Published on April 30, 2019
Eggs: Friend or Foe?
We know that eggs are a nutrient-dense food, a rich source of protein and essential vitamins and minerals, particularly vitamin D, vitamin B12, selenium and choline. However, scientific opinion on the role of eggs in the human diet has changed several times over the past few decades.
In the 1950’s, eggs were marketed as a good source of protein and “the best way to start the day” (Guter and Low, 2008). By the 1960’s, egg consumption peaked in many parts of the world, but this was also the period where the high level of cholesterol content in eggs caught the attention of the health community. Research studies suggested that foods, rich in cholesterol, may elevate blood cholesterol and therefore increase the risk of coronary heart disease (Kannel et al., 1969). The front cover of the popular TIME magazine in 1984 featured an egg and bacon sad face. Its subject was cholesterol, the vital yet dangerous yellowish substance in the bloodstream directly affected by the richness of the diet. The cover was based on the outcome of a 10 year and $150 million USD study, which had a profound impact on how we eat and watch our diets. All the media attention had a big negative impact on egg consumption patterns.
By 1999, the tide had begun to turn. TIME magazine ran as the lead story research on how saturated fats, and not cholesterol, could be a bigger threat to your health. The cover was a direct response to their own 1984 egg story. Last year, researchers from China found that people who ate an average of one egg per day had lower rates of heart disease and an even lower risk of having a bleeding stroke than people who did not consume eggs (Qin et al., 2018). More recently, another study has raised questions about the health benefits of eggs. Zhong et al (2019) published a study in JAMA (Journal of the American Medical Association) that showed a higher consumption of the dietary cholesterol of eggs was significantly associated with a higher risk of incident cardiovascular disease and all-cause mortality in a dose-response manner.
What to believe?
The important thing to remember, as with any type of research, correlation does not always mean causation. Clearly, the research on eggs is contradictory. We can say that conclusions about eggs based on available scientific evidence vary widely, partly because large scale nutrition research is hard to conduct accurately. Dr. Zhong stated in March 2019 in TIME magazine, “the existing literature is still controversial and inconclusive for nutrition experts and researchers to conclude the safety of eggs.” Some researchers have suggested that links between egg consumption and health problems can largely be explained by lifestyle. Heavy egg eaters are also more likely to eat foods that are unhealthy for the heart and less likely to exercise regularly.
There are a few key facts about eggs we know to be true:
- Eggs are a good sources of inexpensive, high quality protein for people of all ages
- They are rich in many important nutrients, including all essential amino acids, choline, B vitamins, vitamin A, and iron
- Egg are low in carbohydrates, and contain about 12 grams of protein and lipids per 100 gram, most of which are monounsaturated
As the existing research is so contradictory, each person must decide for themselves their preferred egg consumption. The only thing clear is that times have changed, but the nutrition of an egg stays the same!
Guter, M.M. and Low, E.M. (2008), ‘‘The British Egg Marketing Board 1957-71 – a reassessment’’, Journal of Agricultural Economics, Vol. 22 No. 3, pp. 247-65.
Kannel, W.B., Castelli, W.P. and McNamara, P.M. (1969), ‘‘Serum lipid fractions and risk of coronary heart disease. The Framingham Study’’, Minnesota Medicine, Vol. 52 No. 8, pp. 1225-30.
Qin C, Lv J, Guo Y, et al. Associations of egg consumption with cardiovascular disease in a cohort study of 0.5 million Chinese adults. Heart 2018;104:1756–1763
Ruxton, C.H.S., Derbyshire, E., Gibson, S., (2010) The nutritional properties and health benefits of eggs, Nutrition & Food Science, Vol. 40 No. 3, 2010, pp. 263-279
Zhong, V.W., Van Horn, L., Cornelis, M.C., Wilkins, J.T. (2019) associations of Dietary Cholesterol or Egg Consumption With Incident Cardiovascular Disease and Mortality. JAMA. 2019; 321(11):1081-1095. doi:10.1001/jama.2019.1572