Vitamin D and Asthma: Association, Causality, or Intervention?

Many observational studies have investigated the potential association between vitamin D and asthma. However, it is difficult to find a temporal causal relationship in cross-sectional or observational studies. This review presents recent clinical trials and the evidence of association between vitamin D and asthma in different patient populations and asthma status. Well-designed clinical trials are warranted in order to define the optimal level of vitamin D, as well as dosing and duration of vitamin D supplementation, in pediatric patients.