The responses of different dosages of egg consumption on blood lipid profile: An updated systematic review and meta-analysis of randomized clinical trials

Effect of egg consumption on health outcomes: An updated umbrella review of systematic reviews and meta-analysis of observational and intervention studies

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.

Eggs, Dietary Choline, and Nonalcoholic Fatty Liver Disease in the Framingham Heart Study

BACKGROUND

Eggs are rich in bioactive compounds, including choline and carotenoids that may benefit cardiometabolic outcomes. However, little is known about their relationship with nonalcoholic fatty liver disease (NAFLD).

OBJECTIVES

We investigated the association between intakes of eggs and selected egg-rich nutrients (choline, lutein, and zeaxanthin) and NAFLD risk and changes in liver fat over ∼6 y of follow-up in the Framingham Offspring and Third Generation cohorts.

METHODS

On 2 separate occasions (2002-2005 and 2008-2011), liver fat was assessed using a computed tomography scan to estimate the average liver fat attenuation relative to a control phantom to create the liver phantom ratio (LPR). In 2008-2011, cases of incident NAFLD were identified as an LPR ≤0.33 in the absence of heavy alcohol use, after excluding prevalent NAFLD (LPR ≤0.33) in 2002-2005. Food frequency questionnaires were used to estimate egg intakes (classified as <1, 1, and ≥2 per week), dietary choline (adjusted for body weight using the residual method), and the combined intakes of lutein and zeaxanthin. Multivariable modified Poisson regression and general linear models were used to compute incident risk ratios (RR) of NAFLD and adjusted mean annualized liver fat change.

RESULTS

NAFLD cumulative incidence was 19% among a total of 1414 participants. We observed no associations between egg intake or the combined intakes of lutein and zeaxanthin with an incident NAFLD risk or liver fat change. Other diet and cardiometabolic risk factors did not modify the association between egg intake and NAFLD risk. However, dietary choline intakes were inversely associated with NAFLD risk (RR for tertile 3 compared with tertile 1: 0.69, 95% CI: 0.51, 0.94).

CONCLUSIONS

Although egg intake was not directly associated with NAFLD risk, eggs are a major source of dietary choline, which was strongly inversely associated with NAFLD risk in this community-based cohort.

Association between egg consumption and mortality risk in United States adults with established coronary heart disease or stroke: A cohort study using data from NHANES 1999-2018

BACKGROUND

To investigate the relationship between egg consumption and mortality in individuals with pre-existing coronary heart disease or stroke.

METHODS

This study utilized data from the National Health and Nutrition Examination Survey conducted between 1999 and 2018. Egg consumption was evaluated through 24 h dietary recalls at baseline. Mortality status was tracked until December 31, 2019. Survey-weighted Cox proportional hazards models were utilized.

RESULTS

The study involved 3,975 participants aged 20 years or older with a median follow-up of 89.00 months. A total of 1,675 individuals died during follow-up. Compared to individuals who did not consume eggs, the consumption of 0-50 g/day (hazard ratio [HR] = 1.033, 95% confidence interval [CI] =0.878-1.214) was not found to have a significant association with all-cause mortality. However, consuming 50-100 g/day (HR = 1.281, 95% CI = 1.004-1.635) and >100 g/day (HR = 1.312, 95% CI =1.036-1.661) exhibited a significant association with an increased risk of all-cause mortality. We identified a non-liner relationship between egg consumption and cardiovascular mortality, where the risk was found to be lowest at an intake of about 50 g/day. For individuals consuming more than 50 g/day, each additional 50 g increment in egg consumption was significantly linked to an elevated risk of cardiovascular mortality (HR = 1.276, 95% CI = 1.009-1.614).

CONCLUSION

In U.S. adults with pre-existing cardiovascular disease, a significant positive association was found between consuming over 50 g of eggs per day and the risk of mortality, highlighting the importance of moderate intake.

Eggs and a Fiber-Rich Diet Are Beneficially Associated with Lipid Levels in Framingham Offspring Study Adults

Background

For many years, United States' dietary policy recommended limiting egg intake to no more than 3/wk in the belief that restricting dietary cholesterol would lower plasma cholesterol levels and thereby reduce the risk of cardiovascular disease. The evidence supporting these recommendations is controversial.

