Writing in the Annals of Internal Medicine, the scientists examined data from a study that followed 3,736 adults from 1992 to 2006.
They found that those adults with the highest circulating levels of trans-palmitoleic acid – the fatty acid found in dairy – were exposed to the lowest risk of diabetes.
The 20 per cent with the highest trans-palmitoleic acid levels were found to have a 60 per cent lower risk of developing diabetes compared to the people at the bottom 20 per cent of the sample.
Lead author Dariush Mozaffarian said: “This represents an almost three-fold difference in risk of developing diabetes among individuals with the highest blood levels of this fatty acid.”
Mozaffarian described the magnitude of the findings as “striking” but added that the study should be followed up with more observational studies and controlled trials to confirm any initial conclusions.
However, the scientist suggested that the positive effect that trans-palmitoleic acid appears to have on diabetes risk may not be that surprising.
He said: “We wonder whether this naturally occurring trans fatty acid in dairy fats may partly mimic the normal biologic role of its cis counterpart, cis-palmitoleic acid, a fatty acid that is produced in the body. In animal experiments, cis-palmitoleic acid protects against diabetes.”
Deepa Khatri, clinical advisor at Diabetes UK, called for more research and advised caution when interpreting the study results.
“People should not take the findings of this research as a reason to exceed the recommended portion amounts of dairy food in order to prevent their risk of developing Type 2 diabetes. Milk and dairy foods can be high in fat, which if eaten in excess can contribute to weight gain.”
Funding for the research was provided by National Heart, Lung, and Blood Institute and the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health.
Source: Annals of Internal Medicine
Trans-Palmitoleic Acid, Metabolic Risk Factors, and New-Onset Diabetes in U.S. Adults
Authors: Dariush Mozaffarian, Haiming Cao, Irena King, Rozenn Lemaitre, Xiaoling Song, David Siscovick, Gokhan Hotamisligil