Dietary Cholesterol Affects Blood Cholesterol Levels

NF-Aug18 Debunking Egg Industry Myths.jpg

In my video, Eggs vs. Cigarettes in Atherosclerosis, I profiled a study showing that both smoking and eating eggs can harm our arteries. But even egg yolks alone were associated with artery-clogging plaque buildup nearly two thirds as bad as smoking.

This certainly ruffled some feathers.

Yes, eggs are by far the number one source of cholesterol in the American diet, but some letters to the editor protested that dietary cholesterol may have very little impact on blood cholesterol levels, citing a study published in 1971 performed on eight people. But if one looks at dozens of studies together, covering hundreds of study subjects, we find that blood cholesterol concentration is "clearly increased by added dietary cholesterol." In my video, Debunking Egg Industry Myths, there is an extreme example just to illustrate: a year in the life of a study subject taken on and off eggs. First, the researchers take him off eggs, putting him on a cholesterol-free diet, and his blood cholesterol plummets within just three weeks. Then they give him lots of eggs, and his cholesterol shoots back up, stays high until they take the eggs away and put him back on the cholesterol free diet, and so on and so forth. The researchers were essentially turning his high blood cholesterol on and off like a light switch (made out of eggs).

Of course the only reason we care our about our cholesterol levels or how much plaque is building up inside our arteries is because we want to avoid the consequences, like a heart attack. So do eggs increase our risk of cardiovascular disease? The latest meta-analysis, the latest compilation of all the best studies on egg consumption and risk of heart disease going back to 1930, found that, overall, those who ate the most eggs had a 19% increased risk of cardiovascular disease, a 68% increased risk of diabetes, and, once you have diabetes, an even greater 85% increased risk of heart disease. It didn't take much; less than a single egg a day was associated with a significantly increased risk of heart disease. Just over half an egg a day may increase heart disease risk 6% (40% in separated diabetes patients), and the risk of diabetes by 29%. The researchers conclude that their findings support the American Heart Association dietary guidelines, which advise restricted egg consumption in adults for preventing cardiometabolic disease, like diabetes, our seventh leading cause of death, and heart disease, our number one killer.

More on the diabetes connection in Eggs and Diabetes and Bacon, Eggs, and Gestational Diabetes During Pregnancy.

More on eggs and the egg industry in general:

There's more to heart disease than just cholesterol buildup. In my video, Eggs and Arterial Function, I explore what effect egg consumption has on endothelial function, the ability of our arteries to relax normally.

In health,
Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my videos for free by clicking here and watch my full 2012 - 2015 presentations Uprooting the Leading Causes of Death, More than an Apple a Day, From Table to Able, and Food as Medicine.

Image Credit: Rebecca Siegel / Flickr

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