Still, she said, “This study found a very consistent association. But eggs have some advantages — amino acids and minerals — and these are beneficial. You do want to reduce the number of eggs, especially egg yolks, as part of a healthy diet. But we don’t want people to walk away thinking they shouldn’t eat any eggs. That’s not the right message.”
Current recommendations regarding dietary cholesterol, and eggs in particular, are indeed confusing. The Dietary Guidelines for Americans 2015-2020, published by the Department of Health and Human Services and the Department of Agriculture, for example, states that we “should eat as little cholesterol as possible while consuming a healthy eating pattern.” But the Scientific Report that accompanies those same guidelines says that “cholesterol is not a nutrient of concern for overconsumption,” suggesting that avoiding eggs is not important.
The scientific literature can be equally confusing, with studies reaching varying conclusions about the importance of dietary cholesterol, or eggs in particular, on overall health.
Several aspects of this study make it different from and, to some experts, more convincing than other reports. The authors were able to isolate data for each individual participant, unlike “most previous meta-analyses, which have combined the results that have already been calculated,” Dr. Allen said. They were also able to record the exact amounts of cholesterol in each person’s diet and to sort out the effects of the cholesterol in eggs from all the other foods that contain cholesterol.
Dr. Frank B. Hu, a professor of nutrition and epidemiology at the Harvard T.H. Chan School of Public Health, found the work interesting and carefully carried out but, he said, “the results are surprising because here even a half-egg a day makes a difference. This study seems to find a much stronger association than what has previously been found.”
The study has limitations. The data depended on self-reports about what people ate, which are not always reliable, and the analyzed studies used varying methods for collecting the diet information. The researchers also relied on a single measurement of egg and dietary cholesterol consumption, even though diets can change over time.
Dr. Allen said of the latest study, “despite its strengths, future studies are needed to understand why we are getting conflicting findings across populations and whether there are some people for whom eating eggs is bad and others who are not affected.”