Effects of conjugated linoleic acid on cholesterol metabolism in swine

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references (leaves 43-46).Issued also on microfiche from Lange Micrographics.Conjugated linoleic acid (CLA) is a collective term used to describe a mixture of all the positional and geometrical isomers of the essential fat linoleic acid. CLA is a natural by-product of ruminant metabolism and is found chiefly in dairy products and meats. This "all-natural" supplement is gaining notoriety for its beneficial health claims, including weight reduction and prevention of cancer and atherosclerosis. Several studies have explored the impact of CLA on lipid metabolism in rodents. This study uses a more appropriate human model, namely swine, to examine this relationship. The purposes of this investigation were to explore the impact of dietary CLA supplementation, using an appropriate human model, on total cholesterol and lipoprotein fractions in plasma, and to document the mechanism by which it may have these effects. Our study consisted of two trials: 1) 18 pigs divided into three groups and fed a basal, sorghum-based diet supplemented with 1.5% corn oil, 1.5% beef tallow, or 1.5% CLA; and 2) 24 pigs divided into 4 groups and fed a basal, sorghum-based diet supplemented with 15% corn oil, 12% corn oil plus 3% CLA, 15% beef tallow, or 12% beef tallow plus 3% CLA. Plasma samples were collected initially, on d 17, and upon slaughter (d 35) and analyzed for total cholesterol, lipoprotein fractions, triglycerides, and fatty acid concentrations. Liver tissue was obtained at slaughter to measure ACAT enzyme activity. Results showed minimal effects from CLA. The only impact CLA induced in cholesterol was an increase, though not statistically significant, in the LDL-cholesterol/HDL-cholesterol. Analysis of fatty acids demonstrated incorporation of CLA into plasma of those animals receiving it in their diet. Also there was evidence of possible []-9 desaturase inhibition. ACAT activity showed no affect from CLA supplementation. In conclusion, our results are in conflict with those of several other studies. However, the relevance of our subject model is key. The differences reported are indicative of a need for further research in this area before any definitive health claims are credited to CLA