Diet and Military

Zwilling et. al (2020) declares the critical demand for interventions to enhance human physical fitness and cognitive performance to enable Airmen in particular, who operate under extreme physical and cognitive pressure, to remain resilient and perform well during missions. A twelve-week randomised controlled trial was conducted on 148 active-duty Air Force Airmen to compare the efficacy of a multimodal intervention that consisted of high-intensity interval aerobic fitness and strength training coupled with a novel nutritional supplement [containing β-hydroxy β-methylbutyrate (HMB), lutein, phospholipids, DHA and selected micronutrients including B12 and folic acid] with another program of high-intensity interval aerobic fitness and strength training paired with a standard placebo drink. The study found the exercise program alone improved several physical fitness attributes: strength and endurance (+8.3%); power (+0.85%); mobility and stability (+22%); heart rate (-1.1%); lean muscle mass (+1.4%). Plus, enhancements in cognitive function were observed with regards to processing efficacy (+7.5%), episodic memory (+9.5%), fluid intelligence accuracy (+19.5%) and executive function reaction time (-4.8%). The addition of the nutritional supplement to the fitness regime further boosted the Airmen’s physical fitness and cognitive performance, indicated by the bettering of working memory by 9%, processing efficiency by 1.8%, lean muscle mass by 1.5%, as well as the reductions in fluid intelligence reaction time by 7.7% and heart rate by 2.4%. This study found the multimodal intervention incorporating aerobic fitness and strength training with a novel nutritional supplement to be effective in enhancing military performance and in providing optimal exercise training and nutritional support for the modern warfighter.

The purpose of this 2020 systematic review was to identify dietary supplements useful for optimising cognitive performance for military personnel. The search was for studies that involved a legal diet supplement, included a comparison control group, assessed cognitive outcomes, and that recruited healthy young adults (18-35 years old). The majority (73%) of the 37 studies that met the inclusion criteria was deemed of low quality, highlighting the need for sound empirical research in this area. The results did suggest tyrosine or caffeine may be of use to enhance cognitive performance while sleep-deprived, since caffeine potentially improves vigilance and attention despite little sleep. The review did not recommend any other specific dietary supplement due to inconsistent findings and limitations in research methodology.

Marriott et al. (2019) explain the designs and methods of the Ranger Resilience and Improved Performance on Phospholipid bound Omega-3's (RRIPP-3) study - a double-blind randomized controlled trial that tested omega-3 highly unsaturated fatty acids (HUFAs) along with krill oil supplementation in individuals undertaking the United States (US) Army Infantry Basic Officer Leaders Course (IBOLC). Omega-3 HUFAs are essential for neural function, normative neurodevelopment, neurotransmitter, and neural immune functions, already proven in observational studies and randomized controlled trials. But as dietary supplements, omega-3 HUFAs such as fish and krill oils differ substantially in their physicochemical properties and nutrient content from the omega-3 HUFAs obtained through diet. In the RRIPP-3 study, the impact of adding the krill oil with the omega-3 HUFAs on cognitive functioning was compared to placebo, in order to determine whether the krill oil supplementation can improve critical cognitive aspects required for success in the battlefield. Basic advancements were observed in the participants’ IBOLC performances following supplementation with HUFAs and krill oil.

This 2017 cross-sectional study aimed to assess the relationship between diet quality and psychological resilience, and also the links between resilience and demographics, anthropometrics, socioeconomic status, and health behavior, by analyzing data on 656 male and female Army and Air Force recruits (before initiation of military training). The recruits’ scores for the 2010 Healthy Eating Index (HEI-2010), which measures diet quality and can be used to quantify adherence to the Dietary Guidelines for Americans, were examined using the Block food frequency questionnaire. While the use of the Connor-Davidson Resilience Scale determined the subjects’ psychological resilience, allowing the splitting of the participants into low- and high-resilience groups. The results showed that diet quality was positively associated with resilience, and a higher HEI could predict a greater chance of being in the high-resilience group after including factors such as race, ethnicity, education, smoking, age, body mass index, sex, and military branch in the analysis. Lutz et al. (2017) highlighted a 22% increased chance of being in the high-resilience group, for every 10-point increment in HEI score. Since these findings suggest that even minor improvements in diet quality correlated with better psychological resilience, registered dietician nutritionists are encouraged to continue provoking positive dietary changes.

