The effect of vitamin C supplementation from fruit and endurance-training on the antioxidant status of athletes

This study was designed to investigate the effect of vitamin C supplementation and endurance-training on the antioxidant status of athletes. Subjects consisted of 20 males in a swimming varsity team. Fresh fruit containing 500 mg vitamin C was given to each athlete every day during a 3-week moderate/high-intense training period. The fasting venous blood was collected to measure the antioxidant parameters and muscle damage. The results showed that vitamin C and SH group levels were elevated, whole blood glutathione peroxidase and erythrocyte superoxide dismutase activities decreased after fruit vitamin C supplementation and endurance-training. However, the lipid peroxidation indicators-plasma thiobarbituric acid-reactive substances and malondialdehyde + 4-hydroxy-2(E)-nonenal were still high after fruit vitamin C supplementation and endurance-training. No significant changes in creatine kinase and lactate dehydrogenase were found. The results suggest supplementation of 500 mg vitamin C from fruits in athletes during moderate/high-intense endurance training can increase antioxidant status slightly, but can not compensate for the oxidative stress absolutely. This implies that supplementation of vitamin C from fruit is helpful to athletes under long term endurance-training, but the quantity and type of supplementation maybe require further clarification.