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Efficacy of Calcium and Vitamin D Supplementation for the Prevention of Stress Fractures in Female Naval Recruits

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Final rept. 1 Oct 2001-30 Aug 2007

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The goal was to determine if calcium and vitamin D supplementation can reduce the incidence of stress fracture in female Naval recruits during basic training. The secondary goal was to examine the potential mechanisms for increasing bone adaptation to intense mechanical loading. We recruited 5201 females who were randomly assigned to calcium 2000 mg and vitamin D 800 I.U. per day or a control placebo group. The intervention and stress fracture monitoring continued through 8 weeks of basic training. We were not able to recruit the targeted number of subjects for the sub-study designed to determine changes in moment of inertia using peripheral quantitative computed tomography pQCT because the Great Lakes Command directed us to stop the study once we reached our target sample size 5201 for the primary study. For the substudy, we enrolled 148 out of a target 560. SFx were ascertained when recruits reported to the Great Lakes clinic with symptoms. All SFx were confirmed with radiography or technetium scan according to the usual Navy protocol. A total of 309 subjects were diagnosed with a SFx resulting in an incidence of 5.9 per eight weeks. Using intention-to-treat analysis by including all enrolled subjects, we found that the calcium and vitamin D group had a 20 lower incidence of SFx than the control group 5.3 vs. 6.6, respectively, P0.0026 for Fisher s Exact test. The per protocol analysis, including only the 3700 recruits who completed the study, found a 21 lower incidence of fractures in the supplemented vs. the control group 6.8 vs. 8.6, respectively, P0.02 for Fisher s Exact test. Generalizing the findings to the population of 14,416 females who entered basic training at the Great Lakes during the 24 months of recruitment, calcium and vitamin D supplementation for the entire cohort would have prevented about 187 persons from fracturing. Such a decrease in SFx would be associated with a significant decrease in morbidity and financial costs.

Subject Categories:

  • Anatomy and Physiology
  • Medicine and Medical Research
  • Stress Physiology

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