Evaluation of an Australian combat ration pack as a sole nutrition source during 23 days of military adventurous training in the tropics.

Abstract

Objectives: To evaluate Australian combat ration packs (CRP) as sole nutrition source during a 23-day military exercise in the tropics.

Design: Evaluation of ration packs based on measurements of nutritional, physiological and psychological criteria. Blood samples were collected for determination of nutritional status (vitamins, cytokines, visceral proteins, and ferritin) and a delayed hypersensitivity skin test was performed before and after the exercise. Measurement of body mass, recording of discarded ration items (packaging and foods), physical fitness testing, collection of saliva (immunoglobulin-A) and urine (cotinine, specific gravity) samples and testing of psychological status (mood and cognition) occurred immediately before and after and at multiple time points.

Subjects: Twenty males (aged 19 to 32 years) were recruited from the British 25 Engineer Regiment (Regular Army).

Setting: Exercise Pelopor Finn, in the jungle of Tawau Hills National Park, Sabah, Malaysia.

Main outcomes: Body mass, nutrient intakes, immune function, micronutrient and visceral protein status, hydration, aerobic capacity, mood states and cognitive ability.

Statistical analysis: Linear regression analyses were used to assess associations between variables. Comparison of means was achieved by use of paired t tests and repeated measures analysis of variance was used for tests with serial measurements.

Results: Mean weight loss was 5.5%, decrements in physical and mental performance were not observed and good immune and hydration status were maintained. Food consumption appeared to be encouraged by, positive mood states, the novelty of new foods, ability to socialise and take meal breaks, ability to self-select food items and number of serves, adequate sleep, good morale and good hydration status.

Conclusion: Although providing sufficient energy and macronutrients, the Australian CRP failed to provide sufficient iron, folic acid, antioxidants and vitamin B6 to prevent a decline in storage of these nutrients.

Key words: combat ration packs, nutrient intake, military, nutrition

Introduction

Australian Defence Force (ADF) members engaged in land operations may expect to be fed fresh foods wherever possible (1). However, there are situations when flesh rationing is not possible for many weeks and combat ration packs (CRP) are provided. For example, at the start of Operation Warden, we were advised by the Commanding Officer of the ADF Catering Group that ADF members of the International Force, East Timor (INTER-FET) were rationed with Combat Ration One Man (CR1M) for at least 35 days.

The effects on military fitness of long-term feeding (i.e. 30 or more days) with Australian CRP have not been determined (2). During operational deployments, when rationing is by CRP it is common for up to 30% of the food to be discarded, and as a result under-consumption, leading to weight loss and eventually to decrements in physical and cognitive performance, appears to be an almost inevitable outcome. Exacerbating this is the observation that carbohydrate, the nutrient of greatest significance to both physical and cognitive performance, is often the nutrient at most risk of being discarded (2,3).

Therefore, simply because a ration is nutritionally adequate (as assessed by nutritional analysis) does not necessarily mean that it will sustain an ADF member indefinitely. The health and psychological effects of CRP feeding during 12 days of military training in a tropical environment were recently investigated (3). Under-consumption of ration pack foods resulted in significant weight loss, protein catabolism, immune suppression (both cell-mediated and humoral) and perceived fatigue. However, the soldiers were able to adapt to restricted food consumption and poor sleep quality with no decrement in physical fitness or cognition. Booth et al. (3) concluded that further study is needed over a much longer period of time to investigate when significant decrements to performance are likely to appear if CRP are the sole form of rationing. The aim of the present study was to determine the acceptability of the Australian CR1M during 23 days of adventurous training (i.e. field conditions devoid of many of the usual operational stresses) by use of easily measured nutritional, physiological and psychological variables.

Methods

Setting

The present study used international adventurous training to investigate the effects of longer-term feeding with CRP. Exercise Pelopor Finn (meaning 'trail blazer', EX PF), an adventurous training exercise involving British soldiers from the 25 Engineer Regiment, was conducted at the Tawau Hills Ranger Station (THRS) in Sabah, Malaysia, during the period February to March 2000. The soldiers constructed an ecological trail, including foot bridges and a helicopter landing area, through steep mountainous terrain (4).

Upon arrival in Kota Kinabalu, soldiers were able to acclimatise for three days before travelling to the ranger station. The scientific team, with members from Australia, the UK and Malaysia, established a small laboratory area at the ranger station and sample collection and testing were conducted by scientists living in the field with the soldiers. Because scientists were often many hours apart (by foot) and carried their scientific as well as personal items, it was not possible to have a controlled study design. Furthermore, the harsh conditions limited the study to simple methods for the measurement of nutritional, physiological and psychological variables such as questionnaires, heart-rate monitoring, observational study, simple fitness tests and robust urine, saliva and blood tests. All soldiers were rationed with CR1M (Table 1) for the 23 days of the study. Close control was not maintained over rationing, and hence participants were able to eat one or more CR1M per day.

Participants

Twenty male soldiers (aged 19 to 32 years, mean 27 years) were recruited from the British 25 Engineer Regiment (Regular Army), selected to take part in EX PF.

Nutritional measurements

Dietary intake analysis

Participants placed their food packaging and uneaten items within name-labelled bags for the investigators to collect. Initially collections were possible every two to three days. However by the end of the study participants were up to six hours' walk over difficult terrain from the field laboratory and collections became less frequent. The amount of food consumed and discarded was averaged over each collection period and recorded as daily means of macronutrients consumed by each participant. Nutrient intake was calculated with FoodWorks software program version 2.10 (Xyris Software, Brisbane, FoodWorks, version 2.10 2000) using an in-house database of CRP macronutrient composition.

