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Eggs, cholesterol, and cardiovascular disease

By Casey Thaler, B.A., NASM-CPT, FNS
July 26, 2020
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Eggs are loaded with high quality protein, as well as rich in copper, iron, zinc, vitamin D, and many B vitamins. Additionally, they are low in carbs and, if you buy the right kind, high in beneficial omega-3 fatty acids. At some point, however—whether because of popular media’s simplistic take on nutrition or the influence of some other marketing scheme—eggs acquired a poor reputation. In fact, for a period, the general opinion of eggs seemed to be that they were one of the unhealthiest foods you could consume.

This negative link was based on the theory that dietary cholesterol could lead to terrible health outcomes. Starting with the hypotheses of American physiologist Ancel Keys in the mid-twentieth century, Americans were told they should avoid saturated fat and cholesterol. In turn, and in simplistic terms, rates of obesity, heart disease, and other diseases skyrocketed to previously unseen levels.

Case in point: It was recently announced that the obesity rate in the United States had reached 40 percent. Almost half of Americans are not just overweight, they’re obese. Sad and staggering, this fact contradicts the idea that saturated fat and cholesterol are the sole cause of the many health problems seen in this country.

So, what does the research say about dietary cholesterol and disease? Are eggs really a cause of many of our health woes?

Overall, the pattern points to eggs improving health, not worsening it.

There have been several epidemiological studies showing higher all-cause mortality rates in those who eat the greatest number of eggs per week. But correlation is not cause, and when you dig deeper into these studies, it becomes clear that in the United States, the people with the highest egg consumption also tend to eat the least healthy diets, in general.

To that end, a fairly recent prospective correlational study from Harvard University showed that dietary cholesterol may have an impact on cardiovascular disease. In the study, for every additional 300 mg of dietary cholesterol eaten per day, the risk of CVD and all-cause mortality was higher by 17 percent and 18 percent, respectively. However, these associations became nonsignificant, after adjustment for consumption of eggs and red meat. Likewise, the association between egg consumption and CVD also became nonsignificant after total dietary cholesterol was accounted for. To the study’s credit, it did control for diet quality.

Nevertheless, for every recent study showing a health risk associated with egg consumption, there are many showing either no risk or even health benefits. A 2020 study published in The Journal of the American Heart Association found no association between eggs and mortality. Another published in the European Journal of Nutrition, by Zamora-Ros, et al., found a mild beneficial correlation with egg consumption.

Overall, the pattern points to eggs improving health, not worsening it. Take the following study, which concluded: “People with prediabetes or type-2 diabetes, who consumed a three-month, high-egg, weight-loss diet with a six-month follow-up exhibited no adverse changes in cardiometabolic markers compared with those who consumed a low-egg weight-loss diet. A healthy diet based on population guidelines and including more eggs than currently recommended by some countries may be safely consumed.”

Another scientific study concluded that: “Eating one egg daily is not associated with an increase in CVD or all-cause mortality. The small observed reduction in stroke risk needs to be confirmed. Our findings support current guidelines recommending eggs as part of a healthy diet and should be considered in other dietary recommendations.”

A further study concluded that: “results from these two randomized controlled acute feeding studies indicate that dietary cholesterol contained in whole egg is not well absorbed and does not increase plasma total cholesterol concentration. These findings provide a mechanism to help explain why dietary cholesterol intake may not affect long-term plasma total cholesterol control.” The researchers of this study put this conclusion in the title of the paper.

Sadly, while the scientific data is clear, the misinformation persists. As is often the case for nutrition science news, a misinterpretation of the data leads to a misunderstanding of the conclusions that can be drawn from it.

Ultimately, the key to preventing CVD—as many of the above studies illustrate—is balance. You need to consume a well-rounded diet—rich with vegetables, healthy proteins, good fats—and stay away from refined foods and sugars. In this context, moderate egg consumption is beneficial. No matter how many eggs you consume per week, if you are drinking alcohol, smoking, eating low-quality meats, and consuming too much sugar, you are greatly increasing your odds of developing any disease—not just cardiovascular disease.

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