Conjugated linoleic acids (CLA) are a group of specific trans fatty acids that differ from other trans fatty acids because of their shape and their properties. Some of them are synthetic in origin (supplements), others are found in industrial products, and most of them originate naturally. Just as you should not confuse trans fatty acids of natural origin with trans fatty acids of industrial origin (because of their different effects on health), you cannot put all CLAs in the same basket. Although studies (in test tubes and in animals) suggest that the main CLA in milk – rumenic acid – could have beneficial effects by reducing the risk of some illnesses, the consumption at high doses of certain other CLAs (mostly of synthetic origin) could be toxic. Intake of CLAs in the form of supplements (capsule, pills, fortified foods) is therefore not advised.