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 .
Annual high-dose oral vitamin D and falls and fractures in older women: a randomized controlled trial.
CONTEXT Improving vitamin D status may be an important modifiable risk factor to reduce falls and fractures ; however , adherence to daily supplementation is typically poor . OBJECTIVE To determine whether a single annual dose of 500,000 IU of cholecalciferol administered orally to older women in autumn or winter would improve adherence and reduce the risk of falls and fracture . DESIGN , SETTING , AND PARTICIPANTS A double-blind , placebo-controlled trial of 2256 community-dwelling women , aged 70 years or older , considered to be at high risk of fracture were recruited from June 2003 to June 2005 and were r and omly assigned to receive cholecalciferol or placebo each autumn to winter for 3 to 5 years . The study concluded in 2008 . INTERVENTION 500,000 IU of cholecalciferol or placebo . MAIN OUTCOME MEASURES Falls and fractures were ascertained using monthly calendars ; details were confirmed by telephone interview . Fractures were radiologically confirmed . In a sub study , 137 r and omly selected participants underwent serial blood sampling for 25-hydroxycholecalciferol and parathyroid hormone levels . RESULTS Women in the cholecalciferol ( vitamin D ) group had 171 fractures vs 135 in the placebo group ; 837 women in the vitamin D group fell 2892 times ( rate , 83.4 per 100 person-years ) while 769 women in the placebo group fell 2512 times ( rate , 72.7 per 100 person-years ; incidence rate ratio [ RR ] , 1.15 ; 95 % confidence interval [ CI ] , 1.02 - 1.30 ; P = .03 ) . The incidence RR for fracture in the vitamin D group was 1.26 ( 95 % CI , 1.00 - 1.59 ; P = .047 ) vs the placebo group ( rates per 100 person-years , 4.9 vitamin D vs 3.9 placebo ) . A temporal pattern was observed in a post hoc analysis of falls . The incidence RR of falling in the vitamin D group vs the placebo group was 1.31 in the first 3 months after dosing and 1.13 during the following 9 months ( test for homogeneity ; P = .02 ) . In the sub study , the median baseline serum 25-hydroxycholecalciferol was 49 nmol/L. Less than 3 % of the sub study participants had 25-hydroxycholecalciferol levels lower than 25 nmol/L. In the vitamin D group , 25-hydroxycholecalciferol levels increased at 1 month after dosing to approximately 120 nmol/L , were approximately 90 nmol/L at 3 months , and remained higher than the placebo group 12 months after dosing . CONCLUSION Among older community-dwelling women , annual oral administration of high-dose cholecalciferol result ed in an increased risk of falls and fractures . TRIAL REGISTRATION anzctr.org.au Identifier : ACTRN12605000658617 ; is rct n.org Identifier : IS RCT N83409867
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 .