Eggs likely aren’t responsible for high cholesterol—but new research may have found the real culprit behind rising cholesterol levels.
The study, published in The American Journal of Clinical Nutrition in July, found that the saturated fat in food, not dietary cholesterol in eggs, was linked to higher cholesterol levels. In fact, participants who ate two eggs a day for five weeks actually saw improved cholesterol levels.
“When it comes to a cooked breakfast, it’s not the eggs you need to worry about—it’s the extra serve of bacon or the side of sausage that’s more likely to impact your heart health,” Jon Buckley, PhD, senior study author and executive dean of the University of South Australia Allied Health and Human Performance Academic Unit, said in a press release.
For years, researchers have gone back and forth on whether eggs raise low-density lipoprotein (LDL) cholesterol—the “bad” kind that can increase the risk of heart disease and stroke.
This is because eggs are packed with cholesterol. One large egg contains around 200 milligrams (mg) of dietary cholesterol, two-thirds of the previously recommended daily limit of 300 mg.
But more recent research has found that it’s actually the saturated fat in foods that raises LDL cholesterol. Most high-cholesterol foods are also high in saturated fat, Buckley told Health, but eggs have very little (1.6 grams), which sparked the debate.
“For much of the past two decades, we’ve had a pretty strong feeling that it’s saturated fat, far more than cholesterol [that raises LDL levels],” Sean Heffron, MD, preventive cardiologist at the Center for the Prevention of Cardiovascular Disease at NYU Langone Heart, told Health.
The new study put this theory to the test. Researchers divided 61 healthy adults into three groups and had them follow a specific diet for five weeks, rotating to experience each eating plan. By the end of the study, 48 people completed all three diets:
- Control diet: High cholesterol and high saturated fat, eating a maximum of one egg per week.
- Egg diet: High cholesterol and low saturated fat, eating two eggs per day.
- Egg-free diet: Low cholesterol and high saturated fat, with no eggs.
Results showed that saturated fat was linked to a rise in LDL cholesterol, but dietary cholesterol was not. Also, compared to the control diet, the egg diet lowered LDL cholesterol (by an average of 5.7 mg/dL), but the egg-free diet did not.
This suggests that saturated fat elevates LDL levels—not dietary cholesterol, Buckley said. “We were a bit surprised that the effect was so clear-cut,” he added.
It’s worth noting that the Egg Nutrition Center, a division of the American Egg Board, provided funding for the study.
While you might have assumed that eating cholesterol raises your body’s cholesterol levels—as experts did for years—it’s not that simple.
Dietary cholesterol, found in foods, is different from blood cholesterol, which refers to the cholesterol in your blood, including both LDL and high-density lipoprotein (HDL) cholesterol.
Most of your blood cholesterol does not come from your diet—it’s made by your liver. Eating a lot of saturated fat can raise your LDL levels because it makes your liver produce more cholesterol overall and clear less LDL cholesterol from your bloodstream.
Meanwhile, “there is evidence that when you increase your dietary cholesterol intake, your own production of cholesterol reduces to compensate,” Buckley said.
“Dietary cholesterol isn’t the villain it was once thought to be,” added Melissa Mroz-Planells, DCN, RDN, a spokesperson for the Academy of Nutrition and Dietetics with a private practice in Chicago and Seattle.
While the message on eggs has shifted over time, there’s now broad agreement that eggs can be part of a balanced, heart-healthy diet, Mroz-Planells told Health. Research shows that eating about one egg per day is safe for your heart.
But experts said you may want to limit your eggs to four or five per week if you have high cholesterol. Michael Miller, MD, a cardiologist at Penn Medicine, told Health that the new study’s results aren’t generalizable to this group.
For instance, eggs can raise LDL levels if you have familial hypercholesterolemia, a genetic condition of high LDL cholesterol that affects about 1.3 million people in the U.S.
When your liver can’t regulate cholesterol due to a condition like that, dietary cholesterol can have a more pronounced impact on LDL levels, Miller explained. Other conditions, like hypothyroidism and several kidney disorders, and certain medications can also raise LDL cholesterol, he said.
If you’re concerned about your cholesterol levels, Sharon Palmer, RDN, a registered dietitian nutritionist from California, suggests sticking to egg whites, as most of the cholesterol and saturated fat in eggs are in the yolk.
Everyone should limit their saturated fat intake to support heart health in general, Buckley said. The American Heart Association recommends eating no more than 13 grams of saturated fat per day.
