In a population-based study published in the European Journal of Nutrition, researchers determined a link between low blood concentrations of vitamins D and K and an increased risk for all-cause mortality.
 
The study evaluated the outcomes of 4742 participants (47% male, 53% female, average age of 52.6 years old) of the Prevention of Renal and Vascular End-Stage Disease (PREVEND) Study, tracking their results from a time in which they were examined for the trial in 2001-2003, until the date of death/cardiovascular event, or the censoring date on January 1, 2017. Vitamins D and K status were determined at baseline through measurements of vitamin D and K metabolites.
 
During a median follow-up of 14.2 years, 620 participants in the trial died, and 142 of those deaths were caused by cardiovascular issues. In total, 970 participants had low vitamin D and K status, representing 20% of the total population. Only 28 participants in the trial reported taking vitamin D supplements. After adjusting for potential cofounders, it was determined that those low in both of these vitamins were more likely to die of all causes, by a hazard ratio of 1.46, and by cardiovascular causes in particular with a hazard ratio of 1.42.
 
While vitamins D and K are each correlated with positive health outcomes, the role of combined vitamin D and K status, rather than each status as a standalone, have not been investigated in the general population to achieve any kind of clinical significance, the authors of the study said. The importance of investigating the combined vitamin statuses is important, however, due to their biomechanisms.
 
“Experimental studies suggest direct effects of vitamin D on vitamin K-dependent metabolism due to stimulation of the synthesis of vitamin K-dependent proteins by active vitamin D,” the authors said. “Excess vitamin D can induce a relative vitamin K deficiency.”
 
Further, vitamin K supplementation can overcome the effect that excess levels of vitamin D have on vascular calcification, the authors wrote, and previous studies on the general population have correlated combined high levels of both vitamins with reduced risks of arterial stiffness and hypertension, however, vitamin K concentrations have a very short half-life, so measurements mainly reflect vitamin K intake of previous days, and not functional vitamin K status. “This implies that the combination of both vitamins could provide enhanced protection against progressive vascular calcification.”
 
“In conclusion, combined low vitamin D and K status was present in 20% of the participants and was associated with a greater risk of mortality after 14.2 year follow-up,” the authors wrote in their conclusion. “The association of combined low vitamin D and K status with mortality was greater than one vitamin insufficiency alone, and amplified these risks.”