The effects of feeding conjugated linoleic acid (CLA) on rat growth performance, serum lipoproteins and subsequent lipid composition of selected rat tissues

Four groups of 12 albino rats (six males and six females), at 4 weeks of age, were fed for 60 days a semi-synthetic diet containing graded amounts of conjugated linoleic acid (CLA; 0.0, 0.5, 1.0 and 1.5%) to determine its effect on growth performance and serum lipoprotein profiles and its incorporation into abdominal and muscle lipids. Rats fed CLA responded by significantly improved body mass gains; however, this effect was observed only with the 1.0% CLA-supplemented diet. It was also true for feed conversion efficiency. The changes in serum total cholesterol (TC) and HDL cholesterol concentrations were insignificant and showed an opposite pattern. However, the resulting HDL cholesterol/TC ratio was significantly (P less than or equal to 0.01) increased. At the same time, serum triacylglycerol (TAG) concentrations were significantly (P less than or equal to 0.01) elevated, thus counteracting the potential antiatherogenicity of the improved HDL cholesterol/TC ratio. Feeding CLA to rats resulted in its substantial incorporation into both abdominal and muscle lipids. Generally, tissue lipids were enriched with CLA at the expense of long-chain polyunsaturated fatty acids, eg Linoleate and arachidonate. This effect is likely to correspond with reduction of arachidonate-derived eicosanoid synthesis. These data together suggest that CLA has a potent effect on lipid transport and metabolism fn rats. Also, they confirm the potential of nutritional methods to provide CLA-enriched functional animal products, especially meat, for human consumption. (C) 2000 Society of Chemical Industry.