Objectives

To examine the impact of eggs, a major contributor to dietary cholesterol intake, on lipid levels and to determine whether these egg effects are modified by other healthy dietary factors in adults.

Methods

Males and females aged 30-64 y with available 3-d diet record data, without cardiovascular disease and not taking lipid- or glucose-lowering medications in the prospective Framingham Offspring cohort were included (n = 1852). Analysis of covariance models were used to compare mean follow-up lipid levels adjusting for age, sex, BMI, and dietary factors. Cox proportional hazard's models were used to estimate risk for elevated lipid levels.

Results

Consuming ≥5 eggs/wk was not adversely associated with lipid outcomes. Among men, consuming ≥5 (compared with <0.5) eggs/wk was associated with an 8.6 mg/dL lower total cholesterol level and a 5.9 mg/dL lower LDL cholesterol level, as well as lower triglycerides. Overall, higher egg intake combined with higher dietary fiber (compared with lower intakes of both) was associated with the lowest total cholesterol, LDL cholesterol, and LDL cholesterol-to-HDL cholesterol ratio. Finally, diets with higher (compared with lower) egg intakes in combination with higher total fish or fiber intakes, respectively, were associated with lower risks of developing elevated (>160 mg/dL) LDL cholesterol levels (hazard ratio: 0.61; 95% confidence interval: 0.44, 0.84; and HR: 0.70; 95% confidence interval: 0.49, 0.98, respectively).

Conclusions

Higher egg intakes were beneficially associated with serum lipids among healthy adults, particularly those who consumed more fish and dietary fiber.

Eggs - a scoping review for Nordic Nutrition Recommendations 2023

Cardiovascular diseases (CVD), type 2 diabetes (T2D), and cancer are a significant public health burden in the Nordic and Baltic countries. High intake of eggs, mainly due to its high cholesterol content, has been suggested to have adverse health effects. The purpose of this scoping review is to describe the evidence related to the impact of egg intake on health. A literature search identified 38 systematic reviews and meta-analyses on egg consumption in relation to health outcomes published between 2011 and 30 April 2022. Overall, current evidence from systematic reviews of randomized clinical trials indicates that higher egg intake may increase serum total cholesterol concentration and the ratio of low-density lipoprotein to high-density lipoprotein cholesterol, but with substantial heterogeneity in the response. However, recent evidence from observational studies does not provide strong support for a detrimental role of moderate egg consumption (up to one egg/day) on the risk of CVD, especially in the European studies. The overall evidence from observational studies indicates that egg consumption is not associated with increased risk of mortality or T2D in European study populations. There is also little support for a role of egg consumption in cancer development, although a weak association with higher risk of certain cancers has been found in some studies, mainly case-control studies. Again, no associations with cancer risk have been observed in European studies. Systematic reviews and meta-analyses of egg consumption in relation to other health-related outcomes are scarce. There are also limited data available on the associations between the consumption of more than one egg/day and risk of diseases. Based on the available evidence, one egg/day is unlikely to adversely affect overall disease risk.

The cluster of differentiation 36 (CD36) rs1761667 polymorphism interacts with dietary patterns to affect cardiometabolic risk factors and metabolic syndrome risk in apparently healthy individuals

