Vitamin D status in female military personnel during combat training

Nancy E Andersen,Sonya J Cable,Harris R Lieberman,Andrew J Young,James P McClung,Kelly W Williams,J Philip Karl,Jennifer C Rood

doi:10.1186/1550-2783-7-38

Abstract

Vitamin D is an essential nutrient for maintaining bone health. Recent data suggest that vitamin D and calcium supplementation might affect stress fracture incidence in military personnel. Although stress fracture is a health risk for military personnel during training, no study has investigated changes in vitamin D status in Soldiers during United States (US) Army basic combat training (BCT). This longitudinal study aimed to determine the effects of BCT on 25-hydroxyvitamin D (25(OH)D) and parathyroid hormone (PTH) levels in female Soldiers. Serum 25(OH)D and PTH were assessed in 74 fasted Soldier volunteers before and after an 8-week BCT course conducted between August and October in Columbia, South Carolina. In the total study population, 25(OH)D levels decreased (mean ± SD) from 72.9 ± 30.0 to 63.3 ± 19.8 nmol/L (P < 0.05) and PTH levels increased from 36.2 ± 15.8 to 47.5 ± 21.2 pg/mL (P < 0.05) during BCT. Ethnicity affected changes in vitamin D status (ethnicity-by-time interaction, P < 0.05); 25(OH)D decreased (P < 0.05) in both Hispanic and non-Hispanic whites, but did not change in non-Hispanic blacks. Ethnicity did not affect BCT-induced changes in PTH. These data indicate that vitamin D status in female Soldiers may decline during military training in the late summer and early autumn months in the Southeastern US. Future studies should strive to determine the impact of military clothing and seasonality on vitamin D status, as well as the functional impact of declining vitamin D status on bone health.

Highlights

Vitamin D is an essential nutrient for maintaining bone health
In the total study population, parathyroid hormone (PTH) levels increased over the course of basic combat training (BCT) (36.2 ± 15.8 vs 47.5 ± 21.2 pg/mL, P < 0.05, Figure 1B); this change was independent of ethnicity (Figure 2B)
Vitamin D is a critical nutrient for active populations, as it contributes to effective bone remodeling and calcium homeostasis

Summary

Introduction

Vitamin D is an essential nutrient for maintaining bone health. Vitamin D sufficiency may prevent fractures in adults, while insufficiency may result in poor bone mineralization, pain, and rickets in children [2]. Suboptimal vitamin D intake and diminished vitamin D status may be important during periods of intense physical activity such as military training, as compromised bone health could contribute to. Poor vitamin D status has been associated with an increased incidence of stress fracture in Soldiers [5]. Stress fractures are one of the most debilitating injuries in military recruits, and occur most often in military personnel beginning exercise regimens that include unaccustomed and physically-demanding activities. During military training regimens such as BCT, up to 21% of female recruits are diagnosed with at least one stress fracture [6]. The impact of stress fractures on military readiness is notable; the attrition rate of female Soldiers with diagnosed stress fractures may be up to 60% [6,7]

Methods

Results

Conclusion