Consumption of a calcium and vitamin D-fortified food product does not affect iron status during initial military training: a randomised, double-blind, placebo-controlled trial.

Ca/vitamin D supplementation maintains bone health and decreases stress fracture risk during initial military training (IMT); however, there is evidence that Ca may negatively affect the absorption of other critical micronutrients, particularly Fe. The objective of this randomised, double-blind, placebo-controlled trial was to determine whether providing 2000 mg/d Ca and 25 µg/d vitamin D in a fortified food product during 9 weeks of military training affects Fe status in young adults. Male (n 98) and female (n 54) volunteers enrolled in US Army basic combat training (BCT) were randomised to receive a snack bar with Ca/vitamin D (n 75) or placebo (snack bar without Ca/vitamin D; n 77) and were instructed to consume 2 snack bars/d between meals throughout the training course. Circulating ionised Ca was higher (P0·05) in markers of Fe status between placebo and Ca/vitamin D groups. Collectively, these data indicate that Ca/vitamin D supplementation through the use of a fortified food product consumed between meals does not affect Fe status during IMT.

Once daily calcium (1000 mg) and vitamin D (1000 IU) supplementation during military training prevents increases in biochemical markers of bone resorption but does not affect tibial microarchitecture in Army recruits.

Basic combat training (BCT) is a period of novel physical training including load carriage resulting in higher risk of stress fracture compared to any other time during military service. Prior trials reported a 20% reduction in stress fracture incidence with Ca and vitamin D (Ca + D) supplementation (2000 mg Ca, 800 IU vitamin D), and greater increases in tibia vBMD during BCT compared to placebo. The primary objective of this randomized, double-blind, placebo-controlled trial was to determine the efficacy of a lower dose of Ca (1000 mg/d Ca, 1000 IU vit D) on PTH, bone biomarkers and tibial microarchitecture during BCT. One hundred volunteers (50 males, 50 females; mean age 21.8 ± 3.5 y) were block randomized by race and sex to receive a daily Ca + D fortified food bar or placebo. Anthropometrics, dietary intake, fasted blood draws and high resolution pQCT scans of the distal and mid-shaft tibia were obtained at the start of BCT and 8 wks later at the conclusion of training. As compliance was 98% in both treatment groups, an intent-to-treat analysis was used. At the distal tibia, total vBMD, Tb.vBMD, Tb.N, Th.Th and Tb.BV/TV increased (+1.07 to 2.12% for all, p < 0.05) and Tb.Sp decreased (0.96 to 1.09%, p < 0.05) in both treatment groups. At the mid-shaft, Ct.Pm increased (+0.18 to 0.21%, p = 0.01) and Ct.vBMD decreased (-0.48 to -0.77%, p < 0.001) in both groups. Ca + D prevented increases in CTX and TRAP, which were observed in the placebo group (group-by-time, p < 0.05). Mean circulating 25OHD, BAP, P1NP and iCa increased and PTH decreased in both treatment groups (p < 0.05). These results, in agreement with other studies, suggest that bone microarchitectural changes indicative of bone formation occur during BCT. While Ca + D supplementation at lower doses than those tested in previous studies prevented increases in biochemical markers of bone resorption in this study, there were no significant changes in bone tissue after 8 wks of Army BCT.

Poor iron status is not associated with overweight or overfat in non-obese pre-menopausal women.

BACKGROUND: Associations between obesity and poor iron status have been described in children and adults. Proposed mechanisms for this association implicate a physiologic etiology, suggesting body fat accretion may progressively degrade iron status. However, the relationship between iron status and body composition in non-obese adults remains unclear. OBJECTIVE: In this study we examined the relationship between body composition, inflammation, and iron status in healthy, non-obese, pre-menopausal females. METHODS: Iron status was assessed using red cell distribution width, transferrin saturation, serum ferritin, and soluble transferrin receptor (sTfR). Tumor-necrosis factor-alpha provided a marker of inflammation, and body fat percentage (BF) was calculated from mean skinfold thickness measurements at 3 sites. RESULTS: In this cohort (n = 207), the prevalence of iron deficiency was similar (p > 0.05) between normal and overweight (BMI 25.0-30.0 kg/m(2)), and normal and overfat (BF >or=30.0%) volunteers. There were no differences in individual iron status indicators, including sTfR, between overweight or overfat volunteers as compared to normal weight and normal fat peers. Logistic regression analyses indicated that overfat volunteers had a lower (p < 0.05) risk of iron deficiency, whereas overweight individuals demonstrated no change in relative risk as compared to peers. CONCLUSION: These findings suggest that, in non-obese adults, decrements in iron status are not associated with increasing adiposity.

