A comparison of egg consumption with other modifiable coronary heart disease lifestyle risk factors: a relative risk apportionment study

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.

Assessment of Consumers' Perception of Chicken Eggs Consumption and Associated Health Implications in the Volta Region of Ghana

Background:

Rather erroneously, eggs consumption is linked to increase in plasma cholesterol content and incidents of cardiovascular diseases, cancer, stroke, or diabetes. This misconception which is more pervasive particularly in sub-Saharan Africa, has led to very low patronage of eggs intake. In this study, egg consumption patterns, desired egg characteristics, and the extent to which the perception of eggs consumption as a health risk is entrenched among consumers in the Volta Region of Ghana, were examined.

Methods:

The study used primary data for the analysis and the 2-stage sampling technique was employed. First, 5 districts (Keta, Ho, Krachi East, Nkwanta South and North Tongu) were selected and afterward, a sample was randomly selected from each of the district. A well designed and pretested questionnaires were administered to the respondents.

Results:

It was found that cheaper price and deep yellow yolk were the most persuasive parameters that motivate consumer purchase. The relationship between educational level and awareness on cholesterol types was significant. More than half of the respondents held the view that egg intake results in an increase in serum cholesterol and leads to the incidence of serious health problems.

Recommendation:

This study proves the urgent need for a concerted national public education effort to raise awareness about the nutritional and health benefits of eggs intake. Success in such awareness creation will go a long way to greatly minimize acute malnutrition in the Ghana.

Towards a Food-Based Intervention to Increase Protein Intakes in Older Adults: Challenges to and Facilitators of Egg Consumption

Abstract: Background: Dietary protein intake is important for health. Eggs, as a protein-rich food with characteristics that appeal to older adults, may provide opportunities for increasing protein intake. Interventions that focus on the challenges or facilitators that affect a large proportion of the population will be of increased impact on a population-wide scale. This work aimed to investigate the relative importance of a number of challenges to and facilitators of egg consumption in a UK population-wide sample of older adults.

METHODS

A cross-sectional postal questionnaire, measuring habitual egg intake, reasons for eating/not eating eggs and a range of demographic and lifestyle characteristics, was administered by post to 1082 older adults.

RESULTS

230 questionnaires suitable for analysis were returned (110 females, ages 55⁻80+ years). Habitual egg intake ranged from 1⁻89 eggs/month, mean (standard deviation) = 18 (13) eggs/month. Reasons for eating/not eating eggs were reduced using Principal Components Analysis to 23 challenges and facilitators of egg consumption. Regression analyses revealed habitual egg intake to be associated with 10 challenges and facilitators (smallest β = 0.14, p = 0.04), and with protein consumption, age and Body Mass Index (smallest β = 0.14, p = 0.03).

DISCUSSION

Many possibilities for future intervention based on existing challenges or facilitators were found. Our results suggest that strategies to increase egg consumption in older adults should focus on: improving liking, tastiness and adding variety; promoting eggs as an everyday type of food; reducing stereotypes about who does and who does not consume eggs; and promoting eggs for people who have noticed the effects of ageing on their food intake. Strategies that highlight value-for-money may be counterproductive. Future work evaluating the value of these strategies for improving protein intake in this age group would be of value.

ENPP1 K121Q (rs1044498 C > A) genetic polymorphism confers a high risk of susceptibility to coronary heart disease: A PRISMA-compliant article

BACKGROUND

Previous studies suggested an association between K121Q (rs1044498 C > A) in ecto-nucleotide pyrophosphatase phosphodiesterase 1 (ENPP1) gene and the risk of coronary heart disease (CHD), but the results have been inconsistent. In this study, we performed a meta-analysis of several trials to systematically summarize their potential association.

METHODS

Relevant articles were identified by searching electronic databases for studies published prior to March 2018. We carefully reviewed published studies on ENPP1 genetic polymorphism in relation to CHD susceptibility. The data extracted from selected high-quality studies were analyzed using STATA statistical software (StataCorp LP, College Station, TX, USA).

RESULTS

Nine eligible studies which contained a combined total of 1547 CHD cases and 2213 healthy controls were chosen in the present meta-analysis. Our results indicated that K121Q strongly correlated with increased risk of CHD. The subgroup analysis on race, sample source, disease type, sex, age, and genotype showed that in Caucasians, K121Q strongly correlated with increased risk of CHD, but no difference was found in Chinese. Both single factor and multiple factor regression showed that race, sample origin, disease type, sex, age, and genotype were not the source of heterogeneity.

