Page 66 - Journal of Special Operations Medicine - Spring 2014

Clinical Relevance of Optimizing Vitamin D Status
in Soldiers to Enhance Physical and Cognitive Performance

Laurel M. Wentz, PhD; Jerad D. Eldred, 18D;
Michael D. Henry, MD; Cristóbal S. Berry-Cabán, PhD

ABSTRACT
Vitamin D deficiency initiates a loss of combat effec- Introduction
tiveness by impairing physical and cognitive functioning Vitamin D deficiency threatens the physical and cogni-
of combat Operators. Synthesized in response to sun- tive functioning of combat Operators. While dietary in-
light and consumed in the diet, vitamin D functions as a take contributes to vitamin D status, it is also synthesized
hormone and regulates gene expression for nearly 300 in the skin when exposed to specific UV wavelengths,
genes throughout the human body. These target genes thereby distinguishing it from other vitamins. Vitamin
are involved processes essential to combat operations, D functions as a hormone and regulates gene expression
such as immune function, response to stress, inflamma- for pathways essential to physical and cognitive perfor-
tion, and regulation of calcium movement. Since wide- mance. Hormonal imbalances, including vitamin D defi-
spread vitamin D deficiency is observed across the U.S. ciency, may result from a combination of environmental
population, poor vitamin D status is expected in Service- exposures, poor nutrition, and strenuous training. Fail-
members. Physical conditions linked to vitamin D defi- ing to correct vitamin D status in a deficient Soldier has
ciency include increased risk for muscle or bone injury, the potential to limit Operator function, reducing com-
muscle weakness, and reduced neuromuscular function. bat power and effectiveness. Conditions linked to vita-
Hormonally, vitamin D levels have been positively cor- min D deficiency include loss of muscle strength, reduced
related with testosterone levels. Vitamin D deficiency is testosterone synthesis, and increased risk of muscle/bone
also associated with cognitive decline, depression, and injury, cognitive decline, depression, and postconcussive
may prolong recovery following mild traumatic brain symptoms.
injury (mTBI). Since vitamin D deficiency elevates sys-
temic inflammation, poor vitamin D status at the time The recent explosion of vitamin D research has invited
of brain injury may prolong the inflammatory response a mixture of criticism and acclaim as vitamin D is now
and exacerbate postconcussive symptoms. Furthermore, recognized to have more biological functions than were
veterans with mTBI experience chronic endocrine dys- previously understood. Thus, conflicting recommenda-
function. While vitamin D status has not been assessed tions for optimal status and dietary intake of vitamin D
post-mTBI, it is plausible that vitamin D levels are al- have created confusion among members of the medical
tered along with testosterone and growth hormone, community.
raising the question of whether vitamin D deficiency
results from trauma-related hormonal abnormalities or The purpose of this review is to highlight the role of vi-
whether vitamin D deficiency increases the risk for en- tamin D in physical and cognitive functions essential to
docrine dysfunction. Through its association with tes- combat operations along with consequences of untreated
tosterone production, vitamin D deficiency may increase deficiencies. The clinical relevance of assessing vitamin
the risk for posttraumatic stress disorder (PTSD) since D status is described as it relates to physiological opera-
testosterone levels are altered in veterans with PTSD. tions required for optimal health and performance.
Therefore, vitamin D status has a significant impact on
Operator health and performance. Supplementing vita-
min D to deficient Operators provides a noninvasive and Special Operation Forces Relevance
low-cost intervention to maintain combat force.
Vitamin D deficiency is widespread across the Special
Operation Forces (SOF) population. Preliminary data
Keywords: vitamin D, 25-hydroxyvitamin D, inflammation, from a review of medical records show that 314 unique
neuroprotection, musculoskeletal performance, combat vitamin D assessments were ordered for SOF person-
readiness
nel at Womack Army Medical Center (WAMC) over the
1
previous 2 years. More than half of the Servicemembers

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