Vitamin D and atopic dermatitis: A systematic review and meta-analysis

Objectives: Despite the evidence supporting the use of vitamin D supplements for managing atopic dermatitis (AD), no meta-analysis providing definite conclusions in this field has been reported. The purpose of the present study was to conduct a systematic review and meta-analysis of all controlled studies of vitamin D for treating AD to elucidate the efficacy of vitamin D for alleviating the symptoms of AD. Methods: Literature searches were conducted using Ovid-MEDLINE, EMBASE, Web of Science, Cochrane Library, and Korean and Chinese databases. Search terms used were "vitamin D", "atopic dermatitis", "randomized", "controlled trial", and "clinical trial". Random effects models were used to calculate the mean difference, with 95% confidence intervals to analyze the effects of vitamin D supplementation for severity of AD. Results: Initial searches yielded 266 citations. Of these original results, nine met specific selection criteria. Four of the randomized controlled trials compared the efficacy of vitamin D with a placebo on severity of AD and were included in the meta-analysis. The vitamin D supplementation interventions showed a higher mean difference in severity of AD symptoms (mean difference = -5.81, 95% CI: -9.03 to -2.59, P = 0.0004, I-2 = 50%). Conclusions: Vitamin D has a potentially significant role for improving the symptoms of AD. The results from this study suggest that vitamin D supplementation may help ameliorate the severity of AD, and can be considered as a safe and tolerable therapy. However, larger-scale studies over a longer duration of treatment are needed to confirm this conclusion. (C) 2016 Elsevier Inc. All rights reserved.