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 .
Low serum 25-hydroxyvitamin D levels are associated with increased all-cause mortality risk in a general population: the Tromsø study.
OBJECTIVE Ecologic and observational studies have suggested an association between serum 25-hydroxyvitamin D ( 25(OH)D ) levels and cardiovascular disease ( CVD ) risk factors , CVD mortality , and cancer mortality . Based on this , low serum 25(OH)D levels should be associated with higher all-cause mortality in a general population . This hypothesis was tested in the present study . DESIGN The Tromsø study is a longitudinal population -based multi purpose study initiated in 1974 with focus on lifestyle-related diseases . Our data are based on the fourth Tromsø study carried out in 1994 - 1995 . METHODS Information about death and cause of death was registered by obtaining information from the National Directory of Residents and the Death Cause Registry .  Serum 25(OH)D  was measured in 7161 participants in the fourth Tromsø study . Results are presented for smokers ( n=2410 ) and non-smokers ( n=4751 ) separately as our immunoassay seems to overestimate 25(OH)D levels for smokers . RESULTS During a mean 11.7 years of follow-up , 1359 ( 19.0 % ) participants died . In multivariate regression models , there was a significantly increased risk of all-cause mortality ( hazard ratio ( HR ) 1.32 , confidence interval ( CI ) 1.07 - 1.62 ) among non-smoking participants in the lowest 25(OH)D quartile when compared with participants in the highest quartile . Equivalent results for smokers were not significant ( HR 1.06 , CI 0.83 - 1.35 ) . CONCLUSIONS Low serum 25(OH)D levels were associated with increased all-cause mortality for non-smokers , but the results did not reach statistical significance for smokers . However , low 25(OH)D levels are known to be associated with impaired general health , and r and omized controlled studies are needed to address the question of causality
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 .