Antioxidants exercise and immune function
While it remains debatable as to whether athletes should take antioxidant supplements, there is some evidence for beneficial effects of high-dose vitamin C supplements (1000 mg/day) on the immune system during prolonged exercise. Fischer et al. (2004) reported that supplementation of
vitamin C (500 mg/day) and vitamin E (400 i.u./day) for 29 days blunted exercise-induced interleukin-6
(a cytokine involved in stimulating immune response) release from contracting human skeletal muscle. A further study investigated the effects of two-week supplementation with vitamin C (1000 mg/day) or a placebo on cortisol, interleukin-6 and neutrophil responses to 2.5 hours of cycling at 60%
VO2 max in nine endurance trained males. All subjects completed both trials utilising a randomized crossover design. While increases in plasma antioxidant capacity and a reduced cortisol response were reported in the vitamin C trial, measures of neutrophil function were significantly lower, suggesting that vitamin C was not effective in protecting against suppression of some aspects of immune function in trained athletes post-exercise (Davision & Gleeson 2006). Athletes may there-fore consider taking vitamin C supplements as an insurance policy in the short-term to protect against illness when dietary intake and availability of fruits and vegetables rich in vitamin C may be restricted, such as when travelling and during competitions (IOC 2010). In terms of other antioxidant potential, the role of quercetin (a plant-derived antioxidant) on the immune system has not been extensively studied. However, one study by Nieman et al; (2007) reported a lower prevalence of URTI in trained cyclists undertaking a period of intensive training – a time when athletes may be more susceptible to colds and infections. While the researchers reported a reduction in illness, no changes in markers of immune system function were observed.
Antioxidants exercise and immune functionWhile it remains debatable as to whether athletes should take antioxidant supplements, there is some evidence for beneficial effects of high-dose vitamin C supplements (1000 mg/day) on the immune system during prolonged exercise. Fischer et al. (2004) reported that supplementation of vitamin C (500 mg/day) and vitamin E (400 i.u./day) for 29 days blunted exercise-induced interleukin-6 (a cytokine involved in stimulating immune response) release from contracting human skeletal muscle. A further study investigated the effects of two-week supplementation with vitamin C (1000 mg/day) or a placebo on cortisol, interleukin-6 and neutrophil responses to 2.5 hours of cycling at 60%VO2 max in nine endurance trained males. All subjects completed both trials utilising a randomized crossover design. While increases in plasma antioxidant capacity and a reduced cortisol response were reported in the vitamin C trial, measures of neutrophil function were significantly lower, suggesting that vitamin C was not effective in protecting against suppression of some aspects of immune function in trained athletes post-exercise (Davision & Gleeson 2006). Athletes may there-fore consider taking vitamin C supplements as an insurance policy in the short-term to protect against illness when dietary intake and availability of fruits and vegetables rich in vitamin C may be restricted, such as when travelling and during competitions (IOC 2010). In terms of other antioxidant potential, the role of quercetin (a plant-derived antioxidant) on the immune system has not been extensively studied. However, one study by Nieman et al; (2007) reported a lower prevalence of URTI in trained cyclists undertaking a period of intensive training – a time when athletes may be more susceptible to colds and infections. While the researchers reported a reduction in illness, no changes in markers of immune system function were observed.
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