Longitudinal decrements in iron status during military training in female soldiers.

Fe is an essential micronutrient required for optimal cognitive and physical performance. Cross-sectional studies indicate that training degrades Fe status in female military personnel; however, longitudinal studies to measure the direct impact of military training on Fe status and performance have not been conducted. As such, the objective of the present study was to determine the longitudinal effects of military training on Fe status in female soldiers. Fe status was assessed in ninety-four female soldiers immediately before and following a 9-week basic combat training (BCT) course. Fe status indicators included Hb, erythrocyte distribution width (RDW), serum ferritin, transferrin saturation and soluble transferrin receptor (sTfR). A 2-mile (3.2 km) run test was performed at the end of BCT to assess aerobic performance. Fe status was affected by BCT, as all Fe status indicators, excluding Hb, were diminished (P < or = 0.01) at the end of BCT. Fe status indicators at the end of BCT (Hb and RDW) were associated (P < or = 0.05) with running performance, as was the change in sTfR over the training period (r 0.320; P < or = 0.05). In conclusion, Fe status in female soldiers is degraded during BCT, and degraded Fe status is associated with diminished aerobic performance. Female athletes and military personnel should strive to maintain Fe status to optimise physical performance.

Role of Drill Sergeants in Nutrition Behaviors of Soldiers in Basic Combat Training.

BACKGROUND: In the US Army, soldiers' nutrition behaviors have a direct impact on their performance. The emphasis in basic combat training is on "soldierization" (transforming a civilian into a soldier), and drill sergeants are instrumental in this process. Limited information about how drill sergeants use their influence to have an impact on nutrition behaviors of new soldiers is available. OBJECTIVE: This study aimed to determine nutrition attitudes, beliefs, and knowledge of drill sergeants; the ways drill sergeants instill new soldiers with an army identity (eg, warrior athlete, army strong); and how healthy eating is perceived to fit with this new identity. DESIGN: This qualitative, phenomenological study used in-depth interviews conducted with army drill sergeants at two southeast US Army posts between July and August 2011 (n=30). MAIN OUTCOME MEASURES: Interviews emphasized drill sergeants' perceptions of the eating environment during basic training, the drill sergeant role, and drill sergeants' main duties. DATA ANALYSIS: An iterative process of group coding using a constant comparative method was used to find distinct themes. Data were analyzed using qualitative data analysis software. RESULTS: Drill sergeants described their main duty as training new soldiers. Drill sergeants identified the ideal soldier as lean and physically fit but did not identify training soldiers how to eat to become the ideal soldier as part of their duties. Confusion about nutrition concepts was common. Overall, drill sergeants recognized that what soldiers eat affects their physical performance and appearance, but they did not see helping soldiers establish healthy eating behaviors as one of their duties or responsibilities during basic combat training. CONCLUSIONS: Drill sergeants are key individuals in the process by which new recruits develop a soldier identity. Additional resources are necessary to help drill sergeants emphasize nutrition and health during basic combat training and help them guide soldiers toward adopting healthy eating as part of their soldier identity to improve weight management, health, and performance.

Adherence to the Dietary Guidelines for Americans Is Associated with Psychological Resilience in Young Adults: A Cross-Sectional Study.

