Modulation of UV-light-induced skin inflammation by d-alpha-tocopherol and l-ascorbic acid: a clinical study using solar simulated radiation

Objective: In this clinical trial we studied whether oral supplementation with d-alpha-tocopherol (α-Toc), l-ascorbic acid (Asc), or α-Toc combined with Asc influenced the solar simulated radiation (SSR) induced skin inflammation in healthy volunteers. Methods: We investigated the following groups in a prospective, randomized and placebo controlled study: Group (1) α-Toc 2 g / day, group (2) Asc 3 g / day, group (3) α-Toc 2 g / day combined with Asc 3 g / day, and group (4) placebo. Before and 50 days after supplementation we analyzed α-Toc and Asc concentrations in keratinocytes. The dose response curve of UV erythema was determined by reflectance spectrophotometry and the minimal erythema dose (MED) by visual grading before and after supplementation. Results: 50 days after supplementation α-Toc keratinocyte levels were increased in groups (1) and (3), Asc concentrations were elevated in groups (2) and (3), and the a/γ-Toc ratio increased in groups (1) and (3). The dose response curve of UVR induced erythema showed a significant flattening and the MED increased from 103 ± 29 mJ/cm2 (before supplementation) to 183 ± 35 mJ/cm2 (after supplementation) in group (3), while there were no significant changes in groups (1) and (2) after vitamin supplementation. Conclusion: α-Toc and Asc act synergistically in suppression of the sunburn reaction.