Body mass

Body mass (kg) was measured on days one, three, ten and 23 by use of calibrated scales (AND, model CH-150K, A&D Mercury Pty Ltd, Melbourne). Soldiers were instructed to drink at least one litre of water in the two to three hours prior to testing and were requested to void their bladders and towel-dry before being weighed in their underwear.

Links with smoking habits

Total nicotine metabolites in urine were determined using a colorimetric assay adapted for an automatic chemistry analyser (Cobass Bio, Roche Diagnostic Systems, Branchburg Township, NJ, USA) (5).

Immune Junction and nutritional status

Immune status was determined by measurement of cell-mediated immunity (delayed-type hypersensitivity skin test, DTH, and plasma cytokines) (6) and humoral immunity (salivary secretory immunoglobulin-A, SIgA). Nutritional status was determined by measurement of the body's stores of visceral protein (plasma insulin-like growth factor 1, IGF-1, and fibronectin), iron (ferritin) and vitamins (riboflavin, vitamin [B.sub.6], folic acid, total antioxidants and vitamin K). Total energy expenditure (TEE) was estimated on selected days using a factorial method (7).

Fasting blood samples were collected before the study (Kota Kinabalu army barracks) and on the final day of the study (day 23 at the ranger station). Saliva samples were collected on days one, three, four, five, six, nine, 13, 16, 19 and 21. Samples were centrifuged on site and the separated RBCs, plasma and saliva were stored frozen (-20[degrees]C) then air-transported frozen to Australia for analysis. Total plasma homocysteine (Hcys), which was measured by HPLC method, was defined as the sum of all homocysteine species in plasma, including homocysteine, homocystine, mixed disulfides, and protein-bound forms (8). Ferritin and fibronectin were measured by particle-enhanced nephelometric assay using manufacturer-supplied reagents (Behring BNA, Dade Behring, Marburg, Germany). Human interleukin-2 (IL2) and interleukin-6 (IL6) were measured by competitive enzyme-linked immunoassay (ELISA) (Accucyte kits, Cytimmune Sciences Inc, Maryland, USA). De-carboxy prothrombin or PIVKA-II (Protein Induced in Vitamin K Absence--factor II) was measured by ELISA (Asserachrom PIVKA-II, Diagnostica Stago, Asnieres, France), interleukin-2 receptor (IL2r) by endpoint ELISA (Milenia kit, DPC, Los Angeles, USA) and IGF-1 by ELISA using a non-extraction procedure (Diagnostic Systems Laboratories, Webster, Texas, USA). Total antioxidant capacity (TAOC) was measured by incubation of plasma with 2,2-azino-di-(3-ethylbenzthiazoline sulphonate) (ABTS[R]) in the presence of a peroxidase and hydrogen peroxide to produce the radical cation ABT[S[R].sup.+] (Randox Laboratories, Crumlin, Co Antrim, UK). Red blood cell riboflavin and vitamin [B.sub.6] were determined by enzyme activation method (9).

Unstimulated saliva collection was put into Salivette tubes (Starstedt, Numbrecht, Germany). Albumin (Alb) and SIgA were measured by nephelometric assay (Behring BNA, Marburg, Germany), using manufacturer-supplied reagents (antisera to Human IgA [alpha] chain and human albumin, Dade Behring, Marburg, Germany). The results were presented as the ratio of SIgA (mg/L) to Alb (mg/L).

Physiological measurements

Tests of physical fitness were conducted on the second day after arrival in Sabah (pre-study, at Malaysian army barracks, Kota Kinabalu) and again on the final day of the study (day 23 at the ranger station). Multistage fitness testing was conducted along with vertical standing jump, sit-ups and hand-grip pre-study on days three, ten and 23.

Physical fitness

The multistage fitness test, commonly referred to as the 'shuttle run' or 'beep test', was conducted to estimate soldiers' aerobic capacity (10). Abdominal muscle strength and endurance was tested by recording the maximum number of correctly performed sit-ups completed within two minutes, and single jump power was tested by recording the greatest of three standing vertical jumps. Hand-grip strength was determined using a hand-grip dynamometer (Jamar Hydraulic Hand Dynamometer, Fredericton, Canada)

Physiological strain, environmental stress and hydration status

Physiological strain and hydration status were determined on selected days by measurement of core body temperature, heart rate monitoring, urine analysis and water consumption. Wet bulb globe temperature (WBGT) was determined as an indication of environmental thermal stress (11). To determine core body temperature gastrointestinal temperature was measured on three days. The method uses a pill that emits a low power radio signal, the frequency of which is temperature-dependent. The signals were captured continuously by a body core temperature monitor (BCTM, PED, Los Angeles, USA). Participants were instructed to swallow a pill on the evening prior to participation to ensure that the pill had left the stomach and had entered the intestine before the measurement period began. In this way, sudden changes to temperature as a result of eating or drinking were avoided. Heart rate was recorded at one-minute intervals from the R-wave frequency of ventricular depolarisation (Polar Sport Tester[R], Polar Electro KY, Hakamaantie Kempeki, Finland) for up to eight hours on selected days. Ambient temperature was measured on selected days using a Metrosonics hs-3700 portable heat stress monitor (Metrosonics Inc. Rochester, NY, USA). The wet bulb, dry bulb and globe temperatures were recorded, from which the WBGT index of environmental stress was calculated. The environment is considered thermally stressful above a WBGT of 26 27[degrees]C (11).

Urine samples were collected at least every third day and were analysed to determine hydration status by specific gravity (SG) measurement (Uricon-NE Urine Specific Gravity Refractometer, Atago Co. Ltd, Tokyo, Japan). The same samples, which bad been stored and transported frozen, were later analysed in Australia for total nicotine metabolites and creatinine. An SG in the range 1.003 to 1.030 g/L was used as the criterion for good hydration status (12).

