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 .
Vitamin D and calcium intakes and breast cancer risk in pre- and postmenopausal women.
BACKGROUND Some evidence suggests that vitamin D may reduce  breast cancer risk . Despite the biological interaction between vitamin D and calcium , few studies have evaluated their joint effects on breast cancer risk . OBJECTIVE The objective was to evaluate the associations and potential interaction between vitamin D and calcium ( from food and supplements ) and breast cancer risk in a population -based case-control study . DESIGN Breast cancer cases aged 25 - 74 y ( diagnosed 2002 - 2003 ) were identified through the Ontario Cancer Registry . Controls were identified by using r and om digit dialing ; 3101 cases and 3471 controls completed epidemiologic and food-frequency question naires . Adjusted odds ratios ( ORs ) and 95 % CIs were estimated by using multivariate logistic regression . RESULTS Vitamin D and calcium intakes from food only and total combined intakes ( food and supplements ) were not associated with breast cancer risk , although the mean intake of vitamin D was low . Vitamin D supplement intake > 10 microg/d ( 400 IU/d ) compared with no intake was associated with a reduced risk of breast cancer ( adjusted OR : 0.76 ; 95 % CI : 0.59 , 0.98 ) . No categories of calcium supplement intake were significantly associated with reduced breast cancer risk , but a significant inverse trend was observed ( P = 0.04 ) . There were no significant interactions involving vitamin D , calcium , or menopausal status . CONCLUSIONS No associations were found between overall vitamin D or calcium intake and breast cancer risk .  Vitamin D from supplements was independently associated with reduced breast cancer risk . Further research is needed to investigate the effects of higher doses of vitamin D and calcium supplements
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 .