Background: High rates of vitamin D deficiency have been reported in athletes. The purpose of this study was to evaluate the associations between vitamin D with bone health and parathyroid hormone (PTH) concentrations in female runners who trained at 30.4° degrees north.
Methods: Serum 25-hydroxyvitamin D (25(OH) D), PTH, body composition, and bone mineral density (BMD) were measured in 59 female runners, aged 18-40 years. Stress fracture history, training duration and frequency were evaluated by questionnaire. As per National Endocrine Society cut-offs, serum vitamin D ranges were: 25(OH)D < 50 nmol/L for deficient; 50-75 nmol/L for insufficient; and ≥ 75 nmol/L for sufficient status.
Results: Mean serum 25(OH)D concentrations were 122.6 ± 63.9 nmol/L, with 18.6% of subjects in the deficient (5.1%) or insufficient (13.5%) range. No significant differences were observed between sufficient and deficient/insufficient subjects for BMD, PTH, history of stress fractures, or demographic data.
Conclusions: The majority of distance runners maintained sufficient vitamin D status, suggesting that training outdoors in latitude where vitamin D synthesis occurs year-round reduces the risk for vitamin D deficiency. Data do not support the indiscriminate supplementation of outdoor athletes in southern latitudes without prior screening.
Keywords: 25-hydroxyvitamin D; athlete; bone mineral density; nutrition.