On February 27, 2023, Fox News reported, “Add an egg (or 3) to your daily diet for heart health. Eggs may significantly reduce heart health risk, a recent study finds.” The Fox News report said, “The study found that eating one to three eggs per week could reduce the risk for cardiovascular disease by up to 60 percent. Those who consumed four to seven eggs per week cut their risk for heart disease by 70 percent.”
However, the authors of the study also found and reported that what you eat in your whole diet and your other lifestyle factors are far more important in determining whether you will get a heart attack than just how many eggs you eat. The authors concluded that eating eggs could help to prevent heart disease only if the rest of your diet was healthful, low in total saturated fats and low in added sugars (Nutrients, Dec 12, 2022;14(24):5291).
This month’s Nutrition Action newsletter tried to set the record straight and tell you what the researchers really said. The authors of the study used a control group to compare those who ate eggs and those who did not eat eggs, correcting for other factors that increase heart attack risk in both of the groups: smoking, overweight, exercise, high blood pressure, high blood cholesterol, saturated fat intake and family history of heart disease. When the authors corrected for these factors in both groups, there was no evidence that eating eggs helped to prevent heart attacks (Nutrition Action, May 2023:3). An earlier review of several other studies found that eating eggs is associated with increased risk for heart attacks (JAMA, Mar 19, 2019;321(11):1081-1095).
How Eggs May Increase Risk for Heart Attacks
Eggs are rich sources of lecithin that may increase heart attack risk (J of Nutr Biochem, Feb 2022;100:108906). Red meat and milk are also rich sources of lecithin, which is broken down into another chemical called choline. Healthful 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 blood levels of TMAO appear to be at increased risk for heart attacks (Dis Markers, Aug 8, 2018;1578320). Multiple animal studies show that TMAO punches holes in arteries (APMIS, May, 2020;128(5):353–366). 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 have also shown 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
What you eat in your total diet is more important than what single foods you eat. Since most North Americans eat a diet that promotes heart attacks (rich in sugar, meat, dairy, eggs, fried foods and refined carbohydrates), most North Americans should not also eat a lot of eggs. Eggs are a rich source of cholesterol, saturated fat and lecithin, all of which are associated with increased risk for heart attacks. For breakfast, try:
• Cooked oatmeal, which can help to lower high blood cholesterol levels because of its high soluble fiber content. You could get the same benefit from other cooked whole grains for breakfast: brown rice, barley, quinoa, 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.
