Association between Egg Consumption and Cholesterol Concentration: A Systematic Review and Meta-analysis of Randomized Controlled 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.

The association between non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio and preserved ratio impaired spirometry: NHANES 2007-2012

BACKGROUND

Preserved ratio impaired spirometry (PRISm) refers to a form of lung function deterioration, and previous studies have established the association with Chronic Obstructive Pulmonary Disease (COPD). Research has also shown the association between COPD and lipid metabolism disturbances. Despite these findings, the association between lipid metabolism markers and PRISm remains poorly understood.

METHODS

This analysis was conducted on the 2007-2012 data from the National Health and Nutrition Examination Survey (NHANES), including a total of 9,431 participants. The Non-High-Density Lipoprotein Cholesterol to High-Density Lipoprotein Cholesterol Ratio (NHHR) was calculated based on lipid profiles, and PRISm patients were classified according to pulmonary function tests. To explore the association between NHHR and PRISm, multivariable logistic regression analysis was used.

RESULTS

A strong linear association was observed between NHHR and PRISm. In Adjusted Model 2, the weighted multivariable logistic regression analysis revealed that each unit increase in NHHR increased the chance of developing PRISm by 8% (OR:1.08, 95%CI:1.01-1.16, P = 0.039).Participants within the highest NHHR tertile demonstrated a 1.36-fold increased likelihood of presenting with PRISm compared to those in the lowest NHHR tertile (OR:1.36, 95% CI: 1.01-1.83, P = 0.048). Additionally, weighted Restricted Cubic Spline affirmed a linear association between NHHR and PRISm (P for non-linearity = 0.637), while clear non-linear associations were found between NHHR and FEV1% predicted (P for non-linearity = 0.010) and FEV1/FVC (P for non-linearity = 0.023). Subgroup analysis and interaction tests revealed a significant interaction effect among different waist circumference categories (P for interaction = 0.020). Notably, in individuals without abdominal obesity, NHHR showed a strong positive association with PRISm (OR = 1.23, 95% CI: 1.07-1.42, P = 0.01).

CONCLUSION

These results indicate that NHHR is positively associated with PRISm and is significantly associated with the decline in lung function. This study offers distinctive perspectives that may contribute to the avoidance and management of early-stage pulmonary dysfunction.

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 Protein-Rich Foods, Nutritional Supplements, and Age of Natural Menopause and Its Symptoms

OBJECTIVE

To investigate the relationship between protein-rich foods, various nutritional supplements, and age of natural menopause and its symptoms.

METHODS

This study was a large-scale cross-sectional survey. A multi-stage stratified random sampling method was used to select a sample of 52,347 residents aged 35-60 years from 26 districts/counties across 13 cities in 12 provinces in China. The mean natural menopause age was represented by the average and median, and logistic regression models were employed to examine the relationship between the intake of protein-rich foods, use of nutritional supplements, and natural menopause age as well as menopausal symptoms.

RESULTS

The average natural menopause age of the study population was 49.46 (±3.22) years, with a median age of 50 years. Logistic regression analysis revealed that with increasing frequency of fish consumption, the natural menopause age was delayed and the severity of menopausal symptoms gradually decreased, especially in relation to physical symptoms, psychological symptoms, and urogenital symptoms, which showed significant negative correlations. Milk and soy products were significantly negatively correlated with various dimensions of menopausal symptoms. Calcium and iron supplements were significantly positively correlated with the severity of menopause symptoms. Subgroup analysis by different age groups and premenopausal versus postmenopausal status showed minimal impact on the study results. In the population with BMI ≥ 18.5, fish consumption was significantly negatively correlated with menopausal symptoms. In the population with BMI between 18.5 and 27.9, milk consumption was significantly negatively correlated with menopausal symptoms. In all the populations, soy product consumption was significantly negatively correlated with menopausal symptoms.

CONCLUSIONS

The intake of fish, milk, and soy products plays a role in alleviating the severity of menopausal symptoms, particularly in delaying natural menopause, with the effect of fish intake being especially significant. Calcium and iron supplements may play a role in exacerbating the severity of menopausal symptoms.

Enhancing impact of dietary nano formulated quercetin on laying performance: egg quality, oxidative stability of stored eggs, intestinal immune and antioxidants related genes expression

BACKGROUND

Nutritional interventions with natural antioxidants can provide a pragmatic solution for modifying hens' performance and maintaining oxidative stability of eggs during storage. Quercetin is the most abundant flavonoids with potent antioxidant and immune stimulant activities. The concept of incorporating of quercetin, as potent antioxidant and immunostimulant, into effective nano-carriers (QNPs) has promoted their bioavailability and stability thus, their effectiveness for the first time were assessed on laying hens' performance and immunity, eggs quality during storage. Four hundred 12-weeks-old Hy-line brown laying hens were distributed to four experimental groups: control group fed basal diets, and other 3 groups fed basal diets fortified with 100, 200 and 300 mg/kg QNPs for 60 weeks.