Psychological measurements

Questionnaires

Three questionnaires were administered at the same time on days two, four, eight, 12, 16 and 20: Army Speed and Accuracy questionnaire (ASA, 1 Psychology Unit, Australian Defence Force, Victoria Barracks, Sydney, Australia); State of Fatigue Inventory (SOFI, Swedish Occupational Fatigue Inventory-20, Arbetslivsinstitutet, Stockholm, Sweden 1998) and Profile of Mood States (POMS--short form, McNair, Lorr and Droppleman, Eds, San Diego CA, USA). The Hopkins Symptoms General Health Checklist (Derogatis R, Johns Hopkins University, Baltimore, USA) was administered on days two and 20.

Statistical analyses

Statistical analyses were performed with SPSS (SPSS Inc, Chicago, SPSS for Windows version 9.0 1999). Descriptive statistics were obtained to establish a measure of central tendency and presented as means, standard deviations, standard error and range. Data were checked for outliers and non-homogeneity of the population by use of pair wise scatter plots, box plots and Q-Q plots. Normality of population distributions was checked by the Shapiro-Wilk and Lilliefors tests and where appropriate data were log transformed to achieve normality.

Significance was accepted at P < 0.05. Multiple linear regression analyses were used to assess associations between variables. Comparison of means was achieved by use of the paired t test and Levene's test was used for comparison of variance. Repeated measures analysis of variance was used for tests with serial measurements. All within-subject F-tests were based on the Huynh-Feldt corrected P-values and within-subject comparisons were obtained as pre-planned contrasts specified in the repeated measures analysis of variance performed by SPSS.

Ethics approval

Experimental procedures were approved by the Australian Defence Human Research Ethics Committee.

Results

Nutritional measurements

Dietary intake and body mass

Mean daily dietary intakes remained stable throughout the study (Table 2). Soldiers appeared to adjust their dietary intake to meet their requirements and as a result body mass losses were small but significant. The mean ([+ or -] SD) change in body mass was -5.4% [+ or -] 2.4 (P < 0.01). The energy consumption ranged from 0.12 MJ/kg to 0.30 MJ/kg over the 23 days and the mean daily energy consumption of 15.7 MJ represented 90% of estimated TEE. Mean daily TEE for a typical trail clearing team was 18 MJ (n = 6, range 12 to 20 MJ). Chain-sawing and load carriage tasks had the greatest estimated TEE.

Links with smoking habits

Participants who smoked tended to eat less carbohydrate than others. For example, concentration of total nicotine metabolites in urine was negatively correlated with carbohydrate consumption and energy consumption (r = -0.69 and r = -0.70 respectively, P < 0.01). Of 19 soldiers tested for urinary nicotine metabolites seven were confirmed as non-smokers. For the 12 smokers tested, urinary nicotine metabolite concentrations ranged from 0.28 to 9.2 [micro]g/mg creatinine (mean = 3.8 [+ or -] 2.9 [micro]g/mg creatinine).

Immune function and nutritional status

At baseline the expedition group had good immune function and generally good nutritional status. However, some micronutrient deficiencies were detected, namely suboptimal plasma antioxidant capacity (range 1.0 to 4.5 mmol/L), elevated PIVKA II (range 0.23 to 4.84 ng/mL) and elevated Hcys (range 3.2 to 141.6 [micro]mol/L), which are indicative of antioxidant nutrients (vitamins, minerals and endogenous non-food derived antioxidants), vitamin K and folic acid status, respectively. No deficiency of iron storage was evident and only one participant had mild deficiency of riboflavin and vitamin [B.sub.6].

Soldiers had good immune function before and after the study period. Cell-mediated immune function remained unchanged (Table 3) while some stimulation of humoral immune function (SIgA:Alb) was detected (F = 17.34, P < 0.01, Figure 1). Soldiers experienced mild metabolic stress with some loss of visceral protein stores (IGF-1 and fibronectin), oxidant stress and decreased vitamin B-6, folic acid and iron stores. Riboflavin status appeared to improve while vitamin K status remained unchanged (Table 4). Mean results for nutritional biochemistry measures along with suggested clinical cut offs are presented in Table 5.

[FIGURE 1 OMITTED]

Oxidant stress (or reduced antioxidant capacity of plasma) was negatively correlated with dietary intake (r = -0.49, -0.52, -0.48 and 0.43) for energy, protein, fat and carbohydrate respectively (P < 0.05) and changes in plasma fibronectin and ferritin status were correlated with the change in aerobic capacity (Figure 2, r = 0.65 and 0.65 P < 0.01).

[FIGURE 2 OMITTED]

Physiological measurements

Physical fitness

Soldiers recorded significantly reduced single jump power between pre- and post-EX PF (P-0.02), no change in abdominal strength and endurance (sit-ups), improved hand-grip strength (F = 7.13, P < 0.01, time series data for right arm) and improved aerobic capacity (F = 12.99, P < 0.01, time series data) (Table 6). However, the improvement in estimated aerobic capacity needs to be viewed in light of body mass losses in the range 0.3% to 9.6%, because the improvement seen in some may be due to reduced body mass and not increased fitness. Changes in physical performance tests were not sensitive to estimated dietary intake, however changed right hand-grip strength was positively correlated with change in body mass (r = 0.45, P = 0.03).

