For decades, we’ve been advised to limit egg consumption to reduce our risk of developing heart disease. The reasoning for this is based on the diet-heart hypothesis, which argues eating foods rich in cholesterol and saturated fat increases risk of developing heart disease. Specifically applied to eggs, the argument states: 1) eggs are rich in cholesterol; 2) eating cholesterol has been shown, in some studies, to increase serum cholesterol; 3) high serum cholesterol promotes heart disease. Using this logic, populations with increased egg consumption should have increased rates of heart disease.
First, let’s address the issue of egg consumption and cholesterol. Does eating eggs, which are high in cholesterol, increase serum cholesterol?
One experimental feeding study found a modest increase in serum cholesterol (1-3%) from eating one additional egg per day. However, larger studies found conflicting results.
The Framingham Heart Study compared cholesterol levels of individuals eating the most and least eggs. When comparing the men with highest egg consumption to those with the lowest, there was no difference in serum cholesterol. Women eating the most eggs actually had slightly lower cholesterol than women eating the least eggs.
Similarly, the Multiple Risk Factor Intervention Trial found that individuals with cholesterol lower than 200 ate more eggs than individuals with cholesterol greater than 220.
Once again, the Third National Health and Nutrition Examination Survey of more than 20,000 participants found that participants eating less than one egg per week had higher serum cholesterol than participants eating more than four eggs per week.
Thus, the hypothesis that egg consumption actually increases serum cholesterol is, at best, tenuous. The more important question is does egg consumption actually affect heart disease risk?
A study of 26,000 California Seventh-Day Adventists found no increase in coronary heart events in participants eating the most eggs versus those eating the least. A study of 5,000 Finish men and women found no effect of egg consumption on death rate from coronary heart disease. The Fakuoka Heart Study examined 660 heart attack patients and found no association between egg consumption and heart attack risk. An Italian case-controlled study found no effect of egg consumption on heart attack risk.
The best study to specifically examine the relationship between egg consumption and coronary heart disease followed 117,000 men and women for 8-14 years, tracking their egg consumption and health outcomes. Compared to those eating less than one egg per week, individuals eating more than seven eggs per week had no increase in coronary heart disease.
Finally, one study examined the relationship between egg consumption and stroke in 37,000 Japanese men and women. Surprisingly, those with daily egg consumption had a 30% reduced rate of stroke compared to individuals who never ate eggs.
In summary, the data does not indicate eggs have a negative impact on heart health. After a long campaign against egg consumption, the American Heart Association gave up the fight in 2000. They still promote limiting cholesterol to less than 300 mg/day (eggs have about 280 mg), but no longer specifically warn against egg consumption.
After looking at the data, I was surprised by the complete lack of association between egg consumption and heart disease. Eggs are exactly the type of food (high in cholesterol and saturated fat) we’ve been told not to eat for decades. Perhaps it’s time to re-evaluate the validity of the diet-heart hypothesis and examine alternative hypotheses that incorporate this new data.
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