The study, published Tuesday in the journal Atherosclerosis, measured the carotid wall thickness of over 1,200 patients attending a vascular prevention clinic. Carotid wall thickness, explains Janis Jibrin, registered dietitian and SELF contributing editor, is usually a result of a build-up of plaque in your arteries, often caused by LDL (the “bad” cholesterol) and is a strong predictor of heart disease.
Study participants also filled out questionnaires regarding their lifestyle and medications, including “pack-years” of smoking (which means how many cigarettes you smoked per day for how many years) and the number of egg yolks consumed per week times the number of years consumed, aka your “egg-yolk years.” What the researchers found is that smoking and eating egg yolks had a similar effect on increasing carotid wall thickness in people over 40. The more they had smoked and/or eaten egg yolks in their lives, the more plaque they had built up in their arteries.
“Compared to people who smoked less than 10 pack-years and were in the lowest quartile of egg yolk intake, egg yolks alone increased plaque area 1.78 times, smoking alone increased it by 2.2 times and the combination increased plaque area 2.88 times, after adjusting for age,” study researcher J. David Spence, M.D., Professor of Neurology and Clinical Pharmacology at Western University in Ontario, Canada, tells HealthySELF. “So egg yolks had about 80 percent of the effect of smoking, and the combination was additive.”
But wait a second — last year, the United States Department of Agriculture reported that eggs have less cholesterol than previously thought. The 2010 Dietary Guidelines Advisory Committee concluded that one egg per day does not result in increased blood cholesterol levels, and is not associated with risk of coronary heart disease or stroke in healthy adults.
For most people, it’s saturated and trans fat in the diet that raises blood cholesterol levels, say Willow Jarosh and Stephanie Clarke, contributing editors at SELF and co-founders of C&J Nutrition, adding that smoking and eggs should not be directly compared in terms of health, since eggs have many healthful qualities like choline and protein and cigarettes most definitely do not. But, they advise, watch your daily tally: The USDA recommends that individuals consume, on average, less than 300 mg of cholesterol per day; a single large egg contains 185 mg of cholesterol, about 220 mg if it’s a “jumbo.”
“We typically recommend that people combine one egg yolk with egg whites when they eat them, so we’re not recommending eating three egg yolks in one sitting either,” they say.
The National Heart Blood and Lung Institute also recommends that Americans limit their cholesterol intake to no more than 300 mg per day, and to eat no more than four whole eggs a week (two if you’re trying to lower your cholesterol), including those in baked goods or processed foods. Jibrin points out that those recommendations lower to 200 mg per day for people who are at a higher risk of heart disease, such as diabetics and people with a family history of cardiovascular disease. In fact, the study authors say 200 mg a day is a better number for anyone’s heart health. Jibrin adds: “If you eat a large, whole egg, you pretty much need to eat vegan for the rest of the day to not exceed 200 mg of cholesterol.”
That said, there certainly are health benefits to eating eggs. “Eggs are a good source of protein, which is very important to your health, your vitality and to your weight-loss goals,” Jibrin says, adding that “you can learn how to work with egg whites, which are themselves a complete protein, without the yolks.” She also advises “keeping your eye on the big picture”: The best way to keep your heart healthy is to exercise regularly, eat a diet filled with fresh vegetables and fruit, stick with whole, unprocessed grains and avoid saturated fats, she explains.