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 .
Prospective association of 25-hydroxyvitamin d3 and d2 with childhood lung function, asthma, wheezing, and flexural dermatitis.
BACKGROUND Higher serum total 25-hydroxyvitamin D ( 25(OH)D ) concentrations have been associated with better lung function and lower risk of allergic disease . 25(OH)D3 constitutes the majority of total 25(OH)D and has been suggested to be more potent than 25(OH)D2 . We studied the prospect i ve associations of 25(OH)D2 and 25(OH)D3 with asthma , wheezing , flexural dermatitis , and lung function in children who participated in the Avon Longitudinal Study of Parents and Children-a population -based contemporary birth cohort of children born in 1991 - 1992 from South West Engl and . METHODS Serum 25(OH)D2 and 25(OH)D3 concentrations , measured at a mean age of 9.8 years , were related to incident cases of wheezing ( study sample : n = 3,323 , 141 cases ; 4 % ) , asthma ( n = 3,323 , 464 cases ; 14 % ) , and flexural dermatitis ( n = 3,748 , 300 cases ; 8 % ) , as well as lung function ( forced expiratory volume in 1 second [ FEV1 ] , forced vital capacity [ FVC ] , and mid-forced expiratory flow assessed at a mean age of 15.5 years : n = 2,259 ) . RESULTS 25(OH)D2 was inversely associated with flexural dermatitis ( adjusted odds ratio per doubling of exposure = 0.83 [ 95 % confidence interval = 0.72 - 0.94 ] ) and wheezing ( 0.83 [ 0.68 - 1.00 ] ) , and 25(OH)D3 was positively associated with flexural dermatitis ( 1.09 [ 1.00 - 1.18 ] ) and wheezing ( 1.14 [ 1.03 - 1.28 ] ) . 25(OH)D2 was weakly positively associated with FEV1 , and FVC . 25(OH)D3 was not associated with lung function . CONCLUSIONS These results suggest that higher 25(OH)D3 concentrations are associated with increased risk of wheezing and flexural dermatitis . Despite being one of the few prospect i ve studies and being able to adjust for confounders , these findings need replication . Our results do not provide strong evidence that lower concentrations of vitamin D are detrimental to  respiratory and allergic health in children
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 .