Today’s post comes from Katherine Brooking, MS, RD.* Brooking is a nutrition communications consultant, appearing regularly in national and local media to discuss nutrition topics. She is also co-author of the popular website and blog, Appetite for Health.
As an RD, I was surprised to see the headlines in August claiming that eating egg yolks may be as bad for your health as smoking cigarettes. This claim runs directly counter to decades of sound research demonstrating that healthy adults can enjoy an egg a day without increasing their risk for heart disease. I decided to dig a bit deeper to understand the latest controversy.
The news reports comparing egg consumption with cigarette smoking emerged as a result of a study published in the August 13 issue of the journal Atherosclerosis. (Spence et. al) In this study, researchers examined data on 1,231 men and women, average age of about 62, who were patients at vascular prevention clinic at London Health Sciences Centre in Canada.
The authors asked study participants about lifestyle practices — including such things as smoking and egg ingestion. People with more plaque in their arteries reported eating more eggs, and researchers concluded that so-called “egg-yolk-years” (that is, the number of eggs eaten per week times the number of years in the study) were a significant predictor of heart disease and that “regular consumption of egg yolk should be avoided by persons at risk of cardiovascular disease.”
There are multiple problems with this recent study, the most obvious of which may remind you of one of the first things you heard in stats class: correlation does not mean causation. Although study participants were asked about egg consumption, the authors failed to control for other aspects of diet. Foods other than eggs (including foods high in saturated fat, a known contributor to heart disease) may have lead to the increases in arterial plaque.
In addition, the study relied on patient dietary recall and patient self-reporting on a yearly basis. As most RDs can attest, dietary recall can be highly inaccurate. Few patients can remember what they ate last week, never mind how many eggs consumed in a year.
At the same time, we have a wealth of data that contradicts the findings of the Spence study. Years of epidemiological evidence indicate that dietary cholesterol does not increase the risk of heart disease in healthy individuals. Clinical studies have shown that two thirds or more of the population do not have a considerable increase in blood cholesterol after a dietary cholesterol challenge for extended periods of time, whereas in those who do respond, both LDL-C and HDLC increase, and therefore they maintain their LDL-C/HDL-C ratio. (Kanter et al.)
Further, in urging some segments of the population to avoid eggs, the Spence study ignores the nutritional contribution of eggs to a healthy, balanced diet. Eggs are a naturally nutrient-dense food, containing varying amounts of 13 essential nutrients in a package with a relatively low number of calories: just 70 for a large 50 gram egg. Eggs are one of the few natural sources of vitamin D and provide an excellent source of choline and selenium and a good source of vitamin B12, phosphorus and riboflavin.
The nutrients in eggs can play a role in weight management, muscle strength, healthy pregnancy, brain function, eye health and more. The high-quality protein in eggs has been shown to contribute to satiety and can help individuals maintain a healthy weight.
Similar thoughts were also expressed in an earlier post by Mitch Kanter, Ph.D and executive director of the Egg Nutrition Center.
The media is often quick to demonize specific food or food groups and slow to find flaws with individual studies. In the case of eggs, the evidence-to-date falls heavily in favor of consuming eggs on a regular basis, as part of a healthy and balanced diet.
*Disclaimer: This post is sponsored by the Egg Nutrition Center. However the views and opinions expressed in this post are my own.