Effects of CLA at different dietary fat levels on the nutritional status of rats during protein repletion

Objective: Protein depletion is associated with decreased body weight gain, low nitrogen balance, intrahepatic lipid accumulation, and hypoalbuminemia. Because conjugated linoleic acid (CLA) can increase lean body mass, enhance feed efficiency, and modulate lipid metabolism, this study investigated the effects of CLA at two levels of dietary fat on energy efficiency, nitrogen retention, and plasmatic and hepatic lipid levels in rats during dietary protein repletion. Methods: The animals were subjected to a moderate protein restriction for 14 d. After that, they were fed a protein repletion diet for 30 d, supplemented or not with CLA at recommended and high-fat levels. Energy efficiency, nitrogen balance, and nutritional parameters in serum and tissues were evaluated. Results: Protein repletion improved most of the nutritional parameters evaluated independently of CLA supplementation at both fat levels. At recommended fat levels, CLA did not have any effect. At high-fat levels, energy efficiency increased more than 20% by fat accumulation in carcasses and epididymal pads, serum cholesterol increased (two-fold), and liver triacylglycerol accumulation remained elevated. However, at high-fat levels, CLA prevented lipid accumulation in liver and adipose tissue. Conclusion: Protein repletion improved the nutritional status of protein-restricted rats with minor effects of CLA at both dietary fat levels. However, when high-fat diets were given, CLA-enriched oil showed preventive effects on liver and adipose tissue lipid accumulation and no deleterious effects were observed. Because there are no studies dealing with CLA effects on protein repletion, this experimental model could improve nutritional interventions to overcome the protein-deficit stage. (C) 2007 Elsevier Inc. All rights reserved.