Lack of effect of dietary conjugated linoleic acids naturally incorporated into butter on the lipid profile and body composition of overweight and obese men

Abstract

Background: Dietary conjugated linoleic acid (CLA) is known to reduce atherosclerosis, plasma total and LDL-cholesterol concentrations , and body fat accumulation in several animal species. Of the few studies that investigated the effects of CLA supplementation in humans, all used commercially formulated oral supplements made from a mixture of CLA isomers. Objective: We compared the effects on plasma lipoproteins and body composition of the consumption of a modified butter naturally enriched with CLA (CLA-B: 4.22 g CLA/100 g butter fat) by the addition of sunflower oil to the diet of dairy cows with the consumption of a control butter (CON-B) that was low in CLA (0.38 g CLA/100 g butter fat). Design: In a crossover design study including an 8-wk washout period, 16 men [x SD age: 36.6 12.4 y; body mass index (in kg/m 2): 31.2 4.4] were fed each of the 2 experimental isoenergetic diets, providing 15% of energy as protein, 45% as carbohydrates, and 40% as lipids, of which Œ60% was derived from experimental fats, for 4 wk. Results: Consumption of the CLA-B diet induced a significantly (P  0.05) smaller reduction in plasma total cholesterol and in the ratio of total to HDL cholesterol (0.02 mmol/L and 0.00, respectively) than did consumption of the CON-B diet (0.26 mmol/L and0.34, respectively). Abdominal adipose tissue area measured by computed tomography showed no difference in accumulation of either visceral or subcutaneous adipose tissue after the 2 experimental diets. Conclusion: These results suggest that a 10-fold CLA enrichment of butter fat does not induce beneficial metabolic effects in overweight or obese men. Am J Clin Nutr 2005;82:309-19.