Maintenance of iron status in healthy men during an extended period of stress and physical activity

Energy Deficiency in Soldiers: The Risk of the Athlete Triad and Relative Energy Deficiency in Sport Syndromes in the Military

Military personnel experience energy deficit (total energy expenditure higher than energy intake), particularly during combat training and field exercises where exercising energy expenditures are high and energy intake is reduced. Low energy availability (energy intake minus exercising energy expenditure expressed relative to fat free mass) impairs endocrine function and bone health, as recognized in female athletes as the Female Athlete Triad syndrome. More recently, the Relative Energy Deficiency in Sport (RED-S) syndrome encompasses broader health outcomes, physical and cognitive performance, non-athletes, and men. This review summarizes the evidence for the effect of low energy availability and energy deficiency in military training and operations on health and performance outcomes. Energy availability is difficult to measure in free-living individuals but doubly labeled water studies demonstrate high total energy expenditures during military training; studies that have concurrently measured energy intake, or measured body composition changes with DXA, suggest severe and/or prolonged energy deficits. Military training in energy deficit disturbs endocrine and metabolic function, menstrual function, bone health, immune function, gastrointestinal health, iron status, mood, and physical and cognitive performance. There are more data for men than women, and little evidence on the chronic effects of repeated exposures to energy deficit. Military training impairs indices of health and performance, indicative of the Triad and RED-S, but the multi-stressor environment makes it difficult to isolate the independent effects of energy deficiency. Studies supplementing with energy to attenuate the energy deficit suggest an independent effect of energy deficiency in the disturbances to metabolic, endocrine and immune function, and physical performance, but randomized controlled trials are lacking.

Analysis of 19 Minerals and Cortisol in Red Deer Hair in Two Different Areas of the Stelvio National Park: A Preliminary Study

Simple Summary

Minerals play an important role in animals’ health and nutritional status and are associated with cortisol, a hormone involved in several physiological processes and with a fundamental role in allostasis, the process of achieving homeostasis. The aim of the present study is to perform a preliminary investigation on the concentration of 19 minerals and cortisol in the hair of red deer coming from two different areas of the Stelvio National Park. Results showed a close association between hair minerals and cortisol concentrations and an effect of deer origin. Hair minerals and cortisol assessment is an easy, rapid, and low cost screening method and it is useful in wildlife management programs, in order to investigate wild animals’ health status, to perform environmental studies, to assess the presence of contaminants in wild species and to determine risks for humans. In addition, it could be helpful in public health programs to estimate contamination risks linked to wild animal meat consumption or to assess the presence of contaminants in food-producing animals.

Abstract

The aim of the study was to perform an investigation on the concentration of 19 minerals and cortisol in red deer (Cervus elaphus) hair, a matrix that is easy to collect with non-invasive and painless sampling, able to represent an integrative values of long-term substance concentrations, and able to give useful information, also when performed on dead animals, given its extreme stability over time. In the study thirty-five animals were included, coming from two different sides of a valley in the Stelvio National Park, where official water analysis had pointed out elevated concentrations of As in one of the two orographic sides. Hair cortisol concentrations were measured using a RIA(Radio Immuno Assay), while minerals were detected using ICP-MS (Inductively Coupled Plasma- Mass Spectrometry). Results showed a negative relationship between cortisol and some mineral concentrations (Li, Co, As, Cd, Cr and Tl) and significant differences in some mineral concentrations between park areas (Al, Co, Cu, Cd and Ni). As, Cr and cortisol differences approached statistical significance. This preliminary study represents a step forward in the study of wildlife allostatic load and a valid method for applications in wildlife management programs, in environmental studies and in public health programs.

The influence of physical activity on hair toxic and essential trace element content in male and female students

The primary aim of the current study is to estimate the effect of different physical activity levels on hair trace element content in male and female students. A total of 113 students (59 women and 54 men) of P. G. Demidov Yaroslavl State University (Yaroslavl, Russia) took part in the current investigation. According to the level of the physical activity, all students were divided into three groups: high, medium, and low physical activity. Essential and toxic metal content (μg/g) in hair samples was assessed by inductively coupled plasma mass spectrometry using NexION 300D + NWR213 (Perkin-Elmer, USA). The obtained data show that hair iodine, zinc, arsenic, nickel, and tin levels are not related to physical activity in male and female students. At the same time, increased physical activity is associated with decreased hair copper, vanadium, bismuth, and mercury content in comparison to the low physical activity groups. Students with higher physical activity are also characterized by significantly higher hair cobalt, iron, manganese, selenium, cadmium, lithium, and lead concentrations. Finally, statistical analysis has revealed maximal gender differences in hair trace element content in the high physical activity groups, whereas in the low activity groups, the hair metal concentrations were nearly similar in females and males.

