Dietary Cholesterol and Egg Yolk Should Be Avoided by Patients at Risk of Vascular Disease

Recent recommendations that limits to dietary cholesterol be dropped were probably heavily influenced by propaganda from the egg industry. After conviction for false advertising, the industry has spent hundreds of millions of dollars to convince the public, physicians, and policy makers that dietary cholesterol and egg yolk are harmless. However, there are good reasons for longstanding recommendations that dietary cholesterol be limited to <200 mg/ day in persons at risk of vascular disease. It is seldom understood that this essentially means all people in developed countries who expect to attain an advanced age. There is abundant evidence that dietary cholesterol increases cardiovascular risk. The misdirection of the egg industry focuses on fasting levels of LDL cholesterol, which are only raised by ~ 10% by consumption of egg yolks. However, the main effect of diet is on the post-prandial state: for ~ 4 hours after a high fat/high cholesterol meal, there is oxidative stress, endothelial dysfunction, and arterial inflammation. One large (65 g) egg yolk contains 237 mg of cholesterol, well above the recommended limit-nearly as much as a 12-ounce hamburger. Besides the very high cholesterol content of egg yolk, the phosphatidylcholine in egg yolk leads, via action of the intestinal microbiome, to production of trimethylamine n-oxide (TMAO), which causes atherosclerosis in animal models. Levels of TMAO in the top quartile after a test dose of two egg yolks were associated with a 2.5-fold increase in the 3-year risk of stroke, death, or myocardial infarction among patients referred for coronary angiography. Persons at risk of cardiovascular disease should limit their intake of cholesterol and egg yolk.