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 Cardiovascular Events
Background — Individuals with vascular or valvular calcification are at increased risk for coronary events , but the relationship between calcium consumption and cardiovascular events is uncertain . We evaluated the risk of coronary and cerebrovascular events in the Women ’s Health Initiative r and omized trial of calcium plus vitamin D supplementation . Methods and Results — We r and omized 36 282 postmenopausal women 50 to 79 years of age at 40 clinical sites to calcium carbonate 500 mg with vitamin D 200 IU twice daily or to placebo .  Cardiovascular disease was a prespecified secondary efficacy outcome . During 7 years of follow-up , myocardial infa rct ion or coronary heart disease death was confirmed for 499 women assigned to calcium/vitamin D and 475 women assigned to placebo ( hazard ratio , 1.04 ; 95 % confidence interval , 0.92 to 1.18 ) . Stroke was confirmed among 362 women assigned to calcium/vitamin D and 377 assigned to placebo ( hazard ratio , 0.95 ; 95 % confidence interval , 0.82 to 1.10 ) . In subgroup analyses , women with higher total calcium intake ( diet plus supplements ) at baseline were not at higher risk for coronary events ( P=0.91 for interaction ) or stroke ( P=0.14 for interaction ) if assigned to active calcium/vitamin D. Conclusions — Calcium/vitamin D supplementation neither increased nor decreased coronary or cerebrovascular risk in generally healthy postmenopausal women over a 7-year use period
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 .