Dietary Supplement Use in US Army Personnel: A Mixed-Methods, Survey and Focus-Group Study Examining Decision Making and Factors Associated With Use.

BACKGROUND: Dietary supplement (DS) use by Army personnel is high and is a safety and readiness issue. OBJECTIVE: Our aim was to examine factors motivating use of DSs among US Army personnel and preferred safety education strategies. DESIGN: This mixed-method study used a validated DS questionnaire and subsequent focus groups that were formed based on questionnaire-identified demographic characteristics. An embedded qualitative dominant design was used. PARTICIPANTS/SETTING: Data were collected from April to July 2015 from active duty soldiers at 3 military installations in the United States. MAIN OUTCOME MEASURES: A self-report questionnaire (n = 289) provided data on demographic characteristics, health, exercise, detailed use, and attitudes regarding DS safety and efficacy. Fourteen focus-group sessions (n = 129) examined factors motivating DS use, education strategies, and identified themes and DS-related behaviors. STATISTICAL ANALYSIS PERFORMED: Descriptive statistics and χ2 analyses were conducted. RESULTS: Of the soldiers who completed questionnaires, 83% were male, 60% were enlisted, and 40% were officers; mean age ± standard deviation was 27.6 ± 0.36 years and 75% used at least 1 type of DS per week: 52% used protein/amino acids, 47% used multivitamins/minerals, and 35% used a combination of products. Focus groups indicated reasons for use included physical appearance, fitness, peer endorsement, ease of access, limited availability of healthy food, occupational demands, and health. Participants requested education from an expert on safe use that was not focused on dangerous products. CONCLUSIONS: Soldiers are high DS users, especially products marked for purported performance enhancement. Motivating factors for DS use are fitness/appearance and occupational demands, but soldiers lack knowledge of DS regulatory requirements and safety/efficacy. Soldiers wished to receive education on DSs from trusted health care professionals, such as registered dietitian nutritionists, that was not focused on dangerous products. Study findings suggest guidance and education should occur before periods of high DS use, such as deployment.

Glycaemic regulation, appetite and ex vivo oxidative stress in young adults following consumption of high-carbohydrate cereal bars fortified with polyphenol-rich berries.

Consumption of certain berries appears to slow postprandial glucose absorption, attributable to polyphenols, which may benefit exercise and cognition, reduce appetite and/or oxidative stress. This randomised, crossover, placebo-controlled study determined whether polyphenol-rich fruits added to carbohydrate-based foods produce a dose-dependent moderation of postprandial glycaemic, glucoregulatory hormone, appetite and ex vivo oxidative stress responses. Twenty participants (eighteen males/two females; 24 (sd 5) years; BMI: 27 (sd 3) kg/m2) consumed one of five cereal bars (approximately 88 % carbohydrate) containing no fruit ingredients (reference), freeze-dried black raspberries (10 or 20 % total weight; LOW-Rasp and HIGH-Rasp, respectively) and cranberry extract (0·5 or 1 % total weight; LOW-Cran and HIGH-Cran), on trials separated by ≥5 d. Postprandial peak/nadir from baseline (Δmax) and incremental postprandial AUC over 60 and 180 min for glucose and other biochemistries were measured to examine the dose-dependent effects. Glucose AUC0-180 min trended towards being higher (43 %) after HIGH-Rasp v. LOW-Rasp (P=0·06), with no glucose differences between the raspberry and reference bars. Relative to reference, HIGH-Rasp resulted in a 17 % lower Δmax insulin, 3 % lower C-peptide (AUC0-60 min and 3 % lower glucose-dependent insulinotropic polypeptide (AUC0-180 min) P<0·05. No treatment effects were observed for the cranberry bars regarding glucose and glucoregulatory hormones, nor were there any treatment effects for either berry type regarding ex vivo oxidation, appetite-mediating hormones or appetite. Fortification with freeze-dried black raspberries (approximately 25 g, containing 1·2 g of polyphenols) seems to slightly improve the glucoregulatory hormone and glycaemic responses to a high-carbohydrate food item in young adults but did not affect appetite or oxidative stress responses at doses or with methods studied herein.

Dietary Zinc Modulates Matrix Metalloproteinases in Traumatic Brain Injury.

