Conjugated Linoleic Acid
CLA is a term describing several geometric and positional isomers of common linoleic acid (an omega-6 fatty acid). CLA, however, has many opposing physiological effects to linoleate, notably in reference to carcinogenesis and inflammation. The unique properties of CLA may in part be due to its postulated antioxidant properties This mechanism, however, has been questioned.
It is more likely that the preliminary positive findings regarding CLA supplementation in athletes are due to other mechanisms. This, however, remains to be elucidated.
Alpha Lipoic Acid
Alpha lipoic acid (ALA) is an antioxidant that has received considerable attention recently, both in the scientific and commercial supplement communities. ALA is present in the mitochondrial proteins necessary for oxidative metabolism. For example, it is a cofactor for dehydrogenase enzymes like PDH, which forms acetyl CoA for the Krebs cycle. In addition, ALA possesses both antioxidant and subchronic glucose disposal activity. This compound can scavenge HO2 , HOCL, and O2 radicals. It is both water- and lipid-soluble, and so may be of benefit to both cellular compartments.
Alpha lipoic acid has been shown to combat age-associated decline in metabolism by improving mitochondrial function via increased oxygen consumption, mitochondrial membrane potential, and ambulatory activity. In addition, this research showed decreased oxidative damage as measured by decreases in MDA and increases in ascorbic acid and glutathione. In exercise-induced oxidative stress, lipoic acid decreased lipid peroxidation and increased glutathione levels.
Research investigating a lipoic acid + vitamin E combination has revealed evidence of decreased plasma LDL oxidation as well as decreased urinary isoprostanes, which are markers of oxidation. Although these preliminary data are exciting, more research is needed to clarify the exact nature of lipoic acid’s beneficial effects as both a glucose disposal agent and an antioxidant.