OBJECTIVE: The objective of the present study was to determine the effects of vitamin C offered through a dietary supplement and an ascorbic acid (AA)-rich diet on exercise-induced oxidative stress. METHODS: The sample consisted of 13 elite swimmers (6 men and 7 women) aged 18 to 26 years. The same athletes were submitted to an acute exercise session in 3 phases, with different treatments: control (C), AA-rich diet (D) and AA supplement (S), where blood samples were collected before, immediately after and 24 hours after exercise. A mixed effects linear regression model was used to compare phases and stages. RESULTS: The habitual consumption of antioxidants did not differ between phases, except that AA intake was higher during the D and S phases than during the C phase. The use of an AA-rich diet provided lower lipid peroxidation due to lower lipid hydroperoxide (FOX) values, a reduction of peroxidation after exercise due to reduction of thiobarbituric acid reactive substances (TBARS), and an increase in vitamin C levels after exercise. The use of an AA supplement also restricted lipid peroxidation after exercise and increased the antioxidant power due to higher levels of reduced glutathione (GSH). Without the addition of AA , the swimmers had greater hepatic damage as shown by higher levels of aspartate aminotransferase (AST), lower antioxidant levels (vitamin C and GSH) and increased uric acid. CONCLUSION: Thus, the changes observed after the addition of AA to the diet of swimmers suggest an important role of this micronutrient in the defense against exercise-induced oxidative stress.
vitamin C; free radicals; dietary supplementation
