Vitamin D and tibial bone density, geometry, and microarchitecture in male military recruits: an observational study and randomized controlled trial

O'Leary, TJ ORCID: 0000-0002-1120-8777, Izard, RM, Jackson, S, Walsh, NP ORCID: 0000-0002-3681-6015, Carswell, AT, Oliver, SJ, Allan, D, Rhodes, LE, Tang, JCY ORCID: 0000-0001-6305-6333, Fraser, WD ORCID: 0000-0003-0556-3358 and Greeves, JP (2025) Vitamin D and tibial bone density, geometry, and microarchitecture in male military recruits: an observational study and randomized controlled trial. Journal of Bone and Mineral Research, 40 (7). pp. 847-859. ISSN 0884-0431

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Abstract

Vitamin D may mitigate bone stress injuries in military training by modulating changes in bone. This cross-sectional observational study (Study 1) and randomized controlled trial (Study 2) investigated associations between vitamin D metabolites and tibial structure and density, and the effect of vitamin D supplementation on tibial adaptations to military training. A total of 343 (Study 1) and 194 (Study 2) male British Army recruits participated. Circulating vitamin D metabolites (biologically "active"and "inactive") and tibial structure were measured in participants during week 1 and week 12 (Study 2 only) of initial military training. Associations between vitamin D metabolites and HRpQCT outcomes at week 1 were tested in Study 1. Participants in Study 2 were randomly assigned to vitamin D (oral pill or simulated sunlight) or placebo (placebo pill or placebo simulated sunlight) supplementation for 12 wk designed to achieve vitamin D sufficiency. There was no association between total 25(OH)D or vitamin D receptor single-nucleotide polymorphisms and any measure of density, geometry, or microarchitecture (p ≥. 063). Higher 1,25(OH) 2D was associated with lower cortical porosity and perimeter (p ≤. 040). Higher total 24,25(OH) 2 D was associated with higher trabecular number and lower trabecular thickness (p =. 016). Higher 25(OH)D:24,25(OH) 2 D (VMR 1) was associated with higher trabecular thickness, trabecular separation, and cortical porosity (p ≤. 034). Higher 1,25(OH) 2 D:24,25(OH) 2 D (VMR 2) was associated with lower trabecular number, and higher trabecular spacing and thickness (p ≤. 035). There was no effect of vitamin D supplementation on any tibial outcome. Training decreased trabecular area (-0.1%), thickness (-4.4%), and separation (-2.1%), and increased cortical thickness (0.8%) and area (0.9%) (p ≤. 042). Vitamin D metabolites and their ratios were associated with tibial size and microarchitecture, but vitamin D supplementation had no impact on the adaptive response to military training.

Item Type:	Article
Additional Information:	This is a pre-copyedited, author-produced version of an article accepted for publication in [insert journal title] following peer review. The version of record Thomas J O’Leary, Rachel M Izard, Sarah Jackson, Neil P Walsh, Alexander T Carswell, Samuel J Oliver, Donald Allan, Lesley E Rhodes, Jonathan C Y Tang, William D Fraser, Julie P Greeves, Vitamin D and tibial bone density, geometry, and microarchitecture in male military recruits: an observational study and randomized controlled trial, Journal of Bone and Mineral Research, Volume 40, Issue 7, July 2025, Pages 847–859 is available online at https://doi.org/10.1093/jbmr/zjaf064
Uncontrolled Keywords:	Tibia; Humans; Vitamin D; Bone Density; Adolescent; Adult; Military Personnel; Male; Young Adult; military; musculoskeletal injury; nutrition; stress fracture; sunlight exposure; Humans; Male; Vitamin D; Military Personnel; Tibia; Bone Density; Young Adult; Adult; Adolescent; 32 Biomedical and Clinical Sciences; Clinical Research; Nutrition; Complementary and Integrative Health; Prevention; Dietary Supplements; Osteoporosis; Clinical Trials and Supportive Activities; Humans; Male; Vitamin D; Military Personnel; Tibia; Bone Density; Young Adult; Adult; Adolescent; 06 Biological Sciences; 09 Engineering; 11 Medical and Health Sciences; Anatomy & Morphology; 31 Biological sciences; 32 Biomedical and clinical sciences
Subjects:	T Technology > TX Home economics > TX341 Nutrition. Foods and food supply Q Science > QP Physiology U Military Science > U Military Science (General)
Divisions:	Sport and Exercise Sciences
Publisher:	Oxford University Press (OUP)
Date of acceptance:	25 April 2025
Date Deposited:	19 Feb 2026 13:42
Last Modified:	19 Feb 2026 13:42
DOI or ID number:	10.1093/jbmr/zjaf064
URI:	https://researchonline.ljmu.ac.uk/id/eprint/28128

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