(CNN) It's been debated for years: Are eggs good or bad for you? People who eat an added three or four eggs a week or 300 milligrams of dietary cholesterol per day, have a higher risk of both heart disease and early death compared with those who eat fewer eggs, new research finds.

"Eggs, specially the yolk, are a major source of dietary cholesterol," wrote Victor Zhong, lead study author and a postdoctoral fellow in the Department of Preventive Medicine at Northwestern University Feinberg School of Medicine in Chicago. In a study published Friday in the medical journal JAMA, he and his colleagues noted that a single large egg contains about 186 milligrams of cholesterol.

The researchers examined data from six US study groups including more than 29,000 people followed for 17½ years on average. Over the follow-up period, a total of 5,400 cardiovascular events occurred, including 1,302 fatal and nonfatal strokes, 1,897 incidents of fatal and nonfatal heart failure and 113 other heart disease deaths. An additional 6,132 participants died of other causes.

Consuming an additional 300 milligrams of dietary cholesterol per day was associated with a 3.2% higher risk of heart disease and a 4.4% higher risk of early death, Zhong's analysis of the data showed. And each additional half an egg consumed per day was associated with a 1.1% higher risk of cardiovascular disease and 1.9% higher risk of early death due to any cause, the researchers found.

A potential reason for inconsistent results in the past was the fact that other studies did not take into account that egg consumption may be related to other unhealthy behaviors, such as low physical activity, smoking and an unhealthy diet. Additionally, cholesterol-containing foods are usually rich in saturated fat and animal protein.

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