March 11, 2016

Evidence Doesn't Back Eggs Causing Diabetes

The incredible edible egg is simple, yet it's attracted more vilification, and praise, than almost any other food. Recently, some have suggested that eggs are linked to risk of type 2 diabetes. Last month a meta-analysis sought to clarify that relationship.

Eggs are valuable because they are a cheap and reliable source of high quality protein (a complete protein), but they have also been suspected of increasing atherogenic cholesterol, lipoproteins, and ultimately, cardiovascular risk. But, the new 2015 dietary nutritional guidelines appropriately removed the dietary cholesterol restriction; the evidence just didn't support the adverse effects like elevated serum cholesterol.

The authors of the meta-analysis, led by Luc Djousse, DSc, MD, at the Harvard Clinical and Translational Science Center, used data from 12 prospective cohorts (eight of them unique) that evaluated the associated risk of egg consumption and risk of developing type 2 diabetes over a range of 5 to 20 years of follow-up. Seven of the studies were from the U.S., two from Japan, one from Finland, one from Spain, and one from France. These studies used self-reported data to organize egg consumption and compare highest category with lowest categories. There were nearly 220,000 subjects with almost 9,000 cases of diabetes in these cohorts.

The bottom line of what they found was that ingestion of fewer than four eggs per week was not associated with a statistically significant increased risk of diabetes, but when looking only at data from the U.S., there was a relative risk (RR) of 1.39 for intake of ≥ three eggs per week. The relative risk in the other countries was a nonsignificant 0.89. This is where the weakness of the study shows and there was no tracking of other foods consumed with the eggs like bacon, sausage, etc.

These results are similar to a meta-analysis in 2013 that showed similar risk of diabetes when comparing one egg daily to those who had never eaten eggs. That same meta-analysis did not show a relationship between eggs and cardiovascular disease, ischemic heart disease, stroke, or mortality. It did, however, show increased risk of cardiovascular morbidity in those with diabetes. That finding was consistent with another meta-analysis looking at similar data thus supporting the notion that whole eggs may best be limited in those at risk of or with type two diabetes.

The authors also noted that there is a lack of association between dietary cholesterol and type 2 diabetes in the literature and cited one trial in patients with type 2 diabetes or impaired glucose tolerance that showed weight loss and improved glycemic measures with high protein diets, including cholesterol from two eggs daily.

For years, there have been many people and organizations that have tried to vilify eggs. But the data simply don't agree with them. Eggs are a nutrient-packed food that seems to have little to no negative effects and even beneficial effects at low doses.

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