BACKGROUND: The 2010 Healthy Eating Index (HEI-2010), a measure of diet quality, is used to quantify adherence to the Dietary Guidelines for Americans. Better HEI scores have been associated with positive health outcomes; however, the relationship between diet quality and psychological resilience, a mental health attribute for coping with adversity, has not been assessed. OBJECTIVE: The objective of the present study was to assess the relationship between diet quality and psychological resilience, and the relationship between resilience and demographics, anthropometrics, socioeconomic status, and health behavior. DESIGN: In this cross-sectional study, HEI-2010 scores and resilience were assessed using the Block food frequency questionnaire and the Connor-Davidson Resilience Scale. Other factors that can affect the relationship between HEI-2010 scores and resilience were assessed using surveys, and height and weight were measured to calculate body mass index. PARTICIPANTS/SETTING: Male and female Army and Air Force recruits (n=834) enrolled in a randomized controlled trial and 656 (mean±standard deviation [SD] age=21±3.3 years) were included in this analysis. Data were collected before the initiation of military training at Fort Sill, OK (2012-2013) and Lackland Air Force Base, TX (2013-2014). STATISTICAL ANALYSIS PERFORMED: Participants were split into low- and high-resilience groups based on Connor-Davidson Resilience Scale scores. Student's t test and χ2 tests were used to determine differences between groups for continuous and categorical variables, respectively. Logistic regression was utilized to identify predictors of resilience. RESULTS: Better diet quality was associated with resilience; higher HEI predicted an increased likelihood (odds ratio=1.02; 95% CI 1.01 to 1.04) of a participant being in the high-resilience group after including race, ethnicity, education, smoking, age, body mass index, sex, and military branch in the full model. The data indicate that with every 10-point increase in HEI score, there was a 22% increased likelihood of being in the high-resilience group. CONCLUSIONS: Registered dietitian nutritionists should continue to encourage attainable changes to improve diet; study data suggest that small improvements in diet quality can be associated with better psychological resilience.

Association Between Single Gene Polymorphisms and Bone Biomarkers and Response to Calcium and Vitamin D Supplementation in Young Adults Undergoing Military Training.

Initial military training (IMT) is associated with increased stress fracture risk. In prior studies, supplemental calcium (Ca) and vitamin D provided daily throughout IMT reduced stress fracture incidence, suppressed parathyroid hormone (PTH), and improved measures of bone health compared with placebo. Data were analyzed from a randomized, double-blind, placebo-controlled trial to determine whether single-nucleotide polymorphisms (SNPs) in Ca and vitamin D-related genes were associated with circulating biomarkers of bone metabolism in young adults entering IMT, and whether responses to Ca and vitamin D supplementation were modulated by genotype. Associations between SNPs, including vitamin D receptor (VDR), vitamin D binding protein (DBP), and 1-alpha-hydroxylase (CYP27B1), and circulating biomarkers were measured in fasting blood samples from volunteers (n = 748) starting IMT. Volunteers were block randomized by race and sex to receive Ca (2000 mg) and vitamin D (1000 IU) or placebo daily throughout Army or Air Force IMT (7 to 9 weeks). Total Ca and vitamin D intakes were calculated as the sum of supplemental intake based on intervention compliance and dietary intake. Relationships between SNPs, Ca, and vitamin D intake tertile and change in biomarkers were evaluated in trial completers (n = 391). At baseline, the minor allele of a DBP SNP (rs7041) was positively associated with both 25OHD (B = 4.46, p = 1.97E-10) and 1,25(OH)2 D3 (B = 9.63, p < 0.001). Combined genetic risk score (GRS) for this SNP and a second SNP in the VDR gene (rs1544410) was inversely associated with baseline 25OHD (r = -0.28, p < 0.001) and response to Ca and vitamin D intake differed by GRS (p < 0.05). In addition, presence of the minor allele of a second VDR SNP (rs2228570) was associated with lower P1NP (B = -4.83, p = 0.04) and osteocalcin (B = -0.59, p = 0.03). These data suggest that VDR and DBP SNPs are associated with 25OHD status and bone turnover and those with the highest GRS require the greatest vitamin D intake to improve 25OHD during IMT. © 2016 American Society for Bone and Mineral Research.

Effects of basic combat training on iron status in male and female soldiers: a comparative study.

OBJECTIVE: Iron is an essential micronutrient known to affect physical and cognitive performance. Studies indicate a significant reduction in iron status in female Soldiers immediately following military training, although the comparative effects of military training on iron status between male and female Soldiers have not been examined. The objective of this study was to compare the longitudinal effects of US Army basic combat training (BCT) on iron status indicators in a group of male and female Soldiers. METHODS: A total of 154 male and female Soldiers (89 and 65, respectively) completed the study. Blood was collected at 4 time-points during BCT (weeks 0, 3, 6, 9) and dietary iron intake was assessed at weeks 0 and 9. Iron status indicators included hemoglobin, serum ferritin (SF), soluble transferrin receptor (sTfR), and transferrin saturation (TS). RESULTS: Iron status was greater in male Soldiers than female Soldiers, as hemoglobin and SF levels were higher (P<.05) and sTfR levels were lower (P<.05) in males as compared to females at each time-point. Despite a mean increase of greater than 25% in iron intake (mg/day) among both male (15±13 to 20.2±14.4) and female Soldiers (12.8±9.7 to 16±6.2) over the course of BCT, iron status declined in both groups. As compared to baseline, SF declined (P<.05) by 21% and 47%, sTfR increased (P<.05) by 17% and 30%, and TS declined (P<.05) by 23% and 54% in male and female Soldiers, respectively, over the course of BCT. CONCLUSIONS: These data indicate that although dietary iron intake improves, iron status declines in both male and female Soldiers during BCT, and the decline in female Soldiers is of a greater magnitude. Future studies should aim to determine the mechanism by which iron status declines during military training, with a focus on functional outcomes affecting Soldier health and performance.