Physiological strain, environmental thermal stress and hydration

During February and March Sabah was hot and humid, with rain showers occurring most days. The nights at THRS, where soldiers were located on the ridge of a mountain and accommodated in hammocks, were mild and perceived as cool to cold once physical activity ceased. The heat of the day caused most soldiers to self-pace by taking frequent rests when working hard physically such as carrying heavy loads (often up hill). Mean WBGT was 23.1[degrees]C, with a maximum of 25.7[degrees]C and a minimum of 19.2[degrees]C taken between 6.00a.m. and 7.00p.m.

No significant levels of cardiovascular strain were observed and thermal strain was not excessive. Maximum core temperatures ranged from 37.85 to 38.71[degrees]C. Core temperatures above 39 to 39.5[degrees]C are considered to indicate excessive thermal strain and high risk of heat-related illness. Mean heart rate across all days was 101 bpm (range 55 to 185 bpm). The time series data showed that soldiers paced themselves by resting and recovering when physiological strain (heart rate and body core temperature) became excessive.

Water delivery to soldiers was difficult, because of the terrain. The river, which was the major water supply for the group, was close to the first campsite at the base of the mountain ridge and was 12 kilometres from the final camp site high up on the mountain ridge. Water resupply was conducted daily by members of the trail (and scientific) teams who carried 20 litre containers of water along the trail. Rain water was collected to supplement this water supply. Hypohydration was common for the first two days (n = 21, SG of 1.027 [+ or -] 0.009 and 1.033 [+ or -] 0.018 for days 1 and 2 respectively), when nearly 50% of soldiers had highly concentrated urines (i.e. an SG [greater than or equal to] 1.030). Thereafter, the incidence of highly concentrated urine stabilised to no more than one or two soldiers on any testing day. Average urine SG over 14 testing days was 1.024 [+ or -] 0.005. Observational studies indicated that water consumption rates from 0.3 to 0.75 litre per hour provided adequate hydration for the trail tasks as determined by urine SG < 1.030.

Psychological measurements

Questionnaires

Apart from minor cuts, bruises, sunburn, insect and leech bites, few health problems were recorded. Although soldiers recorded significantly greater general health problems at the end of the study (P < 0.01), this was only an increase from a mean (SE) score of 16.5 (1.7) to 24.2 (1.9) compared with a maximum possible score of 108. Despite a trend to greater lack of energy (P = 0.06), significantly decreased vigour (F = 2.94, P = 0.04, time series data) and significantly increased physical discomfort (P < 0.01) soldiers steadily improved on the ASA cognitive tests as the study progressed (F = 18.41, P < 0.01, time series data) and did not suffer from lack of motivation (Table 7). Cognition, fatigue, mood and general health measures were insensitive to changes in hydration or nutritional status, including body mass loss and dietary intake.

Discussion

Dietary intake and psychological state

The CRIM provides about 15 MJ. On average, the soldiers consumed 15.7 [+ or -] 4 MJ/day (about 90% of their mean estimated TEE/day) and 560 [+ or -] 130 g carbohydrate/day (Table 2). This corresponds to eating slightly more than one CRIM per person per day (Table 1). This is a higher consumption rate than has been observed for ADF soldiers rationed with CRP under military (operational) field conditions (2,3).

The nature of this training exercise was different to most military operations. For example, although the participants worked hard, were under time constraints to finish their tasks, and experienced some frustration in the completion of their work, they were able to socialise, take meal breaks and have sufficient sleep. As evidenced by the results of the psychology questionnaires the soldiers remained mentally alert and were in good health, good mood and were only mildly fatigued despite the harsh environmental conditions in which they worked (Table 7). This contrasts with the higher levels of fatigue and adverse mood experienced during military training (3). Rations were cached and freely available. Soldiers tended to pull the packs apart, taking components for snacks and individual meals as required for the day's work. These are all factors which would encourage consumption of food. The novelty of being able to eat unfamiliar foods may have further encouraged consumption (Australian rather than British CRP) (13).

Physiological strain, environmental stress and hydration

Operational anorexia as a generalised stress response to severe environment, thermal strain, hypohydration, anxiety, fatigue, aches and pain reduce food consumption (14). Hypohydration, which has been shown to reduce appetite(15), was not a factor adversely affecting consumption of food during this study (average urine SG of soldiers during this study was 1.024 [+ or -] 0.005). The water consumption rates (0.3 to 0.75 litre per hour), which were apparently sufficient for EX PF conditions were less than that required to maintain hydration during a land mine clearance task (sweat rates of 0.47 to 0.63 litre per hour) and more arduous tasks such as pack loaded route marching or patrolling, all conducted in hot environments (16-18). In the latter tasks water consumption of up to 1.5 litres per hour--thought to be the limit of human consumption--is recommended (17,18).

Body mass

It is a common experience of international military operations that soldiers lose body mass during field operations. This exercise was no exception, with body mass losses ranging from less than 1% to over 9%. However, the mean body mass loss of around 5% would not be expected to cause a decrement in physical or mental performance, and this was found to be the case (19).

Links with smoking habits

A concern was the adverse effects of tobacco smoking on food consumption, which were consistent with the findings of a previous CR1M study--those who smoked most tended to eat the least food, particularly carbohydrate-rich foods (3). In the previous study, tobacco smoking was also correlated with urine specific gravity (i.e. it was associated with hypohydration).

