Effect of Vitamin D on the Treatment of Atopic Dermatitis With Consideration of Heterogeneities: Meta-Analysis of Randomized Controlled Trials

Various therapeutic approaches, including supplemental nutritional support, have been tried for the treatment of atopic dermatitis (AD). Previous studies have reported the role of vitamin D in the treatment of AD with inconsistent results. The aim of this study was to evaluate the effectiveness of vitamin D in the treatment of AD, with considerations on the heterogeneities of AD. Randomized controlled trials (RCTs) on the efficacy of vitamin D supplementation for AD treatment, published before June 30, 2021 were identified in the PubMed, EMBASE, MEDLINE, and Cochrane Library databases. The quality of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation system. This meta-analysis included 5 RCTs with 304 cases of AD. We found that vitamin D supplementation did not decrease AD severity, even when AD was classified as severe vs non-severe. However, vitamin D supplementation was found to be effective in the treatment of AD in RCTs that included both children and adults, but not in those that included only children. Geographic location was associated with a significant difference in the therapeutic effect of vitamin D supplementation. Moreover, vitamin D supplementation of > 2,000 IU/day decreased AD severity, but supplementation ≤ 2,000 IU/day did not. Vitamin D supplementation, in general, was not effective for the treatment of AD. However, vitamin D supplementation might provide a therapeutic effect depending on the geographic location and dose of supplementation. The results of the present meta-analysis suggest that vitamin D supplementation might be targeted for patients with AD who may benefit from vitamin D supplementation.