DEAR DOCTOR: I'm old enough to remember when eggs were good, then bad, and then so bad they were probably going to give you a heart attack. Now I'm hearing we've come full circle and eggs are good for you again. What gives?
DEAR READER: We're right there with you on the confusing -- and seemingly endless -- back-and-forth about whether eggs are friend or foe. Now, the continuing line of inquiry that ushered the egg white omelet into our lives has produced new research that comes out in favor of the beleaguered egg. According to findings from a study published in the journal Heart, eating an egg each day may reduce the risk of stroke by as much as 25 percent. This is a departure from previous studies, which had either identified eggs as problematic for cardiovascular health or at best were inconclusive on the subject.
At the root of the egg's bad rep is one particular stat in its nutritional profile. At just about 70 calories each, eggs provide varying amounts of vitamins A, B2, B12 and folate, trace minerals like selenium, iodine, iron and zinc, and about 6 grams of protein. They also contain a hefty dose of cholesterol -- about 210 milligrams each -- which is what landed them on the nutritional blacklist. But as of 2016, the federal government's Dietary Guidelines for Americans dropped its recommendation to limit dietary cholesterol to 300 mg per day, which in turn eased restrictions on eggs.
Meanwhile, because cardiovascular disease and stroke have become a leading cause of death in China, as in the rest of the developed world, researchers there looked into the role of eggs in the diet. They mined data gathered from more than 500,000 participants in an ongoing health initiative known as the China Kadoorie Biobank study, which uses questionnaires, a range of physical measurements, and regular blood samples to track health outcomes. They focused on data from individuals who ranged in age from 30 to 79, came from a wide geographic area, and were free of cancer, cardiovascular disease and diabetes at the time they joined the study.
In sorting the data for the effects of eggs in the diet, researchers discovered that people who ate an egg each day had a lower incidence of cardiovascular disease overall than those who ate no eggs. They had a 25 percent lower incidence of hemorrhagic stroke, which is the rupture of a blood vessel in the brain, and a 12 percent reduction in risk of ischemic heart disease, in which narrowing of the arteries results in less blood and oxygen reaching the heart.
As the study's authors themselves point out, it's important to remember that this is an observational study. While results can be extrapolated, the specific conditions that contributed to the outcomes are not known. What's encouraging for egg lovers is that the results appear to bolster the new(ish) understanding that cholesterol levels in food don't automatically translate to a corresponding rise in blood levels of cholesterol. So while the conversation about eggs is likely to continue for some time, for now, eggs in moderation for people without heart disease or the risk for heart disease have gotten a green light.
Eve Glazier, M.D., MBA, is an internist and associate professor of medicine at UCLA Health. Elizabeth Ko, M.D., is an internist and assistant professor of medicine at UCLA Health.