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 HRT: No benefit additional to that of HRT alone in prevention of bone loss in early postmenopausal women. A 2.5-year randomized placebo-controlled study
The study was design ed to examine the effect of hormone replacement therapy ( HRT ) and low-dose vitamin D ( Vit D ) supplementation on the prevention of bone loss in non-osteoporotic early postmenopausal women and to determine whether Vit D supplementation can give additional benefit to an already optimized estrogen regimen . The effects of HRT and Vit D on bone mineral density ( BMD ) were studied in postmenopausal women in a 2.5-year r and omized placebo-controlled study . The study population was a subgroup of the Kuopio Osteoporosis Risk Factor and Prevention Study ( OSTPRE ) ( n=13100 ) . A total of 464 early postmenopausal women were r and omized to four groups : ( 1 ) HRT ( a sequential combination of 2 mg estradiol valerate and 1 mg cyproterone acetate ( E2Val/CPA ) ; ( 2 ) vitamin D3 ( cholecalciferol , 300 IU/day ) ; ( 3 ) HRT+Vit D ; and ( 4 ) placebo ( calcium lactate ; 93 mg Ca2+/day ) . Lumbar ( L1–4 ) and femoral neck BMD were determined by dual-energy X-ray absorptiometry before and after 2.5 years of treatment . After 2.5 years , lumbar BMD had increased by 1.8 % in the HRT group ( p<0.001 ) and by 1.4 % in the HRT+Vit D group ( p=0.002 ) , whereas lumbar BMD had decreased by 3.5 % ( p<0.001 ) in the Vit D group and by 3.7 % ( p<0.001 ) in the placebo group . The loss of femoral neck BMD was lower in the HRT ( −0.3 % ) and the HRT+Vit D ( −0.9 % ) groups compared with the Vit D ( −2.4 % ) and the placebo groups ( −3.7 % ) . This study confirms the beneficial effect of HRT on BMD . It also shows that low-dose vitamin D supplementation has only a minor effect in the prevention of osteoporosis in non-osteoporotic early postmenopausal women and does not give any benefit additional to that of HRT alone
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 .