Calcium and vitamin D supplementation maintains parathyroid hormone and improves bone density during initial military training: a randomized, double-blind, placebo controlled trial.

Calcium and vitamin D are essential nutrients for bone health. Periods of activity with repetitive mechanical loading, such as military training, may result in increases in parathyroid hormone (PTH), a key regulator of Ca metabolism, and may be linked to the development of stress fractures. Previous studies indicate that consumption of a Ca and vitamin D supplement may reduce stress fracture risk in female military personnel during initial military training, but circulating markers of Ca and bone metabolism and measures of bone density and strength have not been determined. This randomized, double-blind, placebo-controlled trial sought to determine the effects of providing supplemental Ca and vitamin D (Ca+Vit D, 2000mg and 1000IU/d, respectively), delivered as 2 snack bars per day throughout 9weeks of Army initial military training (or basic combat training, BCT) on PTH, vitamin D status, and measures of bone density and strength in personnel undergoing BCT, as well as independent effects of BCT on bone parameters. A total of 156 men and 87 women enrolled in Army BCT (Fort Sill, OK; 34.7°N latitude) volunteered for this study. Anthropometric, biochemical, and dietary intake data were collected pre- and post-BCT. In addition, peripheral quantitative computed tomography was utilized to assess tibia bone density and strength in a subset of volunteers (n=46). Consumption of supplemental Ca+Vit D increased circulating ionized Ca (group-by-time, P=0.022), maintained PTH (group-by-time, P=0.032), and increased the osteoprotegerin:RANKL ratio (group-by-time, P=0.006). Consistent with the biochemical markers, Ca+Vit D improved vBMD (group-by-time, P=0.024) at the 4% site and cortical BMC (group-by-time, P=0.028) and thickness (group-by-time, P=0.013) at the 14% site compared to placebo. These data demonstrate the benefit of supplemental Ca and vitamin D for maintaining bone health during periods of elevated bone turnover, such as initial military training. This trial was registered with ClincialTrials.gov, NCT01617109.

Positive effects of basic training on cognitive performance and mood of adult females.

OBJECTIVE: This study investigated whether a stressful military training program, the 9- to 10-week U.S. Army basic combat training (BCT) course, alters the cognitive performance and mood of healthy young adult females. BACKGROUND: Structured training programs including adolescent boot camps, sports training camps, learning enrichment programs, and military basic training are accepted methods for improving academic and social functioning. However, limited research is available on the behavioral effects of structured training programs in regard to cognitive performance and mood. METHOD: Two separate, within-subject studies were conducted with different BCT classes; in total 212 female volunteers were assessed before and after BCT. In Study 1, Four-Choice Reaction Time, Match-to-Sample, and Grammatical Reasoning tests were administered. The Psychomotor Vigilance Test (PVT) was administered in Study 2. The Profile of Mood States (POMS) was administered in both studies. RESULTS: In Study 1, reaction time to correct responses on all three of the performance tests improved from pre- to post-BCT. In Study 2, PVT reaction time significantly improved. All POMS subscales improved over time in the second study, whereas POMS subscales in the first study failed to meet criteria for statistically significant differences over time. CONCLUSION: Cognition and mood substantially improved over military basic training. These changes may be a result of structured physical and mental training experienced during basic training or other factors not as yet identified. APPLICATION: Properly structured training may have extensive, beneficial effects on cognitive performance and mood; however, additional research is needed to determine what factors are responsible for such changes.

The importance of leadership in Soldiers' nutritional behaviors: results from the Soldier Fueling Initiative program evaluation.

