Component in common dairy foods may cut diabetes risk

BOSTON — Scientists at the Harvard School of Public Health and collaborators from other institutions have identified a natural substance in dairy fat that substantially may reduce the risk of Type 2 diabetes. 

Reporting in the Dec. 21 issue of the Annals of Internal Medicine, investigators led by Dariush Mozaffarian, associate professor in the Department of Epidemiology at HSPH, explained that the compound trans-palmitoleic acid is a fatty acid found in milk, cheese, yogurt and butter that is not produced by the body.

The HSPH researchers examined 3,736 participants in the National Heart, Lung and Blood Institute-funded "Cardiovascular Health Study," who have been followed for 20 years in an observational study to evaluate risk factors for cardiovascular diseases in older adults. Such metabolic risk factors as blood-glucose and insulin levels, and levels of circulating blood fatty acids, including trans-palmitoleic acid, were measured using stored blood samples in 1992. Participants were followed for development of Type 2 diabetes.

At baseline, higher circulating levels of trans-palmitoleic acid were associated with healthier levels of blood cholesterol, inflammatory markers, insulin levels and insulin sensitivity after adjustment for other risk factors. During follow-up, individuals with higher circulating levels of trans-palmitoleic acid had a much lower risk of developing diabetes, with about a 60% lower risk among participants in the highest quintile of trans-palmitoleic acid levels, compared with individuals in the lowest quintile.

"This type of observational finding requires confirmation in additional observational studies and controlled trials, but the magnitude of this association is striking," Mozaffarian stated. "This represents an almost three-fold difference in risk of developing diabetes among individuals with the highest blood levels of this fatty acid."