Protective effect against sunburn of combined systemic ascorbic acid (vitamin C) and d-α-tocopherol (vitamin E)

Background: UV radiation causes acute adverse effects like sunburn, photosensitivity reactions, or immunologic suppression, as well as long-term sequelae like photoaging or malignant skin tumors. UV radiation induces tissues to produce reactive oxygen species, eicosanoids and cytokines. Inhibition of these mediators might reduce skin damage. Antioxidants such as ascorbic acid and d-alpha-tocopherol have been found to be photoprotective in some in vitro studies and animal experiments. Objective: Our purpose was to assess the protective effect of systemic vitamins C and E against sunburn in human beings. Methods: In a double-blind placebo-controlled study, each of 10 subjects took daily either 2 gm of ascorbic acid (vitamin C) combined with 1000 lU of d-alpha-tocopherol (vitamin E) or placebo. The sunburn reaction before and after 8 days of treatment was assessed by determination of the threshold UV dose for eliciting sunburn (minimal erythema dose [MED]) and by measuring the cutaneous blood flow of skin irradiated with incremental UV doses against that of nonirradiated skin. Results: The median MED of those taking vitamins increased from 80 to 96.5 mJ/cm(2) (p < 0.01), whereas it declined from 80 to 68.5 mJ/cm(2) in the placebo group. Cutaneous blood flow changed significantly (p < 0.05) for most irradiation doses with decreases in those given vitamins and increases in the placebo group. Conclusion: Combined vitamins C and E reduce the sunburn reaction, which might indicate a consequent reduced risk for later sequelae of UV-induced skin damage. The increase of sunburn reactivity in the placebo group could be related to "priming" by the previous UV exposure.