INTRODUCTION: Improving Soldiers' nutritional habits continues to be a concern of the US Army, especially amidst increasing obesity and high injury rates. This study examines leadership influence on nutritional behaviors within the context of the Soldier Fueling Initiative, a program providing nutrition education and improved dining facility menus to Soldiers in Basic Combat Training (BCT) and Advanced Individual Training (AIT). METHODS: A mixed methods design using surveys (N=486) and focus groups (N=112) was used to collect data at Fort Jackson, SC, and Fort Eustis, VA, in 2011. RESULTS: Survey results showed 75% of Soldiers in BCT believed their drill sergeant was helpful in making performance-enhancing food choices, and 86% agreed their drill sergeant believed it is important to eat for performance. Soldiers in AIT perceived their cadre as less helpful than their BCT drill sergeants and agreed less frequently that the AIT cadre believed it was important to eat for performance (P<.05). These measures of leader influence were significantly associated with nutritional attitudes and behaviors in both BCT and AIT. Focus groups revealed 5 key themes related to cadre influence and nutrition behavior (listed in order of most to least frequent): (1) cadre influence food choices through consequences related to selection, (2) cadre teach Soldiers how to eat, (3) cadre rush Soldiers to eat quickly to return to training, (4) cadre influence choice through example but often do not make healthy choices, and (5) cadre have no influence on food choices. COMMENT: Leaders influence most Soldiers' nutrition practices within the training environment, particularly within BCT. Given that leader influence can impact Soldiers' attitudes and behaviors, it is critical that military leaders become knowledgeable about optimal nutrition practices to disseminate appropriate information to their Soldiers, avoid reprimand associated with trainees' food choices, reinforce key messages associated with nutrition programming, and lead by example in their own food choices.

Assessment of dietary intake using the healthy eating index during military training.

OBJECTIVE: The objectives of this study were to use the healthy eating index (HEI) as a tool to characterize diet quality in Soldiers (n=135) during basic combat training (BCT), and to assess the effects of BCT on diet quality by comparing HEI scores before and after the training period. METHODS: HEI scores were calculated from a 110-item semiquantitative food frequency questionnaire. Soldiers were then divided into tertiles (high, medium, and low) of diet quality based upon HEI scores at the start of BCT. RESULTS: No relationships between pre-BCT total HEI score and age, sex, racial background, or physical activity were observed. The odds of being a smoker were 4.75 times higher for those in the low HEI tertile and 3.03 times higher for those in the medium HEI tertile when compared to those in the high HEI tertile (95% CI, 1.67, 13.48 and 1.04, 8.82 respectively). Diet quality improved in the medium and low HEI tertiles over the course of BCT, as total HEI scores increased by 22% and 46% respectively (P<.05) with time in these groups. Although different at the start of BCT, HEI scores were similar between the medium and high HEI tertiles at the end of BCT. CONCLUSION: Study findings suggest that the BCT dining environment elicits positive changes in diet quality for Soldiers who enter military training with lower diet quality, and the HEI appears to be a useful tool to identify military personnel with lower diet quality at the start of training. This may provide the opportunity to target interventions such as diet counseling and education in an effort to improve Soldier health and performance.

Vitamin D status, dietary intake, and bone turnover in female Soldiers during military training: a longitudinal study.

BACKGROUND: Vitamin D is an essential nutrient for maintaining bone health, to include protecting against stress fracture during periods of rapid bone turnover. The objective of this longitudinal, observational study was to assess vitamin D status, biomarkers of bone turnover, and vitamin D and calcium intake in female Soldiers (n = 91) during US Army basic combat training (BCT). METHODS: Anthropometric, biological and dietary intake data were collected at wk 0, 3, 6, and 9 of the 10 wk BCT course. Mixed models repeated measures ANOVAs were used to assess main effects of time, race, and time-by-race interactions. RESULTS: White volunteers experienced a decrease in serum 25(OH)D levels, whereas non-white volunteers experienced an increase during BCT. However, serum 25(OH)D levels were lower in non-whites than whites at all timepoints (P-interaction < 0.05). Group mean PTH levels increased (P < 0.05) during the first 3 wk of training, remained elevated for the duration of BCT, and were higher in non-whites compared to whites (P-race < 0.05). Biomarkers of both bone formation (bone alkaline phosphatase and procollagen I N-terminal peptide) and resorption (tartrate-resistant acid phosphatase and C-terminal telopeptide) increased (P < 0.05) during BCT, indicating increased bone turnover. Estimated daily intakes of vitamin D and calcium were below recommended levels (15 µg and 1000 mg/day, respectively), both before (group mean ± SEM; 3.9 µg/d ± 0.4 and 887 mg/d ± 67) and during BCT (4.1 µg/d ± 0.3 and 882 mg/d ± 51). CONCLUSIONS: These findings demonstrate that female Soldiers experience dynamic changes in vitamin D status coupled with increased bone turnover and potentially inadequate vitamin D and calcium intake during military training.

