Effects of Vitamin D levels and supplementation on atopic dermatitis: A systematic review

Background Atopic dermatitis (AD) is a chronic inflammatory skin condition affecting 5%-20% of children worldwide. Studies suggested both a correlation between serum vitamin D (VD) levels and AD severity and a therapeutic potential role for VD supplementation. Objectives Data Sources To determine whether serum VD levels correlate with AD severity and the effects of supplementation for disease improvement in children. Ovid MEDLINE, EMBASE, and Cochrane Library databases were searched. Study Selection Data Extraction Publications with children 0-18 years old with AD and data evaluating effects of VD levels or supplementation on AD severity were included. Author, year, inclusion criteria, study design, location, age, VD levels, VD supplementation regimens, and baseline and final disease severities were extracted. Results Limitations Of the 21 included publications, 15, 5, and 1 evaluated VD level, VD supplementation, and both factors with disease severity, respectively. There were 4 randomized control trials (RCTs), 5 cohort, 6 case-control, and 6 cross-sectional studies. A significant inverse correlation between VD level and severity was described in 62.5% (10/16) of studies. There were 67% (4/6) that reported a significant improvement in AD severity with supplementation. Studies meeting inclusion criteria were limited. Furthermore, papers were heterogeneous in terms of location, season, and VD supplementation regimen. Language and publication bias was another potential limitation. Conclusion In children, the majority of existing literature confirmed a link between serum VD levels and AD severity. Weak evidence was found supporting improvement of AD with VD supplementation. Future large-scale studies are needed to support our findings.