A calcium and vitamin D fortified food product improves bone adaptation during military training (634.3)

Abstract

Stress fracture incidence during military training is high. Prior work suggests calcium (Ca) and vitamin D (vit D) intakes above the RDA may reduce fracture incidence in female trainees. How Ca and vit D affect measures of bone density and strength during initial military training (IMT) is not known. This randomized, double‐blind, placebo‐controlled trial was conducted to determine whether Ca and vit D (2000 mg and 800 IU) delivered as 2 snack bars daily throughout 9 wks of IMT improved trainee bone health. Measures of bone density pre‐ and post‐IMT and strength were assessed using peripheral quantitative computed tomography (n=20 men, n=27 women). Tibia scans were performed on the non‐dominant leg at 4, 14 and 66% of the segment length proximal to the distal end plate. Several parameters increased during training including: trabecular volumetric bone mineral density (vBMD) and bone strength index at the 4% site, cortical vBMD at the 14% and 66% sites, and stress strain index at the 66% site suggesting bone strength improved during IMT (all P<0.05). Those who received Ca and vit D had greater increases in total vBMD at the 4% site (3.0 ± 3.3 vs. 1.2 ± 2.4%; P<0.05) as well as cortical thickness (1.9 ± 2.2 vs. 0.6 ± 1.8%; P<0.05) and bone mineral content (1.6 ± 1.6 vs 0.6 ± 1.8%; P<0.05) at the 14% site. These data indicate that Ca and vit D intakes above the RDA may support bone health during periods of high turnover such as IMT.Grant Funding Source: Research supported by: ORISE and USAMRMC.