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 GRADE approach is reproducible in assessing the quality of evidence of quantitative evidence syntheses.
OBJECTIVE We evaluated the inter-rater reliability ( IRR ) of assessing the quality of evidence ( QoE ) using the Grading of Recommendations , Assessment , Development , and Evaluation ( GRADE ) approach . STUDY DESIGN AND SETTING On completing two training exercises , participants worked independently as individual raters to assess the QoE of 16 outcomes . After recording their initial impression using a global rating , raters grade d the QoE following the GRADE approach . Subsequently , r and omly paired raters su bmi tted a consensus rating . RESULTS The IRR without using the GRADE approach for two individual raters was 0.31 ( 95 % confidence interval [ 95 % CI ] = 0.21 - 0.42 ) among Health Research Methodology students ( n = 10 ) and 0.27 ( 95 % CI = 0.19 - 0.37 ) among the GRADE working group members ( n = 15 ) . The corresponding IRR of the GRADE approach  in assessing the QoE was significantly higher , that is , 0.66 ( 95 % CI = 0.56 - 0.75 ) and 0.72 ( 95 % CI = 0.61 - 0.79 ) , respectively . The IRR further increased for three ( 0.80 [ 95 % CI = 0.73 - 0.86 ] and 0.74 [ 95 % CI = 0.65 - 0.81 ] ) or four raters ( 0.84 [ 95 % CI = 0.78 - 0.89 ] and 0.79 [ 95 % CI = 0.71 - 0.85 ] ) . The IRR did not improve when QoE was assessed through a consensus rating . CONCLUSION Our findings suggest that trained individuals using the GRADE approach improves reliability in comparison to intuitive judgments about the QoE and that two individual raters can reliably assess the QoE using the GRADE system
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 .