Eggs Do Not Prevent Heart Attacks and Strokes


A recent news headline proclaimed, "An Egg a Day May Keep Heart Disease Away" (Time, May 21, 2018), based on a study of 512,891 adults in urban and rural areas of China. Those who ate one egg a day were reported to have an 18 percent reduced incidence of heart attacks and an incredible 26 percent reduction in bleeding strokes (BMJ Heart, May 21, 2018). Studies on benefits or harm from eating eggs are very conflicting, but this is the first large study I have seen that claims to associate eating eggs with a dramatically reduced risk for heart attacks and strokes.

Problems With This Study
Eggs may provide important nutrients to the Chinese population, but in North America, heart disease is usually linked with an overabundance of food, not deprivation or deficiencies which could be present in China. Most studies show that your overall diet is far more important than whether or not you eat any single food such as eggs (Nutrients, 2015 Sep 3;7(9):7399-420). Adding an egg a day to a healthful diet should not cause much damage, but adding eggs to a diet that is already rich in red meat, processed meats, sugar-added foods, sugared drinks and fried foods could be harmful. Unlike the typical North American, most Chinese in this study were not overweight, did not have high blood pressure, high cholesterol or a family history of heart disease, and did not eat the typical western diet. I think it would be foolish to believe that the results of this study from China could be reproduced in North America.

Cholesterol Content is Not the Problem
One egg yolk contains 200 mg of cholesterol, so eggs are one of the richest food sources of cholesterol. However, many studies show that cholesterol you eat in foods is a relatively minor cause of high blood cholesterol (Am J Clin Nutr, 2013;98:146-59). High blood cholesterol is associated with eating:
• refined carbohydrates such as sugar and foods made from flour
• excess calories
• not enough of the foods that contain soluble fiber
• possibly too much animal saturated fats (saturated fats in plants are OK)
A study from McMaster University reported that saturated fat may not be associated with increased risk for arteriosclerosis (BMJ, August 11, 2015).

Sugar and other refined carbohydrates may put you at higher risk for heart attacks than any amount of eggs, so it makes no sense whatever to replace eggs with:
• pancakes or waffles covered with maple syrup
• dry breakfast cereals that are made by grinding grains into flour, removing most of the fiber and adding sugar
• bakery products such as bagels and muffins

Lecithin in Eggs May be Harmful
Red meat, eggs and milk contain lecithin, which is broken down into another chemical called choline. Some of your intestinal bacteria use choline as a source for their energy and then release a breakdown product that is converted by your liver to TMAO (trimethylamine oxide). People with high amounts of TMAO appear to have increased risk for heart attacks. Multiple animal studies show that TMAO punches holes in arteries. These holes can bleed, clot and then start to form plaques which can eventually cause strokes and heart attacks. Researchers at the Cleveland Clinic have shown that TMAO is associated with increased formation of plaques in human arteries (Nature Medicine, April 7, 2013). They also showed that in more than 4,000 patients who had had heart catheterizations, those with the highest TMAO levels had the highest rate of heart attacks, strokes, and dying over the next three years. The Cleveland Clinic group also showed that two minutes after eating two hard-boiled eggs, blood levels of TMAO rise because lecithin in eggs is converted to TMAO very quickly (N Engl J Med, April 25, 2013; 368:1575-1584). They also showed that the intestinal bacteria produced the TMAO, since giving antibiotics to people and animals before they ate an egg prevented the TMAO from being formed. High levels of TMAO have been shown to raise blood pressure (Canadian Journal of Cardiology, December 2014;30(12):1700–1705). Vegetarians and vegans have much lower concentrations of blood TMAO than meat eaters (Nat Med, 2013;19:576-585).

My Recommendations
• I believe that most North Americans should restrict eggs to about three or four a week.
• Cooked oatmeal can help to lower high blood cholesterol levels because of its high soluble fiber content. You can get the same benefit from other cooked whole grains that can be eaten for breakfast: brown rice, wheat berries, barley, quinoa, buckwheat, wild rice and so forth. Add nuts and fruits for flavoring.
• Fresh fruits and most dried fruits do not have added sugar. Dried fruits are good sources of soluble fiber that prevents a high rise in blood sugar. Check the list of ingredients on packages of dried fruits such as cranberries or cherries to see if sugar has been added.
• For more breakfast recommendations, see Best Breakfast