CLA impact on diabetes control

Supplementing the diet with the fatty acid conjugated linoleic acid (CLA) may lead to better weight control and disease management in diabetics, a new study suggests.

Diabetics who added CLA to their diets had lower body mass as well as lower blood sugar levels by the end of the eight-week study, report researchers from Ohio State University in the US. Hyperglycaemia, or high blood sugar, is a hallmark of diabetes.

Researchers also found that higher levels of this fatty acid in the bloodstream led to lower levels of leptin, a hormone thought to regulate fat levels. Many scientists believe that high leptin levels may play a role in obesity, one of the biggest risk factors for adult-onset diabetes.

The research appears in the January issue of the Journal of Nutrition​.

"In previous work, we found that CLA delayed the onset of diabetes in rats,"​ said Martha Belury, the senior author of the study and an associate professor of human nutrition at Ohio State University. "In this study, we found that it also helped improve the management of adult-onset diabetes in humans."​

CLA is made up of various fatty acid isomers - compounds that share the same chemical formula but differ in chemical structure. Related isomers can have very different effects.

In the current study, the researchers found that one particular CLA isomer, t10c12-CLA ( the '10-12 isomer') helped control both body weight and leptin levels.

The researchers asked 21 people with adult-onset diabetes to take either a daily supplement containing a mix of rumenic acid and 10-12 isomer or a safflower oil supplement as a control, for the eight-week period. The group was divided roughly in half. Rumenic acid is the predominant isomer in foods that contain CLA, while the 10-12 isomer is less abundant. CLA can be found in foods such as beef, lamb and dairy products.

"Not only does it taste better, it's also safer and more beneficial to get the nutrients from food,"​ said Belury. "Besides, we don't yet know the long-term effects of taking CLA in supplement form."​

At the end of the trial, the researchers took blood samples from each participant to check CLA levels. By then, fasting blood glucose levels had decreased in nine of the 11 people taking the CLA supplement, but only in two of the 10 taking safflower supplements - a five-fold decrease in patients taking CLA, compared to patients taking the safflower oil.

The researchers also studied the impact each isomer had on changes in body weight and levels of the hormone leptin. They found that the 10-12 isomer, and not rumenic acid, reduced body weight and leptin levels.

There was only a small average weight loss among patients taking CLA supplements (about 3.5 pounds), although they had been asked to not change their normal caloric intake during the study. The group taking safflower supplements neither lost nor gained weight. Leptin levels decreased in the CLA group, and rose slightly in the safflower group.

"The effect of the 10-12 isomer on reducing body mass and leptin levels was key,"​ Belury said, adding that other researchers have shown the 10-12 isomer to be helpful in reducing body mass in animals.

"The amount of CLA, how long it's taken and the type taken all impact the fatty acid's ability to affect obesity in humans, and therefore help manage diabetes,"​ Belury said.

A 2002 study conducted by the Diabetes Prevention Program Research Group found that a modest reduction in body weight resulted in a 58 per cent reduction in the incidence of diabetes in a group of people at high risk for developing the disease.

The research received support from US companies Pharmanutrients and Natural.