Conjugated linoleic acids (CLA) (brand name Tonalin) are a family of at least 28 isomers of linoleic acid found mostly in the meat and dairy products derived from ruminants. CLAs can be either cis- or trans-fats and the double bonds of CLAs are conjugated and separated by a single bond between them.

CLA is marketed as a dietary supplement on the basis of its supposed health benefits.There is, however, no convincing evidence that taking CLA supplements has any benefits for human health.

History
The biological activity of CLA was noted by researchers in 1979 who found it to inhibit chemically-induced cancer in mice. In 2004, one of those researchers noted that the scientific literature was "growing at a phenomenal rate".

The United States Food and Drug Administration categorizes CLA as generally recognized as safe (GRAS) status for certain food categories, including fluid milk, yogurt, meal replacement shakes, nutritional bars, fruit juices and soy milk.[citation needed] With GRAS status, food companies are able to add CLA to products in these food categories.

Health
CLA is marketed in dietary supplement form for its supposed anti-cancer benefit (for which there is no evidence) and as a bodybuilding aid.A 2004 review of the evidence said that while CLA seemed to benefit animals, there was a lack of good evidence of human health benefits, despite the many claims made for it.

CLA has no useful benefit for overweight or obese people as it has no long-term effect on body composition.


CLA has shown an effect on insulin response in diabetic rats but there is no evidence of this effect in humans.