text: Health effects CLA is marketed in dietary supplement form for its supposed anti-cancer benefit (for which there is no strong evidence or known mechanism, and very few studies conducted so far) 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.
  Likewise, there is insufficient evidence that CLA has a useful benefit for overweight or obese people as it has no long-term effect on body composition. Although CLA has shown an effect on insulin response in diabetic rats, there is no evidence of this effect in humans.
  Dietary sources
  Food products from grass-fed ruminants (e.g. mutton and beef) are good sources of CLA and contain much more of it than those from grain-fed animals. Eggs from chickens that have been fed CLA are also rich in CLA, and CLA in egg yolks has been shown to survive the temperatures encountered during frying. Some mushrooms, such as Agaricus bisporus and Agaricus subrufescens, are rare non-animal sources of CLA.
  However, dietary punicic acid—which is abundant in pomegranate seeds—is converted to the CLA rumenic acid upon absorption in rats, suggesting that non-animal sources can still effectively provide dietary CLA.
  History
  In 1979 CLAs were found to inhibit chemically-induced cancer in mice  and research on its biological activity has continued.
  In 2008, the United States Food and Drug Administration categorized CLA as generally recognized as safe (GRAS).