Adults who eat more dietary cholesterol—such as that in eggs—have a significantly higher risk of cardiovascular disease and of death from any cause, a new study reports.
“The take-home message is really about cholesterol, which happens to be high in eggs and specifically yolks,” says co-corresponding study author Norrina Allen, associate professor of preventive medicine at Northwestern University Feinberg School of 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 eaten foods. One large egg has 186 milligrams of dietary cholesterol in the yolk. Other animal products including red meat, processed meat, and high-fat dairy products (butter or whipped cream) also have high cholesterol content, says lead author Wenze Zhong, a postdoctoral fellow in preventive medicine at Northwestern.
Good egg or bad egg?
Scientists have for decades debated the existence of a link between eating dietary cholesterol—or eggs—and cardiovascular disease and death. Eating less than 300 milligrams of dietary cholesterol per day was the recommendation before 2015—but the most recent dietary guidelines omitted a daily limit for dietary cholesterol and included weekly egg consumption as part of a healthy diet.
An adult in the United States gets an average of 300 milligrams per day of cholesterol and eats about three or four eggs per week.
Now, the findings of the new study might mean the current US dietary guideline recommendations for dietary cholesterol and eggs need re-evaluation, the authors write.
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 says.
3-4 eggs a week
“Our study showed if two people had exact same diet and the only difference in diet was eggs, then you could directly measure the effect of the egg consumption on heart disease,” Allen says. “We found cholesterol, regardless of the source, was associated with an increased risk of heart disease.
Exercise, overall diet quality, and the amount and type of fat in the diet didn’t change the association among dietary cholesterol. cardiovascular disease, and death risk.
The new study, which appears in the Journal of the American Medical Association, looked at pooled data on 29,615 US racially and ethnically diverse adults from six prospective cohort studies for up to 31 years of follow up.
The study’s findings include:
- Eating 300 mg of dietary cholesterol per day links to a 17 percent higher risk of incident cardiovascular disease and 18 percent higher risk of all-cause deaths. Cholesterol is the driving factor independent of saturated fat consumption and other dietary fat.
- Eating three to four eggs per week links to a 6 percent higher risk of cardiovascular disease and 8 percent higher risk of any cause of death.
Whites not yolks
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.
But don’t completely banish eggs and other cholesterol-rich foods from meals, Zhong says, 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,” Allen says.
Researchers collected diet data using food frequency questionnaires or from diet histories. They asked each participant a long list of what they’d eaten for the previous year or month. Researchers collected the data during a single visit. The study had up to 31 years of follow up (median: 17.5 years), which included 5,400 cardiovascular events and 6,132 all-cause deaths.
The study did not assess participants’ long-term eating patterns, a major limitation, the researchers say.
“We have one snapshot of what their eating pattern looked like,” Allen says. “But we think they represent an estimate of a person’s dietary intake. Still, people may have changed their diet, and we can’t account for that.”
Source: Northwestern University