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, vitamin D supplementation, and physical function in the Women's Health Initiative.
OBJECTIVES The Women 's Health Initiative ( WHI ) r and omized trial of calcium/vitamin D supplementation found reduced bone loss with active treatment compared to placebo . Now we examine whether the treatment affected self-reported physical functioning and objective measures of physical functioning . DESIGN A r and omized , double-blind , placebo-controlled trial of 1,000 mg calcium carbonate plus 400 IU vitamin D(3 ) per day or matching placebo pills . SUBJECTS/ SETTING The study included 33,067 women ( 50 to 79 years old ) at 40 US study centers . MAIN OUTCOME MEASURES Physical functioning was assessed by question naire at enrollment in WHI , 1 year prior to calcium/vitamin D trial r and omization and at study close-out ( average follow-up 7.1 years ) . Objective physical performance and self-reported exercise measures were collected at WHI baseline ( 1 year prior to calcium/vitamin D enrollment ) and 2 years and 4 years after calcium/vitamin D trial enrollment in a sub sample ( n=3,137 ) . STATISTICAL ANALYSES PERFORMED Calcium/vitamin D effects were tested in unadjusted and interaction linear models for each of the physical function measures . Covariates were baseline total calcium intake , fracture risk score , treatment arm in the hormone therapy and dietary modification trials ( ie , active drug or placebo , low-fat diet intervention or usual diet , respectively ) and age . RESULTS Neither intention to treat nor high adherence analyses produced substantial effects of calcium/vitamin D  compared to placebo on physical functioning or performance . The interaction analyses also did not result in differences because of calcium/vitamin D. CONCLUSIONS As the first long-term r and omized trial to examine the effectiveness of calcium and vitamin D in protecting against decline of physical functioning in older women , the results did not support benefit
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 .