The first results of human studies of human testing of a popular dietary supplement called conjugated linoleic acid suggest that the supplement can help people lose weight and fat and maintain weight loss and lean muscle mass.

"It appears CLA works to aid leanness in several ways: It keeps little fat cells from getting big, it encourages formation of muscle and it enhances the oxidation of fat cells," said Michael Pariza, a professor and director of the Food Research Institute at the University of Wisconsin-Madison.

Pariza presented results from his studies Sunday at the national meeting of the American Chemical Society here. He is one of more than 20 researchers presenting results from human and animal studies of CLA during the conference.

Although it is sold widely as a nutritional supplement, CLA has undergone few studies for effectiveness in humans until recently. In animal studies, it has been found effective in fighting several types of cancer, arterial disease and diabetes, enhancing immune function and helping to control weight.

Eighty overweight people participated in the six-month Wisconsin study, dieting and exercising as well as taking the supplement capsules. As expected, they lost weight, an average of 5 pounds.

But then, when they stopped their diets and workouts, the participants mostly regained the weight they'd lost.

There was a marked difference in how the pounds returned among the two groups, however. Those not taking CLA regained 75 percent fat and 25 percent lean; but those getting the supplement got back about 55 percent fat, the rest lean muscle.

"This is a big difference, much more like what happens when people are doing muscle-building exercises," Pariza said.

"This really leads to the idea that CLA could be useful in weight management. Our results also showed that CLA made it easier for people to stay on their diets," the researcher said.

Similar weight loss and shifts in body makeup were reported in a similar Norwegian study.

CLA is found mainly in dairy products and beef, poultry, eggs and corn oil as a naturally occurring fatty acid. The amount of the substance in foods is so small, however, that supplements appear to be the only way to boost intake, and researchers are unsure how much represents an optimal dose.

While some studies have found the supplement caused stomach upset, no adverse effects were noted in people taking CLA in the studies reported to the chemical society.

A second study in Norway among 60 subjects found they were able to lose weight with CLA even when they were forbidden from dieting. The average weight loss was equal to a 160-pound person losing 2 to 3 pounds over 12 weeks, "which doesn't sound like a lot but is statistically significant," said Ola Gudmundsen, managing director of Scandinavian Clinical Research and a principal investigator for the study.

In another human study, done on 22 volunteers at Purdue University in Indiana, 64 percent of patients with insulin-resistant diabetes showed improvement in their insulin levels over an eight-week test. Insulin levels in people with this type of diabetes are often excessive as the body tries to overcome its inability to process glucose.

Some 6 million American have type 2 diabetes, and the numbers are rising.

"It is of great benefit to find alternatives to pharmaceutical therapy that may aid in the delay or management of this disease," said lead researcher Martha Belury, now at Northwest Hospital in Seattle
　　
　　
　　(From HealthWorld Online)