title: Vitamin D for prevention of respiratory tract infections: A systematic review and meta-analysis.
abstract: OBJECTIVE
  To explore the effect of vitamin D supplementation in prevention of respiratory tract infections on the basis of published clinical trials.
  
  
  METHODS
  Clinical trials were searched from various electronic databases. Five clinical trials were suitable for inclusion. Outcome was events of respiratory tract infections in vitamin D group and placebo group. Data was reported as odds ratio with 95% confidence interval. Both random and fixed model was used for analysis. Analysis was done with the help of Comprehensive meta-analysis software 2.
  
  
  RESULTS
  Events of respiratory tract infections were significantly lower in vitamin D group as compared to control group [Odds ratio = 0.582 (0.417 - 0.812) P = 0.001] according to random model. Results were similar in fixed model. On separate analysis of clinical trials dealing with groups of children and adults, beneficial effect of vitamin D was observed in both, according to fixed model [Odds ratio = 0.579 (0.416 - 0.805), P = 0.001 and Odd ratio = 0.653 (0.472 - 0.9040, P = 0.010 respectively]. On using random model beneficial effect persisted in children's group but became nonsignificant in adults group [Odds ratio = 0.579 (0.416 - 0.805), P = 0.001 and Odd ratio = 0.544 (0.278 - 1.063) P = 0.075 respectively].
  
  
  CONCLUSIONS
  Vitamin D supplementation decreases the events related to respiratory tract infections. There is need of more well conducted clinical trials to reach to a certain conclusion.
authors: Department of Pharmacology, Govt. Medical College, Rajkot, India.
authors: Jaykaran
authors: J
authors: Charan
authors: Jagdish P
authors: JP
authors: Goyal
authors: Deepak
authors: D
authors: Saxena
authors: Preeti
authors: P
authors: Yadav
keywords: Influenza; pneumonia; prevention; respiratory tract infections; vitamin D