Subgroup analyses in the observational studies indicated that risk of mortality was significantly higher in studies with lower baseline use of vitamin D supplements .
The effects observed for vitamin D3 supplementation remained unchanged when grouped by various characteristics .
However , for vitamin D2 supplementation , increased risks of mortality were observed in studies with lower intervention doses and shorter average intervention periods .
Conclusions Evidence from observational studies indicates inverse associations of circulating 25-hydroxyvitamin D with risks of death due to cardiovascular disease , cancer , and other causes .
Objective To evaluate the extent to which circulating biomarker and supplements of vitamin D are associated with  mortality from cardiovascular , cancer , or other conditions  , under various circumstances .
Serum vitamin D levels and survival of patients with colorectal cancer: Post-hoc analysis of a prospective cohort study
Background Recently , serum 25-hydroxyvitamin D ( 25OHD ) levels were shown to be associated with the survival of patients with colorectal cancer . However , 25OHD levels were measured a median of 6 years before diagnosis or were predicted levels . In this study , we directly measured serum 25OHD levels at surgery and examined the association with survival among patients with colorectal cancer . Methods We started a prospect i ve cohort study to find prognostic factors in patients with colorectal cancer from 2003 to 2008 and stored serum sample s and clinical data . As part of a post-hoc analysis ,  serum 25OHD levels  were measured by radioimmunoassay . Association between overall survival and serum 25OHD levels were computed using the Cox proportional hazard model adjusted for month of serum sampling as well as age at diagnosis , gender , cancer stage , residual tumor after surgery , time period of surgery , location of tumor , adjuvant chemotherapy and number of lymph nodes with metastasis at surgery . Unadjusted and adjusted hazard ratios ( HR ) and 95 % confidence intervals ( 95 % CI ) were determined . Results Serum 25OHD levels were measured in 257 patients . Only 3 % had sufficient levels ( 30 ng/ml and greater ) . Based on month of blood sampling , an annual oscillation of 25OHD levels was seen , with levels being lower in spring and higher in late summer . Higher 25OHD levels were associated with better overall survival under multi-variate analysis ( HR , 0.91 : 95 % CI , 0.84 to 0.99 , P = 0.027 ) . Conclusions These results suggest that higher 25OHD levels at surgery may be associated with a better survival rate of patients with colorectal cancer
Subgroup analyses in the observational studies indicated that risk of mortality was significantly higher in studies with lower baseline use of vitamin D supplements .
The effects observed for vitamin D3 supplementation remained unchanged when grouped by various characteristics .
However , for vitamin D2 supplementation , increased risks of mortality were observed in studies with lower intervention doses and shorter average intervention periods .
Conclusions Evidence from observational studies indicates inverse associations of circulating 25-hydroxyvitamin D with risks of death due to cardiovascular disease , cancer , and other causes .
Objective To evaluate the extent to which circulating biomarker and supplements of vitamin D are associated with  mortality from cardiovascular , cancer , or other conditions  , under various circumstances .