New research suggests that whole-fat dairy products -- generally shunned by health experts -- contain a fatty acid that may lower the risk of type 2 diabetes.

The fatty acid is called trans-palmitoleic acid, according to the study in the Dec. 21 issue of the Annals of Internal Medicine, and people with the highest blood levels of this fatty acid reduce their odds of diabetes by 62 percent compared to those with the lowest blood levels of it.

In addition, "people who had higher levels of this fatty acid had better cholesterol and triglyceride levels, lower insulin resistance and lower levels of inflammatory markers," said study author Dr.

Dariush Mozaffarian, co-director of the program in cardiovascular epidemiology at Brigham and Women's Hospital and Harvard School of Public Health.

Circulating palmitoleic acid is found naturally in the human body. It's also found in small quantities in dairy foods. When it's found in sources outside the human body, it's referred to as trans-palmitoleic acid. Whole milk has more trans-palmitoleic acid than 2 percent milk, and 2 percent milk has more of this fatty acid than does skim milk.

"The amount of trans-palmitoleic acid is proportional to the amount of dairy fat," said Mozaffarian.

Animal studies of the naturally occurring palmitoleic acid have previously shown that it can protect against insulin resistance and diabetes, said Mozaffarian. In humans, research has suggested that greater dairy consumption is associated with a lower diabetes risk.

However, the reason for this association hasn't been clear.

To assess whether this overlooked and relatively rare fatty acid might contribute to dairy's apparent protective effect, the researchers reviewed data from over 3,700 adults enrolled in the Cardiovascular Health Study.

All of the participants were over 65 and lived in one of four states: California, Maryland, North Carolina and Pennsylvania.(HealthDay News)