Department of Physiological Sciences

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Browsing Department of Physiological Sciences by Subject "Active oxygen"

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    Association between antioxidant status and MnSOD Ala-9Val polymorphism in trained male athletes (rugby players) and sedentary male students controlled for antioxidant intake
    (Stellenbosch : Stellenbosch University, 2007-03) Seele, Maria; Senekal, M.; Steyn, N. P.; Stellenbosch University. Faculty of Science. Dept. of Physiological Sciences.
    ENGLISH ABSTRACT: The human body has developed an integrated antioxidant defence system to protect against free radical damage. Acute exercise may result in the increased generation of free radicals, including reactive oxygen species, and this may overwhelm antioxidant defence systems resulting in oxidative stress. However, it has been shown that individuals who undergo regular exercise training may have improved antioxidant capacity when compared to sedentary controls. Results from research regarding the association between antioxidant capacity and exercise training are however not conclusive and further investigation is required. Therefore, the aim of this study was to investigate the association between the total plasma antioxidant status and selected plasma indicators of antioxidant status and the MnSOD Ala-9Val (-28C®T) polymorphism in trained male athletes (rugby players) and sedentary male students while controlling for dietary intake of the major antioxidants using a validated dietary assessment method. In order to address the potential confounding effect of dietary antioxidant intake on antioxidant status in the main study, a FFQ that measures vitamin C, vitamin E, carotenoid and flavonoid intake was developed. The reproducibility was assessed by the repeat administration of the FFQ (n = 38), while the va lidity was assessed using a 28-day closeended dietary record and repeated plasma vitamin C values (n = 18). Several statistical tests were conducted to compare the values obtained from the FFQ with values obtained from the various reference methods. While results from Bland-Altman plots suggested that the reproducibility and validity of FFQ was not completely satisfactory, similar mean values, moderate to strong correlation coefficients, and a high percentage of individuals classified correctly according to quartiles of intake indicated satisfactory reproducibility and validity of the FFQ in assessing antioxidant intake. Furthermore, moderate to strong validity coefficients obtained from the method of triads also indicated satisfactory validity for the FFQ. The main study involved a cross-sectional study that compared plasma vitamin C and carotenoid levels as well as total plasma antioxidant status in trained rugby players (n = 76) and sedentary male subjects (n = 39) with different MnSOD genotypes, while controlling for dietary antioxidant intake. Rugby players had significantly higher plasma vitamin C and carotenoid levels compared to sedentary students, which indicated more satisfactory plasma antioxidant status. This was also reflected in the tendency for total plasma antioxidant status (ORAC assay) to be higher in rugby players than sedentary students. MnSOD genotype did not influence plasma vitamin C and carotenoid levels or plasma total antioxidant status, with or without control for dietary antioxidant intake. Dietary vitamin C, vitamin E, carotenoid an flavonoid intake (from foods + supplements) was similar for rugby players and sedentary students and was adequate for both groups. Thus the association between antioxidant status and MnSOD genotype in rugby players and sedentary students seemed not to be influenced by dietary antioxidant intake. In conclusion therefore, rugby players undergoing regular exercise training had a more satisfactory antioxidant status compared to sedentary students. Based on this conclusion, the widespread use of antioxidant supplements by athletes is questioned.