A Fatty Acid May Help
Your Body Burn Fat
ACHES & CLAIMS
By LAURA JOHANNES
September 9, 2008; Page D2
Can a fat help you lose weight? Conjugated linoleic acid, or CLA, is a fatty acid that is sold in capsule form and is now also being added to foods. Companies that sell CLA say daily consumption can help your body burn fat and boost your muscle mass. A number of clinical studies support that claim, but some scientists say more research is needed.
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CLA is a fat found naturally in small quantities in foods such as milk and beef. The recommended daily dose, about three grams a day, contains about 27 calories, but companies that sell CLA supplements say its antifat activity outweighs the calories.
In the laboratory, scientists found that CLA inhibits enzymes that promote fat storage, while boosting action of enzymes that break down fat. Mice lost impressive amounts of weight on CLA. Dozens of human studies -- mostly small and often funded by manufacturers -- have had varied results.
"I'm personally still a skeptic to whether it has an impact," says F. Xavier Pi-Sunyer, director of the New York Obesity Research Center at St. Luke's-Roosevelt Hospital Center. "I don't see that there are any really good convincing studies."
Last year, a meta-analysis concluded that 3.2 grams a day of CLA "produces a modest loss in body fat." The analysis, published in the American Journal of Clinical Nutrition, pooled results from 18 studies to conclude that subjects taking CLA lost an average of two-tenths of a pound of fat a week more than those taking a placebo.
"It's not a wonder drug to make fat melt away from the body in a few weeks and drop 10 dress sizes," says study author Leah D. Whigham, a scientist at the University of Wisconsin in Madison. "What it is doing is resulting in a fat loss over time."
(The University of Wisconsin has researched the basic science behind CLA for years and owns intellectual property licensed by dietary-supplement makers. The Wisconsin Alumni Research Foundation, a nonprofit that handles patents for the university, receives royalties when CLA supplements are sold.)
As a dietary supplement, CLA is sold under dozens of names, the active ingredients of which are mostly supplied by either Germany's Cognis GmbH, which calls its formulation Tonalin, or the Lipid Nutrition unit of Malaysia's IOI Corp., whose ingredient is called Clarinol. A month's supply of capsules typically costs $15 to $20, sometimes more. Both Cognis and Lipid Nutrition say they are negotiating with companies in the U.S. to add their CLA formulations to foods such as milk and yogurt. CLA-fortified milk is sold in some countries, such as Spain and Saudi Arabia.
Don't expect the scale to drop dramatically: When researchers measure weight loss instead of fat loss, CLA often shows no significant effect. The reason is unknown, but Dr. Whigham believes people taking CLA gain some muscle to make up for the fat loss, resulting in a very small total weight loss that is hard to prove in small studies.
CLA pills can occasionally cause nausea, but Cognis says that can be prevented by taking it with food. So far few serious side effects have been found in humans, though a mouse study found very high doses caused fat buildup in the liver. Ohio State University scientist Martha Belury, author of that study, says a human study of 6.4 grams daily found no signs of liver abnormalities, but she recommends limiting intake to about three grams a day until further research is done.
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