Immune function and nutritional status

There was evidence of mild PEM and micronutrient deficiency (Tables 4 and 5). The micronutrients which were found to be limiting were iron, antioxidant nutrients, folic acid and vitamin B6. As discussed previously (3) the measure of antioxidant status used in this study cannot distinguish between the various antioxidants (e.g. vitamin C, vitamin E, carotenoids, selenium) so it cannot be determined if any particular micronutrient(s) was limiting. These findings are consistent with those of a previous study involving CRIM (3) where under consumption of the ration and consequent PEM were worse. In the present study PEM was not sufficient to adversely affect immune function (Table 3) or cognition (Table 7). In fact there was evidence that mucosal immune function improved (Figure 1). There is, however, a suggestion that the mild PEM may have adversely affected aerobic capacity (Figure 2). However, this needs to be viewed in light of the limitations of the shuttle run test, which provides a calculated estimate of aerobic capacity that is influenced by motivation, running technique and changes in body mass. Because there was no evidence of loss of muscular strength (Table 6), the mean dietary intake of carbohydrate (560 [+ or -] 130 g/day or 57% of daily energy intake, Table 2) appears to have been sufficient to prevent any significant loss of muscle protein.

Although the decline in micronutrient status was not accompanied by observable immune suppression or ill health, it is nevertheless a problem which should be addressed, because repeated deployment of soldiers without sufficient nutritional recovery could lead to depletion of micronutrient stores. Prospective data on the micronutrient status of repeatedly deployed soldiers is not available, but a negative inference may be drawn from the apparently poor micronutrient status of this group of British soldiers (Table 5) and that of an Australian group (3). Good stores of micronutrients are needed for maintenance of acute health such as optimal immune function (20) and for prevention of chronic health problems in later life, particularly cardiovascular disease (21,22). As an example, epidemiological evidence indicates that iron status plays an important role in determining susceptibility to and severity of infections (23).

The trend for reduced iron stores found in a previous, medium-term CR1M study (3) was found to be even greater at the completion of the present, longer study. Because the former study involved more pronounced PEM, it may be that a combination of under consumption, prolonged moderate to high physical activity and environmental conditions adversely affects iron status. Although only one individual had iron deficiency on completion of EX PF, the decline in iron status is of concern, because the estimated aerobic capacity of the soldiers correlated with their iron status (Figure 2). This is consistent with controlled studies in which reduced iron stores (i.e. ferritin < 15 [micro]g/L) has been shown to compromise performance during prolonged exercise such as long-distance running (13). The US Committee on Military Nutrition Research recommends that personnel with iron deficiency anaemia should receive appropriate medical treatment and monitoring until laboratory results show a return to normal values, and also that those with iron deficiency anaemia should not be deployed (24).

In conclusion it is apparent that under field conditions where soldiers were able to consume one or more ration packs per day, the CRIM provided sufficient energy and macronutrients to prevent serious protein energy malnutrition for up to 23 days of moderate to high physical activity in a hot environment, but failed to provide sufficient iron, folic acid, antioxidants and vitamin [B.sub.6] to prevent a decline in storage of these nutrients.

Table 1. Example combat ration (one man) menu

                      Example menu (a)

2   Main meals                                 225g retort
                                              pouch or cans
2   Beverage powder, sport                       12 g pkt
2   Biscuits                                     45 g pkt
1   Condiment (curry powder or mustard)         3.5 g pkt
1   Freeze-dried rice or potato, or noodles      55 g pkt
1   Fruit grains                                 15 g pkt
1   Fruit                                       140 g can
1   Fruit spread                                 26 g tube
2   Muesli bar                                   32 g pkt
1   Sauce (tomato or chilli)                     15 g pkt
1   Soup                                         20 g pkt

Non-food items common to all menus

1   Can opener
1   Matches, safety
1   Pad, scouring, soaped
1   Toilet paper, two-ply                       10 sheets

        Items common to all menus

1   Beverage, chocolate           40 g pkt

2   Beverage, coffee, instant    3.5 g pkt
1   Beverage, tea, pot bag       2.5 g pkt
1   Biscuit, crispbread           34 g pkt
1   Candy, chocolate              60 g pkt
2   Candy, hard                   30 g pkt
1   Cheese, cheddar               56 g can
1   Chewing gum                   pkt of 4
1   Chocolate ration              50 g pkt
1   Milk, sweetened, condensed    85 g tube
1   Muesli bar, ANZAC bar         32 g pkt
1   Pepper, black                  2 g pkt

Non-food items common to all menus

1   Salt                           2 g pkt
1   Sauce, tabasco                 3 g pkt
1   Vegetable extract             15 g tube

(a) This ration pack is available in five menus with differing
main meals, fruits, biscuits, soups, muesli bars and sports drink
varieties. Other items such as the tea, coffee, chocolate drink,
ANZAC bar, crispbread, cheese and matches are common to all menus.
The pack contains an average of 570g carbohydrate, 84g protein
and 100g fat.

Table 2. Daily macronutrient intake and energy consumption
per kg body mass on days 1, 3, 10 and 23

                             Daily average (a)

         Energy (MJ)   Protein (g)   Fat (g)   Carbohydrate (g)

N           20              20          20             20
Mean        15.7           114         136            564
SD           3.5            37          37            133
SEM          0.8             8           8             30
Median      15.9           115         136            573

                Energy (MJ) per kg

         Day 1   Day 3   Day 10   Day 23

N        19      20      20       20
Mean      0.19    0.18    0.19     0.20
SD        0.06    0.07    0.06     0.05
SEM       0.01    0.02    0.01     0.01
Median    0.19    0.19    0.20     0.21

(a) The mean daily intake of protein, fat and carbohydrate
represent 12%, 32% and 57% of mean energy intake, respectively.

