Evidence for the role of inadequate vitamin D in asthma severity among children.

Asthma is the most common chronic pediatric medical condition in the United States and accounts for significant morbidity, particularly among minority and disadvantaged populations. Hypovitaminosis D is also highly prevalent throughout the developed world, and many of the risk factors for hypovitaminosis D and asthma are the same. Several recent observational studies have documented a correlation between asthma severity and vitamin D levels; however, there is no strong evidence for causality yet.