Original Article
European Journal of Clinical Nutrition (2009) 63, 778–786; doi:10.1038/ejcn.2008.45; published online 3 September 2008
Effects of conjugated linoleic acid plus n-3 polyunsaturated fatty acids on insulin secretion and estimated insulin sensitivity in men
B Ahrén1, A Mari2, C L Fyfe3, F Tsofliou3, A A Sneddon3, K W Wahle4, M S Winzell1, G Pacini2 and L M Williams3
- 1Division of Medicine, Department of Clinical Sciences, Lund University, Lund, Sweden
- 2Metabolic Unit, Institute of Biomedical Engineering (ISIB CNR), Padova, Italy
- 3Obesity and Metabolic Health Division and Vascular Health Division, Rowett Research Institute, Aberdeen, UK
- 4School of Life Sciences, The Robert Gordon University, Aberdeen, UK
Correspondence: Dr Bo Ahrén, Department of Clinical Sciences, Division of Medicine, B11 BMC, Lund SE-221 84, Sweden. E-mail: Bo.Ahren@med.lu.se
Received 10 March 2008; Revised 15 July 2008; Accepted 30 July 2008; Published online 3 September 2008.
Abstract
Background/Objectives:
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.
Subjects/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/m2) or obese (n=10; BMI 29–35 kg/m2) 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 
-cell dysfunction or insulin resistance in humans but suggest that insulin sensitivity in older obese subjects is reduced.
Keywords:
CLA, n-3 LC-PUFA, humans, insulin secretion, insulin sensitivity, obesity
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