Meta- analysis of a modest number of trials in people with predominantly mild to moderate asthma suggests that vitamin D is likely to reduce both the risk of severe asthma exacerbation and healthcare use .
Children and people with frequent severe asthma exacerbations were under-represented ; additional primary trials are needed to establish whether vitamin D can reduce the risk of severe asthma exacerbation in these groups
BACKGROUND Several clinical trials of vitamin D to prevent  asthma exacerbation  and improve  asthma control  have been conducted in children and adults , but a meta- analysis restricted to double-blind , r and omised , placebo-controlled trials of this intervention is lacking .
OBJECTIVES To evaluate the efficacy of administration of vitamin D and its hydroxylated metabolites in reducing the risk of severe asthma exacerbations ( defined as those requiring treatment with systemic corticosteroids ) and improving asthma symptom control .
Vitamin D reduces eosinophilic airway inflammation in nonatopic asthma.
BACKGROUND Low levels of vitamin D are associated with asthma severity , airway remodeling , and exacerbation rate increase , especially in nonatopic asthma . Reduced steroid responsiveness or impaired antimicrobial defense might be underlying mechanisms . OBJECTIVE We sought to evaluate the effect of vitamin D supplementation on eosinophilic and neutrophilic airway inflammation in patients with nonatopic asthma . METHODS In a double-blind , r and omized , placebo-controlled trial , we investigated the effect of long-acting vitamin D3 ( 400,000 IU ) on sputum neutrophils and eosinophils in 44 patients with nonatopic asthma with neutrophilic ( ≥53 % ) and /or eosinophilic ( ≥3 % ) airway inflammation . Sputum induction was performed at baseline and after 9 weeks . Other measurements included question naires , blood sample s , and pulmonary function . RESULTS Treatment with vitamin D did not significantly affect sputum neutrophils or eosinophils compared with treatment with placebo in the total group . Regarding sputum eosinophils , the effect of vitamin D appeared to be dependent on baseline sputum eosinophil levels ( interaction P = .015 ) . In patients with eosinophil levels  of 26.2 % or more ( median in patients with sputum eosinophilia , > 3 % ) , eosinophils decreased from a median of 41.0 % to 11.8 % after vitamin D treatment as compared with an increase from 51.8 % to 63.3 % in patients receiving placebo ( P = .034 ) . Vitamin D treatment also result ed in slightly better Asthma Control Question naire scores ( P = .08 ) . CONCLUSIONS Vitamin D supplementation  reduced eosinophilic airway inflammation in patients with nonatopic asthma with severe eosinophilic airway inflammation , but did not affect sputum neutrophils . Also , a small effect on asthma control was observed . These findings suggest that vitamin D might have potential as an add-on treatment option in eosinophilic asthma
Meta- analysis of a modest number of trials in people with predominantly mild to moderate asthma suggests that vitamin D is likely to reduce both the risk of severe asthma exacerbation and healthcare use .
Children and people with frequent severe asthma exacerbations were under-represented ; additional primary trials are needed to establish whether vitamin D can reduce the risk of severe asthma exacerbation in these groups
BACKGROUND Several clinical trials of vitamin D to prevent  asthma exacerbation  and improve  asthma control  have been conducted in children and adults , but a meta- analysis restricted to double-blind , r and omised , placebo-controlled trials of this intervention is lacking .
OBJECTIVES To evaluate the efficacy of administration of vitamin D and its hydroxylated metabolites in reducing the risk of severe asthma exacerbations ( defined as those requiring treatment with systemic corticosteroids ) and improving asthma symptom control .