Vitamin D supplement use increased over 7 years of follow-up among participants in the Chronic Renal Insufficiency Cohort (CRIC) study, researchers reported online ahead of print in the Journal of Renal Nutrition.
CRIC is a multicenter prospective observational cohort study that includes 3,939 participants with a mean age of 60 years and estimated glomerular filtration rate (eGFR) of 42.1 mL/min/1.73 m2. The cohort was 54.9% male and 42.1% black, and 48.4% were diabetic.
The proportion of participants reporting vitamin D supplement use increased from 10% at baseline to 44% at 7-year follow-up visits, according to Laura H. Mariani, MD, of the University of Michigan Medical School in Ann Arbor, and colleagues. Supplement use was greater among older, female, non-black, married participants with higher education and lower body mass index, the researchers noted.
Among participants taking supplements, increasing dose was associated with greater serum levels of 25-hydroxyvitamin D after adjusting for race, diabetes, dietary intake, season, eGFR, and proteinuria.