Animal models of mild traumatic brain injury (mTBI) provide opportunity to examine the extent to which dietary interventions can be used to improve recovery after injury. Animal studies also suggest that matrix metalloproteinases (MMPs) play a role in tissue remodeling post-TBI. Because dietary zinc (Zn) improved recovery in nonblast mTBI models, and the MMPs are Zn-requiring enzymes, we evaluated the effects of low- (LoZn) and adequate-Zn (AdZn) diets on MMP expression and behavioral responses, subsequent to exposure to a single blast. MMP messenger RNA expression in soleus muscle and frontal cortex tissues were quantified at 48 h and 14 days post-blast. In muscle, blast resulted in significant upregulation of membrane-type (MT)-MMP, MMP-2, tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 at 48 h post-injury in rats consuming AdZn. At 14 days post-blast, there were no blast or dietary effects observed on MMP levels in muscle, supporting the existence of a Zn-responsive, functional repair and remodeling mechanism. In contrast, blast resulted in a significant downregulation of MT-MMP, TIMP-1, and TIMP-2 and a significant upregulation of MMP-3 levels at 48 h post-injury in cortex tissue, whereas at 14 days post-blast, MT-MMP, MMP-2, and TIMP-2 were all downregulated in response to blast, independent of diet, and TIMP-1 were significantly increased in rats fed AdZn diets despite the absence of elevated MMPs. Because the blast injuries occurred while animals were under general anesthesia, the increased immobility observed post-injury in rats consuming LoZn diets suggest that blast mTBI can, in the absence of any psychological stressor, induce post-traumatic stress disorder-related traits that are chronic, but responsive to diet. Taken together, our results support a relationship between marginally Zn-deficient status and a compromised regenerative response post-injury in muscle, likely through the MMP pathway. However, in neuronal tissue, changes in MMP/TIMP levels after blast indicate a variable response to marginally Zn-deficient diets that may help explain compromised repair mechanism(s) previously associated with the systemic hypozincemia that develops in patients with TBI.

Impact of sleep restriction on local immune response and skin barrier restoration with and without "multinutrient" nutrition intervention.

Systemic immune function is impaired by sleep restriction. However, the impact of sleep restriction on local immune responses and to what extent any impairment can be mitigated by nutritional supplementation is unknown. We assessed the effect of 72-h sleep restriction (2-h nightly sleep) on local immune function and skin barrier restoration of an experimental wound, and determined the influence of habitual protein intake (1.5 g·kg-1·day-1) supplemented with arginine, glutamine, zinc sulfate, vitamin C, vitamin D3, and omega-3 fatty acids compared with lower protein intake (0.8 g·kg-1·day-1) without supplemental nutrients on these outcomes. Wounds were created in healthy adults by removing the top layer of less than or equal to eight forearm blisters induced via suction, after adequate sleep (AS) or 48 h of a 72-h sleep restriction period (SR; 2-h nightly sleep). A subset of participants undergoing sleep restriction received supplemental nutrients during and after sleep restriction (SR+). Wound fluid was serially sampled 48 h postblistering to assess local cytokine responses. The IL-8 response of wound fluid was higher for AS compared with SR [area-under-the-curve (log10), 5.1 ± 0.2 and 4.9 ± 0.2 pg/ml, respectively; P = 0.03]; and both IL-6 and IL-8 concentrations were higher for SR+ compared with SR ( P < 0.0001), suggestive of a potentially enhanced early wound healing response. Skin barrier recovery was shorter for AS (4.2 ± 0.9 days) compared with SR (5.0 ± 0.9 days) ( P = 0.02) but did not differ between SR and SR+ ( P = 0.18). Relatively modest sleep disruption delays wound healing. Supplemental nutrition may mitigate some decrements in local immune responses, without detectable effects on wound healing rate. NEW & NOTEWORTHY The data herein characterizes immune function in response to sleep restriction in healthy volunteers with and without nutrition supplementation. We used a unique skin wound model to show that sleep restriction delays skin barrier recovery, and nutrition supplementation attenuates decrements in local immune responses produced by sleep restriction. These findings support the beneficial effects of adequate sleep on immune function. Additional studies are necessary to characterize practical implications for populations where sleep restriction is unavoidable.

Creating the Future of Evidence-Based Nutrition Recommendations: Case Studies from Lipid Research.