Several studies have examined the association between CD36 rs1761667 polymorphism with cardiometabolic risk factors and metabolic syndrome (MetS). This study aimed to investigate the interactions between rs1761667 polymorphism and dietary patterns on the cardiometabolic risk factors and the risk of MetS in apparently healthy individuals aged 20-70 years. Food consumption data were acquired using a validated semi-quantitative FFQ. Dietary patterns were identified by factor analysis. CD36 rs1761667 was genotyped by PCR-restriction fragment length polymorphism. The gene-diet interaction was detected by the general linear model or logistic regression. Significant or marginally significant interactions were observed between healthy dietary pattern (HDP) and CD36 rs1761667 on weight (P = 0·006), BMI (P = 0·009), waist circumference (P = 0·005), hip circumference (P = 0·06), body muscle percentage (P = 0·02), body fat percentage (P = 0·09), TAG-glucose index (P = 0·057), atherogenic index of plasma (P = 0·07), the risk of MetS (P = 0·02), risk of abdominal obesity (P = 0·02) and elevated blood pressure (P = 0·07). Besides, a gene-diet interaction was detected between the traditional dietary pattern and rs1761667 variants on odds of hypertriglyceridaemia (P = 0·02). The adherence to HDP was associated with a lower weight, BMI and higher odds of HDL-cholesterol only in A-allele carriers. In conclusion, adherence to HDP (a diet with high fibre, fish and dairy products) can be more effective on some cardiometabolic risk factors and risk of MetS components in the A-allele carrier than the GG genotype of rs1761667 polymorphism. However, future studies are required to shed light on this issue.

Nutritional recommendations in the prevention and treatment of atherogenic dyslipidemia

The incorporation of a healthy diet, regular physical exercise and smoking cessation are the initial measures to reduce cardiovascular risk in patients with atherogenic dyslipidemia. In these patients, the nutritional quality of their diet should be improved, replacing foods with a greater atherogenic effect for others with a healthier effect. There is strong evidence that plant-based dietary patterns, low in saturated fatty acids, cholesterol and sodium, with a high content of fiber, potassium and unsaturated fatty acids, are beneficial and reduce the expression of cardiovascular risk factors. This document focuses on the role of nutrition in the prevention and treatment of atherogenic dyslipidemia, providing current evidence to serve as a tool for health professionals in its clinical management. To facilitate the reading of these recommendations, they are presented in a user-friendly table format, with a hierarchy of different levels of evidence.

Effects of different levels of egg protein replacement in weaned diets on hematology, kidney functions, and immunity biomarkers

Eggs are good sources of nutrients essential for the growth and development of infants. Introducing eggs as a weaning food can improve dietary adequacy in infants at risk for protein energy malnutrition (PEM). To evaluate the current objective, 72 pups (36 males and 36 females) were used to calculate the impact of various egg protein levels on blood parameters. Nonisonitrogenous and isocaloric pellet diets were offered to pups for 28 days using nine pups with three replicates according to a completely randomized design (CRD). The water intake and ad libitum diet were offered to weaned pups. The pups were randomly assigned to different concentrations of diet, which contained WF0, control diet, 14% of soybean protein; WF1, 14% of egg protein; WF2, 16% of egg protein; and WF3, 18% of egg protein, respectively. After weaning, the intraperitoneal injection with the drug (xylazine with ketamine) was used to anesthetize before killing on the 28th day. Blood samples were used to measure the blood metabolites. The results indicated that the concentration of red blood cells, white blood cells, serum triglycerides, and serum protein was significantly (p ≤ .05) increased in pups fed with high egg protein levels compared to the control. The highest platelet count was observed in the pups fed WF3 diet. In contrast, the amount of alanine aminotransferase and aspartate aminotransferase was significantly (p ≤ .05) reduced with increasing the level of egg protein in the diets of weaned pups. Immunity biomarkers (immunoglobulin A, immunoglobulin G, and immunoglobulin M) and kidney functions (creatinine and blood urine nitrogen) were nonsignificantly (p ≤ .05) increased in the pups fed a high level of protein due to a high biological value of soybean protein. Moreover, the concentration of immunoglobulin E in all pups remained unchanged. Egg protein in infant formula feed can be used for the growth and development of infants.

Association of egg consumption, metabolic markers, and risk of cardiovascular diseases: A nested case-control study

Background

Few studies have assessed the role of individual plasma cholesterol levels in the association between egg consumption and the risk of cardiovascular diseases. This research aims to simultaneously explore the associations of self-reported egg consumption with plasma metabolic markers and these markers with the risk of cardiovascular disease (CVD).

Methods

Totally 4778 participants (3401 CVD cases subdivided into subtypes and 1377 controls) aged 30-79 were selected based on the China Kadoorie Biobank. Targeted nuclear magnetic resonance was used to quantify 225 metabolites in baseline plasma samples. Linear regression was conducted to assess associations between self-reported egg consumption and metabolic markers, which were further compared with associations between metabolic markers and CVD risk.

