The evidence shows that vitamin D supplementation provides some benefit in fracture prevention ( likely ∼10–15 % relative reduction ) , particularly at a dose ≥800 IU and with calcium ; a likely benefit in the rate of falls , though it is less clear whether the number of fallers changes ; and a possible small ( ∼5 % ) relative reduction in mortality .
Evidence does not support the use of vitamin D supplementation for the prevention of cancer , respiratory infections or rheumatoid arthritis .
Similarly , evidence does not support vitamin D supplementation for the treatment of multiple sclerosis and rheumatoid arthritis or for improving depression/mental well-being .
Regular testing of 25-hydroxyvitamin D is generally not required , and mega-doses ( ≥300,000 IU ) appear to increase harms .
Over the past decade , a large body of observational evidence has suggested an association between  lower vitamin D status ( 25-hydroxyvitamin D ) and multiple acute and chronic disorders , including cancer , multiple sclerosis , depression and respiratory tract infections .
This evidence has fostered the hypothesis that increasing vitamin D intake may treat and prevent such disorders .
Our objective was to perform a critical analysis of the highest-level evidence for ten common beliefs regarding vitamin D for the prevention of falls , fractures and respiratory tract infections , the reduction of cancer incidence/mortality and overall mortality , and the prevention or treatment of depression/mental well-being , rheumatoid arthritis and multiple sclerosis , as well as maximum dosing and regular testing .
Effect of annual intramuscular vitamin D on fracture risk in elderly men and women--a population-based, randomized, double-blind, placebo-controlled trial.
OBJECTIVES Low trauma fractures in older people incur enormous physical , social and economic costs . Previous research indicates that an annual intramuscular injection of vitamin D may reduce fracture rates in this group . This strategy requires validation in a population setting . METHODS R and omized , double-blind , placebo-controlled trial of 300,000 IU intramuscular ( i.m . ) vitamin D2 ( ergocalciferol ) injection or matching placebo every autumn over 3 years . 9440 people ( 4354 men and 5086 women ) aged 75 yrs and over were recruited from general practice registers in Wessex , Engl and . Primary outcome measure was all non-vertebral fracture . Secondary outcomes were hip and wrist fractures , and all falls . RESULTS 585 subjects had incident non-spine fractures  ( hip 110 , wrist 116 , ankle 37 ) . Hazard ratios ( HRs ) for fracture in the vitamin D group were : 1.09 [ 95 % confidence interval ( CI ) 0.93 - 1.28 , P = 0.29 ] for any first fracture , 1.49 ( 95 % CI 1.02 - 2.18 , P = 0.04 ) for hip and 1.22 ( 95 % CI 0.85 - 1.76 , P = 0.28 ) for wrist . There was no effect on falls : HR 0.98 ( 0.93 - 1.04 ) . No protective effect was observed in any subgroup when the cohort was stratified by sex , age , previous fracture or mobility . CONCLUSIONS An annual i.m . injection of 300,000 IU vitamin D2 is not effective in preventing non-vertebral fractures among elderly men and women resident in the general population
The evidence shows that vitamin D supplementation provides some benefit in fracture prevention ( likely ∼10–15 % relative reduction ) , particularly at a dose ≥800 IU and with calcium ; a likely benefit in the rate of falls , though it is less clear whether the number of fallers changes ; and a possible small ( ∼5 % ) relative reduction in mortality .
Evidence does not support the use of vitamin D supplementation for the prevention of cancer , respiratory infections or rheumatoid arthritis .
Similarly , evidence does not support vitamin D supplementation for the treatment of multiple sclerosis and rheumatoid arthritis or for improving depression/mental well-being .
Regular testing of 25-hydroxyvitamin D is generally not required , and mega-doses ( ≥300,000 IU ) appear to increase harms .
Over the past decade , a large body of observational evidence has suggested an association between  lower vitamin D status ( 25-hydroxyvitamin D ) and multiple acute and chronic disorders , including cancer , multiple sclerosis , depression and respiratory tract infections .
This evidence has fostered the hypothesis that increasing vitamin D intake may treat and prevent such disorders .
Our objective was to perform a critical analysis of the highest-level evidence for ten common beliefs regarding vitamin D for the prevention of falls , fractures and respiratory tract infections , the reduction of cancer incidence/mortality and overall mortality , and the prevention or treatment of depression/mental well-being , rheumatoid arthritis and multiple sclerosis , as well as maximum dosing and regular testing .