Vitamin D and lower respiratory tract infection in children: A systematic review and meta-analysis of randomized controlled trials

Background and objectives: Vitamin D has been found to have antimicrobial properties. Studies on vitamin D and lower respiratory tract infection (LRTI) in children have mixed findings. This systematic review aimed to evaluate the effect of vitamin D supplementation for prevention and treatment of LRTI in children. Methods: We searched PubMed, Embase, and Cochrane library for randomized controlled trials (RCTs) concerning vitamin D supplementation and LRTI in children. We extracted data using a structured form and did a meta-analysis using Review Manager version 5. Results: Four studies enrolling a total of 3946 subjects were reviewed, in which vitamin D was used in different doses and for variable duration. Vitamin D supplementation did not reduce the incidence of LRTI (odds ratio, 0.82; 95% confidence interval, 0.47-1.45). Vitamin D did not decrease the time to resolution of LRTI compared with placebo (mean difference, -0.01; 95% confidence interval, -0.56 to 0.54 d). No significant side effects of vitamin D supplementation were seen. Conclusions: The limited number of RCTs on the effect of vitamin D supplementation for prevention and treatment of LRTI in children did not show any beneficial effect. More RCTs are needed to determine the adequate dose, frequency, and duration of vitamin D supplementation and to identify specific groups of children who may benefit from supplementation.