Strategic translational research is designed to address research gaps that answer specific guidance questions. It provides translational value with respect to nutrition guidance and regulatory and public policy. The relevance and the quality of evidence both matter in translational research. For example, design decisions regarding population, intervention, comparator, and outcome criteria affect whether or not high-quality studies are considered relevant to specific guidance questions and are therefore included as evidence within the context of systematic review frameworks used by authoritative food and health organizations. The process used in systematic reviews, developed by the USDA for its Nutrition Evidence Library, is described. An eating pattern and cardiovascular disease (CVD) evidence review is provided as an example, and factors that differentiated the studies considered relevant and included in that evidence base from those that were excluded are noted. Case studies on ω-3 (n-3) fatty acids (FAs) and industrial trans-FAs illustrate key factors vital to relevance and translational impact, including choice of a relevant population (e.g., healthy, at risk, or diseased subjects; general population or high-performance soldiers); dose and form of the intervention (e.g., food or supplement); use of relevant comparators (e.g., technically feasible and realistic); and measures for both exposure and outcomes (e.g., inflammatory markers or CVD endpoints). Specific recommendations are provided to help increase the impact of nutrition research on future dietary guidance, policy, and regulatory issues, particularly in the area of lipids.

Effects of exercise mode, energy, and macronutrient interventions on inflammation during military training.

Load carriage (LC) exercise may exacerbate inflammation during training. Nutritional supplementation may mitigate this response by sparing endogenous carbohydrate stores, enhancing glycogen repletion, and attenuating negative energy balance. Two studies were conducted to assess inflammatory responses to acute LC and training, with or without nutritional supplementation. Study 1: 40 adults fed eucaloric diets performed 90-min of either LC (treadmill, mean ± SD 24 ± 3 kg LC) or cycle ergometry (CE) matched for intensity (2.2 ± 0.1 VO2peak L min(-1)) during which combined 10 g protein/46 g carbohydrate (223 kcal) or non-nutritive (22 kcal) control drinks were consumed. Study 2: 73 Soldiers received either combat rations alone or supplemented with 1000 kcal day(-1) from 20 g protein- or 48 g carbohydrate-based bars during a 4-day, 51 km ski march (~45 kg LC, energy expenditure 6155 ± 515 kcal day(-1) and intake 2866 ± 616 kcal day(-1)). IL-6, hepcidin, and ferritin were measured at baseline, 3-h post exercise (PE), 24-h PE, 48-h PE, and 72-h PE in study 1, and before (PRE) and after (POST) the 4-d ski march in study 2. Study 1: IL-6 was higher 3-h and 24-h post exercise (PE) for CE only (mode × time, P < 0.05), hepcidin increased 3-h PE and recovered by 48-h, and ferritin peaked 24-h and remained elevated 72-h PE (P < 0.05), regardless of mode and diet. Study 2: IL-6, hepcidin and ferritin were higher (P < 0.05) after training, regardless of group assignment. Energy expenditure (r = 0.40), intake (r = -0.26), and balance (r = -0.43) were associated (P < 0.05) with hepcidin after training. Inflammation after acute LC and CE was similar and not affected by supplemental nutrition during energy balance. The magnitude of hepcidin response was inversely related to energy balance suggesting that eating enough to balance energy expenditure might attenuate the inflammatory response to military training.

Effects of Supplemental Energy on Protein Balance during 4-d Arctic Military Training.

