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 .
Calcium Plus Vitamin D Supplementation Has Limited Effects on Femoral Geometric Strength in Older Postmenopausal Women: The Women’s Health Initiative
Calcium plus vitamin D ( CaD ) supplementation has a modest but significant effect on slowing loss of femoral bone mass and reducing risk of hip fractures in adherent postmenopausal women . The goal of this study was to determine if CaD supplementation influences hip structural parameters that are associated with fracture risk . We studied 1,970 postmenopausal women enrolled in the Women ’s Health Initiative r and omized controlled trial of CaD at one of three bone mineral density ( BMD ) clinical centers . Hip structural analysis software measured BMD and strength parameters on DXA scans at three regions : femoral narrow neck , intertrochanter , and shaft . R and om effects models were used to test the average differences in hip BMD and geometry between intervention and placebo . There was greater preservation of hip BMD at the narrow neck with CaD relative to placebo across 6 years of intervention . CaD also altered the underlying cross-sectional geometry at the narrow neck in the direction of greater strength , with small increases in cross-sectional area and section modulus and a decrease in buckling ratio with CaD relative to placebo . While trends at both the intertrochanter and shaft regions were similar to those noted at the narrow neck , no significant intervention effects were evident . There was no significant interaction of  CaD and age or baseline calcium levels for hip structural properties . CaD supplementation is associated with modest beneficial effects on hip structural features at the narrow neck , which may explain some of the benefit of CaD in reducing hip fracture risk
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 .