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 .
Serum vitamin D and falls in older women in residential care in Australia.
OBJECTIVES To determine the prevalence of vitamin D deficiency in older people in residential care and the influence that the level of vitamin D may have on their incidence of falls . DESIGN Prospect i ve cohort . SETTING Residential care facilities for older people in several states of Australia . PARTICIPANTS Six hundred sixty-seven women in low-level care and 952 women in high-level care , mean age 83.7 years . MEASUREMENTS  Serum 25-hydroxyvitamin D ( 25D ) levels and recognized risk factors for falls including current medication use , a history of previous fractures , weight , tibial length ( as a surrogate for height ) , cognitive function , walking ability , and frequency of going outdoors were determined . The women in low-level care and high-level care were followed for an average of 145 and 168 days , respectively . Falls were recorded prospect ively in diaries completed monthly by residential care staff . RESULTS  Vitamin D deficiency ( defined as a serum 25D level below 25 nmol/L ) was present in 144 ( 22 % ) women in low-level care and 428 ( 45 % ) in high-level care . After excluding 358 bed-bound residents and adjusting for weight , cognitive status , psychotropic drug use , previous Colles fracture , and the presence of w and ering behavior , log serum 25D level remained independently associated with time to first fall . The adjusted hazards ratio was 0.74 ( 95 % confidence interval=0.59 - 0.94 ; P=.01 ) , implying a 20 % reduction in the risk of falling with a doubling of the vitamin D level . CONCLUSION Vitamin D deficiency is common in residential care in Australia . A low level of serum vitamin D is an independent predictor of incident falls
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 .