Table 3. Measures of cell-mediated immunity on first and last day

                                First day (mean    Last day (a) (mean
                                  [+ or -] SE)        [+ or -] SE)

Delayed-type hypersensitivity   4.1 [+ or -] 0.2    3.9 [+ or -] 0.1
  skin test (Score)
Interleukin-2 (ng/mL)           2.6 [+ or -] 0.2    2.9 [+ or -] 0.3
Interleukin-2 receptor (U/mL)   393 [+ or -] 24     484 [+ or -] 46
Interleukin-6 (ng/mL)           2.0 [+ or -] 0.4    1.2 [+ or -] 0.3

(a) Paired t test, no significant differences between
first and last day.

Table 4. Biochemical changes between first and last day

                 Percent change       Significance

Variable (a)    Mean [+ or -] SE        P-value

TAOC            -21.0 [+ or -] 2.7      < 0.001
IGF-1            -8.7 [+ or -] 5.8        0.065
PIVKA II         22.8 [+ or -] 12.6       0.468
Ferritin        -18.7 [+ or -] 4.1      < 0.001
Fibronectin     -17.2 [+ or -] 5.7        0.003
Hcys             11.1 [+ or -] 10.4       0.029
EGRAC           -30.9 [+ or -] 19.5       0.003
EASTAC           10.7 [+ or -] 3.3        0.004

(a) TAOC is total antioxidant capacity, IGF-1 is insulin-like
growth factor 1, PIVKA II is protein induced in vitamin K
absence-factor II, Hcys is total plasma homocysteine, EGRAC is
erythrocyte glutathione reductase activation coefficient and EASTAC
is the erythrocyte aspartate transaminase activation coefficient.

Table 5. Biochemical measurements (mean [+ or -] SE) and
proportion of soldiers with measurements outside the clinical
cut-off point on first and last day

                                                  First day

                                       Percent
                                     outside cut-
Variable (a)    Clinical cut-off      off range      Mean [+ or -] SE

TAOC            < 1.2 mmol/L             40%          2.0 [+ or -] 0.2
PIVKA II        > 2.0 [micro]g/L         40%          2.1 [+ or -] 0.3
Ferritin       < 15.0 [micro]g/L          0%        115.0 [+ or -] 13.0
Hcys           > 10.0 [micro]mol/L       95%         17.3 [+ or -] 1.3
EGRAC           > 40% activation          5%         24.0 [+ or -] 3.0
EASTAC          > 120% activation         5%         90.0 [+ or -] 4.0

                            Last day

                 Percent
               outside cut-
Variable (a)    off range      Mean [+ or -] SE

TAOC               60%         1.5 [+ or -] 0.1
PIVKA II           50%         2.3 [+ or -] 0.3
Ferritin            5%        92.0 [+ or -] 12.0
Hcys               90%        19.4 [+ or -] 0.9
EGRAC               5%        14.0 [+ or -] 3.0
EASTAC              0%        98.0 [+ or -] 3.0

(a) TAOC is total antioxidant capacity, PIVKA II is protein induced
in vitamin K absence-factor II,  Hcys is total plasma homocysteine,
EGRAC is erythrocyte glutathione reductase activation coefficient
and EASTAC is the erythrocyte aspartate transaminase activation
coefficient.

Table 6. Fitness test results

                                             Day 3
                            Pre-study   mean [+ or -] SE

V[O.sub.2max]                              48.9 (1.0)
  (mL/kg/min)
Standing                      47.3            45.8
Vertical jump (cm)            (1.5)          (1.3)
Right handgrip (kg)                        50.3 (1.7)
Left handgrip (kg)                         51.6 (1.6)
Sit ups (number in 2 min)    82 (4)          82 (4)

                                 Day 10             Day 23
                            mean [+ or -] SE   mean [+ or -] SE

V[O.sub.2max]                  50.5 (1.3)         52.2 (1.0)
  (mL/kg/min)
Standing                          43.1               45.3
Vertical jump (cm)               (1.5)              (1.7)
Right handgrip (kg)            51.5 (2.0)         54.4 (1.6)
Left handgrip (kg)             51.4 (1.7)         52.8 (1.8)
Sit ups (number in 2 min)        81 (4)             83 (4)

                                 Change
                            mean [+ or -] SE

V[O.sub.2max]                3.5 (a) (0.7)
  (mL/kg/min)
Standing                        -2.1 (a)
Vertical jump (cm)               (0.9)
Right handgrip (kg)            6.7 (3.2)
Left handgrip (kg)             6.6 (4.1)
Sit ups (number in 2 min)        2 (2)

(a) Significantly different at P < 0.05.

Table 7. Scores from psychological questionnaires

                Test                        Day 2
            (max score)                mean [+ or -] SE

Army Speed
  and Accuracy (80)                    31.0 [+ or -] 1
Profile of          Tension (28)        5.8 [+ or -] 0.4
  Mood States
                    Depression          0.1 [+ or -] 0.1
                    (32)
                    Anger (28)          0.6 [+ or -] 0.2
                    Vigour (24)        10.0 [+ or -] 1.1
                    Fatigue (20)        8.1 [+ or -] 1.2
                    Confusion (24)      5.3 [+ or -] 0.4
State of Fatigue    Lack of energy      1.9 [+ or -] 0.4
Inventory last      (6)
24 hr
                    Physical            2.5 [+ or -] 0.4
                      exertion (6)
                    Physical            1.5 [+ or -] 0.4
                      discomfort (6)
                    Lack of             1.2 [+ or -] 0.2
                      motivation (6)
                    Sleepiness (6)      1.6 [+ or -] 0.3
Hopkins
Symptoms
General Health                         16.5 [+ or -] 1.7
Checklist (108)

                Test                        Day 4
            (max score)                mean [+ or -] SE

