Depending on who you ask, eggs are either a nutritional powerhouse, or the devil (make that devilled?) incarnate on a plate. These polarizing opinions have become even more severe, thanks to the results of a new study out of Northwestern University published on March 19, 2019 in the journal JAMA.
The study followed almost 30,000 adults for up to 31 years, and revealed a link between consumption of 300 milligrams of dietary cholesterol per day with an 18 percent higher risk of death and a 17 percent higher risk of heart or cardiovascular disease (CVD). A large egg has 186 milligrams of dietary cholesterol in the yolk. The researchers also found that eating three to four eggs a week was associated with a 6 percent higher risk of CVD and an 8 percent higher risk of death.
"Our study showed if two people had the 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," said Norrina Allen, associate professor of preventive medicine at Northwestern University Feinberg School of Medicine and one of the study authors, in a press release. "We found cholesterol, regardless of the source, was associated with an increased risk of heart disease."
For most people, eggs are their largest daily source of dietary cholesterol. So, the research seems to indicate that adults who consumed more eggs, and thus dietary cholesterol, were at higher risk of cardiovascular disease (CVD) or death.
This is a big bummer for people who love eggs, but it's not terribly surprising, since eggs have long been alternately praised and condemned for their nutrition content. After years of telling Americans that eggs were bad if you were watching your cholesterol, the Dietary Guidelines put out by the U.S. government were revised in 2016 to drop a recommended limit on dietary cholesterol. The newer thinking was that high cholesterol is caused by saturated fat, not by dietary/animal cholesterol that is high in foods like eggs or shrimp.
"Eggs are an inexpensive source of protein, choline and other nutrients," says Sonya Angelone, MS, RDN, spokesperson for the Academy of Nutrition and Dietetics in an email interview. "However, in healthy people, our bodies compensate, to a certain extent, [for] our diets. If you eat more cholesterol, your liver makes less and vice versa. If you eat less, your liver makes a little more. There isn't a direct correlation between dietary cholesterol and heart disease."
So, Should We Stop Eating Eggs?
Some previous studies had shown that eating eggs did not increase the risk of heart disease, but researcher Allen attributed that to the fact that those studies had a less diverse group of participants and a shorter follow-up time.
However, Angelone of the Academy of Nutrition and Dietetics doesn't think that dietary recommendations need to be changed based on the results of this new study. "This was an observational study not a double blind, placebo-controlled prospective study. In other words, it does not prove anything, it only shows a relationship," she says, noting that it did not control for other factors that affect heart disease like smoking or other eating habits.
"Did the participants exercise, eat plenty of heart protective fiber, fruits and vegetables? Did they eat a lot of processed meats and other overly processed foods? They didn't actually know what the participants were eating, they just had them complete a diet questionnaire that asked about egg consumption at the beginning of the study, and that was it," she says, "These people could have been eating bacon with their eggs, but we don't know because this information was not tracked."
Carly Johnston, registered dietician and owner of New England Nutrition Advisors has similar concerns about the study's validity. "Another thing to keep in mind is that the study was based on food recalls. Do you remember exactly what you ate this month?" she says in an email.
Recommended Egg Consumption
The study didn't recommend that people completely stop eating eggs, because they are a good source of other nutrients necessary to a healthy diet. Instead, they suggested opting for egg whites, rather than whole eggs, or simply consuming eggs "in moderation." But what does this mean, exactly?
Angelone says people shouldn't eat more than four eggs a week, and certainly not always with a side of bacon and hash browns. But the recommended amount has a lot to do with your family history and whether you are at risk for high cholesterol (poor diet, no exercise, smoker, etc.)
"Good health doesn't come down to one factor like how many eggs someone eats in a week (unless it's a crazy number!)," she says. "A 6 percent increase in cardiovascular disease or 8 percent increase in all-cause mortality by eating 3-4 eggs/week isn't a huge increase worth panicking over. You can lower your risk even more by adopting healthy diet and lifestyle habits including achieving a healthy weight."
The 2015-2020 Dietary Guidelines for Americans suggest that people replace meat, poultry or eggs with seafood a couple of times a week. "Although the 2015-2020 Dietary Guidelines no longer has a key recommendation with a specific limit on dietary cholesterol, it still recommends healthy eating patterns that are limited in dietary cholesterol," explains Don Wright, M.D., M.P.H., deputy assistant secretary for health and director of the Office of Disease Prevention and Health Promotion for the U.S. Department of Health and Human Services (HHS) in an email. "This is because evidence shows that eating patterns lower in dietary cholesterol are associated with reduced risk of heart disease. Further, the 2015-2020 Dietary Guidelines notes that more research is needed to understand the dose-response relationship between dietary cholesterol and blood cholesterol levels."
The guidelines, which are updated every five years, will be updated again in 2020, with the review committee looking at current scientific evidence related to health and nutrition before making further changes.