Heliotherapy improves vitamin D balance and atopic dermatitis.

BACKGROUND Vitamin D insufficiency during winter is common in the Nordic countries. Heliotherapy (HT) may heal atopic dermatitis (AD) but its effect on vitamin D balance has not been examined. OBJECTIVES To study the effect of HT on serum calcidiol (25-hydroxyvitamin D) concentration and on healing of AD. METHODS Twenty-three adult patients with AD received a 2-week course of HT in the Canary Islands in either January or March 2005. Daily solar ultraviolet (UV) radiation was measured and personal UV exposure calculated as standard erythema doses (SED). Blood samples were taken during HT and during a 1-2 month follow-up. Serum calcidiol concentration was measured by radioimmunoassay. Healing of AD was examined by SCORAD index. RESULTS Before HT 17 (74%) AD patients had vitamin D insufficiency (calcidiol < 50 nmol L(-1)) and four patients high (> 80 nmol L(-1)) serum calcidiol values. The median personal UV dose during the 2-week HT course was 60 SED in the January group and 109 SED in the March group. Serum calcidiol concentration increased significantly in both groups, by 13.4 and 24.0 nmol/L(-1), respectively, and after HT only four (17%) patients had vitamin D insufficiency. SCORAD improved from 34 to 9 in the January HT group and from 30 to 9 in the March group. CONCLUSIONS A 2-week course of HT significantly improved vitamin D balance by increasing serum calcidiol concentration, and caused a marked healing of AD. These parallel positive responses should be taken into account when the benefits of HT are considered.