Conjugated Linoleic Acid: Chemical Structure, Sources and Biological Properties

Conjugated linoleic acid (CLA) is a group of geometrical and positional isomers of linoleic acid (C18:2, cis-9, cis-12). In contrast to linoleic acid, double bonds in CLA are usually located at positions 9 and 11 or 10 and 12 and each double bond can be either in the cis or trans configuration. Meat and dairy products from ruminant animals (such as milk, butter, yogurt and cheese) are the principal natural sources of CLA in the human diet. Egg and meat products from poultry contain less CLA than meat from ruminant animals (0.6 and 0.9 mg/g fat vs. 2.9 to 5.6 mg/g fat, respectively). Meat from turkeys contains much higher CLA relative to meat from chickens. Dietary CLA has been shown to have potent anticarcinogenic and antiatherogenic effects in animal models. CLA was also found to have a potent immune modulating activity characterized by increased blastogenesis and macrophage killing ability. In addition to these biological properties, CLA was reported to reduce body fat content and increase lean body mass in pigs and rodents. Because of these biological properties of CLA, recently there has been a lot of interest in enriching egg, meat and dairy products for human consumption.