The vast majority of studies reported inverse associations between 25(OH)D concentration and all-cause mortality .
This association appeared to be non-linear , with progressively lower mortality with increasing 25(OH)D up to a point , beyond which there was no further decrease .
There is moderate evidence that vitamin D status is inversely associated with cancer mortality and death due to respiratory diseases , while for cardiovascular mortality , there is weak evidence of an association in observational studies , which is not supported by the data from intervention or Mendelian r and omization studies .
Epidemiological evidence suggests that vitamin D deficiency is associated with increased mortality , but it is unclear whether this is explained by reverse causation , and if there are specific causes of death for which vitamin D might be important .
Effect of follow-up time on the relation between prediagnostic serum 25-hydroxyvitamin D and all-cause mortality rate
Evidence continues to mount that vitamin D reduces the risk and mortality rates of many types of disease . However , evidence from prospect i ve cohort studies is sometimes weaker than that from case – control and ecological studies . A suggested reason for this discrepancy is that , because serum levels of 25-hydroxyvitamin D [ 25(OH)D ] change over time , a single 25(OH)D concentration measurement taken at study enrollment does not reliably indicate 25(OH)D concentration related to the health outcome . To evaluate this suggestion further , this paper plots results from 12 prospect i ve cohort studies of all-cause mortality rate vs. follow-up time . The regression fit to the hazard ratio per 20-nmol/l increase in serum 25(OH)D concentration vs. time increased from 0.82 ( 95 % CI , 0.67–1.02 ) for 6 y to 0.96 ( 95 % CI , 0.90–1.01 ) for 14 y. The value extrapolated for zero follow-up time was 0.72 ( 95 % CI , 0.50–1.03 ) , giving a hazard ratio reduction 3.5 times higher than the st and ard result from the meta- analysis [ 0.92 ( 95 % CI , 0.89–0.95 ) ] . Using the example of the Vitamin D Pooling Project of Rarer Cancers , this paper also discusses follow-up time ’s effect in interpreting prospect i ve cohort studies of cancer outcome . This paper recommends that meta-analyses of prospect i ve cohort studies account for follow-up time and , if possible , that studies measure serum 25(OH)D concentration every 2–4
The vast majority of studies reported inverse associations between 25(OH)D concentration and all-cause mortality .
This association appeared to be non-linear , with progressively lower mortality with increasing 25(OH)D up to a point , beyond which there was no further decrease .
There is moderate evidence that vitamin D status is inversely associated with cancer mortality and death due to respiratory diseases , while for cardiovascular mortality , there is weak evidence of an association in observational studies , which is not supported by the data from intervention or Mendelian r and omization studies .
Epidemiological evidence suggests that vitamin D deficiency is associated with increased mortality , but it is unclear whether this is explained by reverse causation , and if there are specific causes of death for which vitamin D might be important .