ABSTRACT
Conjugated linoleic acid (CLA) refers to a group of polyunsaturated fatty acids that exist as positional isomers and stereoisomers of conjugated dienoic octadecadienoate (C18:2). The double bonds of CLA are in the positions of 7,9; 8,10; 9,11; 10,12; 11,13 and the three-dimensional geometric combinations of cis and/or trans configurations.1,2 CLA is found in foods such as beef, lamb, and dairy products derived from these ruminant sources3-6 and ranges from 2.9 to 8.9 mg/g fat.7 The isomers in foods are, in descending order: c9,t11-CLA (also called rumenic acid); t7,c9-CLA; 11,13-CLA (c/t); 8,10-CLA (c/t); t10,c12-CLA; and other, minor isomers.4,8,9 In addition, CLA is present in human blood, tissues, and milk, and is derived from a diet including certain fat-containing foods of ruminant origin.10 Studies showed that increasing dietary CLA led to increases in the CLA content of plasma,11,12 adipose tissue,13 and milk fat14 in humans.
