Supplementation with vitamins C, E, β-carotene and selenium has no effect on anti-oxidant status and immune responses in allergic adults:: a randomized controlled trial

Background Anti-oxidants are of growing interest in early treatment and prevention of allergic diseases in early life, but the effects on allergen-specific immune responses need to be documented further before intervention studies in infants are undertaken. The aim of this study in adults was to determine the effects of dietary anti-oxidants on allergen-specific immune responses in sensitized individuals. Methods In a randomized controlled trial, 54 allergic adults received an anti-oxidant supplement (n=36) comprising beta-carotene (9 mg/day), vitamin C (1500 mg/day), vitamin E (130 mg/day), zinc (45 mg/day), selenium (76 mu g/day) and garlic (150 mg/day) or a placebo (n=18) for 4 weeks. Anti-oxidant capacity (AC), serum levels of vitamin C, vitamin E, beta-carotene and selenium, peripheral blood responses, exhaled nitric oxide (eNO), as a marker of airway inflammation, and plasma F-2 isoprostanes, as a measure of oxidative stress, were measured before and after supplementation. Results Anti-oxidant supplementation resulted in significant increases in serum levels of vitamin C, vitamin E, beta-carotene and selenium levels, compared with the placebo group (P < 0.001). There was no change in serum AC, plasma F-2-isoprostanes, eNO or immune responses following supplementation with anti-oxidants compared with placebo. Conclusion Supplementation with anti-oxidants resulted in significantly increased levels of vitamin C, vitamin E, beta-carotene and selenium but no change in immune responses, serum AC or plasma F-2-isoprostanes.