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 .
Correlation of symptoms with vitamin D deficiency and symptom response to cholecalciferol treatment: a randomized controlled trial.
OBJECTIVE To examine the association of symptoms with vitamin D deficiency and symptom response to cholecalciferol treatment in a r and omized , double-blind , placebo-controlled trial . METHODS Adult primary care patients in Duluth , Minnesota , were screened for vitamin D deficiency in February 2007 . Participants completed question naires pertaining to a variety of symptoms , vitamin D intake , and selected medical conditions . Patients with mild to moderate vitamin D deficiency ( 25-hydroxyvitamin D [ 25(OH)D ] , 10 - 25 ng/mL ) participated in a r and omized controlled trial ( RCT ) of vitamin D replacement and its effect on symptoms . Participants were r and omly assigned to receive 50 000 units of cholecalciferol ( vitamin D3 ) weekly or placebo for 8 weeks . Patients with severe vitamin D deficiency ( 25[OH]D < 10 ng/mL ) were treated in an unblinded fashion , and symptoms were reevaluated post treatment . RESULTS A total of 610 patients underwent initial screening , and 100 patients with mild to moderate vitamin D deficiency participated in the RCT . Thirty-eight severely deficient patients were treated in an unblinded fashion . On initial screening , 46.2 % of participants were deficient in vitamin D. Self-reported vitamin D supplementation , milk intake , celiac disease , gastric bypass , and chronic pancreatitis were predictive of vitamin D status . Severely deficient participants reported increased musculoskeletal symptoms , depression ( including seasonal ) , and higher ( worse ) scores on a fibromyalgia assessment question naire . In the RCT , the treated group showed significant improvement in fibromyalgia assessment scores ( P = 0.03 ) , whereas the placebo-treated participants did not . Severely deficient patients did not show symptom improvement over the 8-week trial period or when followed up 1 year later . CONCLUSIONS Compared with participants in the placebo group , patients in the treatment group showed mild short-term improvement in the overall fibromyalgia impact score , but did not show significant improvement in most musculoskeletal symptoms or in activities of daily living
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 .