Isoflavones May Support Enzymatic Antioxidant Defense System in Athletes
BLACKSBURG, Va.--Isoflavones may help restore the altered redox homeostasis of antioxidant enzymes following exercise, according to a new study published in the June issue of Nutrition Research (24,5: 347-59, 2004) (http://www.sciencedirect.com/science/journal/02715317). Redox homeostasis is a group of processes critical to cell function and prevention of severe cellular damage. Damaging free radicals generated in biological processes such as aerobic exercise may change the cellular redox status, leading to oxidative stress and disruption of redox homeostasis.
The study, designed to test whether isoflavones affected the enzymatic antioxidant defense system in young men undergoing exercise on bicycles for 30 minutes, randomly assigned 15 pairs of subjects to receive either high-genistein isoflavone extract (HGI, 150 mg/d) or placebo. Subjects exercised for two 30-minute sessions prior to and following four weeks of supplementation. The researchers observed a significant increase in plasma genistein and daidzein concentrations following supplementation, indicative of isoflavone bioavailability. In addition, isoflavones were found to significantly increase pre-exercise erythrocytic activity of superoxide dismutase (SOD), a powerful endogenous antioxidant enzyme, prevent exercise-induced decreases in activity of other antioxidant enzymes, including glutathione peroxidase (GPx) and catalase (CAT), and to avert increase of the antioxidant enzyme (AE) ratio, preserving all at pre-exercise levels.