Early research on conjugated linoleic acid (CLA) showed that it destroyed fat cells in mice -- a finding that has made the compound an increasingly popular weight loss supplement. CLA is a modified form of linoleic acid, an omega-6 fatty acid essential for nutrition. It's most abundant in milk, cheese, lamb and beef, but the CLA in most supplements comes from vegetable oils, such as sunflower oil. Most diets provide no more than a gram of CLA per day.
Uses: CLA is used in efforts to prevent cancer, lower cholesterol and lose weight.
Dose: Usually, about 3 grams a day. Research suggests that taking higher doses (seven or more grams a day) doesn't provide any additional benefit.
Precautions: Researchers recently examined CLA's long-term safety, and the supplement doesn't appear to cause any adverse effects -- except for a bit of stomach upset. It may, however, increase the risk of insulin resistance (resulting in increased blood sugar levels) in overweight people.
Research: A large body of test-tube and animal research suggests that CLA supplements can decrease body fat and hamper the growth of colon, breast, prostate and other types of tumors. Human studies, however, have been less conclusive. The supplement doesn't appear to improve cholesterol levels. A recent large-scale study published in the Journal of Nutrition showed that taking 3.4 grams of CLA a day for two years led to a small but significant decrease in body fat in overweight people. But studies have also shown that CLA appears to increase muscle mass. CLA doesn't appear to have an effect on body fat in people of average weight.
Dietary supplement makers are not required by the U.S. government to demonstrate that their products are safe or effective. Ask your healthcare provider for advice on selecting a brand.
-- Elena Conis