乌鸦传媒

The incredible edible egg is simple, yet it's attracted more vilification -- and praise -- than almost any other food.

And recently, some have suggested that eggs are linked to risk of type 2 diabetes; last month sought to clarify that relationship.

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

But what about eggs and type 2 diabetes?

The authors of the meta-analysis, led by , 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 RR in the other countries was a nonsignificant 0.89.

These results are similar to 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 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 noted and questioned the obvious difference between studies outside of the U.S. and cohorts within the U.S. Could this be due to other dietary factors and ? It was suggested that perhaps the usual companion foods with eggs in the U.S. include processed meats like sausage and bacon. They also noted that there is a lack of association between dietary cholesterol and type 2 diabetes in the literature and 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.

While it's fun to search for single foods and nutrients to blame a disease on, let us not forget that a much stronger influence on type two diabetes is abdominal obesity. Type 2 diabetes is very strongly associated with the and degree of , with known pathophysiology driving that relationship. As mentioned above, overall dietary patterns are crucial -- along with in relationship to risk of type 2 diabetes. As obesity is the foundation for development of type 2 diabetes along with the complexities of genetics and other environmental factors, sometimes slight nuances in diet are splitting hairs within the bigger picture.

What should we tell our patients?

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

We are very athletic and admit our personal biases towards higher protein foods like eggs, but we believe the data show that eggs can be a healthy part of our patients' diets. There may be some reason to limit eggs in those with established diabetes, but an egg or two a few times a week, or even daily, is likely not harmful, and it's possibly even beneficial when part of an overall quality diet and exercise routine.

, is board-certified in endocrinology and in internal and obesity medicine. , is a primary care physician board-certified in family and obesity medicine. Both have patient-facing blogs, at and .

Comment