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 .
Prenatal Vitamin D Supplementation and Child Respiratory Health: A Randomised Controlled Trial
Background Observational studies suggest high prenatal vitamin D intake may be associated with reduced childhood wheezing .  We examined the effect of prenatal vitamin D on childhood wheezing  in an interventional study . Methods We r and omised 180 pregnant women at 27 weeks gestation to either  no vitamin D , 800 IU ergocalciferol daily until delivery or single oral bolus of 200,000 IU cholecalciferol  , in an ethnically stratified , r and omised controlled trial . Supplementation improved but did not optimise vitamin D status . Research ers blind to allocation assessed offspring at 3 years . Primary outcome was any history of wheeze assessed by vali date d question naire . Secondary outcomes included atopy , respiratory infection , impulse oscillometry and exhaled nitric oxide . Primary analyses used logistic and linear regression . Results We evaluated 158 of 180 ( 88 % ) offspring at age 3 years for the primary outcome . Atopy was assessed by skin test for 95 children ( 53 % ) , serum IgE for 86 ( 48 % ) , exhaled nitric oxide for 62 ( 34 % ) and impulse oscillometry of acceptable quality for 51 ( 28 % ) . We found no difference between supplemented and control groups in risk of wheeze  [ no vitamin D : 14/50 ( 28 % ) ; any vitamin D : 26/108 ( 24 % ) ( risk ratio 0.86 ; 95 % confidence interval 0.49 , 1.50 ; P = 0.69 ) ] . There was no significant difference in atopy , eczema risk , lung function or exhaled nitric oxide between supplemented groups and controls . Conclusion Prenatal vitamin D supplementation in late pregnancy that had a modest effect on cord blood vitamin D level , was not associated with decreased wheezing in offspring at age three years . Trial Registration Controlled-Trials.com IS RCT
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 .