritional viewpoint, suggests that egg is a healthy and cost-efficient food worldwide.

7.
Effect of Egg Consumption on Health Outcomes: An Updated Umbrella Review of Systematic Reviews and Meta-Analysis of Observational and Intervention Studies.

Formisano E, Lopes Neri LC, Caffa I, et al.

Nutrition, Metabolism, and Cardiovascular Diseases : NMCD. 2025;35(5):103849. doi:10.1016/j.numecd.2025.103849.

New Research

Aims: To evaluate the effect of egg consumption on health outcomes.

Data Synthesis: A systematic search in PubMed, Scopus, Lilacs, and Web of Science was developed using terms ("egg consumption" or "egg intake") and ("health" or "chronic diseases" or "diabetes" or "cancer" or "cholesterol" or "dyslipidemia"), and meta-analyses of observational or interventional studies published since January 2020 were included. The studies' quality was evaluated through AMSTAR-2 and NutriGrade, and the strength of evidence according to sample size, heterogeneity, and quality of articles. Fourteen meta-analyses were included (10 observational, 4 interventional studies). The wide range of outcomes, with substantial variability and high heterogeneity, indicated a lack of robust evidence. The overall quality of studies was critically low. The level of evidence was very weak for all the significant associations: risk of heart failure (RR 1.15; 95%

Ci: 1.02-1.30), cancer mortality (RR 1.13; 95%CI 1.06-1.20), higher levels of LDL cholesterol (WMD 7.39; 95%CI 5.82-8.95), total cholesterol (WMD 9.12; 95%CI 7.35-10.89), and apolipoprotein B-100 (WMD 0.06; 95%CI 0.03-0.08). Conversely, egg intake has been weakly associated with improvements in HDL cholesterol (WMD 1.37; 95%CI 0.49-2.25), apolipoprotein A1 (WMD 0.03; 95%CI 0.01-0.05), and growth parameters in children (WMD 0.47; 95%CI 0.13-0.80). No evidence of association was found among all cardiovascular outcomes and all-cause mortality risk between high vs. low egg consumption.

Conclusion: Due to the critically low strength of studies, insufficient evidence is available to discourage egg consumption, suggesting eggs can be part of a healthy diet.

8.
The Association of Dietary Cholesterol From Egg Consumption on Cardiovascular Diseases Risk Varies From Person to Person.

Zhang F, Li J, Chang C, et al.

Journal of Agricultural and Food Chemistry. 2022;70(48):14977-14988. doi:10.1021/acs.jafc.2c04634.

The public and scientists remain skeptical about egg consumption, given that cardiovascular diseases (CVDs) are the leading causes of death in worldwide. This review mainly explained the recurrence of contradictory conclusions about relationships between egg consumption and CVD risk and discussed effects of egg cholesterol intake on cholesterol homeostasis. Factors including individual health status and cholesterol sensitivity, dietary pattern, region, and race should be distinguished when understanding generalized conclusions. Identified compensatory mechanisms in response to dietary cholesterol and the resulting balance in cholesterol biosynthesis, absorption, and efflux supported the view that moderate egg consumption had no substantial overall impacts on cholesterol homeostasis in healthy people. Excessive cholesterol intake is not recommended in individuals with distempered metabolism. More than cholesterol metabolism, impacts of egg consumption as a part of overall diet on CVD risk should be considered from aspects of nutrient intake, lipid metabolism, and energy supply in the future.

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All of the cholesterol in eggs is the same molecular species—unesterified cholesterol—and is neither "good" nor "bad" in itself; its health impact depends on how it affects serum lipoproteins. Egg yolk cholesterol can raise both low-density lipoprotein (LDL, "bad" cholesterol) and high-density lipoprotein (HDL, "good" cholesterol) levels, but the net effect on cardiovascular risk is determined by the change in the LDL/HDL ratio and the specific LDL particle profile.
Meta-analyses and randomized controlled trials show that egg consumption modestly increases both LDL and HDL cholesterol, with a typical increase in LDL of 5–8 mg/dL and HDL of 2–3 mg/dL per day of egg intake.[1-4] The LDL/HDL ratio is either unchanged or minimally increased, suggesting that the rise in "bad" cholesterol is not fully offset by the rise in "good" cholesterol.[1-2][4] Importantly, eggs may increase small, dense LDL particles, which are more atherogenic, while reducing large, less atherogenic LDL particles.[5]
Eggs also contain apolipoprotein B-100, which is associated with atherogenic lipoproteins, and apolipoprotein A1, which is associated with HDL particles. Egg intake modestly increases apolipoprotein B-100 and apolipoprotein A1, but the clinical significance of these changes is less clear.[3]
In summary, the cholesterol in eggs is not inherently "good" or "bad," but egg consumption modestly raises both LDL and HDL cholesterol, with a net effect that may be neutral or slightly adverse depending on individual response and baseline risk. Eggs do not contain other lipoproteins themselves, but their consumption can alter the profile of circulating lipoproteins, including increasing small, dense LDL particles, which may be harmful.[3-5]

1.
Effects of Egg Consumption on Blood Lipids: A Systematic Review and Meta-Analysis of Randomized Clinical Trials.

Rouhani MH, Rashidi-Pourfard N, Salehi-Abargouei A, Karimi M, Haghighatdoost F.

Journal of the American College of Nutrition. 2018;37(2):99-110. doi:10.1080/07315724.2017.1366878.

Background: It is widely agreed that egg consumption only modestly influences serum lipid concentrations. However, there is no meta-analysis summarizing existing randomized controlled trials.

Objective: The purpose of this study was to conduct a meta-analysis of published randomized controlled trials to explore the quantitative effect of egg consumption on serum lipid concentrations.

Design: Online databases including MEDLINE, Proquest and Google Scholar were systematically searched. Studies that were published after 2000 and compared serum lipids concentrations in egg-consumers and non egg-consumers were included. The data were obtained from 28 studies. Weighted mean differences were calculated as the ultimate effect using random effects model.

Results: Overall, egg consumption increased total cholesterol (TC) by 5.60 mg/dL (95%

Ci: 3.11, 8.09; P<0.0001), low density lipoprotein-cholesterol (LDL-C) by 5.55 mg/dL (95%

Ci: 3.14, 7.69; P<0.0001) and high density lipoprotein-cholesterol (HDL-C) by 2.13 mg/dL (95%

Ci: 1.10, 3.16; P<0.0001) compared with the control group. Heterogeneity found between studies was explained partly by study design and participant response to dietary cholesterol. No effect of increased egg consumption on LDL-C:HDL-C and TC:HDL-C ratios, and triglyceride (TG) concentrations were found. No association was observed between number of eggs consumed per day or study duration and any of the serum lipid markers.

Conclusion: Consumption of egg increases total cholesterol, LDL-C and HDL-C, but not LDL-C:HDL-C, TC:HDL-C and TG compared with low egg control diets. To assess the risk of coronary events, future studies should focus on the postprandial effect of egg consumption and effects on coronary risk.

2.

The association of egg consumption and serum cholesterol concentrations in healthy people has been discussed for a long time. In this study, we aimed to explore association of egg consumption with on low-density lipoprotein cholesterol (LDL-c) and high-density lipoprotein cholesterol (HDL-c) concentrations and the LDL-c/HDL-c ratio through meta-analysis. This systematic review only included randomized controlled trials (RCTs) investigating egg consumption in healthy populations without combination therapy. We extracted mean and standard deviation for LDL-c/HDL-c ratio, LDL-c/HDL-c. The extracted data were pooled in a random-effects model and were presented as mean difference (MD) with 95% confidence interval (CI). Moreover, subgroup analyses were conducted for understanding effects of more egg consumption (MEC) on different intervention periods, egg-consumption levels, classification of responders. Overall, 17 RCTs met the eligibility criteria and pooled results showed MEC group had a higher LDL-c/HDL-c ratio than the control group (MD = 0.14, = 0.001, I = 25%). The MEC group also had higher LDL-c than the control group (MD = 8.14, < 0.0001, I = 18%). Moreover, for the subset of intervention over two months, the MEC group seemed to have a larger effect size than the subset of intervention within two months. This synthesis, the largest meta-analysis on this topic, shows the impact of egg consumption on lipid profiles among healthy subjects. Notably, longer time with MEC may lead to higher LDL-c/HDL-c ratio and LDL-c. However, RCTs with long tern follow-up are needed to guarantee the association between egg consumption and human health.

3.
Effect of Egg Consumption on Health Outcomes: An Updated Umbrella Review of Systematic Reviews and Meta-Analysis of Observational and Intervention Studies.

Formisano E, Lopes Neri LC, Caffa I, et al.

Nutrition, Metabolism, and Cardiovascular Diseases : NMCD. 2025;35(5):103849. doi:10.1016/j.numecd.2025.103849.

New Research

Aims: To evaluate the effect of egg consumption on health outcomes.

Data Synthesis: A systematic search in PubMed, Scopus, Lilacs, and Web of Science was developed using terms ("egg consumption" or "egg intake") and ("health" or "chronic diseases" or "diabetes" or "cancer" or "cholesterol" or "dyslipidemia"), and meta-analyses of observational or interventional studies published since January 2020 were included. The studies' quality was evaluated through AMSTAR-2 and NutriGrade, and the strength of evidence according to sample size, heterogeneity, and quality of articles. Fourteen meta-analyses were included (10 observational, 4 interventional studies). The wide range of outcomes, with substantial variability and high heterogeneity, indicated a lack of robust evidence. The overall quality of studies was critically low. The level of evidence was very weak for all the significant associations: risk of heart failure (RR 1.15; 95%

Ci: 1.02-1.30), cancer mortality (RR 1.13; 95%CI 1.06-1.20), higher levels of LDL cholesterol (WMD 7.39; 95%CI 5.82-8.95), total cholesterol (WMD 9.12; 95%CI 7.35-10.89), and apolipoprotein B-100 (WMD 0.06; 95%CI 0.03-0.08). Conversely, egg intake has been weakly associated with improvements in HDL cholesterol (WMD 1.37; 95%CI 0.49-2.25), apolipoprotein A1 (WMD 0.03; 95%CI 0.01-0.05), and growth parameters in children (WMD 0.47; 95%CI 0.13-0.80). No evidence of association was found among all cardiovascular outcomes and all-cause mortality risk between high vs. low egg consumption.

Conclusion: Due to the critically low strength of studies, insufficient evidence is available to discourage egg consumption, suggesting eggs can be part of a healthy diet.

4.
Impact of Whole Egg Intake on Blood Pressure, Lipids and Lipoproteins in Middle-Aged and Older Population: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Wang MX, Wong CH, Kim JE.

Nutrition, Metabolism, and Cardiovascular Diseases : NMCD. 2019;29(7):653-664. doi:10.1016/j.numecd.2019.04.004.

Background And Aim: Effects of whole egg consumption on cardiovascular diseases (CVD) risk in the middle-aged and older population remain unclear due to inconsistent findings from observational and randomized controlled trials (RCTs). This meta-analysis aimed to assess the impacts of whole egg and egg category (whole eggs versus egg substitutes) intake quantity on CVD risk factors from systematically searched RCTs. Egg substitutes were hypothesized to have minimal effects of the blood lipid and lipoprotein profile as they are void of dietary cholesterol.

Methods And Results: As many as 434 studies identified from PubMed, Cochrane Library, CINAHL and Medline (Ovid) databases were screened and data were extracted from 8 selected RCTs. Quality of the selected studies were assessed and the overall effect sizes of weighted mean differences (WMD) were calculated using a random effects model. Non-differential effects in blood pressures, lipids and lipoproteins were observed when >4 whole eggs/week compared to ≤4 whole eggs/week were consumed. Intake of >4 whole eggs/week compared to equivalent amounts of egg substitutes caused greater elevations in blood total cholesterol (

Wmd: 0.198 mmol/L; 95% CIs: 0.056, 0.339), HDL cholesterol (

Wmd: 0.068 mmol/L; 95% CIs: 0.006, 0.130) and LDL cholesterol (

Wmd: 0.171 mmol/L; 95% CIs: 0.028, 0.315) but did not differentially affect triglycerides concentration.

