My refusal to eat egg yolks has always been a bit of a family joke. During one family breakfast on vacation, when my kids were younger, I mixed the yolks from several hard-boiled eggs with leftover oatmeal to make “yolkmeal.” Not surprisingly, they did not want to eat it. In a silly way, I was trying to teach my kids that while egg whites were a good source of protein and contain no cholesterol, discarding the cholesterol-laden yolks was smart for the heart. The message 20 years ago was that each yolk contains about 200 mg of cholesterol, and too much cholesterol could lead to high cholesterol levels and a higher risk of having a heart attack.
So imagine my chagrin when information in recent years suggested that dietary cholesterol was not as bad as we once thought, and eating whole eggs was okay. Although I have stopped suggesting patients avoid eating eggs, to this day I have not been able to make myself eat an egg yolk, even though at times, I felt that the “yolk” was on me.
Today, I feel redeemed.
In a large trial published Friday in the Journal of the American Medical Association, it appears that too much cholesterol in our diets, especially from egg yolks, can lead to both an increased risk of coronary artery disease and dying, with the degree of the risk correlated with how much cholesterol we eat. This study, done by researchers at Northwestern University in Chicago, looked at a group of 29,615 adults from six ongoing studies in the U.S. Of the participants, the mean age was 52, no one had preexisting heart disease, 45 percent were men, and 31 percent black. Participants were followed for an average of 17.5 years. During that period, there were 1,302 deaths from heart attacks and 6,132 total deaths. The risk of increased dietary cholesterol consumption causing heart disease was higher if subjects were thin, female, and had higher LDL (bad) cholesterol levels.
The findings: A significant association between dietary cholesterol, egg consumption, and heart disease. Eggs accounted for 25 percent of total dietary cholesterol, and meat 42 percent. Each 300 mg increase of cholesterol in the diet, and extra half of an egg per day was associated with a higher risk of coronary disease.
Dietary cholesterol may be a bigger problem in the U.S. than the rest of the world. Our mean cholesterol consumption of 290 mg/day is higher than the global average of 228 mg/day. We are also heavier and as a society guilty of overnutrition. Egg consumption has been increasing in this country in recent years, corresponding with relaxed recommendations.
It is not certain why prior studies have led to so much uncertainty about ill effects of dietary cholesterol, but the most likely reason is that other dietary factors are even worse. Junk carbohydrates and processed foods lead to increased weight gain, higher blood pressure, and are even more hazardous to our health. Of course, smoking cigarettes, diabetes, and lack of physical activity will kill you a lot quicker than an egg.
As recently as September 2018, I wrote an article for the Inquirer in which I answered a question that my patients always ask me: Can I eat eggs, and does cholesterol in my diet really matter? My response then: Eggs are better for you than a diet full of junk carbs, so if you like an occasional egg, enjoy it without guilt.
I think this is still true, but this new study suggests that trying to limit dietary cholesterol really does matter. Egg whites remain a much healthier choice than the whole egg, full of protein and having no cholesterol. If you crave the taste of a yolk, try using three or four egg whites mixed with one yolk. It seems to make sense to limit both eggs and other sources of cholesterol (primarily from animal protein/meat) in our diets, especially if you are trying to stay off cholesterol medications.
Thanks to this new research, I might just go back to making “yolkmeal,” and I can only hope that my kids are not too old to enjoy the mess.
David Becker, M.D., is a frequent Inquirer contributor and a board-certified cardiologist with Chestnut Hill Temple Cardiology in Flourtown, Pa. He has been in practice for 25 years.