Conjugated linoleic acid (CLA) is a type of fat found mostly in meat and dairy products derived from ruminants. CLA is marketed as a dietary supplement on the basis of its supposed health benefits, including reducing body fat deposits and improving immune function. Most CLA supplements are made from safflower oil, which is high in linoleic acid. The average diet supplies 15-174 mg of CLA daily, and people commonly take CLA by mouth for weight loss and bodybuilding. However, there is limited scientific evidence to support these uses.

CLA supplements are generally well-tolerated, but some people report digestive problems such as nausea, vomiting, diarrhea, constipation, stomach pains, and indigestion. CLA supplements have also been associated with some health risks, including increased inflammation and increased accumulation of fat in the liver, which is a stepping stone towards metabolic syndrome and diabetes.

It is important to note that the CLA found in supplements is different from the CLA found naturally in foods, and supplements do not provide the same health effects as CLA from foods. The main dietary sources of CLA are dairy and meat from cows, goats, and sheep. While CLA seems to be safe, researchers disagree about its benefits for health, and more research is needed before CLA supplements can be considered a proven cancer fighter or weight loss aid.