In subgroup analyses , all cause mortality was significantly lower in trials with vitamin D3 supplementation than in trials with vitamin D2 supplementation ( P for interaction=0.04 ) ; neither vitamin D3 nor vitamin D2 was associated with a statistically significant reduction in all cause mortality .
CONCLUSIONS Vitamin D supplementation alone was not associated with  all cause mortality in adults compared with placebo or no treatment .
Vitamin D supplementation reduced the risk of cancer death by 16 % .
Additional large clinical studies are needed to determine whether vitamin D3 supplementation is associated with lower all cause mortality .
OBJECTIVE To investigate whether vitamin D supplementation is associated with lower mortality in adults .
Optimum dose of vitamin D for disease prevention in older people: BEST-D trial of vitamin D in primary care
Summary This trial compared the effects of daily treatment with vitamin D or placebo for 1 year on blood tests of vitamin D status . The results demonstrated that daily 4000 IU vitamin D3 is required to achieve blood levels associated with lowest disease risks , and this dose should be tested in future trials for fracture prevention . Introduction The aim of this trial was to assess the effects of daily supplementation with vitamin D3 4000 IU ( 100 μg ) , 2000 IU ( 50 μg ) or placebo for 1 year on biochemical markers of vitamin D status in preparation for a large trial for prevention of fractures and other outcomes . Methods This is a r and omized placebo-controlled trial in 305 community-dwelling people aged 65 years or older in Oxfordshire , UK . Outcomes included biochemical markers of vitamin D status ( plasma 25-hydroxy-vitamin D [ 25[OH]D ] , parathyroid hormone [ PTH ] , calcium and alkaline phosphatase ) , cardiovascular risk factors and tests of physical function . Results Mean ( SD ) plasma 25(OH)D levels were 50 ( 18 ) nmol/L at baseline and increased to 137 ( 39 ) , 102 ( 25 ) and 53 ( 16 ) nmol/L after 12 months in those allocated 4000 IU , 2000 IU or placebo , respectively ( with 88 % , 70 % and 1 % of these groups achieving the pre-specified level of > 90 nmol/L ) . Neither dose of vitamin D3 was associated with significant deviation outside the normal range of PTH or albumin-corrected calcium . The additional effect on 25(OH)D levels of 4000 versus 2000 IU was similar in all subgroups except for body mass index , for which the further increase was smaller in overweight and obese participants compared with normal-weight participants . Supplementation with vitamin D had no significant effects on cardiovascular risk factors or on measures of physical function . Conclusions After accounting for average 70 % compliance in long-term trials , doses of 4000 IU vitamin D3 daily may be required to achieve plasma 25(OH)D levels associated with lowest disease risk in observational studies
In subgroup analyses , all cause mortality was significantly lower in trials with vitamin D3 supplementation than in trials with vitamin D2 supplementation ( P for interaction=0.04 ) ; neither vitamin D3 nor vitamin D2 was associated with a statistically significant reduction in all cause mortality .
CONCLUSIONS Vitamin D supplementation alone was not associated with  all cause mortality in adults compared with placebo or no treatment .
Vitamin D supplementation reduced the risk of cancer death by 16 % .
Additional large clinical studies are needed to determine whether vitamin D3 supplementation is associated with lower all cause mortality .
OBJECTIVE To investigate whether vitamin D supplementation is associated with lower mortality in adults .