Conclusions Vitamin D supplementation  was safe and it protected against acute respiratory tract infection overall .
Patients who were very vitamin D deficient and those not receiving bolus doses experienced the most benefit .
Objectives To assess the overall effect of vitamin D supplementation on  risk of acute respiratory tract infection  , and to identify factors modifying this effect .
Vitamin D Supplementation Reduces the Risk of Acute Otitis Media in Otitis-prone Children
Background : The aim of this study was to evaluate whether a deficit in vitamin D ( VD ) is associated with an increased risk of recurrent acute otitis media ( AOM ) and whether VD supplementation is effective in reducing the number of AOM episodes in otitis-prone children . Methods : A total of 116 children with a history of recurrent AOM ( ≥3 episodes in preceding 6 months or ≥4 episodes in preceding 12 months ) were prospect ively and blindly r and omized to receive oral VD 1000 IU/d or placebo for 4 months . Episodes of AOM were monitored for 6 months . Results : Fifty-eight children received placebo and 58 with similar characteristics were treated with VD . The number of children experiencing ≥1 AOM episode during the study period was significantly lower in the treatment group ( 26 versus 38 ; P = 0.03 ) . There was a marked difference in the number of children who developed uncomplicated AOM ( P < 0.001 ) , but no difference in the number of children with ≥1 episode of spontaneous otorrhea . The likelihood of AOM was significantly reduced in the patients whose serum VD concentrations were ≥30 ng/mL. Conclusions : VD hypovitaminosis is common in children with recurrent AOM and associated with an increase in the occurrence of AOM when serum 25(OH)D levels are < 30 ng/mL. The administration of VD in a dosage of 1000 IU/d restores serum values of ≥30 ng/mL in most cases and is associated with a significant reduction in the risk of uncomplicated AOM
Conclusions Vitamin D supplementation  was safe and it protected against acute respiratory tract infection overall .
Patients who were very vitamin D deficient and those not receiving bolus doses experienced the most benefit .
Objectives To assess the overall effect of vitamin D supplementation on  risk of acute respiratory tract infection  , and to identify factors modifying this effect .