Metabolic effects of conjugated linoleic acid

Fatty acids containing trans unsaturated double bonds occur in nature, but the most common dietary source are “man-treated” fats. Because of the possible link between trans-fatty acids consumption and human disease-mainly cardiovascular disease and cancer, the health effects of trans-FA have been studied for over the last fifty years. Trans fatty acids are unsaturated fatty acids with at least a double trans configuration, resulting in a more firm molecule close to a saturated fatty acid. These appear in dairy fat because of ruminal activity, and in hydrogenated oils; margarines, shortenings and baked goods contain relatively high levels of trans fatty acids. Conjugated linoleic acids (CLA) are a group of linoleic (18:2)-derived isomers with conjugated double bonds, mostly at carbon atoms 9 and 11 or 10 and 12, with all possible cis and trans combinations. CLA occur naturally in several foods but they are found in highest concentrations in milk fat and body fat of ruminants the predominant fatty acid isomer is the 18:2 9c,11t. CLA are also present in plant oils and partially hydrogenated oils but in very low amounts. In this paper the results of the studies on trans fatty acids in different food products determined by high resolution gas chromatography combined with mass spectrometry are presented and reviewed.