Eggs dramatically raise cholesterol and significantly increase heart disease risk. Healthy people should eat few or no eggs.

The egg carton of 1990 had a health warning. Not a legal requirement exactly, more a product of the dietary consensus that had crystallized over the previous two decades. Eggs were high in cholesterol, cholesterol caused heart disease, therefore eggs caused heart disease. The American Heart Association recommended limiting egg consumption to three per week. Hospital cafeterias switched to egg substitutes. Breakfast menus offered egg-white omelets as the responsible choice.

The chain of reasoning was built on Ancel Keys's diet-heart hypothesis, which proposed that saturated fat raises blood cholesterol and elevated blood cholesterol causes heart disease. Keys's Seven Countries Study, published in 1970, was the foundational document. The USDA's 1977 Dietary Goals for the United States institutionalized the hypothesis into federal nutrition policy, setting a limit of 300 milligrams of dietary cholesterol daily, roughly the amount in one large egg yolk.

The problem was that the relationship between dietary cholesterol and blood cholesterol is more complicated than the simple pipeline model implied. Most people are "cholesterol non-responders" whose bodies compensate for increased dietary cholesterol by producing less. Studies conducted in the 1990s began accumulating evidence that dietary cholesterol had only modest effects on serum LDL in healthy adults. Meanwhile, the nutrients eggs actually deliver, protein, choline, lutein, zeaxanthin, vitamin D, were being ignored in the anti-egg framing.

The pivotal regulatory moment came in 2015, when the Dietary Guidelines Advisory Committee, the expert panel that informs federal nutrition policy every five years, explicitly removed the 300-milligram dietary cholesterol limit. The committee stated that "cholesterol is not a nutrient of concern for overconsumption." The guideline change received considerably less media coverage than the original anti-egg messages had.

Large prospective studies, including a 2018 analysis in the American Journal of Clinical Nutrition following more than 215,000 participants, found no significant association between egg consumption and cardiovascular disease risk in healthy adults. A 2020 JAMA study did find a modest association at very high intake (more than two eggs daily), suggesting the picture is not entirely simple.

The egg debate traces a familiar arc in nutrition science: a hypothesis based on plausible mechanism and early association data becomes policy before the clinical evidence is robust enough to support it, and then takes decades to update even as the evidence shifts. The egg has been largely rehabilitated. The carton no longer carries warnings.