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Changes in conjugated linoleic acid composition within samples obtained from a single source
- Adlof, R.O., Copes, L.C., Walter, E.L.
- Lipids 2001 v.36 no.3 pp. 315
- nutrition, conjugated linoleic acid, high performance liquid chromatography, silver, isomers, dairy products, beef
- Conjugated linoleic acid (CLA; 9c,11t-18:2) and CLA isomers have been reported in animals to exhibit a variety of health-related benefits. Silver ion high-performance liquid chromatography (Ag-HPLC) was found to provide better resolution of the isomers than gas chromatography. Most commercially available samples of CLA, prepared by base-catalysed isomerization of linoleic acid (9c,12c-18:2), are composed of mixtures of four major isomers. While these isomers have been characterized, we found significant changes in CLA isomer ratios within samples obtained from the same producer/commercial supplier over a period of one-and-a-half years (June 1998 and December 1999). In the first sample, the four cis/trans isomers (8t,10c-18:2, 9c,11t-18:2, 10t,12c-18:2 and 11c,13t-18:2) were present in a ratio of approximately 1:2:2:1, while in the 2nd 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 significantly impact these effects. Care must be taken to analyse the CLA used in human and animal studies.