Association between antioxidant status and MnSOD Ala-9Val polymorphism in trained male athletes (rugby players) and sedentary male students controlled for antioxidant intake

[摘要] ENGLISH ABSTRACT: The human body has developed an integrated antioxidant defence system to protectagainst free radical damage. Acute exercise may result in the increased generation of freeradicals, including reactive oxygen species, and this may overwhelm antioxidant defencesystems resulting in oxidative stress. However, it has been shown that individuals whoundergo regular exercise training may have improved antioxidant capacity when comparedto sedentary controls. Results from research regarding the association betweenantioxidant capacity and exercise training are however not conclusive and furtherinvestigation is required. Therefore, the aim of this study was to investigate the associationbetween the total plasma antioxidant status and selected plasma indicators of antioxidantstatus and the MnSOD Ala-9Val (-28C®T) polymorphism in trained male athletes (rugbyplayers) and sedentary male students while controlling for dietary intake of the majorantioxidants using a validated dietary assessment method.In order to address the potential confounding effect of dietary antioxidant intake onantioxidant status in the main study, a FFQ that measures vitamin C, vitamin E, carotenoidand flavonoid intake was developed. The reproducibility was assessed by the repeatadministration of the FFQ (n = 38), while the va lidity was assessed using a 28-day closeendeddietary record and repeated plasma vitamin C values (n = 18). Several statisticaltests were conducted to compare the values obtained from the FFQ with values obtainedfrom the various reference methods. While results from Bland-Altman plots suggested thatthe reproducibility and validity of FFQ was not completely satisfactory, similar mean values,moderate to strong correlation coefficients, and a high percentage of individuals classifiedcorrectly according to quartiles of intake indicated satisfactory reproducibility and validity ofthe FFQ in assessing antioxidant intake. Furthermore, moderate to strong validitycoefficients obtained from the method of triads also indicated satisfactory validity for theFFQ.The main study involved a cross-sectional study that compared plasma vitamin C andcarotenoid 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 controllingfor dietary antioxidant intake. Rugby players had significantly higher plasma vitamin C andcarotenoid levels compared to sedentary students, which indicated more satisfactoryplasma 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 totalantioxidant status, with or without control for dietary antioxidant intake. Dietary vitamin C,vitamin E, carotenoid an flavonoid intake (from foods + supplements) was similar for rugbyplayers and sedentary students and was adequate for both groups. Thus the associationbetween antioxidant status and MnSOD genotype in rugby players and sedentary studentsseemed not to be influenced by dietary antioxidant intake. In conclusion therefore, rugbyplayers undergoing regular exercise training had a more satisfactory antioxidant statuscompared to sedentary students. Based on this conclusion, the widespread use ofantioxidant supplements by athletes is questioned.

[发布机构] Stellenbosch University