Higher egg and cholesterol consumption hikes heart disease, mortality risk
Adults who ate more eggs and dietary cholesterol had a significantly higher risk of cardiovascular disease and death, according to a new study from Northwestern Medicine, which published today in the Journal of the American Medical Association.
The study looked at pooled data on 29,615 U.S. racially and ethnically diverse adults from six prospective cohort studies for up to 31 years of follow up. It found that eating 300 milligrams of dietary cholesterol per day was associated with 17 percent higher risk of incident cardiovascular disease and 18 percent higher risk of all-cause deaths. The cholesterol was the driving factor independent of saturated fat consumption and other dietary fat, the researchers said. In addition, the study found that eating three to four eggs per week was associated with 6 percent higher risk of cardiovascular disease and 8 percent higher risk of any cause of death.
Diet data were collected using food frequency questionnaires or by taking a diet history. Each participant was asked a long list of what they'd eaten for the previous year or month. The data were collected during a single visit. During the follow-up period, 5,400 cardiovascular events and 6,132 all-cause deaths were diagnosed.
A major limitation of the study is participants' long-term eating patterns weren't assessed, researchers said in a March 15 announcement.
"The take-home message is really about cholesterol, which happens to be high in eggs and specifically yolks," said Norrina Allen, PhD, co-corresponding study author and associate professor of preventive medicine. "As part of a healthy diet, people need to consume lower amounts of cholesterol. People who consume less cholesterol have a lower risk of heart disease."
Egg yolks are one of the richest sources of dietary cholesterol among all commonly consumed foods. One large egg has 186 milligrams of dietary cholesterol in the yolk, the researchers said.
Other animal products, such as red meat, processed meat, and high-fat dairy products like butter or whipped cream, also have high cholesterol content, said lead author Wenze Zhong, PhD, a postdoctoral fellow in preventive medicine at Northwestern.
Whether eating dietary cholesterol or eggs is linked to cardiovascular disease and death has been debated for decades. Eating less than 300 milligrams of dietary cholesterol per day was the guideline recommendation before 2015. However, the most recent Dietary Guidelines for Americans omitted a daily limit for dietary cholesterol. The guidelines also include weekly egg consumption as part of a healthy diet.
An adult in the U.S. gets an average of 300 milligrams per day of cholesterol and eats about three or four eggs per week, researchers say. The study findings mean the current U.S. dietary guideline recommendations for dietary cholesterol and eggs may need to be re-evaluated, they said.
The evidence for eggs has been mixed. Previous studies found eating eggs did not raise the risk of cardiovascular disease. But those studies generally had a less diverse sample, shorter follow-up time, and limited ability to adjust for other parts of the diet, Allen said.
Exercise, overall diet quality, and the amount and type of fat in the diet didn't change the association between the dietary cholesterol and cardiovascular disease and death risk, the researchers said.
Based on the study, people should keep dietary cholesterol intake low by reducing cholesterol-rich foods such as eggs and red meat in their diet, researchers said.
But don't completely banish eggs and other cholesterol-rich foods from meals, Zhong said, because eggs and red meat are good sources of important nutrients such as essential amino acids, iron, and choline. Instead, choose egg whites instead of whole eggs or eat whole eggs in moderation.
"We want to remind people there is cholesterol in eggs, specifically yolks, and this has a harmful effect," said Allen. "Eat them in moderation."