Effects of conjugated linoleic acid plus n-3 polyunsaturated fatty acids on insulin secretion and estimated insulin sensitivity in men.
OBJECTIVE
Dietary addition of either conjugated linoleic acid (CLA) or n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFAs) has been shown to alter adiposity and circulating lipids, risk markers of cardiovascular diseases. However, CLA may decrease insulin sensitivity, an effect that may be reversed by n-3 LC-PUFA. Thus, the potential of CLA plus n-3 LC-PUFA to affect insulin secretion and sensitivity in non-diabetic young and old, lean and obese subjects was tested.


METHODS
CLA (3 g daily) plus n-3 LC-PUFA (3 g daily) or control oil (6 g daily) was given to lean (n=12; BMI 20-26 kg/m(2)) or obese (n=10; BMI 29-35 kg/m(2)) young (20-37 years old) or lean (n=16) or obese (n=11) older men (50-65 years) for 12 weeks. The study had a double-blind, placebo-controlled randomized crossover design, and primary end points were insulin secretion and sensitivity during a standardized meal test, evaluated by modeling glucose, insulin and C-peptide data.


RESULTS
The combination was well tolerated. There was no significant difference in fasting levels of glucose, insulin or C-peptide after CLA/n-3 LC-PUFA treatment compared with control oil. Neither insulin secretion nor estimated sensitivity was affected by CLA/n-3 LC-PUFA in lean or obese young subjects or in older lean subjects. However, in older obese subjects, estimated insulin sensitivity was reduced with CLA/n-3 LC-PUFA compared with control (P=0.024).


CONCLUSIONS
The results do not support beneficial effects of CLA/n-3 LC-PUFA for beta-cell dysfunction or insulin resistance in humans but suggest that insulin sensitivity in older obese subjects is reduced.
Ahrén
B
B
Division of Medicine, Department of Clinical Sciences, Lund University, Lund, Sweden. Bo.Ahren@med.lu.se
Mari
A
A
Fyfe
C L
CL
Tsofliou
F
F
Sneddon
A A
AA
Wahle
K W
KW
Winzell
M S
MS
Pacini
G
G
Williams
L M
LM
D000328:Adult; D000367:Age Factors; D000368:Aged; D001786:Blood Glucose; D002097:C-Reactive Protein / Q000378:metabolism; D018592:Cross-Over Studies; D004311:Double-Blind Method; D015525:Fatty Acids, Omega-3 / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance; D000078790:Insulin Secretion; D044243:Linoleic Acids, Conjugated / Q000494:pharmacology* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000188:drug therapy*; D055815:Young Adult
D001786:Blood Glucose; D015525:Fatty Acids, Omega-3; D007328:Insulin; D044243:Linoleic Acids, Conjugated; D002097:C-Reactive Protein