Conclusion: Overall, the results support the notion that quantity of whole egg intake does not affect CVD risk factors and consuming egg substitutes may also be beneficial compared to whole eggs on lowering CVD risk in the middle-aged and older population.

5.
Impact of Dietary Cholesterol From Eggs and Saturated Fat on LDL Cholesterol Levels: A Randomized Cross-Over Study.

Carter S, Hill AM, Yandell C, et al.

The American Journal of Clinical Nutrition. 2025;122(1):83-91. doi:10.1016/j.ajcnut.2025.05.001.

New Research

Background: Cardiovascular disease (CVD) remains a leading cause of death. Although dietary cholesterol from eggs has been a focus of dietary guidelines, recent evidence suggests that saturated fat has a greater impact on LDL cholesterol.

Objectives: This study examined the independent effects of dietary cholesterol and saturated fat on LDL concentrations.

Methods: In this randomized, controlled, cross-over study (clinicaltrials.gov, NCT05267522), 61 adults (age 39 ± 12 y, BMI 25.8 ± 5.9 kg/m2) with baseline LDL cholesterol <3.5 mmol/L (135.3 μg/dL) were assigned to 3 isocaloric diets for 5 wk each: high-cholesterol (600 mg/d), low-saturated fat (6%) including 2 eggs/d (EGG); low-cholesterol (300 mg/d), high-saturated fat (12%) without eggs (EGG-FREE); and a high-cholesterol (600 mg/d), high-saturated fat (12%) control diet (CON) including 1 egg/wk. Outcomes were assessed at the end of each diet phase.

Results: Fifty-four participants completed ≥1 diet phase, and 48 completed all diet phases. Compared with CON, EGG but not EGG-FREE reduced LDL cholesterol (CON 109.3 ± 3.1 μg/dL compared with EGG 103.6 ± 3.1 μg/dL P = 0.02 compared with EGG-FREE 107.7 ± 3.1 μg/dL, P = 0.52). Across all diets, saturated fat intake was positively correlated with LDL cholesterol (β = 0.35, P = 0.002), whereas dietary cholesterol was not (β = -0.006, P = 0.42). Compared with CON, EGG but not EGG-FREE reduced concentrations of large (EGG β = -48.6, P = 0.03; EGG-FREE β = -35.85, P = 0.12) and increased concentrations of small LDL particles (EGG β = 95.1, P = 0.004; EGG-FREE β = 55.82, P = 0.10).

Conclusions: Saturated fat, not dietary cholesterol, elevates LDL cholesterol. Compared with consuming a high-saturated fat diet with only 1 egg/wk, consuming 2 eggs daily as part of a low-saturated fat diet lowers LDL concentrations, which may reduce CVD risk. However, this effect on CVD risk may be mitigated, at least in part, by a reduction in less-atherogenic large LDL particles and an increase in more atherogenic small LDL particles.

Trial Registration: This trial was registered at clinicaltrials.gov as NCT05267522 (https://clinicaltrials.gov/study/NCT05267522?term=eggs%20and%20cholesterol&rank=3).

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Six ounces of lean meat contains approximately 42 grams of protein, whereas 1 egg white contains approximately 3.5 grams of protein.[1-4] Thus, 6 ounces of lean meat provides about 12 times as much protein as a single egg white. Both are considered high-quality, complete proteins with excellent digestibility and amino acid profiles.[1][3-4]

1.
Guidance on Energy and Macronutrients across the Life Span.

Heymsfield SB, Shapses SA.

The New England Journal of Medicine. 2024;390(14):1299-1310. doi:10.1056/NEJMra2214275.

Leading Journal
Energy and Macronutrients > Protein

Proteins, synthesized from amino acids, are the major structural and functional components of the human body. Nine of the 20 amino acids found in human proteins are indispensable (essential); omitting any one of them from the diet leads to physical signs and a negative whole-body protein balance. Six amino acids are recognized as conditionally indispensable, meaning that sufficient amounts cannot be synthesized during periods of rapid growth and severe metabolic stress. The remaining 5 amino acids are dispensable (nonessential); they can be synthesized in vivo to meet the needs of the body. In the 1930s, Rudolf Schoenheimer and his colleagues showed that biomolecules in the body such as proteins are in a dynamic state of continual turnover that requires replacement through the diet to maintain most body functions and health.

Animal sources of protein contain all 9 indispensable amino acids, whereas plant proteins are usually deficient in 1 or more indispensable amino acids. A digestible amino acid score is used to grade protein sources, with a reference set at the digestibility-adjusted indispensable amino acid requirements for a preschool-age child. Cow’s milk, beef, and eggs have the highest score, at a value of approximately 1; rice has a value of approximately 0.5. Soy protein, with a score of approximately 0.9, is a beneficial plant source of amino acids. Vegetarians and vegans can maintain adequate high-quality protein intake by eating a variety of plant-based foods, including legumes, grains, soy products, nuts, and seeds.

Individual amino acid requirements are mainly established by means of isotopic tracer methods. Protein requirements are estimated with the use of nitrogen-balance methods, which monitor nitrogen losses in feces, urine, and skin according to variations in protein intake. An inadequate intake of total protein or any indispensable amino acid leads to adaptations in protein metabolism that can impair infant brain development, immune competence, and many other physiological and metabolic functions. Inadequate intake of energy from fat and carbohydrates can also lead to a negative nitrogen balance. In contrast, excess amino acids that are present during periods of high protein intake can be deaminated to form α-keto acids, which can then be oxidized for energy or converted to glucose or fat.

2.
Lean Beef Contributes Significant Amounts of Key Nutrients to the Diets of US Adults: National Health and Nutrition Examination Survey 1999-2004.

Zanovec M, O'Neil CE, Keast DR, Fulgoni VL, Nicklas TA.

Nutrition Research (New York, N.Y.). 2010;30(6):375-81. doi:10.1016/j.nutres.2010.06.001.

Consumption of lean meat is a valuable addition to a healthy diet because it provides complete protein and is a rich source of vitamin B(12), iron, and zinc. The objective of this study was to examine the nutritional contribution of total beef and lean beef (LB) to the American diet using the USDA definition of LB as defined in MyPyramid. Twenty-four-hour dietary recall data from adults 19 to 50 years of age (n = 7049) and 51+ years (n = 6243) participating in the National Health and Nutrition Examination Survey 1999-2004 were assessed. Lean beef was defined as beef with <9.28 g fat per 100 g (excess was discretionary fat). Fifty percent of adults 19 to 50 years and 41% of adults 51+ years consumed beef on the day of the dietary recall. Total beef consumed among adults 19 to 50 and 51+ years was 49.3 +/- 1.4 g (1.74 oz/d) and 37.1 +/- 1.2 g (1.31 oz/d), respectively. In adults 19 to 50 and 51+ years, LB contributed 3.9% and 3.7% to total energy; 4.5% and 4.1% to total fat, 3.8% and 3.6% to saturated fatty acids; 13% and 11% to cholesterol intake; 15% and 14% to protein; 25% and 20% to vitamin B(12); 23% and 20% to zinc; and 8% and 7% to iron, respectively. Beef was also an important food source of many other nutrients, including niacin, vitamin B(6), phosphorus, and potassium. In addition, beef provided only 1% of total sodium intake. Consumption of beef contributed significantly to intake of protein and other key nutrients by US adults.

3.
Health Functions of Egg Protein.

Matsuoka R, Sugano M.

Foods (Basel, Switzerland). 2022;11(15):2309. doi:10.3390/foods11152309.

Egg protein is a remarkably abundant source of protein, with an amino acid score of 100 and the highest net protein utilization rate. However, there have been relatively fewer studies investigating the health benefits of egg protein. In this review, we have summarized the available information regarding the health benefits of egg proteins based on human studies. In particular, studies conducted on the characteristics of egg whites, as they are high in pure protein, have reported their various health functions, such as increases in muscle mass and strength enhancement, lowering of cholesterol, and visceral fat reduction. Moreover, to facilitate and encourage the use of egg white protein in future, we also discuss its health functions. These benefits were determined by developing an egg white hydrolysate and lactic-fermented egg whites, with the latter treatment simultaneously improving the egg flavor. The health benefits of the protein hydrolysates from the egg yolk (bone growth effect) and eggshell membrane (knee join pain-lowering effect) have been limited in animal studies. Therefore, the consumption of egg protein may contribute to the prevention of physical frailty and metabolic syndromes.

4.
Egg White and Yolk Protein Atlas: New Protein Insights of a Global Landmark Food.

Sarantidi E, Ainatzoglou A, Papadimitriou C, et al.

Foods (Basel, Switzerland). 2023;12(18):3470. doi:10.3390/foods12183470.

(1) Background: The chicken egg is an animal product of great agronomic interest. The egg white and yolk constitute high-quality protein sources for humans with high digestibility and well-balanced amino acid profiles. Despite the egg white and yolk protein's undisputed value, research to unravel their full proteome content and its properties is still ongoing. We aimed to exhaustively analyze the proteome of egg white and yolk by applying intrinsic proteomics and bioinformatics approaches in order to unravel the full protein potential of this landmark food. (2) Methods: A total of 45 freshly laid, unfertilized, chicken eggs were subjected to nanoLC-MS/MS Orbitrap analysis following a peptide pre-fractionation step. A comprehensive bioinformatics processing step was undertaken towards elucidating potential activities and roles of identified molecules. In parallel, the literature was mined concerning all reported egg white and yolk protein identifications. (3) Results: Our analysis revealed 371 and 428 new proteins, reported for the first time to be present in the egg white and yolk, respectively. From the bioactivity standpoint, egg white and yolk proteins showed high enrichment for antioxidant and anti-inflammatory processes, while exerting high relevance for the apoptosis and focal adhesion pathways. (4) Conclusions: Egg white and yolk proteins exert diverse and multifaceted properties. A total of 799 proteins were reported for the first time as being part of the egg and yolk. Our novel protein data enriched those already published in the literature and the first ever chicken egg white and yolk Protein Atlas, comprising 1392 protein entries, was generated. This dataset will provide a cornerstone reference for future studies involving egg proteins.

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10 egg whites contain approximately 35 grams of protein (each large egg white provides about 3.5 grams of protein).[1-3]
Regarding safety, the medical literature indicates that egg whites from commercial sources do not pose a significant health risk from contaminants such as dioxins, mercury, or toxic trace elements when consumed at this level. Studies assessing toxic metals and dioxins in eggs show that concentrations in egg whites are generally low and well below thresholds for non-carcinogenic health risk, even with daily consumption.[4-6] Mercury levels in egg whites are typically undetectable or far below regulatory limits in most regions, except in rare cases of severe environmental contamination.[5][7-8] Dioxin and PCB exposure from eggs is a minor contributor to total dietary intake, and regulatory monitoring has reduced risk in commercial eggs.[6][9-10]
However, eggs from free-range or backyard hens in contaminated environments may contain higher levels of dioxins and PCBs, so sourcing from regulated commercial producers is important for minimizing risk.[6][11-12] For healthy adults, consuming 10 egg whites per day is generally safe with respect to protein load and contaminant exposure, provided the eggs are commercially sourced and not from areas with known environmental contamination.[2-6]

1.
Egg Proteins: Fractionation, Bioactive Peptides and Allergenicity.

Chang C, Lahti T, Tanaka T, Nickerson MT.

Journal of the Science of Food and Agriculture. 2018;98(15):5547-5558. doi:10.1002/jsfa.9150.

