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 .
The effect of vitamin D on airway reactivity and inflammation in asthmatic children: A double-blind placebo-controlled trial.
BACKGROUND Cross-sectional studies have reported an association of vitamin D deficiency with increased asthma prevalence and severity , and with allergies . The effect of vitamin D as sole therapy on airway hyper-reactivity ( AHR ) and airway inflammation has not been reported . AIM To evaluate the effect of vitamin D therapy on AHR as assessed by methacholine concentration , causing a 20 % reduction in FEV1 ( PC20 -FEV1 ) and fractional exhaled nitric oxide ( FeNO ) , systemic markers of allergy and inflammation , and exhaled breath condensate cytokines . PATIENTS AND METHODS Children aged 6 - 18 years with a clinical diagnosis of mild asthma currently not receiving anti-inflammatory therapy and with low vitamin D levels were included in this r and omized , double-blind , placebo-controlled study assessing the effect of 6 weeks of treatment with oral vitamin D 14,000 units once weekly or placebo . RESULTS Of the 39 patients included , 20 received vitamin D treatment and 19 received a placebo . Vitamin D replacement result ed in a significant increase in vitamin levels , which remained unchanged in the placebo group ( P < 0.0001 ) . There was no change in IgE , eosinophil count , high sensitivity C-reactive protein , FeNO levels or PC20 -FEV1 following treatment . Similar values of exhaled breath condensate cytokines ( IL4 , IL5 , IL10 , IL17 , and γ interferon ) were observed in both groups . CONCLUSIONS In our small group of children with mild asthma , no difference could be demonstrated between the effect of vitamin D and placebo , despite significant increases in vitamin D blood levels . Larger interventional studies are needed to fully explore the possible effect of vitamin D in 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 .