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 protective effect of hormone-replacement therapy on fracture risk is modulated by estrogen receptor alpha genotype in early postmenopausal women.
Genetic factors regulate bone mineral density ( BMD ) and possibly development of osteoporosis . It has been suggested that estrogen receptor alpha ( ERalpha ) genotype is associated with BMD , but the association between ERalpha genotype , fracture risk , and postmenopausal hormone replacement therapy ( HRT ) has not been studied . Therefore , we evaluated whether ERalpha polymorphism is associated with fracture risk in a 5-year trial with HRT  in a population -based , r and omized group of 331 early postmenopausal women . The participants consisted of two treatment groups : the HRT group ( n = 151 ) received a sequential combination of 2 mg of estradiol valerate ( E2Val ) and 1 mg of cyproterone acetate with or without vitamin D3 , 100 - 300 IU + 93 mg calcium as lactate per day ; and the non-HRT group ( n = 180 ) received 93 mg of calcium alone or in combination with vitamin D3 , 100 - 300 IU/day . All new symptomatic , radiographically defined fractures were recorded . Pvu II restriction fragment length polymorphism of the ERalpha was determined using polymerase chain reaction ( PCR ) . In all , 28 women sustained 33 fractures  during the approximately 5.1-year follow-up . In the HRT group , the ERalpha genotype ( PP , Pp , and pp ) was not significantly associated with fracture risk ( p = 0.138 ; Cox proportional hazards model ) . When the genotype was dichotomized ( PP + Pp vs. pp ) , the incidence of new fractures in the HRT group was significantly reduced in women with the P allele ( p = 0.046 ) with the relative risk ( HR ) of 0.25 ( 95 % CI , 0.07 - 0.98 ) , in comparison with the non-P allele group . After adjustment for time since menopause and previous fracture , the association between the dichotomous genotype and fracture risk persisted with HR of 0.24 ( 95 % CI , 0.06 - 0.95;p = 0.042 ) . In the  non-HRT group , the ERalpha genotype was not significantly associated with fracture risk . During HRT , women with the pp genotype have a greater fracture risk than those with the P allele . The results suggest that the pp genotype is a relatively hormone-insensitive genotype , and it appears that women with the P allele may benefit more from the protective effect of HRT on fracture risk than women with the pp genotype
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 .