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 .
Low serum 25-hydroxyvitamin D levels are associated with increased all-cause mortality risk in a general population: the Tromsø study.
OBJECTIVE Ecologic and observational studies have suggested an association between serum 25-hydroxyvitamin D ( 25(OH)D ) levels and cardiovascular disease ( CVD ) risk factors , CVD mortality , and cancer mortality . Based on this , low serum 25(OH)D levels should be associated with higher all-cause mortality in a general population . This hypothesis was tested in the present study . DESIGN The Tromsø study is a longitudinal population -based multi purpose study initiated in 1974 with focus on lifestyle-related diseases . Our data are based on the fourth Tromsø study carried out in 1994 - 1995 . METHODS Information about death and cause of death was registered by obtaining information from the National Directory of Residents and the Death Cause Registry .  Serum 25(OH)D  was measured in 7161 participants in the fourth Tromsø study . Results are presented for smokers ( n=2410 ) and non-smokers ( n=4751 ) separately as our immunoassay seems to overestimate 25(OH)D levels for smokers . RESULTS During a mean 11.7 years of follow-up , 1359 ( 19.0 % ) participants died . In multivariate regression models , there was a significantly increased risk of all-cause mortality ( hazard ratio ( HR ) 1.32 , confidence interval ( CI ) 1.07 - 1.62 ) among non-smoking participants in the lowest 25(OH)D quartile when compared with participants in the highest quartile . Equivalent results for smokers were not significant ( HR 1.06 , CI 0.83 - 1.35 ) . CONCLUSIONS Low serum 25(OH)D levels were associated with increased all-cause mortality for non-smokers , but the results did not reach statistical significance for smokers . However , low 25(OH)D levels are known to be associated with impaired general health , and r and omized controlled studies are needed to address the question of causality
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 .