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 .
Annual high-dose vitamin D3 and mental well-being: randomised controlled trial.
BACKGROUND Epidemiological evidence supports a relationship between vitamin D and mental well-being , although evidence from large-scale placebo-controlled intervention trials is lacking . AIMS To examine if vitamin D supplementation has a beneficial effect on mood in community-dwelling older women ; if a single annual large dose of vitamin D has a role in the prevention of depressive symptoms ; and if there is an association between serum 25-hydroxyvitamin D levels and mental health . METHOD A double-blind , r and omised , placebo-controlled trial of women aged 70 or older ( the Vital D Study : IS RCT N83409867 and ACTR12605000658617 ) . Participants were r and omly assigned to receive 500 000 IU vitamin D(3 ) ( cholecalciferol ) orally or placebo every autumn/winter for 3 - 5 consecutive years . The tools utilised at various time points were the General Health Question naire , the 12-item Short Form Health Survey , the Patient Global Impression-Improvement scale and the WHO Well-Being Index . Serum 25-hydroxyvitamin D levels were measured in a subset of 102 participants . RESULTS In this non- clinical population , no significant differences between the vitamin D and placebo groups were detected in any of the measured outcomes of mental health . Serum 25-hydroxyvitamin D levels in the vitamin D group were 41 % higher than the placebo group 12 months following their annual dose . Despite this difference , scores from the question naires did not differ . Furthermore , there was no interaction between those on antidepressant/anxiety medication at baseline and the treatment groups . CONCLUSIONS The lack of improvement in indices of mental well-being in the vitamin D group does not support the hypothesis that an annual high dose of vitamin D(3 ) is a practical intervention to prevent depressive symptoms in older community-dwelling women
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 .