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 .
Calcitriol treatment is not effective in postmenopausal osteoporosis.
STUDY OBJECTIVE To determine if calcitriol is an effective treatment in postmenopausal osteoporosis . DESIGN Double-blind , r and omized clinical trial of 2 years ' duration . SETTING University medical center with patients recruited by media announcements . PATIENTS Eighty-six postmenopausal women with vertebral compression fractures . INTERVENTIONS Patients were treated with calcitriol or placebo . Mean dose was 0.43 micrograms/d . Dietary calcium was 1000 mg/d ( 24.9 mmol/d ) . The medication dose and dietary calcium were adjusted for hypercalciuria or hypercalcemia . MEASUREMENTS AND MAIN RESULTS No significant differences between placebo and control groups were seen in the percent change in total body calcium ( 0.4 % + /- 1.0 compared with 0.0 % + /- 0.9 ) , single photon absorptiometry ( -0.5 % + /- 1.2 compared with -3.1 % + /- 0.9 ) or dual photon absorptiometry ( 0.0 % + /- 1.7 compared with -1.0 % + /- 2.2 ) . New fractures were seen in 16 % of the placebo group and 26 % of the calcitriol groups , so the difference in percent fractures was 10 % ( 95 % CI , -5.7 % to 25.7 % ) . Bone biopsies did not show changes in either group . The calcitriol group had significantly higher serum and urine calcium values , but renal function was not worse than in the placebo group . CONCLUSIONS Calcitriol is not an effective treatment for established postmenopausal osteoporosis
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 .