Eggs are one of the largest sources of
phosphatidylcholine (
lecithin) in the human diet.
[52] A study published in the scientific journal
Nature showed that dietary phosphatidylcholine is digested by bacteria in the gut and eventually converted into the compound
TMAO, a compound linked with increased heart disease.
[53][54]
The 1999
Harvard School of Public Health study of 37,851 men and 80,082 women concluded that its "findings suggest that consumption of up to 1 egg per day is unlikely to have substantial overall impact on the risk of
CHD or stroke among healthy men and women."
[47] In a study of 4,000 people, scientists found that eating eggs increased blood levels of a metabolite promoting
atherosclerosis, TMAO, and that this in turn caused significantly higher risk of heart attack and stroke after three years of follow-up.
[55]
A 2007 study of nearly 10,000 adults demonstrated no correlation between moderate (six per week) egg consumption and
cardiovascular disease or
strokes, except in the subpopulation of
diabetic patients who presented an increased risk of
coronary artery disease.
[56] One potential alternative explanation for the null finding is that background dietary cholesterol may be so high in the usual Western diet that adding somewhat more has little further effect on blood cholesterol.
[57] Other research supports the idea that a high egg intake increases cardiovascular risk in diabetic patients.
[58] A 2009 prospective cohort study of over 21,000 individuals suggests that "egg consumption up to 6/week has no major effect on the risk of
cardiovascular disease and mortality and that consumption of 7+/week is associated with a modest increased risk of total mortality" in males, whereas among males with diabetes, "any egg consumption is associated with an increased risk of all-cause mortality and there was suggestive evidence for an increased risk of
myocardial infarction and
stroke".
[59] A 2013 meta-analysis found no association between egg consumption and heart disease or stroke.
[60][61] A 2013 systematic review and meta-analysis found no association between egg consumption and cardiovascular disease or cardiovascular disease mortality, but did find egg consumption more than once daily increased cardiovascular disease risk 1.69-fold in those with type 2 diabetes mellitus compared to type 2 diabetics who ate less than one egg per week.
[51] Another 2013 meta-analysis found that eating four eggs per week increased the risk of cardiovascular disease by six percent.
[50]
