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 .
Effect of vitamin D and inhaled corticosteroid treatment on lung function in children.
RATIONALE Low vitamin D levels are associated with asthma and decreased airway responsiveness . Treatment with inhaled corticosteroids improves airway responsiveness and asthma control . OBJECTIVES To assess the effect of vitamin D levels on prebronchodilator FEV(1 ) , bronchodilator response , and responsiveness to methacholine ( PC(20 ) , provocative concentration of methacholine producing a 20 % decline in FEV(1 ) ) in patients with asthma treated with inhaled corticosteroids . METHODS We measured  25-hydroxyvitamin D levels  in the serum of children with persistent asthma at the time of enrollment in the Childhood Asthma Management Program . We divided subjects into the vitamin D sufficiency ( > 30 ng/ml ) , insufficiency ( 20 - 30 ng/ml ) , and deficiency ( < 20 ng/ml ) groups . Covariates included age , treatment , sex , body mass index , race , history of emergency department visits , hospitalizations , and season that vitamin D specimen was drawn . Our main outcome measures were change in prebronchodilator FEV(1 ) , bronchodilator response , and PC(20 ) from enrollment to 8 - 12 months . MEASUREMENTS AND MAIN RESULTS Of the 1,024 subjects , 663 ( 65 % ) were vitamin D sufficient , 260 ( 25 % ) were insufficient , and 101 ( 10 % ) were deficient . Vitamin D-deficient subjects were more likely to be older , African American , and have a higher body mass index compared with the vitamin D-sufficient and insufficient subjects . In the inhaled corticosteroid treatment group , prebronchodilator FEV(1 ) increased from r and omization to 12 months by 140 ml in the vitamin D-deficient group and prebronchodilator FEV(1 ) increased by 330 ml in the vitamin D insufficiency group and by 290 ml in the vitamin D sufficiency group ( P = 0.0072 ) , in adjusted models . CONCLUSIONS In children with asthma treated with inhaled corticosteroids , vitamin D deficiency is associated with poorer lung function than in children with vitamin D insufficiency or sufficiency
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 .