Lsoflavones restore altered redox homeostasis of antioxidant enzymes in healthy young men undergoing 80% Peak Oxygen Consumption (VO2pk) exercise

Isoflavones have potential health effects attributed to their antioxidant activity. The objective of this study was to test whether isoflavones affected the enzymatic antioxidant defense system in young men undergoing 80% peak oxygen consumption (Vo(2)pk) exercise on cycle ergometer for 30 minutes. Fifteen pairs of subjects were randomly assigned to receive either high-genistein isollavone extract (HGI, 150 mg/day) or placebo. Subjects engaged in two 30-minute sessions of exercise before and after 4 weeks of supplementation. There was a significant increase in plasma genistein and daidzein concentrations (499 and 415 ng/mL, P < 0.0001) after the supplementation, demonstrating isoflavone bioavailability. Isoflavones significantly increased pre-exercise erythrocyte superoxide dismutase (SOD) activity (P < 0.001). Furthermore, isoflavones prevented the exercise-induced decrease in activities of glutathione peroxidase (GPx) and catalase (CAT) and the increase in antioxidant enzyme (AE) ratio, maintaining all at pre-exercise levels. Our results suggest that isoflavones can restore the altered redox homeostasis of antioxidant enzymes due to exercise. (C) 2004 Elsevier Inc. All rights reserved.