There is currently no firm evidence that vitamin D supplementation decreases or increases cancer occurrence in predominantly elderly community-dwelling women .
Vitamin D₃ supplementation  decreased cancer mortality  and vitamin D supplementation  decreased all-cause mortality , but these estimates are at risk of type I errors due to the fact that too few participants were examined , and to risks of attrition bias originating from substantial dropout of participants .
Combined vitamin D₃ and calcium supplements  increased nephrolithiasis , whereas it remains unclear from the included trials whether vitamin D₃ , calcium , or both were responsible for this effect .
BACKGROUND The evidence on whether vitamin D supplementation is effective in decreasing cancers is contradictory .
OBJECTIVES To assess the beneficial and harmful effects of vitamin D supplementation for prevention of cancer in adults .
Effect of discontinuation of estrogen, calcitriol, and the combination of both on bone density and bone markers.
In a 5-yr r and omized prospect i ve study we examined the treatment effect of estrogen replacement therapy/hormone replacement therapy ( ERT/HRT ) , calcitriol , ERT/HRT and calcitriol , or placebo for 3 yr and the effect of discontinuation of therapy for 2 more yr on bone mineral density ( BMD ) , calciotropic hormones , markers of bone remodeling , and calcium absorption in 489 elderly women . The treatment phase of the study was double-blinded . After discontinuing therapy for 2 yr , there was rapid bone loss in all 3 treatment groups , and most of the decrease in BMD occurred in the first year . In the ERT/HRT group , spine BMD increased 5.5 % in yr 3 , decreased 3.2 % in yr 4 , and decreased 0.7 % in yr 5 ; femoral neck BMD increased 3.7 % in yr 3 , decreased 2.5 % in yr 4 , and decreased 0.4 % in yr 5 ; total body BMD increased 2.1 % in yr 3 , decreased 1.4 % in yr 4 , and decreased 0.6 % in yr 5 . In the combination group , spine BMD increased 7.1 % in yr 3 , decreased 4.3 % in yr 4 , and decreased 0.3 % in yr 5 ; femoral neck BMD increased 4.5 % in yr 3 , decreased 3.0 % in yr 4 , and decreased 0.01 % in yr 5 ; total body BMD increased 2.2 % in yr 3 , decreased 1.5 % in yr 4 , and decreased 0.6 % in yr 5 . In the calcitriol group , spine BMD increased 1.8 % in yr 3 , decreased 1.8 % in yr 4 , and showed no change in yr 5 ; femoral neck BMD increased 0.2 % in yr 3 , decreased 0.2 % in yr 4 , and decreased 0.6 % in yr 5 ; total body BMD decreased 0.4 % in yr 3 , decreased 0.6 % in yr 4 , and decreased 0.4 % in yr 5 . Compared with placebo , all treated groups at yr 5 had significantly higher total body BMD ; only the combination group had significantly higher spine BMD ( 3.4 % ; P < 0.001 ) and total hip BMD ( 2.4 % ; P < 0.01 . ) compared with the placebo group . Compared with baseline , only spine BMD in the combination group was significantly higher ( 2.6 % ; P < 0.001 ) at yr 5 . The increase in calcium absorption and the decrease in serum PTH levels in the calcitriol groups were reversed after discontinuation of treatment , and the decrease in bone markers was reversed in the hormone-treated groups . These results suggest that discontinuation of ERT/HRT and /or calcitriol therapy  in elderly women leads to a decrease in much of the BMD gained on treatment ; however , in the combination group there was a statistically significant residual effect on spine BMD
There is currently no firm evidence that vitamin D supplementation decreases or increases cancer occurrence in predominantly elderly community-dwelling women .
Vitamin D₃ supplementation  decreased cancer mortality  and vitamin D supplementation  decreased all-cause mortality , but these estimates are at risk of type I errors due to the fact that too few participants were examined , and to risks of attrition bias originating from substantial dropout of participants .
Combined vitamin D₃ and calcium supplements  increased nephrolithiasis , whereas it remains unclear from the included trials whether vitamin D₃ , calcium , or both were responsible for this effect .
BACKGROUND The evidence on whether vitamin D supplementation is effective in decreasing cancers is contradictory .
OBJECTIVES To assess the beneficial and harmful effects of vitamin D supplementation for prevention of cancer in adults .