By Joseph E. Scherger, MD, MPH

Core Faculty, Eisenhower Health Family Medicine, Residency Program, Eisenhower Health Center, La Quinta, CA; Clinical Professor, Keck School of Medicine, University of Southern California, Los Angeles

SYNOPSIS: A large meta-analysis showed higher consumption of eggs (eating more than one egg daily) was not associated with an increased risk of cardiovascular disease, and was associated with a lower risk of coronary artery disease.

SOURCE: Krittanawong C, Narasimhan B, Wang Z, et al. Association between egg consumption and risk of cardiovascular outcomes: A systematic review and meta-analysis. Am J Med 2021;134:76-83.

To help settle the controversy over the relationship between egg consumption and risk of cardiovascular disease, a team of researchers from Baylor, Mount Sinai, the Mayo Clinic, Case Western Reserve, and the Cleveland Clinic conducted a systematic review and meta-analysis of the medical literature published from 1966 through January 2020 for observational studies that reported on the association between egg consumption and cardiovascular events. Controlled trials were unavailable. The authors identified 23 prospective studies with a median of 12.28 years of follow-up. These reflected 1.416 million individuals with 157,324 cardiovascular events. Compared with no eggs/day or one egg/day consumption, higher egg consumption was not associated with an increased risk of cardiovascular disease events. Consuming more than one egg/day was associated with significantly lower risk of coronary artery disease.

COMMENTARY

Just as this study was covered in the press, another study from China showed egg consumption was linked to higher mortality from cardiovascular disease and cancer.1 The controversy continues. My preference is to look at nutrition and human biology. What makes sense based on our current scientific understanding of the causes of disease? Observational studies are based on correlations, and these correlations can be spurious.

Insulin resistance is recognized as the basis of most chronic diseases, especially the risk factors for cardiovascular disease and cancer.2,3 The excess body fat of being overweight and obese comes from eating too many carbohydrates. We all have a carbohydrate threshold that, if exceeded, results in insulin resistance, prediabetes and diabetes, and metabolic syndrome, with its elevated blood pressure and dyslipidemia. Consuming eggs does not cause insulin resistance. In fact, with a low carbohydrate diet, the opposite is true.4

There are no carbohydrates in eggs. Like any animal food, how that animal was fed is important. Organic eggs from pasture-raised chickens are different than eggs from grain-fed chickens kept in cages. Mounting evidence from the healthy nutrition literature supports the consumption of quality eggs as part of a healthy diet. One neurologist considers eggs an important food for brain health. Our brains are made largely from cholesterol.5

Even though it is limited by its observational nature, the Krittanawong et al study is of better quality than the recent paper from China. It is high time for randomized, controlled trials of nutritional matters of this importance. Meanwhile, I will continue to consume two organic eggs from pasture-raised chickens every day, and recommend such for my patients.

REFERENCES

  1. Zhuang P, Wu F, Mao L, et al. Egg and cholesterol consumption and mortality from cardiovascular and different causes in the United States: A population-based cohort study. PLoS Med 2021;18:e1003508.
  2. Taubes G. Why We Get Fat: And What to Do About It. Anchor; 2011.
  3. Bikman B. Why We Get Sick: The Hidden Epidemic at the Root of Most Chronic Disease — And How to Fight It. BenBella Books; 2020.
  4. Taubes G. The Case for Keto: Rethinking Weight Control and the Science and Practice of Low-Carb/High-Fat Eating. Knopf; 2020.
  5. Perlmutter D. Brain Maker: The Power of Gut Microbes to Heal and Protect Your Brain — for Life. Yellow Kite; 2015.