Submitted to: Lipids
Publication Type: Research Notes
Publication Acceptance Date: 2/5/2001
Publication Date: N/A
Technical Abstract: Conjugated linoleic acid (CLA; 9c,11t-18:2) has been shown, in animals, to exhibit a variety of health-related benefits. Silver ion HPLC (Ag-HPLC) was found to provide better resolution of the isomers than gas chromatography. Most commercially-available samples of CLA, prepared by base-catalyzed isomerization of linoleic acid (9c,12c-18:2), are composed of mixtures of four isomers. While these isomers have been characterized, we found significant changes in CLA isomer ratios within samples obtained from the same source over a period of 2 years. In the first sample, the four cis/trans isomers (8t,10c-18:2, 9c,11t-18:2, 10t,12c-18:2 and 11c,13t- were present in a ratio of approximately 1:2:2:1, while in the second sample they were present in almost equal proportions. If indeed, certain daily levels of CLA intake are required to produce suggested health benefits in humans, changes in concentrations of specific CLA isomers could dsignificantly impact these effects. Care must be taken to analyze the CLA used in human and animal studies.