Army Speed
  and Accuracy (80)                    31.0 [+ or -] 1.0
Profile of          Tension (28)        5.2 [+ or -] 0.4
  Mood States
                    Depression          1.3 [+ or -] 0.5
                    (32)
                    Anger (28)          0.8 [+ or -] 0.2
                    Vigour (24)         8.5 [+ or -] 1.0
                    Fatigue (20)        7.9 [+ or -] 1.0
                    Confusion (24)      4.9 [+ or -] 0.3
State of Fatigue    Lack of energy      2.3 [+ or -] 0.4
Inventory last      (6)
24 hr
                    Physical            2.6 [+ or -] 0.4
                      exertion (6)
                    Physical            1.9 [+ or -] 0.3
                      discomfort (6)
                    Lack of             1.0 [+ or -] 0.2
                      motivation (6)
                    Sleepiness (6)      1.3 [+ or -] 0.2
Hopkins
Symptoms
General Health
Checklist (108)

                Test                         Day 8
            (max score)                mean [+ or -] SE

Army Speed
  and Accuracy (80)                    36.0 [+ or -] 2.0
Profile of          Tension (28)        5.4 [+ or -] 0.4
  Mood States
                    Depression          1.2 [+ or -] 0.6
                    (32)
                    Anger (28)          1.0 [+ or -] 0.4
                    Vigour (24)         7.7 [+ or -] 1.6
                    Fatigue (20)        8.8 [+ or -] 1.6
                    Confusion (24)      5.1 [+ or -] 0.5
State of Fatigue    Lack of energy      2.4 [+ or -] 0.4
Inventory last      (6)
24 hr
                    Physical            3.0 [+ or -] 0.4
                      exertion (6)
                    Physical            2.1 [+ or -] 0.4
                      discomfort (6)
                    Lack of             1.3 [+ or -] 0.3
                      motivation (6)
                    Sleepiness (6)      1.5 [+ or -] 0.3
Hopkins
Symptoms
General Health
Checklist (108)

                Test                        Day 12
            (max score)                mean [+ or -] SE

Army Speed
  and Accuracy (80)                    34.0 [+ or -] 1.0
Profile of          Tension (28)        5.9 [+ or -] 0.5
  Mood States
                    Depression          1.7 [+ or -] 0.5
                    (32)
                    Anger (28)          2.3 [+ or -] 0.6
                    Vigour (24)         7.4 [+ or -] 1.0
                    Fatigue (20)        9.7 [+ or -] 1.4
                    Confusion (24)      5.5 [+ or -] 0.5
State of Fatigue    Lack of energy      2.9 [+ or -] 0.3
Inventory last      (6)
24 hr
                    Physical            3.3 [+ or -] 0.4
                      exertion (6)
                    Physical            2.8 [+ or -] 0.4
                      discomfort (6)
                    Lack of             1.3 [+ or -] 0.3
                      motivation (6)
                    Sleepiness (6)      2.0 [+ or -] 0.3
Hopkins
Symptoms
General Health
Checklist (108)

                Test                        Day 16
            (max score)                mean [+ or -] SE

Army Speed
  and Accuracy (80)                    38.0 [+ or -] 1.0
Profile of          Tension (28)        5.6 [+ or -] 0.5
  Mood States
                    Depression          1.7 [+ or -] 0.8
                    (32)
                    Anger (28)          1.7 [+ or -] 0.7
                    Vigour (24)         7.5 [+ or -] 1.3
                    Fatigue (20)        9.4 [+ or -] 1.5
                    Confusion (24)      4.9 [+ or -] 0.4
State of Fatigue    Lack of energy      2.4 [+ or -] 0.4
Inventory last      (6)
24 hr
                    Physical            2.7 [+ or -] 0.4
                      exertion (6)
                    Physical            2.4 [+ or -] 0.5
                      discomfort (6)
                    Lack of             1.3 [+ or -] 0.3
                      motivation (6)
                    Sleepiness (6)      1.8 [+ or -] 0.3
Hopkins
Symptoms
General Health
Checklist (108)

                Test                        Day 20
            (max score)                mean [+ or -] SE

Army Speed
  and Accuracy (80)                    36.0 [+ or -] 2.0
Profile of          Tension (28)        5.1 [+ or -] 0.3
  Mood States
                    Depression          0.9 [+ or -] 0.4
                    (32)
                    Anger (28)          1.5 [+ or -] 0.6
                    Vigour (24)         8.7 [+ or -] 1.1
                    Fatigue (20)        6.6 [+ or -] 1.2
                    Confusion (24)      5.0 [+ or -] 0.4
State of Fatigue    Lack of energy      2.7 [+ or -] 0.3
Inventory last      (6)
24 hr
                    Physical            3.0 [+ or -] 0.4
                      exertion (6)
                    Physical            2.9 [+ or -] 0.4
                      discomfort (6)
                    Lack of             1.1 [+ or -] 0.2
                      motivation (6)
                    Sleepiness (6)      1.6 [+ or -] 0.4
Hopkins
Symptoms
General Health                         24.2 [+ or -] 1.9
Checklist (108)

Acknowledgments

The authors would like to thank Steve Myers and Ken Puxley for their assistance as members of the scientific team in Sabah and to thank DERA-CHS UK for their partial financial support of the study. Our gratitude is also extended to the scientific team from DSTC, Malaysia for their invaluable assistance in the planning and conduct of the study, and to the soldiers of 25 Engineer Regiment for their cooperation and good-humoured forbearance as participants in this study.

References

(1.) Army Material Management Agency. Australian Defence Force Ration Scales and Scales of Issue (SUPMAN 4), Edition 5. Support

(2.) Command Australia (Army), Defence Centre. Canberra: Directorate of Publishing; 1999.