RESULTS

Laying performance and quality of laid eggs were improved as expressed by elevated laying rate, egg mass %, eggs weight and yolk weight in QNPs200 and 300. Fortification of QNPs300 remarkably decreased layers serum total cholesterol concurrently with decreased egg yolk saturated fatty acids and cholesterol while increased polyunsaturated fatty acids. Over- 45 days storage period, QNPs enhanced phospholipids, total phenolics and flavonoids, total antioxidant activity (T-AOC) simultaneous with decreased MDA content in eggs. Furthermore, enhanced immune response was detected in both in serum and intestine of QNPs fed hens as reflected by higher lysozymes activity, IgM, IgG and phagocytic index and demotion of NO together with AvBD 6-12, IL-10, IgM and ATg 5-7-12 upregulation and downregulation of IL-1β and TNF-α especially at QNPs200 and 300. Intestinal redox balance was modified via decreasing H2O2 and MDA simultaneous with upregulation of catalase, SOD, GSH-Px, HO-1 and NQO1 in groups fed higher doses of QNPs.

CONCLUSIONS

QNPs supplementation provides a new nutritional strategy towards increasing hen performance, fortification of eggs with natural antioxidants that prevents egg quality deterioration during storage.

Performance, Egg Quality, and Composition in Isa Brown Laying Hens Fed with Different Levels of Desmodium tortuosum Leaf Flour

The objective of this study was to investigate the effects on laying performance, egg quality traits, color, and composition of supplementing a white corn-based diet with Desmodium tortuosum leaf flour. Three hundred 32-week-old hens were distributed to 30 pens of 10 hens each and allocated to six dietary treatments (five replicates per treatment) for 13 weeks. Two control groups of 50 hens received one of either diet Y, based on yellow corn, or diet W, based on white corn. The other groups received a diet based on white corn supplemented with Desmodium tortuosum leaf flour at 2.5%, 5%, 7.5%, or 10% (diet D). Diet D improved laying performance and yolk color at a reduced feed cost per egg but had no effect on cholesterol content. In conclusion, the inclusion of Desmodium tortuosum leaf flour, in a white corn-based diet, is effective in lowering feed cost, increasing egg production, and improving yolk color.

Impact of Nutrition Interventions on Vitamin and Mineral Intake among Native American Children and Parents: Insights from Food Resource Equity for Sustainable Health (FRESH) Study

The Food Resource Equity for Sustainable Health (FRESH) study started as a tribe community-based nutrition education program in 2018, implemented with children and parents in Osage Nation. The purpose of the FRESH study is to examine the effects of a farm-to-school family intervention on diet. The FRESH study did not directly intervene on adult caregiver participants' diet, and, as far as we know, it is the first of its kind to implement a farm-to-school intervention in rural/tribally owned Early Childhood Education. Two communities received intervention and two served as wait-list controls. Outcomes included diet and other secondary health outcomes including vitamin and mineral intake. There were 193 children (n = 106 intervention; n = 87 control) and 170 adults (n = 93 intervention; n = 77 control) enrolled. Among adult caregiver participants, carbohydrate, cholesterol, and caffeine intake significantly decreased after the intervention (p < 0.05). There is a hidden hunger issue among caregivers in Native American populations. The family-based nutritional intervention, which includes educational components for caregivers, might have some effect on improving micronutrient status. Future studies focusing on key micronutrients through efficient methods are warranted.

Longitudinal study of the impact of the COVID-19 pandemic on diet and physical activity among Latinos of Mexican ancestry

BACKGROUND

The COVID-19 pandemic caused societal disruption in the United States and most of the world, affecting many aspects of life, including healthcare and health-related behaviors such as diet, food security, and physical activity. Communities with economic and health disparities may have been particularly affected. This study was undertaken to determine how conditions in the early pandemic (January, 2021-February, 2022) affected Latino patients of Mexican Ancestry at high risk of type 2 diabetes mellitus who participated in El Banco por Salud biobank project in Tucson, Arizona.

METHODS

Baseline, prepandemic measurements were available in 17, 21, and 60 patients with normal hemoglobin A1c (HbA1c), prediabetes, and type 2 diabetes, respectively.

