Conjugated linoleic acid: a novel therapeutic nutrient?

Conjugated linoleic acid (CLA) refers to a group of fatty acid isomers of l inoleic acid. Recent research shows that CLA affects body composition, lipo protein metabolism, inflammation and carcinogenesis. Therefore, CLA may hav e potential as a therapeutic nutrient with respect to many common diseases, including obesity, atherosclerosis, chronic inflammatory diseases and canc er. Animal studies show that CLA is a potent anti-adipogenic nutrient, redu cing adipose tissue mass and increasing lean mass. However, the effect of C LA on body composition in human subjects has been less spectacular. Several studies have demonstrated that CLA significantly improves plasma cholester ol and triacylglycerol metabolism in a number of animal models. These studi es also showed that CLA inhibits the progression and pathogenesis of athero sclerosis. Whilst CLA has also been shown to improve triacylglycerol metabo lism in human subjects, it has not been determined whether CLA affects athe rogenesis. Animal models show that CLA-rich diets modulate the inflammatory response and preliminary trials with human subjects show that CLA affects the cell-mediated immune response. The molecular basis of the health effect s of CLA has not been elucidated, but it is probable that CLA mediates its effect in a number of ways including altered eicosanoid or cytokine metabol ism and/or by a direct effect of dietary fats on gene transcription. Most o f our knowledge is based on in vitro and animal studies; the challenge is t o define the nature and molecular basis of any health effects of CLA in hum an subjects.