UNLABELLED: Soldiers often experience negative energy balance during military operations that diminish whole-body protein retention, even when dietary protein is consumed within recommended levels (1.5-2.0 g·kg·d). PURPOSE: The objective of this study is to determine whether providing supplemental nutrition spares whole-body protein by attenuating the level of negative energy balance induced by military training and to assess whether protein balance is differentially influenced by the macronutrient source. METHODS: Soldiers participating in 4-d arctic military training (AMT) (51-km ski march) were randomized to receive three combat rations (CON) (n = 18), three combat rations plus four 250-kcal protein-based bars (PRO, 20 g protein) (n = 28), or three combat rations plus four 250-kcal carbohydrate-based bars daily (CHO, 48 g carbohydrate) (n = 27). Energy expenditure (D2O) and energy intake were measured daily. Nitrogen balance (NBAL) and protein turnover were determined at baseline (BL) and day 3 of AMT using 24-h urine and [N]-glycine. RESULTS: Protein and carbohydrate intakes were highest (P < 0.05) for PRO (mean ± SD, 2.0 ± 0.3 g·kg·d) and CHO (5.8 ± 1.3 g·kg·d), but only CHO increased (P < 0.05) energy intake above CON. Energy expenditure (6155 ± 515 kcal·d), energy balance (-3313 ± 776 kcal·d), net protein balance (NET) (-0.24 ± 0.60 g·d), and NBAL (-68.5 ± 94.6 mg·kg·d) during AMT were similar between groups. In the combined cohort, energy intake was associated (P < 0.05) with NET (r = 0.56) and NBAL (r = 0.69), and soldiers with the highest energy intake (3723 ± 359 kcal·d, 2.11 ± 0.45 g protein·kg·d, 6.654 ± 1.16 g carbohydrate·kg·d) achieved net protein balance and NBAL during AMT. CONCLUSION: These data reinforce the importance of consuming sufficient energy during periods of high energy expenditure to mitigate the consequences of negative energy balance and attenuate whole-body protein loss.

Absorption of omega-3 fats from carbohydrate and proteinaceous food matrices before and after storage.

Development of n-3 fortified, shelf-stable foods is facilitated by encapsulated docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), since natural n-3 food sources cannot withstand high temperature and prolonged shelf life. Organoleptic stability of n-3 fortified, shelf-stable foods has been demonstrated, but chemical changes in the food matrix throughout storage could conceivably impact digestibility of the protein-based encapsulant thereby compromising n-3 bioavailability. We assessed the effect of prolonged high-temperature storage and variations in food matrix (proteinaceous or carbohydrate) on the time course and magnitude of blood fatty acids changes associated with ingestion of n-3 fortified foods. Low-protein (i.e., cake) and high-protein (i.e., meat sticks) items were supplemented with 600 mg encapsulated DHA+EPA, and frozen either immediately after production (FRESH) or after 6 months storage at 100°F (STORED). Fourteen volunteers consumed one item per week (randomized) for 4 weeks. Blood samples obtained at baseline, 2, 4, and 6 h post-consumption were analyzed for circulating long-chain omega 3 fatty acids (LCn3). There was no difference in LCn3 area under the curve between items. LCn3 in response to cakes peaked at 2-h (FRESH: 54.0 ± 16.8 µg/mL, +18%; STORED: 53.0 ± 13.2 µg/mL, +20%), while meats peaked at 4-h (FRESH: 51.9 ± 12.5 µg/mL, +22%; STORED: 53.2 ± 16.9 µg/mL, +18%). There were no appreciable differences in time course or magnitude of n-3 appearance in response to storage conditions for either food types. Thus, bioavailability of encapsulated DHA/EPA, within low- and high-protein food items, was not affected by high-temperature shelf-storage. A shelf-stable, low- or high-protein food item with encapsulated DHA/EPA is suitable for use in shelf-stable foods.

Protein supplementation in U.S. military personnel.

Protein supplements (PSs) are, after multivitamins, the most frequently consumed dietary supplement by U.S. military personnel. Warfighters believe that PSs will improve health, promote muscle strength, and enhance physical performance. The estimated prevalence of regular PS use by military personnel is nearly 20% or more in active-duty personnel, which is comparable to collegiate athletes and recreationally active adults, but higher than that for average U.S. civilians. Although the acute metabolic effects of PS ingestion are well described, little is known regarding the benefits of PS use by warfighters in response to the metabolic demands of military operations. When dietary protein intake approaches 1.5 g · kg(-1) · d(-1), and energy intake matches energy expenditure, the use of PSs by most physically active military personnel may not be necessary. However, dismounted infantry often perform operations consisting of long periods of strenuous physical activity coupled with inadequate dietary energy and protein intake. In these situations, the use of PSs may have efficacy for preserving fat-free mass. This article reviews the available literature regarding the prevalence of PS use among military personnel. Furthermore, it highlights the unique metabolic stressors affecting U.S. military personnel and discusses potential conditions during which protein supplementation might be beneficial.

Plasma amino acid responses after consumption of beverages with varying protein type.