Differential effects of military training on fat-free mass and plasma amino acid adaptations in men and women.

Fat-free mass (FFM) adaptations to physical training may differ between sexes based on disparities in fitness level, dietary intake, and levels of plasma amino acids (AA). This investigation aimed to determine FFM and plasma AA responses to military training, examine whether adaptations differ between male and female recruits, and explore potential associations between FFM and AA responses to training. Body composition and plasma AA levels were assessed in US Army recruits (n = 209, 118 males, 91 females) before (baseline) and every three weeks during basic combat training (BCT), a 10-week military training course. Body weight decreased in men but remained stable in women during BCT (sex-by-time interaction, P < 0.05). Fifty-eight percent of recruits gained FFM during BCT, with more (P < 0.05) females (88%) gaining FFM than males (36%). Total plasma AA increased (P < 0.05) during BCT, with greater (P < 0.05) increases observed in females (17%) then in males (4%). Essential amino acids (EAA) and branched-chain amino acids (BCAA) were increased (P < 0.05) in females but did not change in males (sex-by-time interaction, P < 0.05). Independent of sex, changes in EAA (r = 0.34) and BCAA (r = 0.27) from baseline were associated with changes in FFM (P < 0.05); greater (P < 0.05) increases in AA concentrations were observed for those who gained FFM. Increases in FFM and plasma AA suggest that BCT elicits a more pronounced anabolic response in women compared to men, which may reflect sex-specific differences in the relative intensity of the combined training and physiological stimulus associated with BCT.

Cardiometabolic risk in US Army recruits and the effects of basic combat training.

BACKGROUND: Cardiometabolic disease risk in US military recruits and the effects of military training have not been determined. This study examined lifestyle factors and biomarkers associated with cardiometabolic risk in US Army recruits (209; 118 male, 91 female, 23 ± 5 yr) before, during, and after basic combat training (BCT). METHODOLOGY/PRINCIPAL FINDINGS: Anthropometrics; fasting total (TC), high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol; triglycerides (TG); glucose; and insulin were measured at baseline and every 3 wks during the 10 wk BCT course. At baseline, 14% of recruits were obese (BMI>30 kg/m(2)), 27% were cigarette smokers, 37% were sedentary, and 34% reported a family history of cardiometabolic disease. TC was above recommended levels in 8%, LDL in 39%, TG in 5%, and glucose in 8% of recruits, and HDL was below recommended levels in 33% of recruits at baseline. By week 9, TC decreased 8%, LDL 10%, TG 13%, glucose 6% and homeostasis model assessment of insulin resistance (HOMA-IR) 40% in men (P<0.05). In women, TC, LDL, glucose and HOMA-IR were decreased from baseline at weeks 3 and 6 (P<0.05), but were not different from baseline levels at week 9. During BCT, body weight declined in men but not women, while body fat percentage declined in both men and women (P<0.05). CONCLUSIONS/SIGNIFICANCE: At the start of military service, the prevalence of cardiometabolic risk in US military recruits is comparable to that reported in similar, college-aged populations. Military training appears to be an effective strategy that may mitigate risk in young people through improvements in lipid profiles and glycemic control.

Randomized, double-blind, placebo-controlled trial of an iron-fortified food product in female soldiers during military training: relations between iron status, serum hepcidin, and inflammation.

