Egg consumption and risk of cardiovascular disease: three large prospective US cohort studies, systematic review, and updated meta-analysis.

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 v 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, I2=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, I2=38.2%), and stroke (22 risk estimates, 1 059 315 participants, 53 617 stroke events; 0.99, 0.91 to 1.07, I2=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, I2=30.8%) or European cohorts (1.05, 0.92 to 1.19, I2=64.7%), but an inverse association was seen in Asian cohorts (0.92, 0.85 to 0.99, I2=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.

Model 1: adjusted for age (months), and stratified by calendar time (in 2-year intervals) and cohort.
Model 1: adjusted for age (months), and stratified by calendar time (in 2-year intervals) and cohort.
Model 1: adjusted for age (months), and stratified by calendar time (in 2-year intervals) and cohort.

Supplemental
AHEI: Alternate Healthy Eating Index; BMI: body mass index; CI: confidence interval; HR: hazard ratio; MET: metabolic equivalent of task; MI: myocardial infarction; T2D: type 2 diabetes. Age, calendar time, smoking status, BMI, physical activity, family history of myocardial infarction, baseline high blood cholesterol, baseline high blood pressure, alcohol intake, multivitamin use, daily intake of total calories, full-fat milk, bacon, red meat, other processed meats, refined grains, fruits, vegetables, potatoes, coffee, fruit juices, and sugar-sweetened beverages * Relative risk estimates were obtained from Cox proportional hazards regression models in all studies. † CHD included coronary artery disease, myocardial infarction, ischemic heart disease; CVD included combined vascular events (CHD and stroke). ‡ The risk estimates from Houston et al. and Trichopoulou et al. among individuals with diabetes were included in the meta-analysis of studies among the general population as no estimate was available for the entire cohort.

Supplemental
Supplemental Figure 5: Funnel plot for assessment of publication bias for the association between egg consumption and risk of cardiovascular disease.