The long-awaited first results of human studies of a popular dietary supplement, conjugated linoleic acid (CLA), indicate that the supplement may help overweight adults to lose weight and fat, maintain weight loss, retain lean muscle mass and control adult-onset diabetes.
The findings, presented here this week at the 220th national meeting of the American Chemical Society, the world’s largest scientific society, could be good news for the 97 million American adults – 55 percent of the U.S. population – who are considered overweight or obese.
Overweight people who participated in two of the studies, one conducted in Norway and the other in the United States, experienced statistically significant reductions in body fat gain with no serious side effects. In another Norwegian study, people who took CLA lost statistically significant amounts of weight, without otherwise changing their diets.
Marketed online and in health food stores as a nutritional supplement, CLA is a naturally occurring fatty acid. Found in many dairy products and in beef, its biological activity has been studied intensively since it was discovered more than a decade ago. In animal studies, CLA has been found effective in fighting several types of cancer, atherosclerosis and diabetes; enhancing immune functioning and energy; and helping to control weight.
Eighty overweight people took part in the six-month U.S. study, conducted at the University of Wisconsin in Madison. The participants dieted and exercised and, as expected, most initially lost weight, according to Michael Pariza, Ph.D., director of the university’s Food Research Institute, and one of the lead researchers for the study. But, as often happens, many regained some of the weight lost when they stopped their diets, he said.
The people who did not take CLA put pounds back on at a ratio of 75 percent fat to 25 percent lean, which is typical for most people, points out Pariza. For the people taking CLA, less fat was regained and more muscle mass was retained. “The ratio was more like 50:50 – 50 percent fat and 50 percent muscle,” according to Pariza. “That is very significant. It leads to the idea that CLA could be useful in weight management,” he said. “Our results also showed that CLA made it easier for people to stay on their diets.”
The body fat mass gain of participants in the Norwegian study also was less for those taking CLA.
Another Norwegian study suggests that CLA could help people take off pounds as well as reduce body fat. The 60 overweight people who participated in the study were not allowed to diet, yet those who took CLA experienced a statistically significant weight loss. The researchers linked this to the supplement.
The average weight loss was equivalent to a 160-pound person losing two or three pounds over 12 weeks, according to Ola Gudmundsen, Ph.D., managing director of Scandinavian Clinical Research and one of the principal investigators. “That doesn’t sound like a lot, but it is statistically significant,” he said.
While he can’t say for sure that the subjects lost weight because they took CLA, Gudmundsen believes “there is an indication that it is.”
In the diabetes study, done at Purdue University in Indiana, 64 percent of volunteers taking CLA showed improvement in their insulin levels. The eight-week clinical trial involved 22 subjects.
Approximately 6 million Americans have type 2 diabetes, which is rising at an alarming rate, according to lead researcher Martha Belury, Ph.D. “It is of great benefit to find alternatives to pharmaceutical therapy that may aid in the delay and/or management of this disease,” says Belury.
Coupling CLA with pharmaceuticals could help reduce health care costs and the side effects of long-term drug use, according to Belury, who is now with Northwest Hospital in Seattle, Wash.