There was no significant effect for asthma symptom scores and lung function .
Conclusions and Relevance R and omized controlled trials provide some low- quality evidence to support vitamin D supplementation for the reduction of asthma exacerbations .
Importance There is growing evidence that vitamin D plays a role in the pathogenesis of asthma but it is unclear whether supplementation during childhood may improve asthma outcomes .
Objectives The objective of this systematic review and meta- analysis was to evaluate the efficacy and safety of vitamin D supplementation as a treatment or adjunct treatment for asthma .
Serum vitamin D levels and severe asthma exacerbations in the Childhood Asthma Management Program study.
BACKGROUND Asthma exacerbations , most often caused by respiratory tract infections , are the leading causes of asthma morbidity and comprise a significant proportion of asthma-related costs . Vitamin D status might play a role in preventing asthma exacerbations . OBJECTIVES We sought to assess the relationship between serum vitamin D levels and subsequent severe asthma exacerbations . METHODS We measured  25-hydroxyvitamin D levels in sera collected from 1024 children with mild-to-moderate persistent asthma at the time of enrollment in a multicenter clinical trial of children r and omized to receive budesonide , nedocromil , or placebo ( as-needed beta-agonists ) : the Childhood Asthma Management Program . Using multivariable modeling , we examined the relationship between baseline vitamin D levels and the odds of any hospitalization or emergency department visit over the 4 years of the trial . RESULTS Thirty-five percent of all subjects were  vitamin D insufficient , as defined by a level of 30 ng/mL or less 25-hydroxyvitamin D. Mean vitamin D levels were lowest in African American subjects and highest in white subjects . After adjusting for age , sex , body mass index , income , and treatment group , insufficient vitamin D status was associated with a higher odds of any hospitalization or emergency department visit ( odds ratio , 1.5 ; 95 % CI , 1.1 - 1.9 ; P = .01 ) . CONCLUSION Vitamin D insufficiency is common in this population of North American children with mild-to-moderate persistent asthma and is associated with higher odds of severe exacerbation over a 4-year period
There was no significant effect for asthma symptom scores and lung function .
Conclusions and Relevance R and omized controlled trials provide some low- quality evidence to support vitamin D supplementation for the reduction of asthma exacerbations .
Importance There is growing evidence that vitamin D plays a role in the pathogenesis of asthma but it is unclear whether supplementation during childhood may improve asthma outcomes .
Objectives The objective of this systematic review and meta- analysis was to evaluate the efficacy and safety of vitamin D supplementation as a treatment or adjunct treatment for asthma .