Does Egg Consumption Damage Your Arteries?

The authors of a recent study testing the impact of egg consumption on flow mediated dilation (FMD) and blood lipids conclude: “To date, the evidence generally mitigates against an association between moderate egg consumption and increased cardiac risk.”¹ The problem with that conclusion is that it appears more in line with what the primary funder of the study wanted than what the data actually showed. The study was funded by the Egg Nutrition Center (ENC), which is part of the American Egg Board. However, such a conclusion appears unwarranted based on the authors own data as well as the bulk of earlier research.

The authors of a recent study testing the impact of egg consumption on flow mediated dilation (FMD) and blood lipids conclude: “To date, the evidence generally mitigates against an association between moderate egg consumption and increased cardiac risk.”¹ The problem with that conclusion is that it appears more in line with what the primary funder of the study wanted than what the data actually showed. The study was funded by the Egg Nutrition Center (ENC), which is part of the American Egg Board. However, such a conclusion appears unwarranted based on the authors own data as well as the bulk of earlier research.This study consisted of 2 clinical trials with 40 middle aged and older subjects who had elevated serum cholesterol levels and/or low HDL-cholesterol levels. The first study examined the impact on FMD following a single breakfast meal consisting of either 3 hard boiled eggs or a cheese and sausage meal with far more calories (189 vs. 310), more than twice as much fat (13 vs 29g) and three times as much saturated fat (12 vs 4) and nearly 4 times as much sodium (185 vs 720mg) as the egg meal. Earlier studies have shown high-fat meals impair FMD. A reduction in FMD is associated with damage to the artery wall and an increased risk of coronary heart disease. While neither the egg or cheese and sausage meal in this study showed a reduction in FMD the authors noted that this may have been the result of poor timing on their part. No doubt but given that the impact of the 3 egg meal was the same as the sausage and cheese meal, which should have reduced FMD based on earlier studies this can hardly be viewed as evidence that eggs do not damage arteries.The second part of this study had the subjects consume either 2 eggs or a cholesterol-free egg substitute for 4 weeks in a crossover design in which those measuring blood lipids and FMD were unaware of which group the subjects were in. In this sustained phase of the study the subjects consuming the egg substitute experienced a significantly greater drop in LDL-Cholesterol (LDL-C) level. By contrast, those consuming the 2 whole eggs daily experienced no significant change in their LDL-C level - suggesting that their normal baseline breakfast must have also been pretty high in saturated fat and/or cholesterol. The fact that LDL-C dropped 8% when the egg substitute was consumed and remained basically unchanged with the egg meal is consistent with most previous studies that show dietary cholesterol raises LDL-C. Long-term epidemiological studies show an 8% higher LDL-C seen in the whole egg compared to egg substitute group after 4 weeks would be expected to lead to at least a 20% increased risk of heart attacks over several decades.In addition this second part of this study also measured the change in FMD at baseline after an overnight fast and then again after consuming either the egg substitute or the 2 whole eggs daily for 4 weeks. The data showed a significant improvement in FMD (5.8 to 6.9%) when the subjects consumed the egg substitute for 4 weeks compared to their usual diet. By contrast, the subjects showed a small but not statistically significant worsening of FMD (5.6 to 5.3%) after consuming the two whole eggs daily for 4 weeks. Clearly the data from this study show that reducing whole egg and cholesterol intake results in a significantly lower LDL-C level and also improved FMD after just 4 weeks. Given the known association between increased atherosclerotic events in people with elevated LDL-C levels and/or impaired FMD, the results of this study suggest that people interested in reducing their risk of coronary heart disease ought to reduce their consumption of dietary cholesterol from whole eggs.Bottom Line:The authors of this study concluded: “Egg consumption was found to be non-detrimental to endothelial function and serum lipids in hyperlipidemic adults, while egg substitute consumption was beneficial.” That is quite a stretch. It appears that the authors were more interested in spinning their results to please their sponsor (the ENC) than they were in drawing the logically more correct conclusion.References:1. Nutrition Journal 2010;9:28By James J. Kenney, PhD, RD, FACN.