Eggs are an important source of macro and micronutrients within the diet, comprised of proteins, lipids, vitamins, and minerals. They are constituted by a shell, the white (containing 110 g kg proteins: ovalbumin, ovotransferrin, ovomucoid, lysozyme and ovomucin), and the yolk (containing 150-170 g kg proteins: lipovitellins, phosvitin, livetins, and low-density lipoproteins). Owing to their nutritional value and biological characteristics, both the egg white and yolk proteins are extensively fractionated using different techniques (e.g., liquid chromatography, ultrafiltration, electrophoresis, and chemical precipitation), in which liquid chromatography is the most commonly used technique to obtain individual proteins with high protein recovery and purity to develop novel food products. However, concerns over allergenic responses induced by certain egg proteins (e.g., ovomucoid, ovalbumin, ovotransferrin, lysozyme, α-livetin, and lipoprotein YGP42) limit their widespread use. As such, processing technologies (e.g., thermal processing, enzymatic hydrolysis, and high-pressure treatment) are investigated to reduce the allergenicity by conformational changes. In addition, biological activities (e.g., antioxidant, antimicrobial, antihypertensive, and anticancer activities) associated with egg peptides have received more attention, in which enzyme hydrolysis is demonstrated as a promising way to break polypeptides sequences and produce bioactive peptides to provide nutritional and therapeutic benefits for human health. © 2018 Society of Chemical Industry.

2.
The Health Benefits of Egg Protein.

Puglisi MJ, Fernandez ML.

Nutrients. 2022;14(14):2904. doi:10.3390/nu14142904.

Once the general public accepts that dietary cholesterol is not a concern for cardiovascular disease risk, foods that have been labeled as high-cholesterol sources, including eggs, may be appreciated for their various other dietary components. One of the nutrients in eggs that deserves further discussion is egg protein. Egg protein has been recognized to be highly digestible and an excellent source of essential amino acids, with the highest attainable protein digestibility-corrected amino acid score. Egg protein has been shown to decrease malnutrition in underdeveloped countries, possibly increase height in children, and protect against kwashiorkor. Egg protein has been demonstrated to be important to skeletal muscle health and protective against sarcopenia. Egg protein also can decrease appetite, resulting in a reduction in the caloric intake from the next meal and weight reduction. Other protective effects of egg protein addressed in this review include protection against infection as well as hypotensive and anti-cancer effects.

3.
Health Functions of Egg Protein.

Matsuoka R, Sugano M.

Foods (Basel, Switzerland). 2022;11(15):2309. doi:10.3390/foods11152309.

Egg protein is a remarkably abundant source of protein, with an amino acid score of 100 and the highest net protein utilization rate. However, there have been relatively fewer studies investigating the health benefits of egg protein. In this review, we have summarized the available information regarding the health benefits of egg proteins based on human studies. In particular, studies conducted on the characteristics of egg whites, as they are high in pure protein, have reported their various health functions, such as increases in muscle mass and strength enhancement, lowering of cholesterol, and visceral fat reduction. Moreover, to facilitate and encourage the use of egg white protein in future, we also discuss its health functions. These benefits were determined by developing an egg white hydrolysate and lactic-fermented egg whites, with the latter treatment simultaneously improving the egg flavor. The health benefits of the protein hydrolysates from the egg yolk (bone growth effect) and eggshell membrane (knee join pain-lowering effect) have been limited in animal studies. Therefore, the consumption of egg protein may contribute to the prevention of physical frailty and metabolic syndromes.

4.
Isotopic and Elemental Fingerprint of Edible Egg Parts-the Health Risk Assessment Based on Potentially Toxic Elements Content.

Cristea G, Dehelean A, Puscas R, Hategan AR, Magdas DA.

Molecules (Basel, Switzerland). 2023;28(2):503. doi:10.3390/molecules28020503.

The present study investigated the isotopic and elemental profile (by IRMS and ICP-MS) of edible egg parts (29 egg whites and 29 yolks) mainly collected from Romania. In order to differentiate the egg white and yolk coming from different hen rearing systems (backyard and barn), Partial Least Square-Discriminant Analysis (PLS-DA) models were developed. The models' accuracies for the discrimination according to the hen growing system were 96% for egg white and 100% for egg yolk samples, respectively. Elements that proved to have the highest discrimination power for both egg white and yolk were the following: δ13C, Li, B, Mg, K, Ca, Mn, Fe, Co, Zn, Rb, Sr, Mo, Ba, La, Ce, and Pb. Nevertheless, the important compositional differentiation, in terms of essential mineral content, between the edible egg parts (egg white and egg yolk) were also pointed out. The estimated daily intake (EDI), the target hazard quotient (THQ) for Cr, Mn, Fe, Co, Ni, Cu, Zn, Se, Cd, Pb, and As, as well as the hazard index (HI) were used to assess non-carcinogenic human health risks from egg consumption. The obtained results showed no noticeable health risks related to egg consumption for humans from the point of view of the potentially toxic metals.

5.
The Impact of Strain and Feed Intake on Egg Toxic Trace Elements Deposition in Laying Hens and Its Health Risk Assessment.

Hashemi M, Sadeghi A, Dankob M, et al.

Environmental Monitoring and Assessment. 2018;190(9):540. doi:10.1007/s10661-018-6811-3.

The impact of strain or feed intake on food trace elements and its health risk assessment is still ambiguous, and therefore, available facts are rare. Therefore, this study aimed to assess the effects of both strains and feed intake on trace elements depositions to egg, toxic heavy metals concentration, and health risk assessment of egg consumption. In the current cross-sectional study, the selected strains, including Shaver White, Hy-Line W36, Bovanse White, Lohman LSL-Lite, and Native laying hens of Khorasan Razavi province, were examined. A total number of 50 samples of eggs and 15 samples of their feed was purchased from poultry farms. Yolk and white were separately analyzed. Sample preparation was performed by wet digestion followed by Inductively Coupled Plasma Mass Spectrometry. Trace metals Pb, As, Cd, Hg, Cr, and Ni were detected. Statistical analysis was performed in Stata11.2 portable software. Although there was a significant difference in strains and feed, no significant difference was observed in trace elements in egg contents (weight of egg white and egg yolk). Mercury concentration in all the samples was below the instrument detection limit. In this study, the target hazardous quotients were below one for all trace elements. Therefore, Iranian does not experience the adverse health effects due to the consumption of egg.

6.
Risk for Animal and Human Health Related to the Presence of Dioxins and Dioxin-Like PCBs in Feed and Food.

Knutsen HK, Alexander J, Barregård L, et al.

EFSA Journal. European Food Safety Authority. 2018;16(11):e05333. doi:10.2903/j.efsa.2018.5333.

The European Commission asked EFSA for a scientific opinion on the risks for animal and human health related to the presence of dioxins (PCDD/Fs) and DL-PCBs in feed and food. The data from experimental animal and epidemiological studies were reviewed and it was decided to base the human risk assessment on effects observed in humans and to use animal data as supportive evidence. The critical effect was on semen quality, following pre- and postnatal exposure. The critical study showed a NOAEL of 7.0 pg WHO2005-TEQ/g fat in blood sampled at age 9 years based on PCDD/F-TEQs. No association was observed when including DL-PCB-TEQs. Using toxicokinetic modelling and taking into account the exposure from breastfeeding and a twofold higher intake during childhood, it was estimated that daily exposure in adolescents and adults should be below 0.25 pg TEQ/kg bw/day. The CONTAM Panel established a TWI of 2 pg TEQ/kg bw/week. With occurrence and consumption data from European countries, the mean and P95 intake of total TEQ by Adolescents, Adults, Elderly and Very Elderly varied between, respectively, 2.1 to 10.5, and 5.3 to 30.4 pg TEQ/kg bw/week, implying a considerable exceedance of the TWI. Toddlers and Other Children showed a higher exposure than older age groups, but this was accounted for when deriving the TWI. Exposure to PCDD/F-TEQ only was on average 2.4- and 2.7-fold lower for mean and P95 exposure than for total TEQ. PCDD/Fs and DL-PCBs are transferred to milk and eggs, and accumulate in fatty tissues and liver. Transfer rates and bioconcentration factors were identified for various species. The CONTAM Panel was not able to identify reference values in most farm and companion animals with the exception of NOAELs for mink, chicken and some fish species. The estimated exposure from feed for these species does not imply a risk.

7.
Mercury Level in Worldwide Poultry Food Products: A Systematic Review.

Alves ACN, de Almeida Santos AN, Dos Santos SM, et al.

Biological Trace Element Research. 2025;:10.1007/s12011-025-04659-1. doi:10.1007/s12011-025-04659-1.

New Research

Mercury is a metal known for its toxic effects on environmental, animal and human health. The presence of Hg in poultry and its potential impact on food safety still need to be explored, especially considering that poultry is the most consumed source of protein in the global population. This study aimed to systematically review mercury and methylmercury levels in poultry meat and eggs worldwide. The searches were conducted in the Web of Science, PubMed, and Scopus databases, resulting in 123 studies, of which only 30 were deemed suitable. Studies were found across sixteen countries: India, Thailand, Malaysia, China, Poland, Egypt, Ghana, Nigeria, Bangladesh, Iran, USA, Italy, Colombia, Romania, Tanzania, Algeria, and Saudi Arabia. Five poultry species were reported, with chicken being the most recorded species in 16 countries. Among biological samples, eggs and liver were the most used for measuring mercury and methylmercury levels. Levels above those permitted by regulatory organizations such as the United States Department of Agriculture (USDA), China's National Health Commission (NHC), and Thailand's Ministry of Public Health - set at 0.05, 0.05, and 0.02 mg.kg-1 respectively - were observed in 12 of the 17 countries, with the highest concentrations detected in chicken eggs from Colombia. Therefore, poultry production is not Hg-free and contamination by this metal must be monitored.

8.
Metabolisms of Both Inorganic and Methyl-Mercury in Hens Reveal Eggs as an Effective Bioindicator for Environmental Hg Pollution.

Wang Z, Liao J, Gai P, et al.

Journal of Hazardous Materials. 2024;465:133191. doi:10.1016/j.jhazmat.2023.133191.

Leading Journal

Mercury (Hg) is a globally distributed toxic metal and could pose serious harm to birds, which may ultimately threaten human health through poultry consumption. However, the avian Hg metabolism remains unclear. Poultry, like chickens, are more accessible human dietary sources than wild birds and are ideal proxies to study Hg metabolism in birds. In this study, the avian Hg metabolism is carefully investigated with hens fed by Hg-spiked (both inorganic mercury IHg and methylmercury MeHg) foods. Our results demonstrate that feces and eggs are the main removal pathways of Hg from hens, rather than feathers. Eggs show particularly rapid responses towards Hg exposures, thus could be more sensitive to environmental Hg pollution than feathers, feces or internal organs (and tissues). Egg yolk (with THg peak of 55.92 ng/g on Day 6) and egg white (THg peak of 1195.03 ng/g on Day 4) react as an effective bioindicator for IHg and MeHg exposure, respectively. In 90-day-single-dose exposure, IHg is almost completely excreted, while approximately 11% of MeHg remains in internal organs. Our study provides new insight into the metabolism and lifetime of IHg and MeHg in birds, advancing the understanding of the dynamics for human exposure to Hg through poultry products.

9.
Dioxins and PCBs in Feed and Food--Review From European Perspective.

Malisch R, Kotz A.

The Science of the Total Environment. 2014;491-492:2-10. doi:10.1016/j.scitotenv.2014.03.022.

