Effects of cis-9,trans-11 and trans-10,cis-12 conjugated linoleic acid on immune cell function in healthy humans.
BACKGROUND
Animal studies have suggested that conjugated linoleic acid (CLA), a natural component of ruminant meat and dairy products, may confer beneficial effects on health. However, little information on the effects of CLA on immune function is available, especially in humans. Furthermore, the effects of individual isomers of CLA have not been adequately investigated.


OBJECTIVE
This study investigated the effects of supplementing the diet with 3 doses of highly enriched cis-9,trans-11 CLA (0.59, 1.19, and 2.38 g/d) or trans-10,cis-12 CLA (0.63, 1.26, and 2.52 g/d) on immune outcomes in healthy humans.


METHODS
The study had a randomized, double-blind, crossover design. Healthy men consumed 1, 2, and 4 capsules sequentially that contained 80% of either cis-9,trans-11 CLA or trans-10,cis-12 CLA for consecutive 8-wk periods. This regimen was followed by a 6-wk washout and a crossover to the other isomer.


RESULTS
Both CLA isomers decreased mitogen-induced T lymphocyte activation in a dose-dependent manner. There was a significant negative correlation between mitogen-induced T lymphocyte activation and the proportions of both cis-9,trans-11 CLA and trans-10,cis-12 CLA in peripheral blood mononuclear cell lipids. However, CLA did not affect lymphocyte subpopulations or serum concentrations of C-reactive protein and did not have any consistent effects on ex vivo cytokine production.


CONCLUSIONS
CLA supplementation results in a dose-dependent reduction in the mitogen-induced activation of T lymphocytes. The effects of cis-9,trans-11 CLA and trans-10,cis-12 CLA were similar, and there was a negative correlation between mitogen-induced T lymphocyte activation and the cis-9,trans-11 CLA and trans-10,cis-12 CLA contents of mononuclear cells.
Tricon
Sabine
S
Hugh Sinclair Unit of Human Nutrition, School of Food Biosciences, The University of Reading, Reading, United Kingdom.
Burdge
Graham C
GC
Kew
Samantha
S
Banerjee
Tapati
T
Russell
Jennifer J
JJ
Grimble
Robert F
RF
Williams
Christine M
CM
Calder
Philip C
PC
Yaqoob
Parveen
P
D000328:Adult; D002097:C-Reactive Protein / Q000032:analysis; D018592:Cross-Over Studies; D016207:Cytokines / Q000096:biosynthesis*; D019587:Dietary Supplements; D004306:Dose-Response Relationship, Immunologic; D004311:Double-Blind Method; D005434:Flow Cytometry; D006801:Humans; D007111:Immunity, Cellular / Q000187:drug effects* / Q000502:physiology; D007536:Isomerism; D007963:Leukocytes, Mononuclear / Q000276:immunology; D044243:Linoleic Acids, Conjugated / Q000494:pharmacology*; D008055:Lipids / Q000097:blood; D008213:Lymphocyte Activation / Q000187:drug effects*; D008297:Male; D008875:Middle Aged
D016207:Cytokines; D044243:Linoleic Acids, Conjugated; D008055:Lipids; D002097:C-Reactive Protein