Are eggs bad for your heart? What the research shows

Few foods have swung between villain and health food as often as the egg. Egg yolks are rich in cholesterol, and for decades eggs had a reputation as a threat to the heart. More recent research has softened that view, though not every study agrees.

The largest analysis, covering 1.7 million people, found no link between eating up to one egg a day and heart disease. A large US study found a small link, which appeared to run through total cholesterol intake rather than eggs themselves. Heart health groups have since moved away from a specific cholesterol limit toward advice about overall eating patterns.

What cholesterol in food and blood is

MedlinePlus explains that cholesterol is a waxy, fat-like substance found in every cell, and that your body makes all the cholesterol it needs. It is also found in foods from animal sources, such as egg yolks, meat and cheese.

Too much cholesterol in the blood can combine with other substances to form plaque in the arteries, which can narrow or block the heart’s arteries. LDL cholesterol is often called bad cholesterol because high levels build plaque, while HDL is called good cholesterol because it helps clear cholesterol away. MedlinePlus lists eating lots of saturated fat, found in red meat and full-fat dairy, as one of the most common causes of high blood cholesterol.

What the large egg studies found

A 2020 study in the BMJ followed more than 215,000 US women and men in three long-running cohorts, the Nurses’ Health Studies and the Health Professionals Follow-Up Study, for up to 32 years. None had heart disease, diabetes or cancer at the start, and 14,806 later developed heart disease.

People who ate more eggs differed in other ways: they had a higher body mass index, were less likely to take statins and ate more red meat. After accounting for those differences, eating at least one egg a day was not linked to heart disease compared with eating less than one a month. Most people ate between one and five eggs a week.

The researchers then pooled studies from around the world, covering 1,720,108 people. An extra egg a day was not linked to heart disease, coronary heart disease or stroke. In Asian cohorts, eggs were linked to slightly lower risk. The authors concluded that moderate egg consumption (up to one egg per day) is not associated with cardiovascular disease risk overall.

Why some egg studies disagree

A 2019 study in JAMA reached a different headline. It pooled six US cohorts with 29,615 adults, followed for a median of 17.5 years, and found that eating more eggs, and more cholesterol overall, was linked to higher risk of heart disease and death in a dose-response manner, meaning more intake went with more risk. For each additional half egg a day, the absolute difference in heart disease risk over the whole follow-up was about 1 percentage point.

The detail that matters is what happened next. When the researchers also accounted for total dietary cholesterol, the link between eggs and heart disease disappeared. That suggests the pattern tracked cholesterol intake in general, of which eggs are one large source, rather than something specific to eggs.

Studies can also differ because of how they handle the rest of the diet. People who eat many eggs may also eat more red meat and processed foods, and different choices about which of these to adjust for can push results in different directions.

What guidelines say about eggs and dietary cholesterol

In 2019 the American Heart Association (AHA) published a science advisory on dietary cholesterol. It notes that recent guidelines had dropped specific cholesterol targets, and that observational studies from several countries generally do not show a clear link between dietary cholesterol and heart disease.

It also notes that most intervention studies associate intakes of cholesterol that exceed current average levels with higher total or LDL cholesterol in the blood. Its conclusion is that guidance focused on dietary patterns is more likely to improve diet quality than a single number. It points to Mediterranean-style and DASH-style (Dietary Approaches to Stop Hypertension) diets, which are naturally fairly low in cholesterol and emphasize fruits, vegetables, whole grains, nuts and liquid vegetable oils.

Why egg research is hard to interpret

Nearly all the evidence is observational and relies on people reporting what they eat, often years before heart disease appears. People told they have high cholesterol may cut back on eggs, which can blur the link. Eggs are also eaten with very different foods in different places, which may help explain why results varied between US, European and Asian cohorts.

What the egg research cannot tell us yet

There are no long-term trials that assign people to eat different numbers of eggs and then count heart attacks and strokes. The studies also cannot show how any one person’s blood cholesterol responds to eggs, and the AHA notes that meta-analyses of intervention studies differ in their findings.

What the egg evidence adds up to

For most people in these studies, eating up to one egg a day was not linked to heart disease. One large US study found a small increase in risk with more eggs, tied to total cholesterol intake. Heart health guidance now focuses on the overall pattern of the diet rather than a single food or a cholesterol limit.

How eggs fit into any one person’s diet depends on the rest of what they eat and on their own cholesterol and heart risk.