Opposing effects of cis-9,trans-11 and trans-10,cis-12 conjugated linoleic acid on blood lipids in healthy humans.
BACKGROUND
Conjugated linoleic acid (CLA) is reported to have weight-reducing and antiatherogenic properties when fed to laboratory animals. However, the effects of CLA on human health and, in particular, the effects of individual CLA isomers are unclear.


OBJECTIVE
This study investigated the effects of 3 doses of highly enriched cis-9,trans-11 (0.59, 1.19, and 2.38 g/d) or trans-10,cis-12 (0.63, 1.26, and 2.52 g/d) CLA preparations on body composition, blood lipid profile, and markers of insulin resistance in healthy men.


METHODS
Healthy men consumed 1, 2, and 4 capsules sequentially, containing either 80% cis-9,trans-11 CLA or 80% trans-10,cis-12 CLA for consecutive 8-wk periods. This phase was followed by a 6-wk washout and a crossover to the other isomer.


RESULTS
Body composition was not significantly affected by either isomer of CLA. Mean plasma triacylglycerol concentration was higher during supplementation with trans-10,cis-12 CLA than during that with cis-9,trans-11 CLA, although there was no influence of dose. There were significant effects of both isomer and dose on plasma total cholesterol and LDL-cholesterol concentrations but not on HDL-cholesterol concentration. The ratios of LDL to HDL cholesterol and of total to HDL cholesterol were higher during supplementation with trans-10,cis-12 CLA than during that with cis-9,trans-11 CLA. CLA supplementation had no significant effect on plasma insulin concentration, homeostasis model for insulin resistance, or revised quantitative insulin sensitivity check index.


CONCLUSIONS
Divergent effects of cis-9,trans-11 CLA and trans-10,cis-12 CLA appear on the blood lipid profile in healthy humans: trans-10,cis-12 CLA increases LDL:HDL cholesterol and total:HDL cholesterol, whereas cis-9,trans-11 CLA decreases them.
Hugh Sinclair Unit of Human Nutrition, School of Food Biosciences, University of Reading, Whiteknights, Reading RG6 6AP, United Kingdom.
Sabine
S
Tricon
Graham C
GC
Burdge
Samantha
S
Kew
Tapati
T
Banerjee
Jennifer J
JJ
Russell
Emma L
EL
Jones
Robert F
RF
Grimble
Christine M
CM
Williams
Parveen
P
Yaqoob
Philip C
PC
Calder
D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism; D000328:Adult; D001786:Blood Glucose / Q000187:drug effects; D001823:Body Composition / Q000187:drug effects*; D002784:Cholesterol / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D018592:Cross-Over Studies; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance; D007536:Isomerism; D044243:Linoleic Acids, Conjugated / Q000737:chemistry / Q000494:pharmacology*; D008074:Lipoproteins / Q000097:blood*; D008297:Male; D008875:Middle Aged; D014280:Triglycerides / Q000097:blood
D001786:Blood Glucose; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D007328:Insulin; D044243:Linoleic Acids, Conjugated; D008074:Lipoproteins; D014280:Triglycerides; D002784:Cholesterol