Cross-sectional relationship between chronic stress and mineral concentrations in hair of elementary school girls

Chronic stress exposure is associated with diverse negative health outcomes. It has been hypothesised that stress may also negatively affect the body's mineral status. This study investigates the association between chronic stress and long-term mineral concentrations of calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), phosphorus (P) and zinc (Zn) in scalp hair among elementary school girls. Complete information on child-reported stress estimates (Coddington Life Events Scale (CLES)), hair cortisone and hair mineral concentrations, and predefined confounders in the stress-mineral relationship (i.e. age, body mass index, physical activity, diet, hair colour and parental education) was provided cross-sectionally for 140 girls (5-10 years old). The relationship between childhood stress measures (predictor) and hair minerals (outcome) was studied using linear regression analysis, adjusted for the abovementioned confounders. Hair cortisone concentrations were inversely associated with hair mineral concentrations of Ca, Mg, Zn and the Ca/P ratio. Children at risk by life events (CLES) presented an elevated Ca/Mg ratio. These findings were persistent after adjustment for confounders. This study demonstrated an independent association between chronic stress measures and hair mineral levels in young girls, indicating the importance of physiological stress-mineral pathways independently from individual or behavioural factors. Findings need to be confirmed in a more heterogeneous population and on longitudinal basis. The precise mechanisms by which stress alters hair mineral levels should be further elucidated.

Field studies of exercise and food deprivation

PURPOSE OF REVIEW

The increase in obesity in developed societies drives interest in the interplay of energy intake, metabolic energy expenditure, and body energy stores. A better understanding of energy management in physically active and undernourished humans should help guide strategies to manage obesity safely and effectively. This review focuses on field studies of men and women engaged in prolonged strenuous activities, ranging from ranger training to extreme expeditions.

RECENT FINDINGS

Although scientifically unconventional and limited, field studies of exercise and food deprivation have yielded interesting findings: 4-5% body fat is the normal lower limit to fat reserves in physically active underfed young adult men, and in response to exercise and underfeeding, women used more fat mass and less fat-free mass to meet metabolic fuel requirements.

SUMMARY

Field studies have shown that fat energy reserves in young adult men can be estimated as percentage body fat minus 5%, and initial body fat mass has a significant positive influence on fat oxidation rates per kilogram of fat-free mass during rapid weight loss associated with underfeeding and exercise. Data logging pedometers, activity monitors, global positioning systems, and wireless body and personal-area networks promise to make it easier to study and care for free-living humans.

Prevalence of iron deficiency and iron deficiency anemia among three populations of female military personnel in the US Army

BACKGROUND

Iron deficiency is the most prevalent micronutrient deficiency disease in the world and occurs in young women in the United States. Female military personnel represent a unique population faced with intense physical and cognitive demands.

OBJECTIVE

The objective of this study was to determine the prevalence of iron deficiency and iron deficiency anemia among three populations of female military personnel in the US Army.

METHODS

Iron status was assessed in 1216 volunteers. Volunteers were recruited from three groups: immediately following initial entry to the Army (IET), immediately following basic combat training (AIT), or following at least six months of permanent assignment (PP). Iron deficiency was determined using a three variable model, including cut-off values for serum ferritin, transferrin saturation, and red cell distribution width (RDW). Iron deficiency anemia was categorized by iron deficiency and a hemoglobin (Hgb) value of <12 g/dL.

RESULTS

The prevalence of iron deficiency was greater in women in the AIT group (32.8%) than in the IET and PP groups (13.4 and 9.6%, respectively). The prevalence of iron deficiency anemia was greater in the AIT group (20.9%) than in the IET and PP groups (5.8 and 4.8%, respectively). Furthermore, the prevalence of iron deficiency anemia was greater in Hispanic (21.9%) and African-American military personnel (22.9%) than in Caucasian military personnel (10.5%).

CONCLUSIONS

These data indicate that female military personnel experience diminished iron status following training, and that iron nutriture is an important issue facing females in the military.

Nutritional formula enhanced immune function and reduced days of symptoms of upper respiratory tract infection in seniors

OBJECTIVES

To assess whether an experimental nutritional formula, given as a supplement, would reduce days of symptoms of upper respiratory tract infection (URTI) and affect antibody and lymphocyte proliferative responses to influenza vaccine.

DESIGN

A prospective, randomized, double-blind, controlled trial was conducted between October 1999 and April 2000.

SETTING

Assisted- and independent-living facilities in North Central Florida.

PARTICIPANTS

Sixty-six individuals, aged 65 and older.

INTERVENTION

Subjects received 8 oz/d of an experimental formula containing antioxidants, zinc, selenium, fermentable oligosaccharides, and structured triacylglycerol or an isoenergetic, isonitrogenous control formula for 183 days.

MEASUREMENTS

Subjects recorded daily symptoms of URTI. Antibody titers and lymphocyte proliferation to three influenza vaccine components were measured on Days 57 and 183.

