Vitamin D supplementation is important in military research because of its role in musculoskeletal health. This systematic review examined the effects of vitamin D supplementation on serum 25-hydroxyvitamin D (25(OH)D) concentrations and musculoskeletal health outcomes in military personnel (1). Reviewers independently screened titles, abstracts, and full texts of the articles using predefined criteria. The results showed that four RCTs were included in the qualitative analyses. The 25(OH)D concentrations was improved with 2000 IU/d supplementation (mean difference = 3.90 ng/mL; 95% CI, 0.22-7.58). A trial on female Navy recruits showed a significant decrease in stress fractures (risk ratio, 0.77; 95% CI, 0.62-0.95), particularly tibial fractures, from daily supplementations of 800 IU vitamin D and 2000 mg calcium. The authors conclude that there was a positive trend in 25(OH)D concentrations from higher doses of supplementary vitamin D in military submariners and a possible benefit to bone health when vitamin D was combined with calcium.