(21-06-09) Effects of conjugated linoleic acid plus n-3 polyunsaturated fatty acids on insulin secretion and estimated insulin sensitivity in men




B Ahr?n1, A Mari2, C L Fyfe3, F Tsofliou3, A A Sneddon3, K W Wahle4, M S Winzell1, G Pacini2 and L M Williams3
1. 1Division of Medicine, Department of Clinical Sciences, Lund University, Lund, Sweden
2. 2Metabolic Unit, Institute of Biomedical Engineering (ISIB CNR), Padova, Italy
3. 3Obesity and Metabolic Health Division and Vascular Health Division, Rowett Research Institute, Aberdeen, UK
4. 4School of Life Sciences, The Robert Gordon University, Aberdeen, UK
Correspondence: Dr Bo Ahr?n, Department of Clinical Sciences, Division of Medicine, B11 BMC, Lund SE-221 84, Sweden. E-mail: [email protected]
Received 10 March 2008; Revised 15 July 2008; Accepted 30 July 2008; Published online 3 September 2008.

Top of page 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.


Source: European Journal of Clinical Nutrition (2009) 63, 778?786