Antioxidant supplementation enhances neutrophil oxidative burst in trained runners following prolonged exercise

The influence of an antioxidant vitamin supplement on immune cell response to prolonged exercise was determined using a randomized, double-blind, placebo-controlled, cross-over study. Twelve healthy endurance subjects (n = 6 male, n = 6 female; mean +/- SD for age, 30.1 +/- 6.2 yr; height, 1.76 +/- 7 m; body mass, 72.2 +/- 10.2 kg; VO2max, 63.7 +/- 12 ml x kg(-1) x min(-1)) participated in the study. Following a 3-week period during which subjects ingested a multivitamin and -mineral complex sufficient to meet the recommended daily allowance, they took either a placebo or an antioxidant vitamin supplement (containing 18 mg beta-carotene, 900 mg vitamin C, and 90 mg vitamin E) for 7 days prior to a 2-h treadmill run at 65% VO2max. Blood samples were drawn prior to and immediately following exercise. These were analyzed for neutrophil oxidative burst activity, cortisol and glucose concentrations, and white blood cell counts, as well as serum anti-oxidant vitamin concentrations. Plasma vitamin C, vitamin E, and beta-carotene concentrations significantly increased following 7-day supplementation (p < .05). In comparison to the placebo group, neutrophil oxidative burst was significantly higher following exercise (p < .05), but no differences were found in any other parameter following the 7-day supplementation period. Although the impact of exercise on neutrophil function is multifactorial, our data suggest that antioxidant supplementation may be of benefit to endurance athletes for the maintenance of this particular function of the innate immune system following the 7-day supplementation period.