Leading Journal

During the 1990s, a number of adverse contamination incidents focussed the attention of the media and the general public on food safety. This led to the evaluation of safety measures with regard to dioxin intake from food. Important aspects regarding dioxins and PCBs in the food chain are reviewed here, allowing a contextual understanding of the present situation through its chronological developments. About 90-98% of the average exposure of humans to dioxins and PCBs results from dietary intake, with food of animal origin being the predominant source. Therefore, animal feed contributes considerably to the presence of these compounds in food. The detection of the "real" source of a contamination event in the food chain is a complex scientific problem and requires specific knowledge on production processes and changes of patterns during bioaccumulation. This is demonstrated by complex investigations performed in three studies on two continents to identify the source (e.g. from contamination of cow's milk in Germany, to citrus pulp pellets from Brazil as an ingredient in feed, then to contaminated lime for neutralization and finally to a landfill with residues of vinyl chloride monomer production). This example shows also the substantial economic losses resulting from incidents in the food chain and the consequences to global trade. In 2001, the EU Scientific Committee on Food established a group tolerable weekly intake (TWI) of 14 pg WHO-TEQ/kg body weight and concluded that a considerable proportion of the European population would exceed this TWI. On the global level, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) provides scientific advice to the Codex Alimentarius Commission and therefore contributes to harmonized international food standards. In its evaluation of 2001, JECFA derived a provisional tolerable monthly intake (PTMI) of 70 pg TEQ/kg body weight. The sum of the median intake of PCDD/F-TEQ and PCB-TEQ exceeded the PTMI in Western European countries, was in the PTMI range in North America, but lower in Japan and New Zealand. The 90th percentile of PCDD/F-TEQ exceeded the PTMI in Western European countries and North America, the 90th percentile of coplanar PCBs in Western European countries. Therefore, in 2001 the EU Commission developed a strategy to reduce the presence of dioxins and PCBs in the environment and in the food chain. The legislative measures comprised maximum levels and action levels for feed and food, and a Rapid Alert System for detected incidents was introduced. The network of the EU Reference Laboratory and National Reference Laboratories contributes to harmonization within the EU Member States and developed analytical criteria for screening and confirmatory methods for control of feed and food. After all these efforts it is of general interest to see whether these measures had an effect. The 2012 evaluation of the European Food Safety Authority (EFSA) based on comprehensive monitoring data of 26 European countries shows a general decrease in dietary exposure of dioxins and DL-PCBs between 2002-2004 and 2008-2010, estimated to be between 16.6% and 79.3% for the different population groups. A smaller decrease was observed for NDL-PCBs. The percentage of individuals exposed above the TWI of 14 pg TEQ/kg b.w. was estimated to be between 1.0 and 52.9%. Toddlers and other children were the most exposed groups (being at the upper end of these ranges). Fish, meat and dairy products appeared to be the highest contributing food groups to dietary exposure.

10.
Fish Intake, Contaminants, and Human Health: Evaluating the Risks and the Benefits.

Mozaffarian D, Rimm EB.

JAMA logoJAMA. 2006;296(15):1885-99. doi:10.1001/jama.296.15.1885.

Leading Journal
Evidence Synthesis > Risks of PCBs and Dioxins

PCBs are synthetic organochlorine compounds previously used in industrial and commercial processes. Dioxins—commonly referring to dibenzodioxins and dibenzofurans—are organochlorine by-products of waste incineration, paper bleaching, pesticide production, and production of polyvinyl chloride plastics. Manufacture and processing of PCBs was prohibited in 1977, and regulatory and industry efforts have reduced dioxin emissions by more than 90% since 1987. Nevertheless, these contaminants persist for long periods in the environment, and thus while levels are steadily declining, PCBs and dioxins continue to be present in low concentrations in many foods (Table 2).

Cancer Risks . Animal experiments and some evidence in humans indicate that PCBs and dioxins are carcinogenic, possibly related to effects on the aryl hydrocarbon receptor, a transcription factor affecting gene expression. Multiple congeners (structural variants) of PCBs and dioxins exist. Potential toxicities of foods are calculated using toxic equivalence (TEQ): the sum of each congener's level in the food multiplied by that congener's toxic equivalency factor (standardized against 2,3,7,8-tetrachlorodibenzo-p-dioxin). In the United States, PCBs comprise 28% and dioxins 72% of total TEQ exposure. Among adults, major dietary sources of PCBs and dioxins are beef, chicken, and pork (34% of total TEQ); dairy products (30%); vegetables (22%); fish and shellfish (9%); and eggs (5%). Dietary sources are similar for children.

Although major sources of exposure to PCBs and dioxins are meats, dairy products, and vegetables, considerable attention has been given to fish sources (Table 2). When PCBs and dioxins were measured in farmed and wild salmon, levels were similar to those in several other foods (Table 2).

11.

PCDD/Fs and PCBs are environmentally persistent substances that have been associated with adverse effects on human health. Contamination of soils, animal feed and pastures leads to their bioaccumulation of in food products of animal origin, which are considered the major source of intake of these contaminants in humans. We analyzed eggs from free-range hens, sampled from small farms, located within a distance of 4.5 km from a secondary aluminum smelter in Northern Italy. The concentrations of PCDD/Fs, DL-PCBs and NDL-PCBs were higher in eggs from locations close to the plant, and strongly exceeded the limits set by EU Regulation 1259/2011 (2.5 pg WHO TEQ fat g(-1) for PCDD/Fs, 5.0 pg WHO TEQ g(-1) for PCDD/Fs and DL-PCBs L, 40 ng g(-1) for NDL-PCBs). Without the prompt and immediately applied control strategies, the consumption of contaminated eggs may have posed [corrected] a risk for human health, especially for children (≤9 years) and infants (≤3 years), due to the 2-fold excess of the current exposure limits.

12.
Soil as a Source of Dioxin Contamination in Eggs From Free-Range Hens on a Polish Farm.

Piskorska-Pliszczynska J, Mikolajczyk S, Warenik-Bany M, Maszewski S, Strucinski P.

The Science of the Total Environment. 2014;466-467:447-54. doi:10.1016/j.scitotenv.2013.07.061.

Leading Journal

The transfer of dioxins from contaminated soil into the food chain has recently become an up-and-coming topic in the environmental policy and health-related consumer protection. Within the framework of the 2011 National Food Survey that monitored the levels of PCDD/Fs and PCBs in foods of animal origin, the sum of the WHO-PCDD/F/PCB-TEQ concentrations exceeding two-fold the European Union's maximum level was detected in eggs from a free-range farm (12.55 ± 2.37 pg WHOPCDD/F/PCB-TEQ/g fat). Investigations have revealed that the source of egg contamination was the backyard soil on which the hens were foraging. A follow-up study of laying hens from this farm has demonstrated the transfer of dioxins into all tested tissues (breast and leg muscles, abdominal fat), liver and ovarian follicles. The bioaccumulation of dioxins was found to be congener and tissue-dependent. The highest concentration was found in the liver, followed by the ovarian follicles, and the adipose tissue. The PCDD/F levels in the liver often were approximately two times higher from those in other materials from the same hen. The potential dioxin intakes with eggs were expressed as the percent of the Tolerable Weekly Intake (TWI), and the Provisional Tolerable Monthly Intake (PTMI). The weekly intake of dioxins would be 3.5 pg WHO-TEQ/kg b.w. (24.9% TWI) for an adult and 20.3 pg WHO-TEQ/kg b.w. (145.2% TWI) for a 3-year old child. Considering a monthly consumption of such contaminated eggs, intake of dioxins would be slightly lower, but still over 100% of the PTMI for a child. The obtained results complement the knowledge on possible dioxin sources in food and are important for risk management authorities.

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Consuming 10 egg whites per day provides high-quality, complete protein with minimal cholesterol and is generally safe for healthy adults, with evidence supporting benefits for muscle mass, satiety, and metabolic health.[1-3] Large US cohort studies indicate that egg white or substitute consumption is associated with lower all-cause and cardiovascular mortality compared to whole eggs, and replacing whole eggs with egg whites or plant proteins may further reduce risk.[4-6]
However, multiple large cohort and review studies consistently show that higher plant protein intake is associated with lower all-cause and cardiovascular mortality, and substituting plant for animal (including egg) protein is linked to improved long-term health outcomes.[5-9] While egg whites are a high-quality protein source, plant proteins offer additional cardiometabolic and mortality benefits, including lower blood pressure, improved lipid profiles, and reduced risk of chronic disease. Protein adequacy from plant sources requires careful dietary planning, especially for children and older adults, as some plant-based diets may be lower in certain indispensable amino acids or total protein if not well constructed.[10-11]
In summary, consuming 10 egg whites per day is more beneficial than harmful for healthy adults, but obtaining protein from plant sources is generally healthier for long-term cardiometabolic and mortality outcomes, provided the diet is well planned to ensure protein and amino acid adequacy.

1.
The Health Benefits of Egg Protein.

Puglisi MJ, Fernandez ML.

Nutrients. 2022;14(14):2904. doi:10.3390/nu14142904.

Once the general public accepts that dietary cholesterol is not a concern for cardiovascular disease risk, foods that have been labeled as high-cholesterol sources, including eggs, may be appreciated for their various other dietary components. One of the nutrients in eggs that deserves further discussion is egg protein. Egg protein has been recognized to be highly digestible and an excellent source of essential amino acids, with the highest attainable protein digestibility-corrected amino acid score. Egg protein has been shown to decrease malnutrition in underdeveloped countries, possibly increase height in children, and protect against kwashiorkor. Egg protein has been demonstrated to be important to skeletal muscle health and protective against sarcopenia. Egg protein also can decrease appetite, resulting in a reduction in the caloric intake from the next meal and weight reduction. Other protective effects of egg protein addressed in this review include protection against infection as well as hypotensive and anti-cancer effects.

2.
Health Functions of Egg Protein.

Matsuoka R, Sugano M.

Foods (Basel, Switzerland). 2022;11(15):2309. doi:10.3390/foods11152309.

Egg protein is a remarkably abundant source of protein, with an amino acid score of 100 and the highest net protein utilization rate. However, there have been relatively fewer studies investigating the health benefits of egg protein. In this review, we have summarized the available information regarding the health benefits of egg proteins based on human studies. In particular, studies conducted on the characteristics of egg whites, as they are high in pure protein, have reported their various health functions, such as increases in muscle mass and strength enhancement, lowering of cholesterol, and visceral fat reduction. Moreover, to facilitate and encourage the use of egg white protein in future, we also discuss its health functions. These benefits were determined by developing an egg white hydrolysate and lactic-fermented egg whites, with the latter treatment simultaneously improving the egg flavor. The health benefits of the protein hydrolysates from the egg yolk (bone growth effect) and eggshell membrane (knee join pain-lowering effect) have been limited in animal studies. Therefore, the consumption of egg protein may contribute to the prevention of physical frailty and metabolic syndromes.

3.
Consumption of Different Egg-Based Diets Alters Clinical Metabolic and Hematological Parameters in Young, Healthy Men and Women.

Andersen CJ, Huang L, Zhai F, et al.

Nutrients. 2023;15(17):3747. doi:10.3390/nu15173747.

Eggs-particularly egg yolks-are a rich source of bioactive nutrients and dietary compounds that influence metabolic health, lipid metabolism, immune function, and hematopoiesis. We investigated the effects of consuming an egg-free diet, three egg whites per day, and three whole eggs per day for 4 weeks on comprehensive clinical metabolic, immune, and hematologic profiles in young, healthy adults (18-35 y, BMI < 30 kg/m2 or <30% body fat for men and <40% body fat for women, n = 26) in a 16-week randomized, crossover intervention trial. We observed that average daily macro- and micronutrient intake significantly differed across egg diet periods, including greater intake of choline during the whole egg diet period, which corresponded to increased serum choline and betaine without altering trimethylamine N-oxide. Egg white and whole egg intake increased serum isoleucine while whole egg intake reduced serum glycine-markers of increased and decreased risk of insulin resistance, respectively-without altering other markers of glucose sensitivity or inflammation. Whole egg intake increased a subset of large HDL particles (H6P, 10.8 nm) and decreased the total cholesterol:HDL-cholesterol ratio and % monocytes in female participants using combined oral contraceptive (COC) medication (n = 11) as compared to female non-users (n = 10). Whole egg intake further increased blood hematocrit whereas egg white and whole egg intake reduced blood platelet counts. Changes in clinical immune cell counts between egg white and whole egg diet periods were negatively correlated with several HDL parameters yet positively correlated with measures of triglyceride-rich lipoproteins and insulin sensitivity. Overall, the intake of whole eggs led to greater overall improvements in micronutrient diet quality, choline status, and HDL and hematologic profiles while minimally-yet potentially less adversely-affecting markers of insulin resistance as compared to egg whites.

