Conjugated linoleic acid

Abstract

Conjugated linoleic acid (CLA) is a collective term which refers to positional and geometrical isomers of conjugated octadecadienoic acid, structural relatives of linoleic acid. CLA is present in human tissue and body fluids, and its levels can be increased by a diet rich in CLA. CLA occurs in the lipid fraction of many kinds of food, but the richest dietary sources are ruminant milk and meat products. In the past decade CLA has been the object of considerable interest because of its potential health-promoting properties. Animal and in vitro studies have shown CLA to be an effective anticarcinogenic agent. It has also been suggested that CLA might reduce the risk of atherosclerosis, and it has been shown to alter body composition. However, the mechanism of CLA's action is still largely unknown, and there are no published data regarding CLA effects in humans. Further, the CLA used in the studies has been a CLA mixture containing 40% or less of the c9,t11- isomer, which is considered to be the biologically active isomer of CLA. Therefore, the possibility that there are distinct differences in effects attributable to different CLA isomers cannot be excluded without further study. More studies are needed to determine whether CLA also possesses health-promoting activity in humans.