RESULTS

People with healthy HbA1c were significantly younger, less obese, and had higher HDL cholesterol. HbA1c was unaffected by the pandemic in any group. Triglycerides, total and HDL cholesterol levels fell in all groups during the pandemic. Physical activity levels in all groups were remarkably low, with most reporting no engagement in any voluntary physical activity. Engagement in physical activity or its enjoyment was lower in patients with diabetes and prediabetes than in younger, less obese patients. Major diet differences were between men and women and were present before the pandemic. Women consumed significantly more vegetables, fruit, and salad than men. The only pandemic-related change in diet was a drop in egg consumption, possibly explaining the fall in total cholesterol.

CONCLUSION

Societal disruption during the COVID-19 pandemic had minimal effects on adverse health-related behaviors, cardiometabolic risk, or changes in glycemic control in a Latino community with diabetes and healthcare disparities in the Southwest US.

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.

Dietary saturated fat and cholesterol: cracking the myths around eggs and cardiovascular disease

Whilst dietary cholesterol guidelines have waivered through the years with historic restrictions lifted for the majority of the general population, recommendations to reduce saturated fat intake have been the mainstay of dietary guidelines since the 1980s and were recently reinforced by the Scientific Advisory Committee on Nutrition (SACN). Cholesterol metabolism is complex, with saturated fat known to have a more significant contribution at raising levels of low-density lipoprotein (LDL) cholesterol, a well-established risk factor for cardiovascular disease (CVD). However, it is clear from metabolic research that hyper-responsiveness to both dietary cholesterol and saturated fat exists; hence, for specific subsets of the population, reductions in both nutrients may be indicated. With this in mind, the current article aims to provide an overview of the mechanisms underlying biological variation in responsiveness and introduces research currently underway which will hopefully identify simple biomarkers that can be used to predict responsiveness and permit tailored, personalised, dietary advice. Eggs are a well-known source of dietary cholesterol whilst being low in saturated fat. A common question encountered in clinical practice is must individuals limit intake to manage blood cholesterol levels. This article summarises key recent papers which confirm that eggs can be enjoyed as part of a healthy balanced diet, whilst highlighting the need for further research in certain population groups, e.g. in individuals with diabetes.

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

Hen's eggs (from Gallus gallus domesticus) 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.

Effects of Fatty-Type and Lean-Type on Growth Performance and Lipid Droplet Metabolism in Pekin Ducks

Simple Summary

Lipid deposition in animals is closely related to lipid anabolism. In order to further explore how differences in different metabolic types regulate lipid deposition, we compared the growth performance and lipid droplet metabolism of fatty-type ducks and lean-type ducks. The results showed that fatty-type ducks showed a faster growth rate and more fat deposition in the early growth stage after feeding the same diet, and produced more lipoproteins in serum and deposited in adipose tissue. However, fewer triglycerides accumulated in the liver. We believe that this performance of fatty-type ducks is caused by the increased expression level of lipid droplet-related genes.

Abstract

The reasons for differences in lipid depositions between fatty-type (F-T) and lean-type (L-T) ducks remain unknown. The present study aimed to compare the growth performance, lipid deposition, and gene expression related to lipid droplet formation in F-T and L-T Pekin ducks. One-day-old, 140 each L-T and F-T male ducks were selected and distributed separately into 20 replicate cages. All ducks were fed commercial diets up to 35 d of age. F-T ducks had a higher average daily gain from 21 to 28 d of age. On 35-day-old, F-T ducks had higher serum levels of high- and low-density lipoprotein cholesterol, cholesterol, albumin, and hydroxybutyrate dehydrogenase activity than L-T ducks. F-T ducks had higher abdominal fat and subcutaneous fat percentages than those in L-T ducks. Liver histological examination showed that L-T ducks contained more lipid droplets in the liver, which gradually decreased with increasing age. The average adipocyte area and diameter of abdominal fat and subcutaneous fat in the F-T and L-T ducks increased with age and were higher in F-T ducks than those in L-T ducks. Furthermore, the gene expression of perilipin 1, perilipin 2, angiopoietin-like protein 4, adipose triglyceride lipase, alpha/beta-hydrolase domain-containing protein 5 (ABHD5), and serine/threonine kinase 17a in the liver, abdominal fat, and subcutaneous fat of F-T ducks was higher than that in L-T ducks, and it increased with age. Compared to L-T ducks, F-T ducks had higher expression of ABHD5 in the abdominal fat and subcutaneous fat and lower expression in the liver. Thus, F-T ducks displayed lower hepatic lipid deposition and a higher percentage of abdominal fat and subcutaneous fat, suggesting that F-T ducks had higher lipid storage capacity due to increased gene expression related to lipid droplets.

