Incorporation ofcis-9,trans-11 conjugated linoleic acid and vaccenic acid (trans-11 18:1) into plasma and leucocyte lipids in healthy men consuming dairy products naturally enriched in these fatty acids

Abstract

The present study investigated whether consuming dairy products naturally enriched incis-9,trans-11 (c9,t11) conjugated linoleic acid (CLA) by modification of cattle feed increases the concentration of this isomer in plasma and cellular lipids in healthy men. The study had a double-blind cross-over design. Subjects aged 34–60 years consumed dairy products available from food retailers for 1 week and then either control (0·17 gc9,t11 CLA/d; 0·31 gtrans-vaccenic acid (tVA)/d) or CLA-enriched (1·43 gc9,t11 CLA/d; 4·71 gtVA/d) dairy products for 6 weeks. After 7 weeks washout, this was repeated with the alternate products.c9,t11 CLA concentration in plasma lipids was lower after consuming the control products, which may reflect the two-fold greaterc9,t11 CLA content of the commercial products. Consuming the CLA-enriched dairy products increased thec9,t11 CLA concentration in plasma phosphatidylcholine (PC) (38%;P=0·035), triacylglycerol (TAG) (22%;P<0·0001) and cholesteryl esters (205%;P<0·0001), and in peripheral blood mononuclear cells (PBMC) (238%;P<0·0001), whiletVA concentration was greater in plasma PC (65%;P=0·035), TAG (98%;P=0·001) and PBMC (84%;P=0·004). Overall, the present study shows that consumption of naturally enriched dairy products in amounts similar to habitual intakes of these foods increased thec9,t11 CLA content of plasma and cellular lipids.