A genomics-based approach will target specific genes that may explain the response in biomarkers and symptoms before and after supplementation. One objective is to generate evidence-based recommendations for vitamin D supplementation in Soldiers who often experience musculoskeletal disorders and immune dysfunction impacting physical performance and military readiness. The investigation is designed to address these specific aims: 1) explore vitamin D status in 105 Service Members to determine common symptoms associated with deficiency; 2) examine the effect of vitamin D levels on gene expression from select genes known to influence metabolism, bone density, and immune function; and 3) evaluate changes in gene expression between groups receiving high or low supplementation, and compare to healthy controls. Follow-up at 15 months will evaluate circulating vitamin D.

A genomics-based approach will target identified candidate genes and search for variants that may explain the response observed in biomarkers and symptoms when deficient individuals are repleted. The long-term objective of this study is to translate findings from next-generation sequencing (NGS) technology into clinically meaningful data regarding vitamin D supplementation for Service Members (SM) who may be at risk for musculoskeletal disorders and immune dysfunction that impacts physical performance and military readiness. We propose the following specific aims: 1) explore the phenotypic expression of vitamin D status in a cohort of SM to determine common symptoms associated with deficiency/insufficiency states; 2) examine the effect of vitamin D levels on broad gene expression from carefully chosen candidate genes known to influence vitamin D status, bone density, and immune function; 3) evaluate changes in gene expression levels between and within groups supplemented with low vs high vitamin D, and compare to healthy controls, and 4) examine the relationship between vitamin D deficiency and the clinically relevant outcomes of stress fracture and high blood pressure before and after supplementation to a therapeutic plasma level of 25(OH)D. This prospective, randomized, double-blind trial will enroll 105 SM in the Northwest to evaluate frequency, symptoms, and genomic expression of vitamin D levels using survey instruments, immunologic and bone biomarkers, and NGS of white blood cells pre- and post-supplementation with oral vitamin D over 3 months. Participant follow-up at 12 months will evaluate maintenance of adequate circulating vitamin D; this timeframe represents a typical deployment period.

Inclusion Criteria:

- active duty service member, age 18 years or older, ability to read and understand English, not deploying in the next 15 months, and subjectively in good health.

Exclusion Criteria:

- family members, beneficiaries, or civilians, pregnant or currently breastfeeding females, anyone with chronic health problems (e.g. eating disorders, kidney disease, liver disease, intestinal malabsorption), any active duty SM taking >400 IU/day vitamin D supplementation and unwilling to discontinue this, current or healing stress fractures, taking medications for an endocrine disorder, such as synthroid, or those identified as having a high potential for interaction with vitamin D including anti-seizure medications, cyclosporine, and indinavir (Crixivan).