For the last 50 years, health authorities have widely cautioned Americans against eating eggs. It was thought that their high cholesterol content would raise blood cholesterol and increase the risk of heart disease. But such fears were not based on much actual science. In fact, dietary cholesterol has relatively little effect on blood cholesterol in most people (saturated and trans fats are the bigger culprits). And more recent research has largely exonerated eggs and even suggested that they may provide some heart benefits.
For instance, in a study from the University of Connecticut, published in late 2012 in Metabolism, 40 middle-aged people with coronary risk factors ate either three eggs or cholesterol-free egg substitute daily, while also restricting carbohydrates. After 12 weeks, total and LDL (“bad”) blood cholesterol did not change in either group. Moreover, though both groups showed improvements in a range of cholesterol-related factors due to the carbohydrate restriction, the egg eaters had a greater boost in HDL (“good”) cholesterol as well as increases in the size of both HDL and LDL particles (bigger is better), which was attributed, at least in part, to compounds in eggs called phospholipids.
Because the study—which was funded by the American Egg Board—lasted only a few months, the long-term effects of eating so many eggs are still unknown, however.
Another study—this one an analysis of eight observational studies—found no relationship between eggs (one a day) and heart disease or stroke. Published in BMJ earlier this year by researchers with no declared ties to the egg industry, it included nearly half a million people who were followed for 8 to 22 years.
An exception: Eggs were linked to increased heart disease risk in people with diabetes, though there were not enough data from this subgroup for the researchers to come to a firm conclusion.
Bottom line: Eggs are an excellent and relatively inexpensive source of protein and also provide vitamins A and D, some B vitamins, iron, zinc and other healthful substances, including choline and the carotenoids lutein and zeaxanthin. For most people, eating an egg a day, on average—or perhaps more—has no ill effects. It may even be beneficial.