Egg lovers may have some unsettling news coming their way. A recent study published in The Journal of the American Medical Association (JAMA) points to higher consumption of eggs and dietary cholesterol as an increased risk of cardiovascular disease and all-cause death [1].
This large study, led by a team in the Department of Preventive Medicine at Northwestern University Feinberg School of Medicine, included data from 29,615 adults with results showing that those who consumed 300 mg of dietary cholesterol a day had a 17% higher risk of cardiovascular disease and 18% higher risk of all-cause death, independent of saturated fat or other dietary fats [1]. And the main culprit of cholesterol intake—according to this article—may be eggs.
One large egg yolk has 186 milligrams of cholesterol, making it one of the largest sources among consumed foods. An additional ½ egg eaten each day significantly increased the risk of cardiovascular disease incident and all-death mortality, and those who consumed three to four eggs a week had a 6% higher risk of cardiovascular disease and 8% higher risk of death from any cause [1].
“The take-home message is really about cholesterol, which happens to be high in eggs and specifically yolks,” said co-corresponding study author Dr. Norrina Allen, associate professor of preventive 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” [1].
Conflicting Information
Hard evidence regarding cholesterol has often conflicted in past studies, and these recent findings are likely to fuel that flame. A 2015 meta-analysis from Tufts Medical Center of 40 studies and over 300,000 subjects, for instance, noted no statistically significant association between dietary cholesterol and coronary artery disease, ischemic stroke, or hemorrhagic stroke [3].
Allen refutes these claims, citing less diverse sample populations, shorter follow-up time, and impaired ability to adjust for other aspects of the diet. “Our study showed that if two people had the exact same diet and the only difference in diet was eggs, then you could directly measure the effect of egg consumption on heart disease,” Allen said. “We found cholesterol, regardless of the source, was associated with an increased risk of heart disease.”
Certainly, limitations can also be found within the Northwestern study. One is the reliance on a single measurement of egg and dietary cholesterol consumption. With the average follow-up being 17.5 years, there is also large variability in potential for individual dietary changes. Furthermore, due to the prospective and observational nature of the study, causality cannot be established—only possible association.
Should we eliminate eggs from our diets?
The answer isn’t so simple. While research now suggests a link between consumption and cardiovascular disease and death, Dr. Anthony Komaroff from Harvard University adds that eggs have been shown to contain healthy nutrients including lutein, choline, and vitamins A, B, and D. He states that evidence from Harvard Medical School studies has shown the cholesterol in one egg a day to be safe for most people.
“Of course, it matters greatly what you eat with your eggs,” says Komaroff. “The saturated fat in butter, cheese, bacon, sausage, muffins, or scones, for example, raises your blood cholesterol much more than the cholesterol in your egg” [4].
According to the Northwestern study authors, eggs and other cholesterol-heavy foods shouldn’t be completely cut out as they remain a source of important nutrients. Instead, it is important to recognize the harmful effects of high-cholesterol diets and re-evaluate current trends in dietary consumption and dietary recommendations.
[1] Zhong VW, Van Horn L, Cornelis MC, et al. Associations of dietary cholesterol or egg consumption with incident cardiovascular disease and mortality. JAMA. 2019:1081-1095.
[2] Office of Disease Prevention and Health Promotion. Dietary guidelines 2015-2020. https://health.gov/dietaryguidelines/2015/guidelines/. Updated 2015.
[3] Berger S, Raman G, Vishwanathan R, Jacques PF, Johnson EJ. Dietary cholesterol and cardiovascular disease: A systematic review and meta-analysis. . 2015;102(2). https://doi.org/10.3945/ajcn.114.100305
[4] Komaroff A. Are eggs risky for heart health? Harvard Health Publishing Web site. https://www.health.harvard.edu/heart-health/are-eggs-risky-for-heart-health. Updated 2017. Accessed January, 2020.
[5] Paul M. Bad news for egg lovers. Northwestern Now Web site. https://news.northwestern.edu/stories/2019/03/eggs-cholesterol/. Updated 2019.
Spencer Bayless is a member of The University of Arizona College of Medicine-Phoenix Class of 2023. He graduated from Arizona State University with a degree in Biological Sciences and an emphasis in Neurobiology. Spencer has special interests in health care economics, policy, and quality improvement. He enjoys traveling, ping-pong, and seeking new experiences.