Effects of CLA Dependent on Isomer Type

VITORIA, Spain--The effects of conjugated linoleic acid (CLA) on liver composition and hepatic fatty acid oxidation depend on the type of isomer, according to a hamster study published in Nutrition (21, 4: 512-519 , 2005) (www.sciencedirect.com/science/journal/08999007).

Animals were divided into three groups, fed diets promoting fatty degeneration of the inner coat of the arteries, and supplemented with 0.5 percent linoleic acid, cis-9,trans-11 (c9,t11) CLA, or trans-10,cis-12 (t10,c12) CLA for six weeks. Their livers were assayed for lipids, protein, water, DNA contents, histologic structure and other characteristics. Serum levels of triacylglycerols and other compounds were evaluated.

Hamster livers exposed to t10,c12 CLA were significantly heavier and contained lower levels of triacylglycerols, cholesterol and phospholipids, as well as a larger total number of cells. No changes were observed in livers of hamsters given c9,t11 CLA. t10,c12 CLA was recovered in significantly lower proportions than c9,t11 in liver triacylglycerols. Histopathologic analysis of livers from all three experimental groups showed no abnormalities.

The researchers concluded the addition of 0.5 percent of these CLA isomers to the diet do not induce toxic effects in the liver after six weeks of feeding. Intake of t10,c12 CLA but not of c9,t11 CLA increases liver fatty acid oxidation, leading to decreased hepatic and serum triacylglycerols.