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 .
The Women's Health Initiative calcium-vitamin D trial: overview and baseline characteristics of participants.
Osteoporosis is a major public health issue leading to significant morbidity , loss of independence and excess loss of life . It has been estimated that 13 to 17 million postmenopausal women have low bone mass or osteoporosis ( 1 , 2 ) . This is associated with almost 1.5 million fractures annually , including 300,000 hip fractures ( 2 , 3 ) . A review of the evidence by Cumming in 1990 ( 4 ) and subsequently published r and omized clinical trials have shown that calcium and /or vitamin D supplements may play a role in the prevention and treatment of osteoporosis by slowing the rates of bone loss in postmenopausal and elderly women ( 5–9 ) . However , there are a limited number of calcium and /or vitamin D trials ( 10–13 ) and observational studies [ review of evidence by Cumming and Nevitt ( 14 ) and Kanis ( 15 ) ] , to support a role for calcium and vitamin D supplementation in the reduction of hip and other fractures . It has also been suggested that calcium and vitamin D supplementation may play a role in the reduction of colorectal cancer incidence ( 16–21 ) . To address these major health concerns of postmenopausal women , the Calcium-Vitamin D ( CaD ) trial of the Women ’s Health Initiative ( WHI ) was design ed to test the primary hypothesis that women who are r and omized to receive calcium and vitamin D supplementation will have a lower risk of hip fracture and secondarily , a lower risk of all fractures and colorectal cancer than women receiving corresponding placebo . The objective of this paper is
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 .