4.
Egg and Cholesterol Consumption and Mortality From Cardiovascular and Different Causes in the United States: A Population-Based Cohort Study.

Zhuang P, Wu F, Mao L, et al.

PLoS Medicine. 2021;18(2):e1003508. doi:10.1371/journal.pmed.1003508.

Leading Journal

Background: Whether consumption of egg and cholesterol is detrimental to cardiovascular health and longevity is highly debated. Data from large-scale cohort studies are scarce. This study aimed to examine the associations of egg and cholesterol intakes with mortality from all causes, cardiovascular disease (CVD), and other causes in a US population.

Methods And Findings: Overall, 521,120 participants (aged 50-71 years, mean age = 62.2 years, 41.2% women, and 91.8% non-Hispanic white) were recruited from 6 states and 2 additional cities in the US between 1995 and 1996 and prospectively followed up until the end of 2011. Intakes of whole eggs, egg whites/substitutes, and cholesterol were assessed by a validated food frequency questionnaire. Cause-specific hazard models considering competing risks were used, with the lowest quintile of energy-adjusted intake (per 2,000 kcal per day) as the reference. There were 129,328 deaths including 38,747 deaths from CVD during a median follow-up of 16 years. Whole egg and cholesterol intakes were both positively associated with all-cause, CVD, and cancer mortality. In multivariable-adjusted models, the hazard ratios (95% confidence intervals) associated with each intake of an additional half of a whole egg per day were 1.07 (1.06-1.08) for all-cause mortality, 1.07 (1.06-1.09) for CVD mortality, and 1.07 (1.06-1.09) for cancer mortality. Each intake of an additional 300 mg of dietary cholesterol per day was associated with 19%, 16%, and 24% higher all-cause, CVD, and cancer mortality, respectively. Mediation models estimated that cholesterol intake contributed to 63.2% (95% CI 49.6%-75.0%), 62.3% (95% CI 39.5%-80.7%), and 49.6% (95% CI 31.9%-67.4%) of all-cause, CVD, and cancer mortality associated with whole egg consumption, respectively. Egg white/substitute consumers had lower all-cause mortality and mortality from stroke, cancer, respiratory disease, and Alzheimer disease compared with non-consumers. Hypothetically, replacing half a whole egg with equivalent amounts of egg whites/substitutes, poultry, fish, dairy products, or nuts/legumes was related to lower all-cause, CVD, cancer, and respiratory disease mortality. Study limitations include its observational nature, reliance on participant self-report, and residual confounding despite extensive adjustment for acknowledged dietary and lifestyle risk factors.

Conclusions: In this study, intakes of eggs and cholesterol were associated with higher all-cause, CVD, and cancer mortality. The increased mortality associated with egg consumption was largely influenced by cholesterol intake. Our findings suggest limiting cholesterol intake and replacing whole eggs with egg whites/substitutes or other alternative protein sources for facilitating cardiovascular health and long-term survival.

Trial Registration: ClinicalTrials.gov NCT00340015.

5.
Association Between Plant and Animal Protein Intake and Overall and Cause-Specific Mortality.

Huang J, Liao LM, Weinstein SJ, et al.

JAMA logoJAMA Internal Medicine. 2020;180(9):1173-1184. doi:10.1001/jamainternmed.2020.2790.

Discussion

In this analysis of a large prospective cohort of men and women in the US with 16 years of observation, we found higher plant protein intake was associated with reduced risk of overall mortality, with men and women experiencing (respectively) 12% and 14% lower mortality per 10 g/1000 kcal intake increment (5% lower mortality per 1-SD increment). The inverse association was apparent for CVD and stroke mortality in both sexes, was independent of several risk factors, and was evident in most other cohort subgroups. Replacement of 3% energy from various animal protein sources with plant protein was associated with 10% decreased overall mortality in both sexes. Of note, substitution analyses suggested that replacement of egg protein and red meat protein with plant protein resulted in the most prominent protective associations for overall mortality, representing 24% and 21% lower risk for men and women, respectively, for egg protein replacement, and 13% and 15% lower risk for men and women for red meat protein replacement. The effect sizes of these risk estimates were small.

Relatively few prospective studies have examined the association between dietary protein sources and overall mortality. Concordant with the present findings, the NHS and HPFS cohorts found an inverse association for higher plant protein intake and overall and CVD mortality, and reduced overall mortality for greater substitution of plant protein for animal protein. Increased plant protein intake was also associated with lower risk of total and CVD mortality in a cohort in Japan, whereas a study of postmenopausal women in the US showed that replacement of animal protein with plant protein led to decreased coronary heart disease mortality. Collectively, the present and previous studies indicate the importance and diverse effects of primary dietary protein sources, including beneficial associations for higher plant protein intake in long-term health outcomes.

Considerable evidence has accumulated supporting a beneficial role for plant-based diets in the prevention of cardiovascular disease. Dietary plant protein has been associated with reduced CVD risk factors, including lower systolic and diastolic blood pressure, improved lipid and lipoprotein profiles, and decreased circulating concentrations of insulin-like growth factor-1.

6.
Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality.

Song M, Fung TT, Hu FB, et al.

JAMA logoJAMA Internal Medicine. 2016;176(10):1453-1463. doi:10.1001/jamainternmed.2016.4182.

Discussion

After adjusting for other dietary and lifestyle factors, animal protein intake was associated with a higher risk for CVD mortality, whereas higher plant protein intake was associated with lower all-cause and cardiovascular mortality. However, in the stratified analysis, these associations were confined to participants with at least 1 lifestyle risk factor. Moreover, we observed that substitution of plant protein for animal protein from a variety of food sources, particularly processed red meat, was associated with a lower risk for mortality, suggesting that the protein source is important for long-term health.

Although short-term randomized clinical trials have shown a beneficial effect of high protein intake, the long-term health consequences of protein intake remain controversial. In a randomized clinical trial with a 2-year intervention, 4 calorie-restricted diets with different macronutrient compositions did not show a difference in the effects on weight loss or on improvement of lipid profiles and insulin levels. When protein is substituted for other macronutrients, the dietary source of protein appears to be a critical determinant of the outcome.

To our knowledge, only 2 cohort studies have examined animal and plant protein intake in relation to mortality. In the Iowa Women’s Health Study, although neither animal nor plant protein was associated with all-cause mortality, an inverse association was found between plant protein and CVD mortality, and substituting plant protein for animal protein was associated with a substantially lower CVD mortality. In a recent report from the National Health and Nutrition Examination Survey III, higher protein intake was related to an increased risk for all-cause mortality among participants younger than 65 years. However, when animal protein intake was controlled for, this association was eliminated, suggesting that animal protein was responsible for the effect of higher protein intake, if any, on increased mortality. Although a direct comparison of these studies is difficult, given the variation in the study methods, these data together with our current findings support the importance of protein sources for the long-term health outcome and suggest that plants constitute a preferred protein source compared with animal foods.

Indeed, unlike animal protein, plant protein has not been associated with increased insulinlike growth factor 1 levels and has been linked to lower blood pressure, reduced low-density lipoprotein levels, and improved insulin sensitivity.

7.
Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality in a Japanese Cohort.

Budhathoki S, Sawada N, Iwasaki M, et al.

JAMA logoJAMA Internal Medicine. 2019;179(11):1509-1518. doi:10.1001/jamainternmed.2019.2806.

Discussion

This discrepancy in findings for animal protein between our present study and the US study may be attributable to the difference in percentage of energy from animal protein, which was higher in the US study (median intake, as expressed in percentage of energy, of 14%) than in the present study (7.7%). The discrepancy might also be attributable to a difference in the main dietary source of animal protein, which was red and processed meat in the US study vs fish intake in the present study. Collectively, these findings suggest that proteins from animal and plant sources may have differing effects on long-term health and that a preference for plant-based foods in obtaining the required protein may provide long-term health benefits.

Indeed, intake of plant protein, but not animal protein, has been associated with favorable changes in blood pressure level, waist circumference, and weight. Plant protein, unlike animal protein, was not significantly associated with higher insulinlike growth factor 1 levels. A recent systematic review found that consumption of plant protein (soy protein with isoflavones) was more strongly linked to lower levels of total and low-density lipoprotein cholesterol than the consumption of animal protein, whereas another study found that substitution of nonmeat protein for meat protein was favorably associated with fasting insulin levels and insulin resistance. Other evidence suggests a null or even lower risk of type 2 diabetes associated with higher intake of plant protein vs increased risk associated with animal protein. Moreover, intake of nuts and grains or legumes, a rich source of plant protein, was associated with lower CVD-related and all-cause mortality, whereas higher intake of red or processed meat, major sources of animal protein, was associated with higher all-cause and CVD-related mortality, including cancer mortality.

Cereals, pulses, vegetables, and fruits were the major sources of plant protein intake and carbohydrates. Because these foods are also often represented in healthy dietary patterns, replacing them may have adverse health effects. Thus, we also conducted substitution analysis within protein groups by protein food source. In this analysis, substitution of plant protein for red and processed meat protein was associated with lower total mortality, a finding that accords with the US study.

8.
Animal- And Plant-Based Protein Sources: A Scoping Review of Human Health Outcomes and Environmental Impact.

Ferrari L, Panaite SA, Bertazzo A, Visioli F.

Nutrients. 2022;14(23):5115. doi:10.3390/nu14235115.

Dietary proteins are indispensable to human nutrition. In addition to their tissue-building function, they affect body composition and regulate various metabolic pathways, as well as satiety and immune system activity. Protein use can be examined from a quantitative or qualitative viewpoint. In this scoping review, we compare animal- and plant-based protein sources in terms of their effects on human health and the environment. We conclude that the consumption of vegetable protein sources is associated with better health outcomes overall (namely, on the cardiovascular system) than animal-based product use. The healthier outcomes of vegetable protein sources dovetail with their lower environmental impact, which must be considered when designing an optimal diet. Indeed, the health of the planet cannot be disjointed from the health of the human being. Future research will clarify the mechanisms of action underlying the health effects of plant-based protein sources when compared with animal sources, fostering better agronomic practices and influencing public health in a direction that will benefit both the planet and its inhabitants.

9.
Animal and Plant Protein Sources and Cardiometabolic Health.

Mariotti F.

Advances in Nutrition (Bethesda, Md.). 2019;10(Suppl_4):S351-S366. doi:10.1093/advances/nmy110.

Leading Journal

The sources or types of protein in the diet have long been overlooked regarding their link to cardiometabolic health. The picture is complicated by the fact that animal and plant proteins are consumed along with other nutrients and substances which make up the "protein package" so plant and animal protein come with clear nutrient clusters. This review aimed at deciphering the relation between plant and animal protein and cardiometabolic health by examining different nutritional levels (such as amino acids, protein type, protein foods, protein patterns, and associated overall dietary and nutrient patterns) and varying levels of scientific evidence [basic science, randomized controlled trials (RCTs), observational data]. Plant protein in Western countries is a robust marker of nutrient adequacy of the diet, whereas the contribution of animal protein is highly heterogeneous. Yet recent data from large cohorts have confirmed that total and animal proteins are associated with the risk of cardiovascular disease and diabetes, even when fully adjusting for lifestyle and dietary or nutritional factors. Here again, there is marked variability depending on the type of animal protein. Protein from processed red meat and total red meat on the one hand, and from legumes, nuts, and seeds on the other, are often reported at the extremes of the risk range. RCTs using purified proteins have contributed little to the topic to date, inasmuch as the findings cannot readily be extrapolated to current or near-future diets, but RCTs studying whole protein foods have shown a beneficial effect of pulses. Despite the fact that many of the benefits of plant protein reported in observational or interventional studies may stem from the protein package that they convey and the nutrients that they displace, there are also important indications that protein per se may affect cardiometabolic health via the many amino acids that are present in typically contrasting levels in plant compared with animal proteins.