CONCLUSIONS

Our meta-analysis revealed that the K121Q (rs1044498 C > A) in the ENPP1 gene is a risk factor for CHD.

Molecular Pathways Underlying Cholesterol Homeostasis

Cholesterol is an essential molecule that exerts pleiotropic actions. Although its presence is vital to the cell, its excess can be harmful and, therefore, sustaining cholesterol homeostasis is crucial to maintaining proper cellular functioning. It is well documented that high plasma cholesterol concentration increases the risk of atherosclerotic heart disease. In the last decades, several studies have investigated the association of plasma cholesterol concentrations and the risk of cardiovascular diseases as well as the signaling pathways involved in cholesterol homeostasis. Here, we present an overview of several mechanisms involved in intestinal cholesterol absorption, the regulation of cholesterol synthesis and uptake. We also discuss the importance of reverse cholesterol transport and transintestinal cholesterol transport to maintain cholesterol homeostasis and prevent atherosclerosis development. Additionally, we discuss the influence of dietary cholesterol on plasma cholesterol concentration and the new recommendations for cholesterol intake in a context of a healthy dietary pattern.

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

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.

Eggs: good or bad?

Eggs have one of the lowest energy to nutrient density ratios of any food, and contain a quality of protein that is superior to beef steak and similar to dairy. From a nutritional perspective, this must qualify eggs as 'good'. The greater burden of proof has been to establish that eggs are not 'bad', by increasing awareness of the difference between dietary and blood cholesterol, and accumulating sufficient evidence to exonerate eggs from their associations with CVD and diabetes. After 60 years of research, a general consensus has now been reached that dietary cholesterol, chiefly from eggs, exerts a relatively small effect on serum LDL-cholesterol and CVD risk, in comparison with other diet and lifestyle factors. While dietary guidelines have been revised worldwide to reflect this view, associations between egg intake and the incidence of diabetes, and increased CVD risk in diabetes, prevail. These associations may be explained, in part, by residual confounding produced by other dietary components. The strength of evidence that links egg intake to increased CVD risk in diabetes is also complicated by variation in the response of serum LDL-cholesterol to eggs and dietary cholesterol in types 1 and 2 diabetes. On balance, the answer to the question as to whether eggs are 'bad', is probably 'no', but we do need to gain a better understanding of the effects of dietary cholesterol and its association with CVD risk in diabetes.

Bioactive Egg Components and Inflammation

Inflammation is a normal acute response of the immune system to pathogens and tissue injury. However, chronic inflammation is known to play a significant role in the pathophysiology of numerous chronic diseases, such as cardiovascular disease, type 2 diabetes mellitus, and cancer. Thus, the impact of dietary factors on inflammation may provide key insight into mitigating chronic disease risk. Eggs are recognized as a functional food that contain a variety of bioactive compounds that can influence pro- and anti-inflammatory pathways. Interestingly, the effects of egg consumption on inflammation varies across different populations, including those that are classified as healthy, overweight, metabolic syndrome, and type 2 diabetic. The following review will discuss the pro- and anti-inflammatory properties of egg components, with a focus on egg phospholipids, cholesterol, the carotenoids lutein and zeaxanthin, and bioactive proteins. The effects of egg consumption of inflammation across human populations will additionally be presented. Together, these findings have implications for population-specific dietary recommendations and chronic disease risk.

Egg consumption and cardiovascular disease among diabetic individuals: a systematic review of the literature

BACKGROUND

This study reviewed epidemiological and experimental evidence on the relationship between egg consumption and cardiovascular disease (CVD) risks among type II diabetes mellitus (T2DM) individuals, and T2DM risk in nondiabetic subjects.

RESULTS

Four of the six studies that examined CVD and mortality and egg consumption among diabetics found a statistically significant association. Of the eight studies evaluating incident T2DM and egg consumption, four prospective studies found a statistically significant association. Lack of adjustment for dietary confounders was a common study limitation. A small number of experimental studies examined the relationship between egg intake and CVD risk biomarkers among diabetics or individuals with T2DM risk factors. Studies among healthy subjects found suggestive evidence that dietary interventions that include eggs may reduce the risk of T2DM and metabolic syndrome.

CONCLUSION

Differences in study design, T2DM status, exposure measurement, subject age, control for confounders and follow-up time present significant challenges for conducting a meta-analysis. Conflicting results, coupled with small sample sizes, prevent broad interpretation. Given the study limitations, these findings need to be further investigated.

