Effects of oral vitamin E and ?-carotene supplementation on ultraviolet radiation-induced oxidative stress in human skin

McArdle, Frank, Rhodes, Lesley E., Parslew, Richard A., Close, Graeme L., Jack, Catherine I. A., Friedmann, Peter S. and Jackson, Malcolm J. (2004) Effects of oral vitamin E and ?-carotene supplementation on ultraviolet radiation-induced oxidative stress in human skin. American Journal of Clinical Nutrition, 80 (5), 1270-1275.

Abstract

Background: Ultraviolet radiation (UVR) generates reactive oxygen species in skin that can play a role in skin damage, but reports about the photoprotective properties of oral antioxidant supplements are conflicting.
Objective: We examined the ability of 2 lipid-soluble antioxidants, vitamin E and ß-carotene, to reduce markers of oxidative stress and erythema in human skin exposed to UVR.
Design: Sixteen healthy subjects took either {alpha}-tocopherol (n = 8; 400 IU/d) or ß-carotene (n = 8; 15 mg/d) for 8 wk. Biopsy samples before and after supplementation were taken from unexposed skin and skin 6 h after 120 mJ/cm2 UVR. The effects of supplements on markers of oxidative stress in skin and the minimal erythema dose to UVR were assessed.
Results: Supplementary vitamin E was bioavailable, the plasma concentration increased from 14.0 ± 0.66 ( ± SEM) to 18.2 ± 0.64 µg/mL (P < 0.01), and the skin concentration increased from 0.55 ± 0.09 to 1.6 ± 0.19 ng/mg protein (P < 0.01). Supplementary ß-carotene increased plasma concentrations from 1 ± 0.3 to 2.25 ± 0.3 µg/mL (P < 0.05), but skin concentrations were undetectable. Before vitamin E supplementation, UVR increased the skin malondialdehyde concentration from 0.42 ± 0.07 to 1.24 ± 0.16 nmol/mg protein (P < 0.01), whereas oxidized or total glutathione increased from 9.98 ± 0.4% to 12.0 ± 1.0% (P < 0.05). Vitamin E supplementation significantly decreased the skin malondialdehyde concentration, but neither vitamin E nor ß-carotene significantly influenced other measures of oxidation in basal or UVR-exposed skin.
Conclusions: Vitamin E or ß-carotene supplementation had no effect on skin sensitivity to UVR. Although vitamin E supplements significantly reduced the skin malondialdehyde concentration, neither supplement affected other measures of UVR-induced oxidative stress in human skin, which suggested no photoprotection of supplementation.

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