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 .
Correlation of vitamin D with Foxp3 induction and steroid-sparing effect of immunotherapy in asthmatic children.
BACKGROUND Vitamin D promotes different toleragenic processes of the immune system ; however , its role in allergen specific immunotherapy ( SIT ) is still undefined . OBJECTIVE To determine whether the immunologic and clinical effectiveness of allergen SIT depends on the serum level of 25-hydroxyvitamin D ( 25[OH]D ) and its changes during SIT in asthmatic children . METHODS This is a retrospective secondary analysis of pooled data obtained from our 2 recently published prospect i ve , r and omized , placebo-controlled trials on asthmatic children undergoing allergen immunotherapy .  Both trials , which assessed the effect of different pharmacologic modulation of SIT effectiveness , were conducted according to the same study protocol . Children from the placebo arms in these trials were treated with immunotherapy only and were included in the present analysis . The study population consisted of 36 children . Data concerning clinical ( asthma symptoms score and percent change in minimal daily inhaled corticosteroid dose ) and immunologic parameters ( including serum level of 25[OH]D ) were analyzed in all patients . RESULTS Patients with a higher serum level of 25(OH)D experienced more significant reduction in asthma symptoms score and steroid-sparing effect of SIT and had higher transforming growth factor â production and higher Foxp3 induction during SIT . Steroid-sparing effect correlated with 25(OH)D serum level at baseline , after 3 months of SIT , and with the changes in serum level of 25(OH)D during the build-up phase of SIT . Better response to SIT was observed among children with an 25(OH)D serum level higher than 30 ng/mL. CONCLUSION The efficacy of allergen SIT correlates with 25(OH)D serum concentration . It seems that a serum level of 25(OH)D higher than 30 ng/mL facilitates the optimal effect of allergen immunotherapy
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 .