10.
Guidance on Energy and Macronutrients across the Life Span.

Heymsfield SB, Shapses SA.

The New England Journal of Medicine. 2024;390(14):1299-1310. doi:10.1056/NEJMra2214275.

Leading Journal
Energy and Macronutrients > Protein

Proteins, synthesized from amino acids, are the major structural and functional components of the human body. Nine of the 20 amino acids found in human proteins are indispensable (essential); omitting any one of them from the diet leads to physical signs and a negative whole-body protein balance. Six amino acids are recognized as conditionally indispensable, meaning that sufficient amounts cannot be synthesized during periods of rapid growth and severe metabolic stress. The remaining 5 amino acids are dispensable (nonessential); they can be synthesized in vivo to meet the needs of the body. In the 1930s, Rudolf Schoenheimer and his colleagues showed that biomolecules in the body such as proteins are in a dynamic state of continual turnover that requires replacement through the diet to maintain most body functions and health.

Animal sources of protein contain all 9 indispensable amino acids, whereas plant proteins are usually deficient in 1 or more indispensable amino acids. A digestible amino acid score is used to grade protein sources, with a reference set at the digestibility-adjusted indispensable amino acid requirements for a preschool-age child. Cow’s milk, beef, and eggs have the highest score, at a value of approximately 1; rice has a value of approximately 0.5. Soy protein, with a score of approximately 0.9, is a beneficial plant source of amino acids. Vegetarians and vegans can maintain adequate high-quality protein intake by eating a variety of plant-based foods, including legumes, grains, soy products, nuts, and seeds.

Individual amino acid requirements are mainly established by means of isotopic tracer methods. Protein requirements are estimated with the use of nitrogen-balance methods, which monitor nitrogen losses in feces, urine, and skin according to variations in protein intake. An inadequate intake of total protein or any indispensable amino acid leads to adaptations in protein metabolism that can impair infant brain development, immune competence, and many other physiological and metabolic functions. Inadequate intake of energy from fat and carbohydrates can also lead to a negative nitrogen balance. In contrast, excess amino acids that are present during periods of high protein intake can be deaminated to form α-keto acids, which can then be oxidized for energy or converted to glucose or fat.

11.
Evaluation of Protein Adequacy From Plant-Based Dietary Scenarios in Simulation Studies: A Narrative Review.

Soh BXP, Smith NW, R von Hurst P, McNabb WC.

The Journal of Nutrition. 2024;154(2):300-313. doi:10.1016/j.tjnut.2023.11.018.

Although a diet high in plant foods can provide beneficial nutritional outcomes, unbalanced and restrictive plant-based diets may cause nutrient deficiencies. Protein intake from these diets is widely discussed, but the comparison of animal and plant proteins often disregards amino acid composition and digestibility as measurements of protein quality. Poor provision of high-quality protein may result in adverse outcomes, especially for individuals with increased nutrient requirements. Several dietary modeling studies have examined protein adequacy when animal-sourced proteins are replaced with traditional and novel plant proteins, but no review consolidating these findings are available. This narrative review aimed to summarize the approaches of modeling studies for protein intake and protein quality when animal-sourced proteins are replaced with plant foods in diet simulations and examine how these factors vary across age groups. A total of 23 studies using dietary models to predict protein contribution from plant proteins were consolidated and categorized into the following themes-protein intake, protein quality, novel plant-based alternatives, and plant-based diets in special populations. Protein intake from plant-based diet simulations was lower than from diets with animal-sourced foods but met country-specific nutrient requirements. However, protein adequacy from some plant-sourced foods were not met for simulated diets of children and older adults. Reduced amino acid adequacy was observed with increasing intake of plant foods in some scenarios. Protein adequacy was generally dependent on the choice of substitution with legumes, nuts, and seeds providing greater protein intake and quality than cereals. Complete replacement of animal to plant-sourced foods reduced protein adequacy when compared with baseline diets and partial replacements.

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One egg white from a large chicken egg contains approximately 1 ounce (28–33 grams) of liquid egg white.[1-2] This value is consistent across standard large eggs, though minor variation occurs with egg size and breed. The protein content of this amount is about 3.5 grams per egg white.[3-4]

1.
The Relationships Among Measures of Egg Albumen Height, pH, and Whipping Volume.

Silversides FG, Budgell K.

Poultry Science. 2004;83(10):1619-23. doi:10.1093/ps/83.10.1619.

A total of 2123 eggs obtained from Brown Leghorn hens (unselected since 1965, ISA Brown, commercial brown egg layer) and Babcock hens (commercial white egg layer) at 32, 50, and 68 wk of age were used to investigate relationships among measures of albumen quality and a functional property of albumen. The eggs were sampled fresh and after storage for 5 and 10 d. At sampling, eggs were weighed and broken, and albumen height, pH, and volume after whipping for 80 s were measured. Also, yolks were weighed, dried shells were weighed, and albumen weight was determined by difference. Egg weight and the weights of the 3 principal components of the egg all increased with increasing age of the hen, with yolk weights increasing proportionately more. With storage, egg and albumen weights decreased, whereas yolk weight increased. Eggs from Brown Leghorn hens were smallest but had proportionately the largest yolks. Albumen height decreased with time in storage, and albumen pH and whipping volume increased. Differences between lines suggested that selection has changed the proportion of the yolk, albumen, and shell and has increased albumen height. Albumen height and whipping volume were negatively correlated, and differences between lines suggest that selection could have decreased the foaming ability of albumen, a principal reason for including eggs in many processed food products.

2.
Physical Quality and Composition of Retail Shell Eggs.

Jones DR, Musgrove MT, Anderson KE, Thesmar HS.

Poultry Science. 2010;89(3):582-7. doi:10.3382/ps.2009-00315.

There are a number of specialty shell eggs available to consumers in the US retail market. A survey consisting of white and brown large shell eggs with various production and nutritional differences (traditional, cage-free, free-roaming, pasteurized, nutritionally enhanced, and fertile) was conducted to determine if physical quality and compositional differences exist. Identical brands of eggs were purchased from the same retail outlets on 3 occasions (replicates) in a single city. The average range of time from processing to purchase for all eggs was 7.67 to 25.33 d, with traditional white eggs in retail having the shortest time. Haugh unit values ranged from 66.67 (cage-free, docosahexaenoic acid, and n-3 enhanced) to 84.42 (traditional white). Albumen height followed a similar pattern. Egg weight was greater for brown eggs (61.12 vs. 58.85 g). Brown eggs also had greater static compression shell strength than white eggs (4,130.61 vs. 3,690.31 g force). Vitelline membrane strength was greatest for traditional brown eggs (2.24 g force). Percentage of total solids and crude fat was greatest in the cage-free, n-3-enhanced white eggs (25.07 and 11.71%, respectively). Although significant differences were found between white and brown shell eggs and production methods, average values for quality attributes varied without one egg type consistently maintaining the highest or lowest values.

3.
A Nutrient Re-Evaluation of Shell Eggs.

Cotterill OJ, Marion WW, Naber EC.

Poultry Science. 1977;56(6):1927-34. doi:10.3382/ps.0561927.

Most data on the nutrient composition of shell eggs were obtained before 1950. Since then, management systems for egg production and analytical methods for many components have changed. Freeze-dried whole egg, yolk and white samples were prepared from eggs obtained from a single source of 15 month old White Leghorns. The sample were packaged under nitrogen and held at -20 degrees C. until analyzed. Conversion factors are included for expressing the amount of each component on a per egg as well as a per 100 g. edible liquid basis. This re-evaluation of nutrient data included total solids, lipid, protein, cholesterol, ash, calories, amino acids, fatty acids, vitamins and minerals.

4.
Health Functions of Egg Protein.

Matsuoka R, Sugano M.

Foods (Basel, Switzerland). 2022;11(15):2309. doi:10.3390/foods11152309.

Egg protein is a remarkably abundant source of protein, with an amino acid score of 100 and the highest net protein utilization rate. However, there have been relatively fewer studies investigating the health benefits of egg protein. In this review, we have summarized the available information regarding the health benefits of egg proteins based on human studies. In particular, studies conducted on the characteristics of egg whites, as they are high in pure protein, have reported their various health functions, such as increases in muscle mass and strength enhancement, lowering of cholesterol, and visceral fat reduction. Moreover, to facilitate and encourage the use of egg white protein in future, we also discuss its health functions. These benefits were determined by developing an egg white hydrolysate and lactic-fermented egg whites, with the latter treatment simultaneously improving the egg flavor. The health benefits of the protein hydrolysates from the egg yolk (bone growth effect) and eggshell membrane (knee join pain-lowering effect) have been limited in animal studies. Therefore, the consumption of egg protein may contribute to the prevention of physical frailty and metabolic syndromes.

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Section 1: Protein Quality Comparison
Both 6 ounces of lean meat and 6 egg whites are considered high-quality protein sources. Six ounces of lean beef (e.g., tenderloin, top sirloin) provides approximately 42 grams of protein, with a digestible indispensable amino acid score (DIAAS) typically >100, indicating excellent digestibility and a complete amino acid profile suitable for supporting muscle protein synthesis and metabolic health.[1-2] Six egg whites provide about 21 grams of protein, with an amino acid score of 100 and the highest net protein utilization rate among dietary proteins. Egg white protein is highly digestible, efficiently utilized, and supports muscle mass and metabolic health.[3-4] While both are complete proteins, egg white protein is slightly superior in digestibility and utilization, especially for older adults and those with increased protein needs.[3-4]
Section 2: Cardiovascular Risk
Lean meat, particularly unprocessed red meat, is lower in saturated fat and cholesterol than fattier cuts, but red meat intake is associated with increased cardiovascular disease (CVD) risk in large cohort studies and meta-analyses.[5-7] The American Heart Association recommends limiting red meat and choosing lean cuts if meat is desired, but substitution analyses consistently show that replacing red meat with poultry, fish, egg whites, or plant proteins lowers CVD and all-cause mortality risk.[6][8] Egg whites are free of cholesterol and saturated fat, and their consumption is associated with lower all-cause and CVD mortality compared to whole eggs or red meat.[8-10] Replacing whole eggs or red meat with egg whites or plant proteins is consistently linked to improved cardiovascular outcomes.[8][10] Therefore, egg whites are healthier than lean red meat for cardiovascular risk reduction, especially in individuals with elevated baseline risk.
Section 3: Contaminant Exposure
Lean meat may contain persistent organic pollutants (dioxins, PCBs, PBDEs), heavy metals, and chemical residues, but levels are generally below regulatory limits in the US and Europe.[11-12] Occasional outliers exist, and organic meats may have higher levels of certain contaminants, but overall risk is low for commercially sourced products.[12] Egg whites can contain mycotoxins (e.g., deoxynivalenol, ochratoxin A), endocrine disruptors, and trace pollutants, with concentrations usually below safety thresholds except in high-risk regions (e.g., China, Egypt, Jordan).[13-14] In the US and most developed countries, both foods are generally safe, but local environmental contamination and sourcing practices can affect risk.[11][13-14] Children are more susceptible to mycotoxin exposure from eggs, but for adults, the risk from egg whites is low.
Section 4: Areas Needing Further Research
Long-term comparative data on chronic contaminant exposure and individual metabolic responses to different protein sources are limited. Further research is needed to clarify the impact of cumulative low-level exposure and to optimize dietary recommendations for specific populations.
In summary, egg whites are healthier to consume than 6 ounces of lean meat in terms of protein quality, cardiovascular risk, and potential exposure to contaminants, particularly for adults in developed countries with access to regulated food supplies. Plant proteins may offer additional cardiometabolic benefits when used as primary protein sources.

