Products containing CLA, or conjugated linoleic acid, line supplement store shelves boasting fat-burning and metabolism-boosting power. Many of their labels also claim that CLA is scientifically proven for weight management and, in a sense, that's true. There are studies that support claims that the ingredient CLA, an omega-6 fatty acid found in beef and dairy products, can reduce fat mass in the body and even build lean muscle.
But that's not the end of the story. Products containing CLA are still unlikely to do you much good because the CLA in supplements don't come from the animal sources shown to produce the health benefits.
"CLA is related to the omega-6 fatty acids that help increase metabolic rates, keep cholesterol levels normal, and boost the immune system, according to animal studies," says Dr. Pam Peeke, assistant professor of medicine at the University of Maryland and author of The Hunger Fix. "However, the CLA found in supplements are not from natural sources, so the effects are small."
The CLA in supplement products is derived from safflowers, and evidence to support CLA's benefits from supplement forms are less impressive than CLA from grass-fed animals, with mixed results in humans. In addition, CLA supplements on their own — rather than consumed in whole foods — likely lack the additional vitamins and minerals such as calcium, magnesium, potassium, omega-3s, vaccenic acid that transforms into CLA, beta-carotene, and Vitamin E.
Another problem with the pill is the side effects that concentrated CLA can have for some people, who can experience breakouts, headaches, and nausea. They might also have a negative effect on cholesterol levels, according to the National Institutes of Health, but study results on this point have also been inconsistent. CLA can also cause blood pressure to drop too much if you're taking a medication for blood pressure levels.
CLA in "sports chews" form are particularly useless. "Sport chews are only good for refueling while working out for 75 minutes or longer to keep energy levels steady," Peeke says. "The CLA in these chews are less than those in pills and capsules, and you can go natural with gumdrops or fig bars for the same effect with fewer calories and carbs."