BACKGROUND: Iron status degrades in female soldiers during military training. Inflammation-mediated up-regulation of hepcidin, a key mediator of iron homeostasis, may be a contributing factor. OBJECTIVE: We measured the efficacy of an iron-fortified food product for maintaining iron status in female soldiers during basic combat training (BCT) and examined relations between iron status, serum hepcidin concentrations, and inflammation. DESIGN: A randomized, double-blind, placebo-controlled trial was conducted. Volunteers received an iron-fortified food product (total dose = 56 mg Fe/d) or a placebo twice daily during the 9-wk BCT course. Iron-status indicators, serum hepcidin concentrations, and markers of inflammation were measured pre- and post-BCT. RESULTS: BCT affected iron status; serum ferritin concentrations decreased (P < or = 0.05), and concentrations of soluble transferrin receptor (sTfR) and hemoglobin and the red cell distribution width increased (P < or = 0.05). Consumption of the iron-fortified food product attenuated declines in iron status in iron-deficient anemic soldiers; a group-by-time interaction was observed for hemoglobin and sTfR concentrations (P < or = 0.05). Serum hepcidin concentrations were not affected by BCT; however, hepcidin concentrations were lower in iron-deficient anemic soldiers than in those with normal iron status (P < or = 0.05) and were positively associated with serum ferritin (P < or = 0.05) and C-reactive protein (P < or = 0.05) concentrations pre- and post-BCT. CONCLUSIONS: Twice-daily consumption of an iron-fortified food product improved iron status in iron-deficient anemic soldiers but not in iron-normal or iron-deficient nonanemic soldiers. Serum hepcidin concentrations were not affected by training but were associated with iron status and inflammation pre- and post-BCT. This trial was registered at clinicaltrials.gov as NCT01100905.

Vitamin D status in female military personnel during combat training.

Vitamin D is an essential nutrient for maintaining bone health. Recent data suggest that vitamin D and calcium supplementation might affect stress fracture incidence in military personnel. Although stress fracture is a health risk for military personnel during training, no study has investigated changes in vitamin D status in Soldiers during United States (US) Army basic combat training (BCT). This longitudinal study aimed to determine the effects of BCT on 25-hydroxyvitamin D (25(OH)D) and parathyroid hormone (PTH) levels in female Soldiers. Serum 25(OH)D and PTH were assessed in 74 fasted Soldier volunteers before and after an 8-week BCT course conducted between August and October in Columbia, South Carolina. In the total study population, 25(OH)D levels decreased (mean ± SD) from 72.9 ± 30.0 to 63.3 ± 19.8 nmol/L (P < 0.05) and PTH levels increased from 36.2 ± 15.8 to 47.5 ± 21.2 pg/mL (P < 0.05) during BCT. Ethnicity affected changes in vitamin D status (ethnicity-by-time interaction, P < 0.05); 25(OH)D decreased (P < 0.05) in both Hispanic and non-Hispanic whites, but did not change in non-Hispanic blacks. Ethnicity did not affect BCT-induced changes in PTH. These data indicate that vitamin D status in female Soldiers may decline during military training in the late summer and early autumn months in the Southeastern US. Future studies should strive to determine the impact of military clothing and seasonality on vitamin D status, as well as the functional impact of declining vitamin D status on bone health.

Randomized, double-blind, placebo-controlled trial of iron supplementation in female soldiers during military training: effects on iron status, physical performance, and mood.

BACKGROUND: Decrements in iron status have been reported in female soldiers during military training. Diminished iron status adversely affects physical and cognitive performance. OBJECTIVE: We wanted to determine whether iron supplementation could prevent decrements in iron status and improve measures of physical performance and cognitive status in female soldiers during basic combat training (BCT). DESIGN: In this 8-wk randomized, double-blind, placebo-controlled trial, soldier volunteers (n = 219) were provided with capsules containing either 100 mg ferrous sulfate or a placebo. Iron status indicator assays were performed pre- and post-BCT. Two-mile running time was assessed post-BCT; mood was assessed by using the Profile of Mood States questionnaire pre- and post-BCT. RESULTS: The BCT course affected iron status: red blood cell distribution width and soluble transferrin receptor were elevated (P < 0.05), and serum ferritin was lowered (P < 0.05) post-BCT. Iron supplementation attenuated the decrement in iron status; group-by-time interactions (P < 0.01) were observed for serum ferritin and soluble transferrin receptor. Iron supplementation resulted in improved (P < 0.05) vigor scores on the Profile of Mood States post-BCT and in faster running time (P < 0.05) in volunteers reporting to BCT with iron deficiency anemia. CONCLUSIONS: Iron status is affected by BCT, and iron supplementation attenuates the decrement in indicators of iron status in female soldiers. Furthermore, iron supplementation may prove to be beneficial for mood and physical performance during the training period. Future efforts should identify and treat female soldiers or athletes who begin training regimens with iron deficiency or iron deficiency anemia.