(3.) Forbes-Ewan C. Revision of Australian Combat Ration Packs [internal report]. DSTO, Scottsdale: Defence Nutrition Research Centre; 2000.

(4.) Booth C, Coad R, Forbes-Ewan C. Thomson G, Niro P. Effects of medium-term combat ration feeding during a ground defence training exercise in Far North Queensland. Mil Med 2003;168:63-70.

(5.) Workman M. Sabah 2000: Exercise Pelopor Finn--the Collaboration of Multidisciplinary Scientific Research and British Military Training, an Assessment. Exercise Pelopor Finn 1999-2000 Post Expedition Report 25 Engineer Regiment. UK: Corps of Royal Engineers UK; 2000.

(6.) Pickert A, Lingenfelser T, Pickert C, Birbaumer N, Overkamp D, Eggstein M. Comparison of a mechanised version of the 'Konig' reaction and a fluorescence polarisation immunoassay for the determination of nicotine metabolites in urine. Clin Chim Acta 1993;217:143-52.

(7.) Kniker WT, Anderson CT, Roumiantzeff M. The multi-test system: A standardized approach to evaluation of delayed hypersensitivity and cell-mediated immunity. Annals Allergy 1979;43:73-9.

(8.) Ainsworth E, Haskell W, Leon A, Jacobs D, Montoye H, Sallis J, et al. Compendium of physical activities: Classification of energy costs of human physical activities. Med Sci Sports Exerc 1993;25:71-80.

(9.) Ji A, Savon S, Jacobsen D. Determination of total serum sulfite by HPLC with fluorescence detection. Clin Chem 1995;41:897-903.

(10.) Mount J, Heduan E, Herd C, Jupp R, Keamey E, Marsh A. Adaption of coenzyme stimulation assays for the nutrition assessment of vitamin B1, B2 and B6 using the Cobas Bin centrifugal analyser. Ann Clin Biochem 1987;24:41-6.

(11.) Brewer J, Ramsbottom R, Williams C. Multistage fitness test. A progressive shuttle-run test for the prediction of maximum oxygen uptake. Canberra: Australian Coaching Council; 1988.

(12.) Astrand P, Rodahl K. Textbook of work physiology: Physiological bases of exercise. 3rd ed. Sydney: McGraw-Hill Book Company; 1987. p. 613-7.

(13.) Walmsley RN, White GH. A guide to diagnostic clinical chemistry. Melbourne: Blackwell; 1994. p. 270-1.

(14.) Committee on Military Nutrition Research. Food and Nutrition Board, Institute of Medicine. Marriott BM, editor. Not eating enough. Overcoming under consumption of military operational rations. Washington DC: National Academy Press; 1995. p. 10-8.

(15.) Committee on Military Nutrition Research. Food and Nutrition Board, Institute of Medicine. Marriott BM, editor. Not eating enough. Overcoming under consumption of military operational rations. Washington DC: National Academy Press; 1995. p. 211-2.

(16.) Committee on Military Nutrition Research. Food and Nutrition Board, Institute of Medicine. Marriott BM, editor. Not eating enough. Overcoming under consumption of military operational rations. Washington DC: National Academy Press; 1995. p. 222-6.

(17.) Amos D, Cotter JD, Lau WM, Forbes-Ewan CH. A methodology for measuring the physiological strain of enhanced soldiers: The 1998 Soldier Combat System Enhancement Study. DSTO-TR-0747. Melbourne: AMRL; 1998.

(18.) Cotter JD, Roberts WS, Amos D, Lau WM, Prigg SK. Soldier performance and heat strain during evaluation of combat fitness assessment in Northern Australia. DSTO-TR-1023. Melbourne: AMRL; 2000.

(19.) Lau WM, Roberts WS, Forbes-Ewan C. Physiological performance of soldiers conducting long range surveillance and reconnaissance in hot, dry environments. DSTO-TR-0894. Melbourne: AMRL; 1999.

(20.) Committee on Military Nutrition Research. Food and Nutrition Board, Institute of Medicine. Military strategies for sustainment of nutrition and immune function in the field. Washington DC: National Academy Press; 1999. p. 7-8.

(21.) Rall C, Meydani N. Vitamin B6 and immune competence. Nutr Revs 1993;51:217-24.

(22.) Boushey C, Beresford S, Omenn G, Motulsky A. A quantitative assessment of plasma homocysteine as a risk factor for vascular disease--probable benefits of increasing folic acid intakes. JAMA 1995;274:1049-57.

(23.) Braam L, Dissel P, Gijsbers B, Spronk H, Hamulyak K, Soute B, et al. Assay for human matrix Gla protein in serum: Potential applications in the cardiovascular field. Arterioscler Thromb Vasc Biol 2000;20:125-61.

(24.) Scrimshaw N, SanGiovanni J. Synergism of nutrition, infection, and immunity: an overview. Am J Clin Nutr 1997;66 Suppl:464S-77S.

(25.) Committee on Military Nutrition Research. Food and Nutrition Board, Institute of Medicine. Military strategies for sustainment of nutrition and immune function in the field. Washington DC: National Academy Press: 1999. p. 60-3.

Disclaimer: Results from this research have been used in an internal DSTO Report series DSTO-RR-0243.

Defence Science and Technology Organisation, Scottsdale, Tasmania

C. Booth, BSc(Hons), DipEd, GradDipNutrDiet, PhD, APD, Defence research scientist

R. Coad, BAppSc, Defence research scientist

W. Roberts, MAppSc. Defence research scientist

Correspondence: C. Booth, DSTO-Scottsdale, PO Box 147, Scottsdale TAS 7260. Email: [e-mail]