Association of Serum Vitamin D Levels and Stress Fractures in Collegiate Athletes

Abstract

Background: Low vitamin D levels along with high-intensity athletic training may put an athlete at increased risk for a stress fracture. Purpose: To assess whether supplementation with vitamin D is associated with a reduced risk of stress fractures in college athletes. We also assessed differences in vitamin D levels among athletes participating in outdoor versus indoor sports. Study Design: Cohort study; Level of evidence, 2. Methods: The study participants included 802 National Collegiate Athletic Association Division I intercollegiate athletes (497 men and 305 women) on a sports team for at least 1 semester from 2012 to 2018. All athletes who had a baseline vitamin D level in their medical record were included. Athletes with vitamin D levels <40 ng/mL were given vitamin D supplements. We assessed differences in the rate of stress fracture among those who maintained or improved vitamin D levels to ≥40 ng/mL and those who did not, as well as differences in average baseline vitamin D levels by sport type (indoor vs outdoor). Results: The rate of stress fracture was 12% higher (95% CI, 6-19; P