1.
Nutrient Analysis of Raw and Cooked USDA Prime Beef Cuts.

Mortensen EG, Fuerniss HF, Legako JF, Thompson LD, Woerner DR.

Nutrients. 2024;16(17):2912. doi:10.3390/nu16172912.

Nutrient composition data that accurately represent available beef products are critical to understanding beef's role in healthy dietary patterns. The quality of beef products has changed over the past several decades, and updated nutrient data are warranted as USDA Prime beef cuts become more available. In an effort to provide a complete nutrient profile for frequently purchased USDA Prime beef cuts, five USDA Prime cuts; strip loin steak, tenderloin steak, ribeye steak, top sirloin steak, and rib roast were collected from retail stores in six geographical locations over three collections for macro- and micronutrient analysis in both the raw and cooked state. The separable lean portion of all analyzed USDA Prime cuts qualified as a good or excellent source, providing 10-19% or at least 20% of the daily value, respectively, for protein, niacin, vitamin B12, selenium, phosphorus, and zinc per FDA labeling claim standards. There was not a significant difference in cholesterol content between any of the cuts, raw or cooked (p ≥ 0.44 and 0.34, respectively). The percent lipid in raw, separable lean portions of the rib roast and strip loin steak was significantly greater than the lipid portion in tenderloin and top sirloin steaks (p ≤ 0.01). Per USDA standards, the separable lean portions of tenderloin steak and top sirloin steak qualify as lean beef, containing less than 10 g total fat, less than 4.5 g saturated fat, and less than or equal to 95 mg cholesterol. The current study provides the most up-to-date nutrient analysis for USDA Prime beef cuts, helping consumers and health professionals better identify the role of high-quality beef cuts in healthy dietary patterns.

2.
Most Meat Products Have Digestible Indispensable Amino Acid Scores That Are Greater Than 100, but Processing May Increase or Reduce Protein Quality.

Bailey HM, Mathai JK, Berg EP, Stein HH.

The British Journal of Nutrition. 2020;124(1):14-22. doi:10.1017/S0007114520000641.

An experiment was conducted to test the hypothesis that meat products have digestible indispensable amino acid scores (DIAAS) >100 and that various processing methods will increase standardised ileal digestibility (SID) of amino acids (AA) and DIAAS. Nine ileal-cannulated gilts were randomly allotted to a 9 × 8 Youden square design with nine diets and eight 7-d periods. Values for SID of AA and DIAAS for two reference patterns were calculated for salami, bologna, beef jerky, raw ground beef, cooked ground beef and ribeye roast heated to 56, 64 or 72°C. The SID of most AA was not different among salami, bologna, beef jerky and cooked ground beef, but was less ( < 0·05) than the values for raw ground beef. The SID of AA for 56°C ribeye roast was not different from the values for raw ground beef and 72°C ribeye roast, but greater ( < 0·05) than those for 64°C ribeye roast. For older children, adolescents and adults, the DIAAS for all proteins, except cooked ground beef, were >100 and bologna and 64°C ribeye roast had the greatest ( < 0·05) DIAAS. The limiting AA for this age group were sulphur AA (beef jerky), leucine (bologna, raw ground beef and cooked ground beef) and valine (salami and the three ribeye roasts). In conclusion, meat products generally provide high-quality protein with DIAAS >100 regardless of processing. However, overcooking meat may reduce AA digestibility and DIAAS.

3.
Health Functions of Egg Protein.

Matsuoka R, Sugano M.

Foods (Basel, Switzerland). 2022;11(15):2309. doi:10.3390/foods11152309.

Egg protein is a remarkably abundant source of protein, with an amino acid score of 100 and the highest net protein utilization rate. However, there have been relatively fewer studies investigating the health benefits of egg protein. In this review, we have summarized the available information regarding the health benefits of egg proteins based on human studies. In particular, studies conducted on the characteristics of egg whites, as they are high in pure protein, have reported their various health functions, such as increases in muscle mass and strength enhancement, lowering of cholesterol, and visceral fat reduction. Moreover, to facilitate and encourage the use of egg white protein in future, we also discuss its health functions. These benefits were determined by developing an egg white hydrolysate and lactic-fermented egg whites, with the latter treatment simultaneously improving the egg flavor. The health benefits of the protein hydrolysates from the egg yolk (bone growth effect) and eggshell membrane (knee join pain-lowering effect) have been limited in animal studies. Therefore, the consumption of egg protein may contribute to the prevention of physical frailty and metabolic syndromes.

4.
Understanding Dietary Protein Quality: DIAAS and Beyond.

Matthews JJ, Arentson-Lantz EJ, Moughan PJ, et al.

The Journal of Nutrition. 2025;:S0022-3166(25)00428-6. doi:10.1016/j.tjnut.2025.07.005.

New Research

Dietary protein quality refers to the capacity of a food to meet the human metabolic needs for essential amino acids (EAAs) and nitrogen. This is critical in low- and middle-income countries, where severe protein malnutrition occurs; and relevant in higher-income countries, where increasing dietary EAA intake may improve health and function. There are several methods to assess protein quality, each with different objectives. Chemical scoring metrics, like the digestible indispensable amino acid score (DIAAS), describe the EAA composition and digestibility of a protein source. However, these methods do not capture the metabolic activity of food-derived amino acids. Overreliance on a single metric leads to generic dietary recommendations lacking individual context. This review draws upon chemical score and stable isotope methods to provide a comprehensive assessment of dietary protein quality. We translate these findings into practical recommendations for improving protein quality in the context of whole diets. High-quality protein sources are characterized by high EAA density (%EAAs/kcals), digestibility, bioavailability, and the capacity to stimulate protein synthesis. Practically, protein quality improves when using processing and cooking methods that reduce antinutrients, denature proteins, and reduce food particle size and structure. Conversely, protein quality decreases when exposing foods to prolonged storage, heat sterilization, and high surface temperatures. Diet modelling studies show that EAA density and protein quality are higher in omnivorous and lacto-ovo-vegetarian diets, and diets high in whole food plant-derived proteins may require greater total protein and energy intakes to compensate for lower protein quality. For incomplete plant-derived proteins, consuming complementary proteins may be beneficial. Considerations for dietary protein quality in older adults include chewing efficiency, food particle size, and higher EAA density and leucine intakes to maximize muscle protein synthesis. Recognizing dietary protein quality as a multifaceted, modifiable metric is essential to improving dietary recommendations and public health outcomes.

5.
The Impact of Type of Dietary Protein, Animal Versus Vegetable, in Modifying Cardiometabolic Risk Factors: A Position Paper From the International Lipid Expert Panel (ILEP).

Zhubi-Bakija F, Bajraktari G, Bytyçi I, et al.

Clinical Nutrition (Edinburgh, Scotland). 2021;40(1):255-276. doi:10.1016/j.clnu.2020.05.017.

Proteins play a crucial role in metabolism, in maintaining fluid and acid-base balance and antibody synthesis. Dietary proteins are important nutrients and are classified into: 1) animal proteins (meat, fish, poultry, eggs and dairy), and, 2) plant proteins (legumes, nuts and soy). Dietary modification is one of the most important lifestyle changes that has been shown to significantly decrease the risk of cardiovascular (CV) disease (CVD) by attenuating related risk factors. The CVD burden is reduced by optimum diet through replacement of unprocessed meat with low saturated fat, animal proteins and plant proteins. In view of the available evidence, it has become acceptable to emphasize the role of optimum nutrition to maintain arterial and CV health. Such healthy diets are thought to increase satiety, facilitate weight loss, and improve CV risk. Different studies have compared the benefits of omnivorous and vegetarian diets. Animal protein related risk has been suggested to be greater with red or processed meat over and above poultry, fish and nuts, which carry a lower risk for CVD. In contrast, others have shown no association of red meat intake with CVD. The aim of this expert opinion recommendation was to elucidate the different impact of animal vs vegetable protein on modifying cardiometabolic risk factors. Many observational and interventional studies confirmed that increasing protein intake, especially plant-based proteins and certain animal-based proteins (poultry, fish, unprocessed red meat low in saturated fats and low-fat dairy products) have a positive effect in modifying cardiometabolic risk factors. Red meat intake correlates with increased CVD risk, mainly because of its non-protein ingredients (saturated fats). However, the way red meat is cooked and preserved matters. Thus, it is recommended to substitute red meat with poultry or fish in order to lower CVD risk. Specific amino acids have favourable results in modifying major risk factors for CVD, such as hypertension. Apart from meat, other animal-source proteins, like those found in dairy products (especially whey protein) are inversely correlated to hypertension, obesity and insulin resistance.

6.
2021 Dietary Guidance to Improve Cardiovascular Health: A Scientific Statement From the American Heart Association.

Lichtenstein AH, Appel LJ, Vadiveloo M, et al.

Circulation. 2021;144(23):e472-e487. doi:10.1161/CIR.0000000000001031.

Leading Journal

Dietary patterns rich in red meat have been associated with higher CVD incidence and mortality, 58–62 and body mass index and waist circumference, as well. 63 , 64 Several systematic reviews and meta-analyses have documented a direct association between red meat intake and CVD incidence and mortality, although the magnitude of the association is less strong than that for processed meat. 58 , 65 , 66 Substitution analyses based on large cohort studies found that the replacement of red and processed meat with alternative foods such as unprocessed poultry, fish, nuts, and legumes was associated with a lower risk of total and CVD mortality. 62 The potential adverse effect of red meat on CVD risk has been attributed to a combination of factors, including saturated fat and heme iron content, and gut microbiota metabolism of l-carnitine and phosphatidylcholine. 45 , 67 , 68
The term “processed meats” includes meat, poultry, or seafood products preserved by smoking, curing, or salting or the addition of chemical preservatives. 9 Common examples include bacon, sausage, hot dogs, deli meat (eg, turkey, ham), pepperoni, and salami. Ingredients used to make these foods include sodium and nitrites. Many processed meats are high in salt, saturated fat, cholesterol, heme iron, and polycyclic aromatic hydrocarbons, and heterocyclic amines (depending on the heating method), as well. Substitution analyses indicate that the replacement of processed meats with other protein sources is associated with lower mortality rates. 69 Available evidence does not support an adverse association of unprocessed poultry with CVD. 70–72

7.
Protein Foods From Animal Sources, Incident Cardiovascular Disease and All-Cause Mortality: A Substitution Analysis.

Zhong VW, Allen NB, Greenland P, et al.

International Journal of Epidemiology. 2021;50(1):223-233. doi:10.1093/ije/dyaa205.

Background: Protein-rich foods are major parts of the human diet and are highly heterogeneous in nutrient composition and health effects. Designing healthy diets for disease prevention requires careful consideration of substituting unhealthier protein foods with healthier protein foods.

Methods: This was a pooled analysis of six prospective cohort studies of 29 682 US participants. Data were collected in 1985-2016. Adjusted hazard ratios (HRs) and 30-year absolute risk differences (ARDs) were calculated for the associations between simultaneous substitution of one or more animal protein foods with other animal or plant protein foods at various amounts, and incident cardiovascular disease (CVD) and all-cause mortality.

Results: Substituting eggs, processed meat, unprocessed red meat or poultry with nuts, whole grains, legumes or fish was associated with lower risks of incident CVD and all-cause mortality. According to different substitution amounts (varying from one serving per week to one serving per day) and different numbers of protein foods being simultaneously substituted (varying from one to four), estimates ranged between 1%: HR, 0.99 [95% confidence interval (CI), 0.98-1.00], and 54%: HR, 0.46 (0.35-0.60), lower risks on the relative scale and between 0.3%: ARD, -0.29% (-0.48% to -0.05%), and 14.0%: ARD, -13.96% (-17.29% to -9.96%) lower risks on the absolute scale.

Conclusions: Nuts, whole grains, legumes and fish appeared to be healthier protein sources than eggs, processed meat, unprocessed red meat and poultry for preventing incident CVD and premature death. The magnitude of lower risk for incident CVD and all-cause mortality was driven by amount and number of animal protein foods substituted.