This 2014 review summarizes the relationship vitamin D has with physical and cognitive performance in relation to the needs of military personnel. Deficiencies in vitamin D, which are widespread across the U.S. population and expected to be prevalent in Servicemembers, may be connected to increased risk for muscle or bone injury, muscle weakness, reduced neuromuscular function, cognitive decline, depression, longer recovery times following mild traumatic brain injury (mTBI). Although vitamin D status has not been assessed after mTBI, veterans with traumatic brain injuries also experience chronic endocrine dysfunction, indicating vitamin D deficiency could possibly raise the risk for endocrine dysfunction. Since a relationship between vitamin D status and testosterone levels has been previously identified, and the concentrations of this hormone are low in veterans with posttraumatic stress disorder (PTSD), it has been suggested poor vitamin D status also enhances risk for PTSD. Wentz et al. (2014) makes it clear vitamin D status has a significant impact on Operator health and performance, and therefore supports vitamin D supplementation since the intervention required would be noninvasive and low-cost and would help maintain the Operators’ combat strength.

This 2020 study on Gulf War veterans aimed to determine if a low glutamate diet can reduce the symptoms of the Gulf War Illness (GWI), a multi-symptom chronic pain condition. The 40 veterans were firstly randomly allocated to either a low-glutamate diet or a wait-listed control group (starting the diet one month later), and then randomized to a double-blind placebo-controlled crossover challenge with monosodium glutamate (MSG)/placebo to assess whether symptoms return/worsen in each condition. The participants were assessed on symptoms, myalgic scores, tender point count, and dolorimetry. After one month, the overall average number of symptoms presented was significantly different between those who received the diet with the wait-listed controls (11 in the diet group vs. 18 in wait-listed control group), with a p-value of 0.0007. Also no adverse effects were observed and the effect size of the diet was large (d = 1.17). Furthermore, the mean number of symptoms at baseline (21) dropped after the 1 -month diet to 12 (p<0.0001) among the subjects who were given the low-glutamate diet from the start of the study. The severity of remaining symptoms was also significantly reduced (all P < 0.0001) and 72% of the whole sample met the PGIC criteria for improvement. Highly significant enhancements were observed for myalgic score (P < 0.0001), number of tender points (P < 0.0001), and average dolorimetry (P < 0.001). Holton et al. (2020) presents convincing evidence that suggests low glutamate diets can effectively treat chronic pain and the symptoms associated with Gulf War illness.

Hibbeln & Gow (2014) evaluated the effectiveness of nutrients in the military diet in reducing risk of or to treat psychiatric distress, particularly focusing on highly unsaturated essential fatty acids. The increase in omega-6 that accompanies lower fish consumption has been related to greater risk of clinical depressive symptoms while one meta-analysis provided moderate to strong evidence that elevated levels of omega-3 highly unsaturated fatty acids (HUFAs) (eicosapentaenoic acid, docosapentaenoic acid, and docosahexaenoic acid) are associated with decreased risk of clinical depressions. Support also arrived from other meta-analytic reviews of randomized placebo-controlled trials that showed moderate to strong evidence that depressive symptoms improved after subjects consumed a formulation with over 50% eicosapentaenoic acid. There is also modest proof of omega-3 HUFAs’ effectiveness in treating attention-deficit hyperactivity disorder. Hibbeln & Gow (2014) recommended a rebalancing of the essential fatty acid composition of U.S. military diets to help reduce military psychiatric distress and simultaneously increase force efficacy considerably. Since several meta-analyses have indicated that Mediterranean diet patterns lowers depression risk, it may be advisable to aim for tissue compositions of HUFAs consistent with traditional Mediterranean diets.

