What does Conjugated Linoleic Acid do?

Conjugated linoleic acid (CLA) is a slightly altered form of the essential fatty acid linoleic acid.

Preliminary animal and test tube research suggests that CLA might reduce the risk of cancers at several sites, including breast, prostate, colorectal, lung, skin, and stomach.^{1 2 3 4} Whether CLA will have a similar protective effect for people has yet to be demonstrated in human research.

In a double-blind study, volunteers participating in an exercise program received 600 mg of CLA or a placebo three times per day for 12 weeks. Compared with placebo, CLA significantly reduced percent body fat, but did not significantly reduce body weight.⁵ In a double-blind study of obese men, supplementation with 4.2 grams of CLA per day for four weeks produced a small but statistically significant reduction in waist size. However, compared with the placebo, CLA did not promote weight loss.⁶ At present, there is not sufficient evidence to support the use of CLA as a treatment for obesity.

Animal research suggests an effect of CLA supplementation on reducing body fat.^{7 8} Limited controlled human research found 5.6-7.2 grams per day of CLA produced nonsignificant gains in muscle size and strength in experienced⁹ and inexperienced¹⁰ weight-training men.

Animal research also suggests an effect of CLA supplementation on limiting food allergy reactions,¹¹ preventing atherosclerosis,^{12 13} and improving glucose tolerance.¹⁴ As with the cancer research, the effects of CLA on these conditions in humans remains unclear.