8.
Egg and Cholesterol Consumption and Mortality From Cardiovascular and Different Causes in the United States: A Population-Based Cohort Study.

Zhuang P, Wu F, Mao L, et al.

PLoS Medicine. 2021;18(2):e1003508. doi:10.1371/journal.pmed.1003508.

Leading Journal

Background: Whether consumption of egg and cholesterol is detrimental to cardiovascular health and longevity is highly debated. Data from large-scale cohort studies are scarce. This study aimed to examine the associations of egg and cholesterol intakes with mortality from all causes, cardiovascular disease (CVD), and other causes in a US population.

Methods And Findings: Overall, 521,120 participants (aged 50-71 years, mean age = 62.2 years, 41.2% women, and 91.8% non-Hispanic white) were recruited from 6 states and 2 additional cities in the US between 1995 and 1996 and prospectively followed up until the end of 2011. Intakes of whole eggs, egg whites/substitutes, and cholesterol were assessed by a validated food frequency questionnaire. Cause-specific hazard models considering competing risks were used, with the lowest quintile of energy-adjusted intake (per 2,000 kcal per day) as the reference. There were 129,328 deaths including 38,747 deaths from CVD during a median follow-up of 16 years. Whole egg and cholesterol intakes were both positively associated with all-cause, CVD, and cancer mortality. In multivariable-adjusted models, the hazard ratios (95% confidence intervals) associated with each intake of an additional half of a whole egg per day were 1.07 (1.06-1.08) for all-cause mortality, 1.07 (1.06-1.09) for CVD mortality, and 1.07 (1.06-1.09) for cancer mortality. Each intake of an additional 300 mg of dietary cholesterol per day was associated with 19%, 16%, and 24% higher all-cause, CVD, and cancer mortality, respectively. Mediation models estimated that cholesterol intake contributed to 63.2% (95% CI 49.6%-75.0%), 62.3% (95% CI 39.5%-80.7%), and 49.6% (95% CI 31.9%-67.4%) of all-cause, CVD, and cancer mortality associated with whole egg consumption, respectively. Egg white/substitute consumers had lower all-cause mortality and mortality from stroke, cancer, respiratory disease, and Alzheimer disease compared with non-consumers. Hypothetically, replacing half a whole egg with equivalent amounts of egg whites/substitutes, poultry, fish, dairy products, or nuts/legumes was related to lower all-cause, CVD, cancer, and respiratory disease mortality. Study limitations include its observational nature, reliance on participant self-report, and residual confounding despite extensive adjustment for acknowledged dietary and lifestyle risk factors.

Conclusions: In this study, intakes of eggs and cholesterol were associated with higher all-cause, CVD, and cancer mortality. The increased mortality associated with egg consumption was largely influenced by cholesterol intake. Our findings suggest limiting cholesterol intake and replacing whole eggs with egg whites/substitutes or other alternative protein sources for facilitating cardiovascular health and long-term survival.

Trial Registration: ClinicalTrials.gov NCT00340015.

9.
Meat Consumption and Risk of Ischemic Heart Disease: A Systematic Review and Meta-Analysis.

Papier K, Knuppel A, Syam N, Jebb SA, Key TJ.

Critical Reviews in Food Science and Nutrition. 2023;63(3):426-437. doi:10.1080/10408398.2021.1949575.

Leading Journal

There is uncertainty regarding the association between unprocessed red and processed meat consumption and the risk of ischemic heart disease (IHD), and little is known regarding the association with poultry intake. The aim of this systematic review and meta-analysis was to quantitatively assess the associations of unprocessed red, processed meat, and poultry intake and risk of IHD in published prospective studies. We systematically searched CAB Abstract, MEDLINE, EMBASE, Web of Science, bioRxiv and medRxiv, and reference lists of selected studies and previous systematic reviews up to June 4, 2021. All prospective cohort studies that assessed associations between 1(+) meat types and IHD risk (incidence and/or death) were selected. The meta-analysis was conducted using fixed-effects models. Thirteen published articles were included (ntotal = 1,427,989; ncases = 32,630). Higher consumption of unprocessed red meat was associated with a 9% (relative risk (RR) per 50 g/day higher intake, 1.09; 95% confidence intervals (CI), 1.06 to 1.12; nstudies = 12) and processed meat intake with an 18% higher risk of IHD (1.18; 95% CI, 1.12 to 1.25; nstudies = 10). There was no association with poultry intake (nstudies = 10). This study provides substantial evidence that unprocessed red and processed meat, though not poultry, might be risk factors for IHD.

10.
Associations of Dietary Cholesterol or Egg Consumption With Incident Cardiovascular Disease and Mortality.

Zhong VW, Van Horn L, Cornelis MC, et al.

JAMA logoJAMA. 2019;321(11):1081-1095. doi:10.1001/jama.2019.1572.

Leading Journal
Key Points

Question Is consuming dietary cholesterol or eggs associated with incident cardiovascular disease (CVD) and all-cause mortality?

Findings Among 29 615 adults pooled from 6 prospective cohort studies in the United States with a median follow-up of 17.5 years, each additional 300 mg of dietary cholesterol consumed per day was significantly associated with higher risk of incident CVD (adjusted hazard ratio [HR], 1.17; adjusted absolute risk difference [ARD], 3.24%) and all-cause mortality (adjusted HR, 1.18; adjusted ARD, 4.43%), and each additional half an egg consumed per day was significantly associated with higher risk of incident CVD (adjusted HR, 1.06; adjusted ARD, 1.11%) and all-cause mortality (adjusted HR, 1.08; adjusted ARD, 1.93%).

Meaning Among US adults, higher consumption of dietary cholesterol or eggs was significantly associated with higher risk of incident CVD and all-cause mortality in a dose-response manner.

11.
Polychlorinated Dioxins, Furans, and Biphenyls, and Polybrominated Diphenyl Ethers in a U.S. Meat Market Basket and Estimates of Dietary Intake.

Huwe JK, Larsen GL.

Environmental Science & Technology. 2005;39(15):5606-11. doi:10.1021/es050638g.

Leading Journal

Persistent environmental contaminants including polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), non-ortho-polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) were analyzed in 65 meat samples collected from supermarkets across the U.S. in 2001. The samples included hamburger, sirloin steaks, pork chops, bacon, and whole chickens from nine different cities. The average PCDD/F/non-ortho-PCB toxic equivalency (TEQ) for all the samples was 0.55 pg/g of lipid (nd (nondetect) = DL (detection limit)/2) with a range from nondetectable to 3.21 pg/g of lipid. For PBDEs, eight congeners were routinely found in the meat samples with an average sum of 1.71 ng/g of lipid (nd = DL/2) and a range from nondetectable to 16.6 ng/g of lipid. While average TEQs were similar to recent values reported in Europe and Asia, the sums of PBDEs in chicken and pork were 3-20 times higher than levels reported in Spain and Japan for these foods. The presence of a few outliers raised the average PBDE sums and indicated that isolated sources of contamination may exist that, if identified, could be removed from the U.S. animal production chain. Using these TEQ and PBDE values and USDA food consumption data, the estimated dietary intake ranges from meat products were 5.3-16.0 pg TEQ and 14.9-44.7 ng of PBDEs/d or 0.1-0.3 pg TEQ and 0.3-0.5 (ng of PBDEs/kg of body mass)/d for an average individual, similar to intakes in other countries.

12.
Micropollutants and Chemical Residues in Organic and Conventional Meat.

Dervilly-Pinel G, Guérin T, Minvielle B, et al.

Food Chemistry. 2017;232:218-228. doi:10.1016/j.foodchem.2017.04.013.

Leading Journal

The chemical contamination levels of both conventional and organic meats were assessed. The objective was to provide occurrence data in a context of chronic exposure. Environmental contaminants (17 polychlorinated dibenzodioxins/dibenzofurans, 18 polychlorinated biphenyls (PCBs), 3 hexabromocyclododecane (HBCD) isomers, 6 mycotoxins, 6 inorganic compounds) together with chemical residues arising from production inputs (75 antimicrobials, 10 coccidiostats and 121 pesticides) have been selected as relevant compounds. A dedicated sampling strategy, representative of the French production allowed quantification of a large sample set (n=266) including both conventional (n=139) and organic (n=127) raw meat from three animal species (bovine, porcine, poultry). While contamination levels below regulatory limits were measured in all the samples, significant differences were observed between both species and types of farming. Several environmental contaminants (Dioxins, PCBs, HBCD, Zn, Cu, Cd, Pb, As) were measured at significantly higher levels in organic samples.

13.

Mycotoxins, such as aflatoxins (AFs), deoxynivalenol (DON), zearalenone (ZEN), and ochratoxin A (OTA), present significant health risks due to their carcinogenic and toxic properties. This study conducted a systematic review and meta-analysis to assess the global prevalence, concentration, and associated health risks of mycotoxins in domestic bird eggs. Following the PRISMA guideline, a comprehensive search was performed across PubMed, Scopus, and Web of Science (2005-2024). Thirteen studies, encompassing 8,410 egg samples, were analyzed. The pooled prevalence and concentration of mycotoxins were estimated using random-effects models, while probabilistic risk assessment was performed via Monte Carlo simulation, calculating the Margin of Exposure (MOEs) and Hazard Quotient (HQ). The prevalence ranking of aflatoxins (AFs) in eggs was as follows: AFB1 (19%) > AFB2 (12%) > AFG1 (10%) ≈ AFG2 (10%). In terms of mean pooled concentration, mycotoxins followed this order: DON (83.93 µg/kg) > ZEN (6.00 µg/kg) > AFs (5.604 µg/kg) > OTA (2.52 µg/kg). Concentrations of DON and OTA were higher in egg white than in yolk, whereas ZEN levels were higher in yolk. From a public health perspective, risk assessment revealed alarming exposure levels, particularly in China, Egypt, and Jordan, where MOEs values for AFB1 were significantly below the safety threshold (MOEs < 10,000). Children were found to be at heightened risk due to their lower body weight and developing physiological systems, with MOEs as low as 3 in China. Additionally, HQ analyses indicated non-negligible risks from DON, OTA, and ZEN, particularly in China and Poland, where dietary exposure may contribute to chronic toxicity or endocrine disruption.

14.
Determination of Selected Endocrine Disruptors in Organic, Free-Range, and Battery-Produced Hen Eggs and Risk Assessment.

Kuzukiran O, Yurdakok-Dikmen B, Sevin S, et al.

Environmental Science and Pollution Research International. 2018;25(35):35376-35386. doi:10.1007/s11356-018-3400-5.

An increasing amount of evidence suggests that phthalic acid esters (PAE), polychlorinated biphenyls (PCB), polybrominated diphenyl ethers (PBDE), and organochlorine pesticides (OCP) are related to mutagenic, carcinogenic, and endocrine disruptor effects (EDCs). These lipophilic compounds are highly resistant to breakdown processes, and consequently remain in the environment, followed by uptake into the food chain. Human exposure to lipophilic compounds results from the consumption of food containing EDCs, mainly foodstuffs of animal origin with a high fat content, since these contaminants accumulate in fatty tissues. Foodstuffs in which EDCs can accumulate include meat, fish, eggs, and milk. We investigated the contamination in edible eggs to determine whether relative differences in the contaminants' residue levels appeared in three types of egg production (i.e., battery, free-range, and organic). The results showed that PAEs, especially dimethyl phthalate contamination, was the most abundant in the battery eggs, and the PCBs, PBDEs, and OCPs were the most abundant in the free-range eggs. The eggs were contaminated by more than one chemical, and as many as five contaminants (PCB180, PBDE47, dimethyl phthalate, diethyl phthalate, and di-n-butyl phthalate in battery eggs, and PCB138, PCB153, PCB180, diethyl phthalate, and di-2-ethylhexyl phthalate in organic eggs) were detected in the same egg. However, none of the chemicals detected were at the maximum limit of acceptable risk.