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 .
The Effects of Vitamin D Supplementation on Physical Function and Quality of Life in Older Patients With Heart Failure: A Randomized Controlled Trial
Background —Low 25-hydroxyvitamin D levels , commonly found in older patients with heart failure , may contribute to the chronic inflammation and skeletal myopathy that lead to poor exercise tolerance . We tested whether vitamin D supplementation of patients with heart failure and vitamin D insufficiency can improve physical function and quality of life . Methods and Results —In a r and omized , parallel group , double-blind , placebo-controlled trial , patients with systolic heart failure aged ≥70 years with 25-hydroxyvitamin D levels < 50 nmol/L ( 20 ng/mL ) received 100000 U of oral vitamin D2 or placebo at baseline and 10 weeks . Outcomes measured at baseline , 10 weeks , and 20 weeks were 6-minute walk distance , quality of life ( Minnesota score ) , daily activity measured by accelerometry , Functional Limitations Profile , B-type natriuretic peptide , and tumor necrosis factor-&agr;. Participants in the vitamin D group had an increase in their 25-hydroxyvitamin D levels compared with placebo at 10 weeks ( 22.9 versus 2.3 nmol/L [ 9.2 versus 0.9 ng/mL ] ; P<0.001 ) and maintained this increase at 20 weeks . The 6-minute walk did not improve in the treatment group relative to placebo . No significant benefit was seen on timed up and go testing , subjective measures of function , daily activity , or tumor necrosis factor . Quality of life worsened by a small , but significant amount in the treatment group relative to placebo . B-type natriuretic peptide decreased in the treatment group relative to placebo ( −22 versus + 78 pg/mL at 10 weeks ; P=0.04 ) . Conclusions —Vitamin D supplementation did not improve functional capacity or quality of life in older patients with heart failure with vitamin D insufficiency . Clinical Trial Registration —www.controlled-trials.com . Identifier : IS RCT N51372896
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 .