Here we go again. Another dietary flip-flop to digest (pardon the pun). The latest one involves eggs, a food that’s been a source of controversy for decades.
A large study published in the Journal of the American Medical Association (JAMA) concluded a higher intake of eggs and dietary cholesterol significantly increased the risk of cardiovascular disease and premature death.
The debate over eggs revolves around their high cholesterol-content (185 milligrams for every large egg, all in the yolk). Consuming too much cholesterol has been thought to raise LDL (bad) blood cholesterol, an established risk factor for heart attack and stroke.
The new findings come not long after the U.S. government removed the daily cholesterol limit of 300 mg from its 2015-20 Dietary Guidelines for Americans, stating cholesterol is no longer a “nutrient of concern for overconsumption.” The consensus among scientists: Cholesterol in food has little effect on the amount of cholesterol in the bloodstream.
In the face of this contradictory information, however, here’s what you need to know about the latest research.
About the new study
The JAMA study analyzed data from 29,615 healthy adults who were enrolled in six different studies, spanning up to 31 years of follow-up, in order to determine if dietary cholesterol or egg consumption was associated with the risk of cardiovascular disease or death from any cause.
Cardiovascular disease was defined as the composite of fatal and nonfatal coronary heart disease, stroke, heart failure and cardiovascular death from other causes.
The main finding was that higher consumption of eggs and cholesterol (sources included eggs and meats), beyond average intake, was tied to a significantly greater risk of both outcomes in a dose-dependent manner.
Study participants consumed, on average, 285 mg of cholesterol a day and two eggs a week.
Eating an additional 300 mg of cholesterol a day was found to increase the risk of cardiovascular disease and all-cause death by 17 and 18 per cent, respectively. Eating an extra three to four eggs each week was tied to a 6 per cent higher risk of cardiovascular disease and 8 per cent increased risk of any cause of death.
These findings remained true after accounting for age, exercise, smoking status, alcohol intake and overall diet quality. Even in the context of a heart-healthy diet, a higher cholesterol intake was found to be harmful.
Like most nutrition studies, this one is not without limitations. And there are a few.
The six studies included in the JAMA analysis relied on self-reported data; having to recall what you ate in the past month is prone to error.
What’s more, dietary data was collected only once at the beginning of each study. The fact that long-term eating patterns were not assessed is a major limitation, since people may have changed their diets over the years of follow up.
LDL blood cholesterol levels, which, when elevated, are a risk factor for cardiovascular disease, were not assessed.
This observational study suggests only that a relationship exists between dietary cholesterol and cardiovascular disease; it does not prove that higher egg and cholesterol consumption causes it.
Keep in mind, also, that previous studies have come to opposite conclusions.
Still, this doesn’t mean that these findings should be completely dismissed. According to an editorial in JAMA, the study’s large dataset and rigorous methodology make a strong case that eggs and dietary cholesterol intake influence the risk of cardiovascular disease.
And while the overall relationship between cholesterol and cardiovascular disease was modest, the results suggest that the risk may be greater for people who consume eggs and cholesterol substantially above average intakes.
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So now what?
Should you swap your sunny-side up for a whites-only omelet?
It’s not necessary to stop eating whole eggs, which are packed with nutrition.
They’re an excellent source of protein, 42 per cent of which is found in the yolk. Eggs also deliver plenty of vitamin B12 (half a day’s worth in one large egg) and selenium, a mineral that protects DNA in cells and is needed for thyroid function.
That said, if you eat a lot of egg yolks (e.g., two or more a day), consider eating them in moderation.
Remember, too, that preventing cardiovascular disease is about a whole lot more than watching your egg or cholesterol intake.
Maintaining a healthy weight, getting regular exercise and eating an overall healthy diet that emphasizes fibre-rich whole grains, fruits, vegetables and plant proteins and limits refined starchy foods, added sugars and saturated and trans fats remain important preventive strategies.
Leslie Beck, a Toronto-based private practice dietitian, is Director of Food and Nutrition at Medcan.
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