Low Vitamin D Status May Increase Mortality Risk
In this meta-analysis of prospective cohort studies investigating the effects of vitamin D status on risk of mortality, the evidence suggest that as circulating 25(OH)D levels increase, the risk of mortality decreases in a non-linear manner, with optimal concentrations between 75 and 87.5 nmol/L. Results from 14 prospective cohort studies which involved 5,562 deaths (out of 62,548 subjects) and which included data on relative risks for mortality at different 25(OH)D concentrations were analyzed and it was found that the estimated summary RR of mortality was 0.71 for the highest 25(OH)D level versus the lowest. The authors applied parametric modeling to 11 studies which included data from 59,231 subjects and results of these found the estimated summary RRs of mortality to be 0.86, 0.77, and 0.69 for individuals with an increase of 12.5, 25, and 50 nmol/L 25(OH)D serum values/L, respectively, from a median reference category of approximately 27.5 nmol. No significant decreas e in mortality was found when an increase of ~87.5 nmol/L above the reference category occurred. The authors conclude, "Data suggest a nonlinear decrease in mortality risk as circulating 25(OH)D increases, with optimal concentrations ~75-87.5 nmol/L."
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