PURPOSE: To examine how different proteins in a carbohydrate-protein beverage affect postprandial amino acid (AA), glucose, and insulin responses. METHODS: Two randomized, repeated-measures experiments were performed. In one, 10 volunteers drank 3 carbohydrate-protein beverages (380 kcal, 76 g carbohydrate, 19 g protein, 2 g fat) in separate (>7 days) trials, each differing in protein type. All drinks consisted of cocoa (4 g) and nonfat dry milk (1 g) supplemented with casein (CAS), whey (WP), or a casein and whey blend (CAS-WP). Ten additional volunteers consumed the same drinks after 60 min of varying-intensity exercise (60% and 85% VO2peak). Blood glucose, insulin, glucose-dependent insulinotrophic polypeptide (GIP), and AAs were measured every 15-30 min for 4 hr after beverage consumption. RESULTS: Branched-chain AA concentrations peaked at 30 min and did not differ between beverages at rest (0.69 +/- 0.12 mmol/L) or postexercise (0.70 +/- 0.07 mmol/L). There were no significant differences between beverages with respect to initial (time 0-60) or total area under the curve (time 0-240) for any outcome measures at rest or postexercise. CONCLUSION: High-carbohydrate beverages containing various proportions of milk proteins procured from a supplier to the commercial industry had no impact on AA concentration. Retrospective chemical analysis of commercial proteins showed that casein was partially hydrolyzed; therefore, consumers should carefully consider the manufacturer (to ensure that the product contains intact protein) or other factors (i.e., cost or taste) when procuring these beverages for their purported physiological effects.

Use of phosphocreatine kinetics to determine the influence of creatine on muscle mitochondrial respiration: an in vivo 31P-MRS study of oral creatine ingestion.

Recent human isolated muscle fiber studies suggest that phosphocreatine (PCr) and creatine (Cr) concentrations play a role in the regulation of mitochondrial respiration rate. To determine whether similar regulatory mechanisms are present in vivo, this study examined the relationship between skeletal muscle mitochondrial respiration rate and end-exercise PCr, Cr, PCr-to-Cr ratio (PCr/Cr), ADP, and pH by using (31)P-magnetic resonance spectroscopy in 16 men and women (36.9 +/- 4.6 yr). The initial PCr resynthesis rate and time constant (T(c)) were used as indicators of mitochondrial respiration after brief (10-12 s) and exhaustive (1-4 min) dynamic knee extension exercise performed in placebo and creatine-supplemented conditions. The results show that the initial PCr resynthesis rate has a strong relationship with end-exercise PCr, Cr, and PCr/Cr (r > 0.80, P < 0.001), a moderate relationship with end-exercise ADP (r = 0.77, P < 0.001), and no relationship with end-exercise pH (r = -0.14, P = 0.34). The PCr T(c) was not as strongly related to PCr, Cr, PCr/Cr, and ADP (r < 0.77, P < 0.001-0.18) and was significantly influenced by end-exercise pH (r = -0.43, P < 0.01). These findings suggest that end-exercise PCr and Cr should be taken into consideration when PCr recovery kinetics is used as an indicator of mitochondrial respiration and that the initial PCr resynthesis rate is a more reliable indicator of mitochondrial respiration compared with the PCr T(c).

Diet and physical performance.

This paper provides a historical summary of military nutrition research into the role of diet for sustaining soldier physical performance. Studies of underfeeding document that physical performance is preserved during several days of underfeeding provided sufficient carbohydrate and minerals are consumed to minimize the diuresis associated with semi-starvation diets and serial intake of carbohydrate is available to support metabolism during prolonged work. The Military Recommended Dietary Allowances, AR 40-25, currently recommends that when restricted rations are required, that the ration contain at least 1,100-1,500 kcal, 50-70 g of protein, and a minimum of 100 g of carbohydrate on a daily basis. This low energy diet, however, is not recommended for subsistence for longer than 10 consecutive days. Dietary carbohydrate intakes of approximately 300-400 g will more closely match the quantity of carbohydrate oxidized to meet daily energy requirements during field operations. Research into the potential advantages of dietary supplements has generally not proved advantageous when compared to eating a well balanced diet. Future investigations of the role of diet for sustaining soldier health and performance should be directed toward a better understanding of the influence of energy intake and macro-nutrient composition for preserving lean body mass, reducing susceptibility to illness and injury and enhancing recovery during and after sustained operations.