Could Vitamin D Deficiency Increase Risk of Death?

A new study finds a greater risk for all-cause mortality among individuals with genetically low concentrations of vitamin D, which may provide evidence of a causal association between a deficiency of the vitamin and increased risk of death.

A team of researchers from Copenhagen University Hospital evaluated 95,766 individuals from Denmark who had been assessed for variants in the genes DHCR7 and CYP2RI, which the authors note is known to reduce levels of vitamin D in the body. Participants were identified from 3 cohorts: the Copenhagen City Heart Study, the Copenhagen General Population Study, and the Copenhagen Ischemic Heart Disease Study.
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The investigators recorded vitamin D levels—as measured by 25-hydroxyvitamin D concentrations—among the study’s 35,334 participants, as well as other factors that may impact mortality, such as physical activity levels, alcohol consumption, body mass index, blood pressure, cholesterol levels, and smoking status.

Participants with genetically low vitamin D levels were found to be at higher risk of all-cause mortality—including cancer—in comparison to those who did not have genetically low vitamin D levels, according to the authors, who note that they found no connection between genetically low vitamin D concentrations and a higher risk of cardiovascular mortality.

The findings of this study “suggest that low vitamin D is a direct cause of increased mortality,” says Børge G Nordestgaard, MD, DMSc, professor at the University of Copenhagen, chief Physician at Herlev Hospital and Copenhagen University Hospital, and lead author of the study.

As such, Nordestgaard suggests advising patients to “get enough sunshine—up to 30 minutes on the arms, face, and neck a couple times a week—and to eat fatty fish,” says Nordestgaard, who notes that determining whether vitamin D supplements are advisable for healthy people “await[s] publication of large randomized trials in 2017.”

—Mark McGraw

Reference

1. Afzal S, Brondum-Jacobsen P, et al. Genetically low vitamin D concentrations and increased mortality: mendelian randomization analysis in three large cohorts. BMJ. 2014.