Since few interventions have been developed to enhance health among military spouses despite them experiencing multiple threats to their physical and mental health, this 2019 quasi-experimental study implemented either a standard educational intervention or an interactive, theory-based intervention on 231 military spouses. The educational intervention directed participants to content on the existing website, Operation Live Well, while the interactive intervention was based on Self-Determination Theory, delivered weekly content via podcasts, and encouraged participants to complete weekly challenges to improve physical activity, diet, and mental health. Although there were no significant group by time interaction effects, the study observed significant improvements in all mental health outcomes, total physical activity, and sugar consumption. Mailey et al. (2019) deduced from the results that web-based interventions may promote positive changes in mental health and health behaviours among military spouses, and thus suggested future studies to determine the minimum needed from the interventions to elicit meaningful changes in the spouses.

In this 2018 study, military spouses were evaluated on their barriers to health behaviors using surveys and focus group sessions. Participating in health behaviors such as physical activity and healthy eating may have a positive impact on spouses' physical and mental health, but research into spouses’ behaviors was limited. Subjects taking part in the surveys (n=230) indicated up to 3 of their most frequent barriers to physical activity, diet, social connection, and stress management, while the 22 people who participated in the focus groups allowed the researchers to gain a greater understanding of the challenges military spouses face when trying to maintain a healthy lifestyle. The surveys revealed lack of time was the most prevalent barrier for physical activity, social connection, and stress management, and the second most prevalent barrier for diet. Financial concern was voted most often as a barrier to maintaining a healthy diet, while obstacles related to parent/family responsibilities were also commonly reported across all health behaviors. During the focus group sessions, the transient military lifestyle was found to have a significant impact on all of the health behaviors, while deployments and the necessity to "do it all" alone were also discussed by the spouses and could be a contributor. Interestingly, many of the subjects had rigid definitions of what “counts” as exercise and healthy eating. Generally, the sample population sacrificed participating in health habits to attend other priorities. Although some of the barriers reported here were similar to barriers reported by civilians, this study uncovered unique stressors associated with military life that further impeded participation in health behaviors.

The purposes of this 2020 review were to firstly determine what is known about the assessment and reporting of dietary intakes within both military and veteran populations and secondly, to find out if studies reporting on the dietary consumption of military personnel/veterans include comparisons with dietary guidelines. Six databases were searched to discover a total of 89 observational and intervention studies that met the inclusion criteria. The majority of the studies (n=76, 85%) assessed diet through one method only while only 15% (13) studies utilised multiple methods. The most frequent methodology used was food frequency questionnaires (FFQ) (n = 40, 45%) followed by 24-hour recalls (n = 8, 9%) and food records (n = 8, 9%). The review also uncovered the main dietary outcome, with 76% of the studies reporting these, were the macronutrients (carbohydrate, protein, fat, and alcohol), with total energy intake measured in 66% (n=59). Comparisons were made with country-specific dietary and military guidelines in 54 (61%) and 14 (16%) studies, respectively. Collins et al. (2020) learnt that dietary intake in military settings were most frequently assessed using food FFQs and 24-hr recalls, the dietary outcomes were mainly related to energy and macronutrient consumption, and that few studies compared dietary intake to the military guidelines, with most comparisons made against national dietary guidelines.

Varanoske et al. (2021) reveal that β-alanine (BA) supplementation has demonstrated its ability to enhance cognition, mitigate symptoms of anxiety and depression associated with aging, and positively influence mood and physical performance during military operations. But it is not yet known whether beta-alanine can reduce mood fluctuations and cognitive dysfunction connected to the anticipatory stress before the person has experienced simulated military operations. This study therefore enrolled healthy males with limited inflammation and oxidative stress and randomized the participants to either receive BA or placebo for 14 days before undertaking a 24-hour simulated military operation. The subjects’ cognitive function, mood, and circulating brain-derived neurotrophic factor (BDNF; increase correlates with aging, neurological disorders, and physical exertion) before and after supplementation. The results showed that cognitive function and BDNF concentrations were not significantly affected, but the BA supplementation group reported reduced feelings of depression. Whereas the placebo group felt less vigor. It was concluded that β-alanine given at high dose and for a short period of time may reduce the onset of negative mood states in healthy males prior to a simulated military operation.