Daniel Dudenkov, MD, of the Mayo Clinic in Rochester, Minnesota, reported on a 25-hydroxyvitamin D level study, at the annual meeting of the American Society for Bone and Mineral Research. The comprehensive population-based study involved people ages 18 and older in Olmsted County, Minn., who were enrolled in a Rochester Epidemiology Project from the years 2005 to 2011. Previous studies had not been population based, so he conducted a retrospective study to clarify those observations. Participants in the study were followed after 30 days from their first measurement of vitamin D, until one of three things happened: leaving the study, December 31, 2014, or death. There were 11,022 individuals with a mean age of 54, over three-quarters were women, and close to 90% were white. The analysis was adjusted for sex, age, race, the comorbidity index, and which month the level was obtained. They had a mean vitamin D level of 30 ng/mL with 643 participants having levels below 12, 1,605 having levels between 12 and 19, 8,210 having levels between 20 and 50, and 564 with levels higher than 50 ng/mL.
During a 4.8-year follow-up, there were 723 deaths. Increased all-cause mortality was associated with low vitamin D levels. Individuals with serum 25-hydroxyvitamin D levels below 20 ng/mL had an adjusted hazard ratio for death of 2.37 and 12 to 20 ng/mL 1.28. Below 20 ng/mL and above 50 ng/mL were associated with chronic adverse events which included increased cancer, cardiovascular, and respiratory diseases mortality. There was a significant interaction by race. Whites with vitamin D levels below 12 ng/mL, the hazard rate (HR) was 2.83 while for non-whites, the HR was 1.76. Whites with levels between 12 and 19 ng/mL had an HR of 1.42 while non-whites had an HR of 1.52. White men with levels below 12 ng/mL had an HR of 4.46, and non-white men had a 2.77. White women had corresponding HRs of 2.83 and 1.76. A difference was also seen for whites and non-whites according to age. Participants age 70 and older with vitamin D levels below 12 ng/mL had an HR for whites of 1.30 compared with 0.81 for non-whites.
Vitamin D is very important because it has a role in bone metabolism, as well as falls and fractures, and it has effects on diabetes, cancer, the cardiovascular system, calcification of blood vessels, and some effects in the brain.
NOTE: This study was presented at a conference and was published as an abstract. The data and conclusions should be recognized as preliminary until they are published in a peer-reviewed journal.
