British Journal of Nutrition

Research Article

Incorporation of cis-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

Graham C. Burdgea1 c1, Sabine Tricona2, Rebecca Morgana3, Kirsty E. Kliema3, Caroline Childsa1, Emma Jonesa2, Jennifer J. Russella1, Robert F. Grimblea1, Christine M. Williamsa2, Parveen Yaqooba2 and Philip C. Caldera1

a1 Institute of Human Nutrition, Biomedical Sciences Building, University of Southampton, Bassett Crescent East, Southampton SO16 7PX, UK

a2 Hugh Sinclair Unit of Human Nutrition, University of Reading, Reading, UK

a3 Centre for Dairy Research, Department of Agriculture, University of Reading, Reading, UK


The present study investigated whether consuming dairy products naturally enriched in cis-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 g c9, t11 CLA/d; 0·31 g trans-vaccenic acid (tVA)/d) or CLA-enriched (1·43 g c9, t11 CLA/d; 4·71 g tVA/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 greater c9, t11 CLA content of the commercial products. Consuming the CLA-enriched dairy products increased the c9, 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), while tVA 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 the c9, t11 CLA content of plasma and cellular lipids.

(Received January 05 2005)

(Revised April 13 2005)

(Accepted April 20 2005)


c1 *Corresponding author: Dr Graham C. Burdge, fax +44 2380 594379, email