RESULTS

Eighteen subjects in the control group and 16 subjects in the experimental group consumed an average of 7 ounces of formula daily and completed the 183-day study. Median days of symptoms of URTI were 3 (range 0-69, total days=156) and 0 (range 0-49, total days=78) for the control and experimental groups, respectively (P=.049). On Day 57, seven of 17 (41%) subjects in the control group and 13 of 15 (87%) subjects in the experimental group achieved a fourfold or greater increase in serum antibody titer to A/Beijing (P=.012). Lymphocyte proliferation to influenza vaccine components was greater in the experimental (median=1,365 cpm, range=0-14,955 cpm) than the control group (median=136 cpm, range=0-4,270 cpm) (P=.013).

CONCLUSION

Subjects consuming an experimental nutritional formula experienced enhanced immune function and fewer days of URTI symptoms.

Distúrbios nutricionais em atletas femininas e suas inter-relações

Pesquisas indicam que é elevada a prevalência de distúrbios alimentares em atletas femininas jovens envolvidas em esportes que preconizam a magreza e o baixo peso corporal, tais como ginástica olímpica e corridas de longa distância. A fim de compreender a etiologia destes problemas, esta revisão apresenta os principais distúrbios nutricionais encontrados em atletas femininas, incluindo definições, critérios para diagnóstico, fatores de risco, presença de desordens inter-relacionadas - anemia, irregularidades menstruais e desmineralização óssea e suas conseqüências sobre a saúde e rendimento atlético. É fundamental ressaltar a importância da nutrição no desempenho físico. A presença de um baixo peso corporal e um consumo energético severamente restrito é o principal fator de risco para o desenvolvimento de tais distúrbios. Como as atletas e seus treinadores não apresentam adequados conhecimentos sobre nutrição, é necessária uma orientação nutricional individualizada, de forma a evitar o desenvolvimento destas alterações.

Endocrine markers of semistarvation in healthy lean men in a multistressor environment

We tested the hypothesis that key endocrine responses to semistarvation would be attenuated by changing only the food intake in a multistressor environment that also included sustained workload, inadequate sleep, and thermal strain. Serum hormones were compared within and between two groups of healthy young male volunteers participating in the 8-wk US Army Ranger course, with four repeated cycles of restricted energy intakes and refeeding: group 1 (n = 49) and group 2 (n = 48); energy deficits averaged 1,200 and 1,000 kcal/day, respectively. After 8 wk, most of group 1 achieved a minimum body fat, serum 3,5,3'-triiodothyronine (T(3)) was below normal (78 +/- 20 ng/dl), testosterone (T) approached castrate levels (4.5 +/- 3.9 nmol/l), insulin-like growth factor I (IGF-I) declined by one-half (75 +/- 25 microg/l), and cholesterol rose from 158 +/- 31 to 217 +/- 39 mg/dl. Bioavailable T(3) and T were further reduced by increases in their specific binding proteins in response to declining insulin. Refeeding, even with continuation of the other stressors, produced prompt recovery of T(3), T, and IGF-I. Higher energy intakes in group 2 attenuated the subclinical hypothyroidism and hypercholesterolemia, whereas consistent luteinizing hormone suppression indicated centrally mediated threshold effects on gonadal hormone suppression. We conclude that low T, T(3), and IGF-I remained reliable markers of acute energy deficits in the presence of other stressors; elevated cholesterol and cortisol provided information about chronic status, corresponding to diminishing body fat stores.

Development and biomedical testing of military operational rations

This article gives a brief history of military nutrition research in this century and reviews recent advances made through field testing. Although modern rations are nutritionally complete, ration developers are challenged to improve palatability to promote increased intakes in field training and combat settings. The principal goal for military nutritionists is to identify the optimal macronutrient mix and specific ration components that sustain a soldier's performance in the face of operational stressors such as sleep deprivation, intense physical activity, climatic extremes, and hypobaric hypoxia. Energy expenditures during typical field-training exercises average approximately 4000 kcal/day, whereas energy intakes are usually 3000 kcal/day or less when operational rations are consumed. One way to ameliorate the effects of this shortfall is to provide soldiers with a carbohydrate beverage supplement.

Micronutrients and exercise: anti-oxidants and minerals

Exercise has been shown to increase indirect measures of lipid peroxidation. However, exercise and training appear to augment the body's anti-oxidant defence system. Whether this augmented defence system can keep up with the increase in lipid peroxidation with exercise is not known. Iron depletion is experienced by many athletes, especially female endurance athletes and adolescents, but iron deficiency anaemia is rare. Iron depletion could affect the ability to train and recover from strenuous exercise, but this has not been examined. There is a concern that female athletes, especially adolescents, are not ingesting sufficient calcium, and this may affect the development of peak bone mass and increase the risk of bone fractures. Further research is needed on mineral and trace mineral intake and loss in athletes. It appears that most athletes have adequate status of chromium, zinc, phosphate and magnesium. Athletes who are restricting energy intake to achieve a low body mass (for example, endurance runners), may not have adequate vitamin or mineral status. More data are needed on vitamin/mineral status of athletes from underdeveloped countries. The general recommendation for athletes is that foods rich in anti-oxidants and minerals should be ingested rather than supplements.