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 .
Effect of vitamin D supplementation on antibiotic use: a randomized controlled trial.
BACKGROUND Observational data suggested that supplementation with vitamin D could reduce risk of infection , but trial data are inconsistent . OBJECTIVE We aim ed to examine the effect of oral vitamin D supplementation on antibiotic use . DESIGN We conducted a post hoc analysis of data from pilot D-Health , which is a r and omized trial carried out in a general community setting between October 2010 and February 2012 . A total of 644 Australian residents aged 60 - 84 y were r and omly assigned to receive monthly doses of a placebo ( n = 214 ) or 30,000 ( n = 215 ) or 60,000 ( n = 215 ) IU oral cholecalciferol for ≤12 mo . Antibiotics prescribed during the intervention period were ascertained by linkage with pharmacy records through the national health insurance scheme ( Medicare Australia ) . RESULTS People who were r and omly assigned 60,000 IU cholecalciferol had nonsignificant 28 % lower risk of having antibiotics prescribed at least once than did people in the placebo group ( RR : 0.72 ; 95 % CI : 0.48 , 1.07 ) . In analyses stratified by age , in subjects aged ≥70 y , there was a significant reduction in antibiotic use in the high-dose vitamin D compared with placebo groups ( RR : 0.53 ; 95 % CI : 0.32 , 0.90 ) , whereas there was no effect in participants aged < 70 y ( RR : 1.07 ; 95 % CI : 0.58 , 1.97 ) ( P-interaction = 0.1 ) . CONCLUSION Although this study was a post hoc analysis and statistically nonsignificant , this trial lends some support to the hypothesis that supplementation with 60,000 IU vitamin D/mo is associated with lower risk of infection , particularly in older adults . The trial was registered at the Australian New Zeal and Clinical Trials Registry ( anzctr.org.au ) as ACTRN12609001063202
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 .