Vitamin D supplementation decrease asthma exacerbations in children: a systematic review and meta-analysis of randomized controlled trials

Background: Observational studies have linked low vitamin D (VD) levels to increased asthma attacks in children. Subsequent meta-analyses of adults and children revealed that VD treatment might benefit asthmatic patients by reducing the incidence of exacerbations. Therefore, this review aims to analyze the effects of VD supplementation in reducing asthma exacerbations in children. Methods: Published reports from PubMed, Cochrane, and Google Scholar were systematically searched until April 2023. The study protocol was registered in the PROSPERO database CRD42023411796. Randomized controlled trial studies were included in this review. Meta-analysis was performed using Cochrane RevMan 5.1 and presented with 95% confidence intervals (CIs). Results: Ten relevant studies enrolled 1243 asthmatic children (631 children receiving vitamin D3 supplementation, 612 children receiving placebo) were included in this review. Our pooled analysis found that VD supplementation had a significant effect on lowering the total number of asthma exacerbations (RR 0.62; 95% CI: 0.44, 0.87; p = 0.01). Subgroup analysis revealed that a daily dose of VD given based on standard daily dose recommendation had a significant improvement on asthma exacerbations [(RR 0.41; 95% CI: 0,18, 0,92; p = 0.03). Conclusions: Vitamin D supplementation can lower the occurrence of exacerbations in children with asthma, along with the improvement of FEV1.