Single and Repeated Supplementation of SOD Differently Improve Antioxidant Capacity Against Exercise Challenges

OBJECTIVES: Oxidative stress, commonly exposed in our daily life, produces free radicals. Excessively produced free radicals damage body components and eventually promote degenerative diseases. It has been reported that the reinforcement of superoxide dismutase (SOD), the first barrier of the antioxidant system, protects our body from oxidative stress by enhancing the subsequent redox cycle. The use of SOD, an enzymatic antioxidant rather than a simple antioxidant, is still insufficient to evaluate its safety and efficacy. Therefore, the purpose of this study is to evaluate the long-term consumption safety for enzymatic antioxidants and the effect of SOD supplementation on exercise-induced oxidative stress. METHODS: This study was designed as a randomized, double-blind, placebo-controlled in 80 healthy adults. The subjects consumed SOD (250 IU/capsule) daily for 8 weeks and induced oxidative stress via acute aerobic exercise at the beginning and end of the experimental period. The exercise challenge was performed on a treadmill for 30 minutes at an intensity of 60% of each subject's maximal oxygen consumption (VO(2 max)). Blood and urine samples have collected a total of three times, after overnight fasting, immediately after exercise, and after a 30-minute rest, which was used to evaluate the safety of long-term enzymatic antioxidant supplementation, as well as functional indicators of antioxidant systems and oxidative stress. RESULTS: Endogenous antioxidant defense systems, oxidative damage, and even antioxidant balance indicators were compared by considering the interaction between the group and status over time. A single intake of SOD significantly reduced the level of oxidative damage and inflammation indicators (P < 0.05) as it sequentially activated antioxidant enzymes (P < 0.10). Furthermore, long-term intake of SOD showed a stabilized defense response against the same oxidative stress load and improved balance between antioxidant enzymes immediately after exercise (P < 0.05) without any side effects. CONCLUSIONS: These findings suggest that single and repeated supplementation of SOD may differently improve the antioxidant defense system without side effects. FUNDING SOURCES: This work was supported by the BK21 Fostering Outstanding Universities for Research funded by the Ministry of Education (Korea) and the National Research Foundation of Korea.