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 .
Prospective study of serum 25-hydroxyvitamin D level, cardiovascular disease mortality, and all-cause mortality in older U.S. adults.
OBJECTIVES To evaluate the association between serum 25-hydroxyvitamin D ( 25(OH)D ) levels and mortality in a representative U.S. sample of older adults . DESIGN Prospect i ve cohort from the Third National Health and Nutrition Examination Survey ( NHANES III ) and linked mortality files . SETTING Noninstitutionalized U.S. civilian population . PARTICIPANTS Three thous and four hundred eight NHANES III participants aged 65 and older enrolled from 1988 to 1994 and followed for mortality through 2000 . MEASUREMENTS Primary exposure was  serum 25(OH)D level  at enrollment . Primary and secondary outcomes were all-cause and cardiovascular disease ( CVD ) mortality , respectively . RESULTS During the median 7.3 years of follow-up , there were 1,493 ( 44 % ) deaths , including 767 CVD-related deaths . Median 25(OH)D level was 66 nmol/L. Adjusting for demographics , season , and cardiovascular risk factors , baseline 25(OH)D levels were inversely associated with all-cause mortality risk ( adjusted hazard ratio (HR)=0.95 , 95 % confidence interval (CI)=0.92 - 0.98 , per 10 nmol/L 25[OH]D ) . Compared with subjects with 25(OH)D levels of 100 nmol/L or higher , the adjusted HR for subjects with levels less than 25.0 nmol/L was 1.83 ( 95 % CI=1.14 - 2.94 ) and for levels of 25.0 to 49.9 nmol/L was 1.47 ( 95 % CI=1.09 - 1.97 ) . The association appeared stronger for CVD mortality ( adjusted HR=2.36 , 95 % CI=1.17 - 4.75 , for subjects with 25[OH]D levels<25.0 nmol/L vs those > or = 100.0 nmol/L ) than for non-CVD mortality ( adjusted HR=1.42 , 95 % CI=0.73 - 2.79 , for subjects with 25[OH]D levels<25.0 nmol/L vs those > or = 100.0 nmol/L ) . CONCLUSION In noninstitutionalized older adults , a group at high risk for all-cause mortality , serum 25(OH)D levels had an independent , inverse association with CVD and all-cause mortality . R and omized controlled trials of vitamin D supplementation in older adults are warranted to determine whether this association is causal and reversible
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 .