Subgroup analyses in the observational studies indicated that risk of mortality was significantly higher in studies with lower baseline use of vitamin D supplements .
The effects observed for vitamin D3 supplementation remained unchanged when grouped by various characteristics .
However , for vitamin D2 supplementation , increased risks of mortality were observed in studies with lower intervention doses and shorter average intervention periods .
Conclusions Evidence from observational studies indicates inverse associations of circulating 25-hydroxyvitamin D with risks of death due to cardiovascular disease , cancer , and other causes .
Objective To evaluate the extent to which circulating biomarker and supplements of vitamin D are associated with  mortality from cardiovascular , cancer , or other conditions  , under various circumstances .
Prevention of bone loss by vitamin D supplementation in elderly women: a randomized double-blind trial.
The purpose of the study was to determine the effect of vitamin D supplementation on bone turnover and bone loss in elderly women . Three hundred forty-eight women , ages 70 yr and older , were r and omized to receive 400 IU vitamin D3 per day ( n = 177 ) or placebo ( n = 171 ) , double-blind , for a period of 2 yr . Main outcome measures were bone mineral density of both hips ( femoral neck and trochanter ) and the distal radius , as well as biochemical markers of bone turnover . The effect of vitamin D supplementation was expressed as the difference in mean ( percentage ) change between the placebo group and the vitamin D group . The measurements were repeated in 283 women after 1 yr and in 248 women after 2 yr . Vitamin D supplementation significantly increased serum 25-hydroxyvitamin D ( 250HD ) ( + 35 nmol/L ) and 1,25-dehydroxyvitamin D [ 1,25-(OH)2D ] ( + 7.0 pmol/L ) levels and urinary calcium/creatinine ratios ( + 0.5 % ) and significantly decreased PTH(1 - 84 ) secretion ( -0.74 pmol/L ) after 1 yr . No effect was found for the parameters of bone turnover . The effect on the bone mineral density of the left femoral neck was + 1.8 % in the first yr , + 0.2 % in the second yr , and + 1.9 % during the whole period ( 95 % confidence interval 0.4 , 3.4 % ) . At the right femoral neck the effects were + 1.5 % , + 1.1 % , and + 2.6 % ( confidence interval 1.1 , 4.0 % ) , respectively . No effect was found at the femoral trochanter and the distal radius . Supplementation with 400 IU vitamin D3 daily in elderly women slightly decreases PTH secretion and increases bone mineral density at the femoral neck
Subgroup analyses in the observational studies indicated that risk of mortality was significantly higher in studies with lower baseline use of vitamin D supplements .
The effects observed for vitamin D3 supplementation remained unchanged when grouped by various characteristics .
However , for vitamin D2 supplementation , increased risks of mortality were observed in studies with lower intervention doses and shorter average intervention periods .
Conclusions Evidence from observational studies indicates inverse associations of circulating 25-hydroxyvitamin D with risks of death due to cardiovascular disease , cancer , and other causes .
Objective To evaluate the extent to which circulating biomarker and supplements of vitamin D are associated with  mortality from cardiovascular , cancer , or other conditions  , under various circumstances .