Egg consumption in relation to risk of cardiovascular disease and diabetes: a systematic review and meta-analysis

BACKGROUND

The associations of egg consumption with cardiovascular disease (CVD) and diabetes are still unclear.

OBJECTIVE

We aimed to quantitatively summarize the literature on egg consumption and risk of CVD, cardiac mortality, and type 2 diabetes by conducting a meta-analysis of prospective cohort studies.

DESIGN

A systematic literature review was conducted for published studies in PubMed and EMBASE through March 2012. Additional information was retrieved through Google or a hand review of the reference from relevant articles. Studies were included if they had a prospective study design, were published in English-language journals, and provided HRs and 95% CIs for the associations of interest. Data were independently extracted by 2 investigators, and the weighted HRs and 95% CIs for the associations of interest were estimated by using a random-effects model.

RESULTS

A total of 22 independent cohorts from 16 studies were identified, including participants ranging in number from 1600 to 90,735 and in follow-up time from 5.8 to 20.0 y. Comparison of the highest category (≥1 egg/d) of egg consumption with the lowest (<1 egg/wk or never) resulted in a pooled HR (95% CI) of 0.96 (0.88, 1.05) for overall CVD, 0.97 (0.86, 1.09) for ischemic heart disease, 0.93 (0.81, 1.07) for stroke, 0.98 (0.77, 1.24) for ischemic heart disease mortality, 0.92 (0.56, 1.50) for stroke mortality, and 1.42 (1.09, 1.86) for type 2 diabetes. Of the studies conducted in diabetic patients, the pooled HR (95% CI) was 1.69 (1.09, 2.62) for overall CVD.

CONCLUSIONS

This meta-analysis suggests that egg consumption is not associated with the risk of CVD and cardiac mortality in the general population. However, egg consumption may be associated with an increased incidence of type 2 diabetes among the general population and CVD comorbidity among diabetic patients.

Rethinking dietary cholesterol

PURPOSE OF REVIEW

The perceived notion that dietary cholesterol is associated with increased risk for coronary heart disease (CHD) has led to dietary recommendations of no more than 300  mg/day for healthy populations in the USA. This study will review the recent evidence that challenges the current dietary restrictions regarding cholesterol while it presents some beneficial effects of eggs (an icon for dietary cholesterol) in healthy individuals.

RECENT FINDINGS

The European countries, Australia, Canada, New Zealand, Korea and India among others do not have an upper limit for cholesterol intake in their dietary guidelines. Further, existing epidemiological data have clearly demonstrated that dietary cholesterol is not correlated with increased risk for CHD. Although numerous clinical studies have shown that dietary cholesterol challenges may increase plasma LDL cholesterol in certain individuals, who are more sensitive to dietary cholesterol (about one-quarter of the population), HDL cholesterol also rises resulting in the maintenance of the LDL/HDL cholesterol ratio, a key marker of CHD risk.

SUMMARY

The lines of evidence coming from current epidemiological studies and from clinical interventions utilizing different types of cholesterol challenges support the notion that the recommendations limiting dietary cholesterol should be reconsidered.

Egg consumption and risk of cardiovascular disease in the SUN Project

BACKGROUND/OBJECTIVES

Egg consumption has been associated with the risk of cardiovascular diseases (CVDs), but evidence is scarce and inconsistent. Our aim was to examine the association between egg consumption and incidence of CVD in a prospective dynamic Mediterranean cohort of 14,185 university graduates.

SUBJECTS/METHODS

Egg intake was assessed using a 136-item-validated food-frequency questionnaire. Baseline consumption was categorized into no consumption or <1 egg/week, 1 egg/week, 2-4 eggs/week and >4 eggs/week. The presence of cardiovascular risk factors was assessed by questionnaire at baseline, and the incidence of CVD was assessed using biennial assessments. The median follow-up was 6.1 years. Cox regression models were fitted to estimate multivariable-adjusted hazard ratios (HRs) for CVD (myocardial infarction, revascularization procedures or stroke). Outcomes were confirmed by review of medical records.

RESULTS

During a median follow-up of 6.1 years, 91 new confirmed cases of CVD were observed. No association was found between egg consumption and the incidence of CVD (HR: 1.10, 95% confidence interval: 0.46-2.63) for the highest versus the lowest category of egg consumption after adjusting for age, sex, total energy intake, adherence to the Mediterranean food pattern and other cardiovascular risk factors. Results were robust to different analytical scenarios.

