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 .
Effect of oral cholecalciferol 2,000 versus 5,000 IU on serum vitamin D, PTH, bone and muscle strength in patients with vitamin D deficiency
Summary Treatment of vitamin D deficiency for 3 months with oral cholecalciferol 5,000 IU daily was more effective than 2,000 IU daily in achieving optimal serum 25-hydroxyvitamin D ( 25OHD ) concentrations . Optimal 25OHD serum level calculated to be 63.8 nmol/L. All parameters of muscle strength improved following administration of cholecalciferol for 3 months . Introduction The aim of this study was to determine the optimal dose of cholecalciferol required to achieve target serum 25OHD level ≥75 nmol/L and its relationship to both bone turnover and muscle strength . Methods Thirty deficient patients ( serum 25OHD ≤50 nmol/L ) were r and omly assigned into two groups — i.e . 2,000 and 5,000 IU/day . Data were collected at baseline , at 2 and 3 months post-therapy : ( a ) clinical demographics , ( b ) dietary calcium recall , ( c ) physical tests of muscle function and ( d ) biochemistry . Statistical analysis used paired student t test and analysis of variance . Regression analysis was used to determine relationship between serum 25OHD and parathyroid hormone ( PTH ) . Results Twenty-six ( 87 % ) patients completed 3 months of therapy . The percent increase in serum 25OHD ( compared to baseline ) was 82.7 % in 2,000-IU group and 219.5 % in 5,000-IU group . All participants ( 100 % ) achieved a serum 25OHD concentration > 50 nmol/L ; only 5 subjects ( 45.4 % ) in 2,000-IU group compared to 14 subjects ( 93.3 % ) in 5,000-IU group achieved final 25OHD concentration ≥75 nmol/L ( p < 0.01 ) . In the regression analysis , the reflexion point at which the PTH level increased above the normal range was calculated to be 63.8 nmol/L 25OHD . All parameters of muscle strength showed trends in improvements following the administration of both the 2,000 and 5,000 IU doses . No patient reported untoward side effects and no patient developed hypercalcaemia . Conclusion Treatment for 3 months with oral cholecalciferol 5,000 IU daily may be more effective than 2,000 IU daily in achieving optimal serum 25OHD concentrations in vitamin D-deficient patients
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 .