Supplements containing the dietary fat conjugated linoleic acid (CLA) may help overweight kids curb the amount of fat they gain over time, a small study suggests.

Researchers found that overweight and obese children who took the CLA supplement for seven months showed less fat accumulation than a comparison group of children given a placebo.

However, children on the supplement also showed a dip in their blood levels of “good” HDL cholesterol and a lesser gain in bone mass over time.

The findings suggest that while CLA might help slow body fat gain, its overall safety and effectiveness for children needs to be studied further, the researchers note in the American Journal of Clinical Nutrition.

CLA is an unsaturated fatty acid found in beef, lamb and dairy products; the CLA in supplements is generally derived from vegetable oils that are rich in linoleic acids.

Animal research has found that CLA can help melt away body fat, and some studies have suggested the same may hold true in humans. One recent study, for example, found that obese women with diabetes shed a couple pounds of body fat, on average, after taking CLA for four months.

Lab research on the fatty acid has suggested that it may be particularly effective at preventing fat accumulation in young animals. But the effects on overweight children have been largely unknown.

For the current study, researchers led by Natalie M. Racine of the University of Wisconsin-Madison recruited 62 overweight or obese children between the ages of 6 and 10. They randomly assigned the children to take either a CLA or placebo mixture - both chocolate- flavored and added to milk - once a day for seven months.

The CLA supplement, marketed as Clarinol, was provided by Netherlands-based manufacturer Lipid Nutrition BV, which also partially funded the study.

After seven months, the researchers found, children on the CLA supplement showed a small dip, on average, in the percentage of their total body weight that was fat - as measured by X-ray. Children in the placebo group showed a gain, of 1.3 percent versus a decline of 0.5 percent in the CLA group.

When it came to overall body mass index (BMI) - a measure of weight in relation to height - children on CLA had a smaller gain than those on the placebo. However, the gains in both groups were still higher than what would be expected for the typical child in the same age group, the researchers note.

Children on the CLA supplement also showed a reduction in heart-healthy HDL cholesterol - by five points, on average - and a smaller rate of bone mass accumulation.

The effects on HDL are similar to what’s been seen in some studies of adults, Racine and her colleagues write, but the bone mass findings are “surprising” and have not been seen before.

They recommend that any future studies of CLA in children monitor bone density changes, as well as the overall safety of the supplement.

Two co-researchers on the study are employees of Lipid Nutrition, and another was named on a use patent application the company submitted for CLA.

SOURCE: American Journal of Clinical Nutrition, online March 3, 2010.