CONCLUSIONS

No association between egg consumption and the incidence of CVD was found in this Mediterranean cohort.

Revisiting dietary cholesterol recommendations: does the evidence support a limit of 300 mg/d?

The perceived association between dietary cholesterol (DC) and risk for coronary heart disease (CHD) has resulted in recommendations of no more than 300 mg/d for healthy persons in the United States. These dietary recommendations proposed in the 1960s had little scientific evidence other than the known association between saturated fat and cholesterol and animal studies where cholesterol was fed in amounts far exceeding normal intakes. In contrast, European countries, Asian countries, and Canada do not have an upper limit for DC. Further, current epidemiologic data have clearly demonstrated that increasing concentrations of DC are not correlated with increased risk for CHD. Clinical studies have shown that even if DC may increase plasma low-density lipoprotein (LDL) cholesterol in certain individuals (hyper-responders), this is always accompanied by increases in high-density lipoprotein (HDL) cholesterol, so the LDL/HDL cholesterol ratio is maintained. More importantly, DC reduces circulating levels of small, dense LDL particles, a well-defined risk factor for CHD. This article presents recent evidence from human studies documenting the lack of effect of DC on CHD risk, suggesting that guidelines for DC should be revisited.

Egg consumption and CHD and stroke mortality: a prospective study of US adults

OBJECTIVE

To evaluate the relationship between egg consumption and CHD and stroke mortality using the Third National Health and Nutrition Examination Survey 1988-1994 (NHANES III) and follow-up survey.

DESIGN

A cross-sectional survey using a stratified, multi-stage probability sample was analysed, adjusting for survey design. Egg consumption was obtained from the FFQ and separated into categories of egg intake. Hazard ratios (HR) were calculated for CHD and stroke mortality using multivariate Cox regression models.

SETTING

A health and nutrition survey conducted in the USA from 1988 to 1994 with follow-up through 31 December 2000.

SUBJECTS

The study population included men and women who were free of CVD and had completed a FFQ at baseline.

RESULTS

Multivariate models adjusting for health, lifestyle and dietary factors indicated that 'high' egg consumption (≥ 7 times/week v. <1 time/week) was not associated with significantly increased CHD mortality (HR = 1·13, 95 % CI 0·61, 2·11 (men); HR = 0·92, 95 % CI 0·27, 3·11 (women)). There was a statistically significant inverse association between 'high' egg consumption and stroke mortality among men (HR = 0·27, 95 % CI 0·10, 0·73), but the estimate was imprecise because of sparse data. We did not observe a statistically significant positive association between 'high' egg consumption and CHD or stroke mortality in analyses restricted to individuals with diabetes, but these analyses may be limited due to the small number of diabetics.

CONCLUSIONS

We did not find a significant positive association between egg consumption and increased risk of mortality from CHD or stroke in the US population. These results corroborate the findings of previous studies.

Single food focus dietary guidance: lessons learned from an economic analysis of egg consumption

Background

There is a large body of literature evaluating the impact of various nutrients of eggs and their dietary cholesterol content on health conditions. There is also literature on the costs of each condition associated with egg consumption. The goal of the present study is to synthesize what is known about the risks and benefits of eggs and the associated costs from a societal perspective.

Methods

A risk apportionment model estimated the increased risk for coronary heart disease (CHD) attributable to egg cholesterol content, the decreased risk for other conditions (age-related macular degeneration (AMD), cataract, neural tube defects, and sarcopenia) associated with egg consumption, and a literature search identified the cost of illness of each condition. The base 795 case scenario calculated the costs or savings of each condition attributable to egg cholesterol or nutrient content.

Results

Given the costs associated with CHD and the benefits associated with the other conditions, the most likely scenario associated with eating an egg a day is savings of $2.82 billion annually with uncertainty ranging from a net cost of $756 million to net savings up to $8.50 billion.

Conclusion

This study evaluating the economic impact of egg consumption suggests that public health campaigns promoting limiting egg consumption as a means to reduce CHD risk would not be cost-effective from a societal perspective when other benefits are considered. Public health intervention that focuses on a single dietary constituent, and foods that are high in that constituent, may lead to unintended consequences of removing other beneficial constituents and the net effect may not be in its totality a desirable public health outcome. As newer data become available, the model should be updated.