Submitted to: Annual Meeting and Expo of the American Oil Chemists' Society
Publication Type: Abstract only
Publication Acceptance Date: 5/8/2002
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Animal studies suggest that conjugated linoleic acid has potential health benefits but no definitive metabolic data are available to support the possibility that it has physiological activity in humans. The purpose of this study was to determine the effect of dietary conjugated linoleic acid (CLA) on oleic, linoleic, and conjugated linoleic acid isomers. The subjects were healthy adult women consuming normal and CLA supplemented (3.7 g/d) diets. A mixture of 10t,12c-18:2- d4, 9c,11t-18:2-d6, 9c-18:1-d8 and 9c,12c-18:2-d2 was fed to each subject, and plasma lipids were analyzed by mass spectrometry. The results show that the 2H-CLA isomers were 20-25% less well absorbed than oleic and linoleic acid and that dietary CLA supplementation had little influence on the metabolism of the deuterium-labeled fatty acids. The 2H-CLA isomers were not metabolically equivalent. The largest differences were a four-fold higher incorporation of 10t,12c-18:2-d4 than 9t,11c-18:2-d6 in 1-acyl phosphatidylcholine and a two to three- fold higher incorporation of 9c,11t-18:1-d6 than 10t,12c-18:2-d4 in cholesterol esters. In general, accumulation of 10t,12c-18:2-d4 and 9c,11t-18:2-d6 in plasma lipids was characteristic of cis and trans 18:1 isomers rather than 18:0, 9c-18:1 or 9c,12c-18:2. Conversion of CLA to desaturated and elongated polyunsaturated fatty acids was low. The only 2H-CLA metabolite present in amounts large enough for reliable quantification was 6c,10t,12c-18:3-d4. In conclusion, absorption of the CLA isomers into blood lipids was less than 9c-18:1 and, while metabolically different, the CLA isomers were incorporated in a manner similar to cis and trans 18:1 isomers, not 18:0 or 9c,12c-18:2.