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 .
The effect of vitamin D and frailty on mortality among non-institutionalized US older adults
BACKGROUND / OBJECTIVES : Although both frailty and low vitamin D have been separately associated with an increased risk for adverse health , their joined effects on mortality have not been reported . The current study examined prospect ively the effects of frailty and vitamin D status on mortality in US older adults . SUBJECTS/ METHODS : Participants aged ⩾60 years in The Third National Health and Nutrition Examination Survey with 12 years of mortality follow-up were included in the analysis ( n=4731 ) . Frailty was defined as meeting three or more criteria and pre-frailty as meeting one or two of the five frailty criteria ( low body mass index ( BMI ) , slow walking , weakness , exhaustion and low physical activity )  . Vitamin D status  was assessed by serum 25-hydroxyvitamin D ( 25(OH)D )  and categorized into quartiles . Analyses were adjusted for gender , race , age , smoking , education , latitude and other comorbid conditions . RESULTS : Serum 25(OH)D concentrations were lowest in participants with frailty , intermediate in participants with pre-frailty and highest in participants without frailty . The odds of frailty in the lowest quartile of serum 25(OH)D was 1.94 times the odds in the highest quartile ( 95 % confidence interval ( CI ) : 1.09–3.44 ) . Mortality was positively associated with frailty , with the risk among participants who were frail and had low serum 25(OH)D being significantly higher than those who were not frail and who had high concentrations of serum 25(OH)D ( hazards ratio 2.98 ; 95 % CI : 2.01–4.42 ) . CONCLUSION : Our results suggest that low serum 25(OH)D is associated with frailty , and there is additive joint effects of serum 25(OH)D and frailty on all-cause mortality in older adults
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 .