Results

Egg consumption was associated with 24 out of 225 markers, including positive associations for apolipoprotein A1, acetate, mean HDL diameter, and lipid profiles of very large and large HDL, and inverse associations for total cholesterol and cholesterol esters in small VLDL. Among these 24 markers, 14 were associated with CVD risk. In general, the associations of egg consumption with metabolic markers and of these markers with CVD risk showed opposite patterns.

Conclusions

In the Chinese population, egg consumption is associated with several metabolic markers, which may partially explain the protective effect of moderate egg consumption on CVD.

Funding

This work was supported by the National Natural Science Foundation of China (81973125, 81941018, 91846303, 91843302). The CKB baseline survey and the first re-survey were supported by a grant from the Kadoorie Charitable Foundation in Hong Kong. The long-term follow-up is supported by grants (2016YFC0900500, 2016YFC0900501, 2016YFC0900504, 2016YFC1303904) from the National Key R&D Program of China, National Natural Science Foundation of China (81390540, 81390541, 81390544), and Chinese Ministry of Science and Technology (2011BAI09B01). The funders had no role in the study design, data collection, data analysis and interpretation, writing of the report, or the decision to submit the article for publication.

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

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.

Egg consumption and health effects: A narrative review

This study was planned and conducted to investigate the effects of egg consumption on metabolic syndrome components and potential mechanisms of action on humans. Egg, an important source of animal protein, is defined as a functional food containing various bioactive compounds that can affect the proinflammatory and anti-inflammatory pathways. As a matter of fact, the egg can show immunomodulatory, anti-inflammatory, antioxidant, anticancer, or antihypertensive effects with its bioactive components. It is claimed that egg consumption may protect individuals against metabolic syndrome by increasing HDL-C levels and reducing inflammation. The increase in egg consumption creates the perception that it may lead to cardiovascular diseases due to its cholesterol content. However, there is insufficient evidence as to whether dietary cholesterol-lowers LDL-C. The possible potential mechanisms of egg impact on human health, MEDLINE, Embase, the Cochrane Central, www.ClinicalTrials.gov, PubMed, Science Direct, Google Scholar, and selected websites including) and databases were examined in this regard. With a view to delving into the rather mysterious relationship between egg cholesterol and blood cholesterol, it is necessary to understand the absorption of cholesterol from the egg and to know the functioning of the intestinal microbiota. Studies conducted to date have generally yielded inconsistent results regarding egg consumption and risks of CVD, diabetes, and metabolic syndrome.

Egg Consumption and Stroke Risk: A Systematic Review and Dose-Response Meta-Analysis of Prospective Studies

Background: The present study was performed to systematically quantify the association between egg consumption and stroke risk as inconsistent results have been produced.

Methods: Three electronic databases (PubMed, Embase, and Cochrane Library), previous reviews, meta-analyses, and bibliographies of relevant articles were retrieved from prospective cohort studies published before July 1, 2020. The random-effects model was employed to estimate summary relative risks (RRs) and 95% confidence intervals (CIs). A dose-response analysis was also performed when data were available.

Results: Sixteen publications involving 24 prospective cohort studies were included in our final meta-analysis. No significant association between egg consumption and stroke risk was identified (RR = 0.92, 95% CI: 0.84–1.01) for the highest vs. the lowest quintiles of egg intake. Subgroup analysis indicated that geographic location significantly modified the effect of egg consumption on stroke risk. Higher egg consumption was attributed to a reduced probability of stroke in Asia (RR = 0.83, 95% CI: 0.73–0.94), but not in North America (RR = 0.95, 95% CI: 0.77–1.16) or Europe (RR = 1.02, 95% CI: 0.91–1.16). Dose-response analysis demonstrated a nearly J-shaped curve between egg consumption and risk of stroke. A decreased risk was observed for the intake of one to four eggs weekly and an increased risk for the intake of more than six eggs weekly. The results were significant at an intake of 10 eggs weekly.

Conclusions: The evidence from this meta-analysis showed that a J-shaped association exists between egg consumption and stroke risk.