Longitudinal association of egg intake frequency with cardiovascular disease in Chinese adults

BACKGROUND AND AIMS

Reducing dietary cholesterol is generally acceptable for the prevention of cardiovascular disease (CVD). Eggs are nutrient-dense and common food items across the world, while rich in cholesterol. The potential effects of egg intake on cardiovascular health remain uncertainty and have been under debate in past decades.

METHODS AND RESULTS

A nationwide cohort of 20,688 participants aged 16-110 years without CVD at baseline were derived from the China Family Panel Studies. Egg consumption was assessed by a semi-quantitative food frequency questionnaire. We adopted stratified Cox proportional hazards model with random intercepts for provinces to evaluate associations of egg intake with CVD incidence. During a median follow-up of 6.0 years, we identified 2395 total CVD incidence and mean egg consumption was 3 times/week. Egg intakes were associated lower risks of CVD incidence in the multivariate-adjusted model. Compared with the non-consumers, the corresponding HRs (95% confidence interval) for total CVD events were 0.84 (0.74-0.94) for 1-2 times per week, 0.78 (0.69-0.88) for 3-6/week, and 0.83 (0.72-0.95) for ≥7/week. Similar relationships were found in hypertension. Approximately non-linear relationships were observed between egg consumption with total CVD and hypertension incidence, identifying the lowest risk in 3-6 times/week. Subgroup analyses estimated lower risks of total CVD and hypertension in females only, with significant effect modification by sex (P for interaction = 0.008 and 0.020).

CONCLUSION

Egg consumption may be associated with lower risks of CVD incidence among Chinese adults. Our findings could have implications in CVD prevention and might be considered in the development of dietary guidelines.

What Is the Current Direction of the Research on Carotenoids and Human Health? An Overview of Registered Clinical Trials

Carotenoids have been the object of numerous observational, pre-clinical and interventional studies focused on elucidating their potential impacts on human health. However, the large heterogeneity among the trials, in terms of study duration and characteristics of participants, makes any conclusion difficult to draw. The present study aimed to explore the current carotenoid research trends by analyzing the characteristics of the registered clinical trials. A total of 193 registered trials on ClinicalTrials.gov and ISRCTN were included in the revision. Eighty-three studies were performed with foods, one-hundred-five with food supplements, and five with both. Among the foods tested, tomatoes and tomato-based foods, and eggs were the most studied. Lutein, lycopene, and astaxanthin were the most carotenoids investigated. Regarding the goals, 52 trials were focused on studying carotenoids’ bioavailability, and 140 studies investigated the effects of carotenoids on human health. The main topics included eye and cardiovascular health. Recently, the research has focused also on two new topics: cognitive function and carotenoid–gut microbiota interactions. However, the current research on carotenoids is still mostly focused on the bioavailability and metabolism of carotenoids from foods and food supplements. Within this context, the impacts/contributions of food technologies and the development of new carotenoid formulations are discussed. In addition, the research is still corroborating the previous findings on vision and cardiovascular health. Much attention has also been devoted to new research areas, such as the carotenoid–microbiota interactions, which could contribute to explaining the metabolism and the health effects of carotenoids; and the relation between carotenoids and cognitive function. However, for these topics the research is still only beginning, and further studies are need.

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.

Relationship between Egg Consumption and Body Composition as Well as Serum Cholesterol Level: Korea National Health and Nutrition Examination Survey 2008-2011

We analyzed the relationship between egg consumption, body composition, and serum cholesterol levels. We obtained data on egg consumption by using a food frequency questionnaire (FFQ) (13,132 adults) and the 24-h dietary recall (24HR) (13,366 adults) from the fourth and fifth Korea National Health and Nutrition Examination Surveys (2008-2011). In men, consuming 2-3 eggs/week was associated with higher fat mass (FM), percentage body fat (PBF), and fat-to-muscle ratio (FtoM), compared to consuming <1 egg/week. In women, consuming 1-6 eggs/week was associated with higher low-density lipoprotein cholesterol, consuming 2-6 eggs/week was associated with higher total cholesterol, and consuming 4-6 eggs/week was associated with higher FM and high-density lipoprotein cholesterol, compared to consuming <1 egg/week. There was no relationship between egg consumption and the prevalence of dyslipidemia, and there was no relationship between egg consumption, body composition, and serum cholesterol levels according to the 24HR. However, there was some association with other cardiovascular diseases and consumption of certain amounts of eggs. Egg consumption investigated by FFQ was associated with body composition and serum cholesterol levels. However, the egg consumption investigated by the 24HR resulted in no health benefit or harm with respect to body composition and cholesterol.

Nutritional Viewpoints on Eggs and Cholesterol

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.

Egg and cholesterol consumption and mortality from cardiovascular and different causes in the United States: A population-based cohort study

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.