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The nutritional, physiological and psychological status of a group of British sappers after 23 days of adventure training in the hot wet tropics

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Abstract

The nutritional adequacy of both Australian combat ration packs and local feeding with fresh foods was evaluated during Exercise Pelopor Finn, a 23-day adventure training exercise conducted in Sabah, Malaysia. Thirty one males (aged 19 to 32 years) from the British 25 Engineer Regiment participated in the study. Blood samples were collected for determination of nutritional status and a skin immune- function test was performed before and after the exercise. Measurement of body mass, recording of food consumption, fitness fitness testing, collection of saliva samples (immunoglobulin-A) and testing of psychological status (mood and cognition) occurred immediately before and after and at multiple time points during the study. Mean weight loss was 5.5%, decrements in and and mental performance were not observed and good immune status was maintained. Food consumption was encouraged by 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. Tobacco smoking and alcohol consumption were shown to be detrimental to nutritional status and alcohol may have had a particular negative effect on iron status.

Executive Summary

Although troops engaged in land operations should expect to be fed to the best possible standard, using fresh foods wherever possible, there are situations when fresh rationing is not possible, or when its introduction will be delayed because the tactical situation does not allow field kitchens to be established for many weeks after deployment. Furthermore, the Army after Next requirement is for rapid force projection, increased mobility and improved sustainment. The re-supply of smaller and more highly dispersed fighting units places an emphasis on innovative feeding systems and greater use of combat ration packs (CRP). The effect on military performance and long-term health of extended CRP feeding is not known. The present study was designed to investigate the effects of longer-term feeding with CRP. The study was conducted in association with Exercise Pelopor Finn (meaning “trail blazer�, EX PF) an adventure training exercise conducted by a British engineer unit (25-Engineer Regiment) in Sabah, Malaysia. EX PF presented an opportunity to test the acceptability of the Australian combat ration one man (CR1M) under field conditions devoid of many of the usual operational stresses. Thirty-one male sappers participated in the study. Twenty sappers were at Tawau Hills Ranger Station (THRS) and were fed solely with CR1M and eleven were at the Danum Valley Field Centre (DVFC) and were fed with local fresh foods. The two locations were five hours apart by four-wheel-drive vehicle. Close control was not maintained over rationing, and hence sappers were able to access more than one CR1M per day at THRS and self-selected serves of food from the kitchen at DVFC. A weekly barbecue meal was provided for sappers at DVFC, with beer and soft drinks. In addition, all sappers at DVFC were given brew kits containing tea, coffee, biscuits, chocolate, milk, sports drink and sugar. The engineering tasks involved construction of an ecological trail (THRS), construction of observation towers 40 to 60 m above ground in rainforest trees (DVFC) and a survey of roads in the Danum Valley conservation area (DVFC). The DVFC group did not constitute a control for evaluation of CR1M; however they did provide important information relating to food acceptability, consequent energy balance and nutritional status measures. Blood samples were collected for determination of nutritional status (vitamins, cytokines, visceral proteins, and ferritin) and a delayed hypersensitivity skin test (immune function) was performed before and after the exercise. Measurement of body mass, recording of discarded ration items at THRS (packaging and foods) and recording of foods eaten at DVFC, physical fitness testing, collection of saliva samples (immunoglobulin-A) and testing of psychological status (mood and cognition) occurred immediately before and after and at multiple time points during the 23 day study. The measurement outcomes were body mass, nutrient intakes, immune function, micronutrient and visceral protein status, hydration status, aerobic capacity, mood states and cognitive ability. At both locations sappers ate about 90% of their mean estimated energy requirement (between 0.8 and 1.3 ration packs per day at THRS). This ensured that weight losses were less than 10% of body weight over 23 days (average loss of 5.5%) and decrements in physical and mental performance were not observed. Furthermore good immune status was maintained throughout the exercise. Factors which may have encouraged food consumption included the novelty of eating 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. However, tobacco smoking and alcohol consumption contributed to under consumption of food and alcohol consumption may have had a particular negative affect on iron status. Some conclusions could be drawn about the adequacy of the CR1M: − To meet the energy requirements of an engineering task involving prolonged moderate to hard physical activity, a group of British sappers needed to eat more than the contents of one CR1M ration per day. − Under field conditions where soldiers consume one or more ration packs per day, the CR1M provides sufficient energy and macronutrients to prevent serious protein energy malnutrition for up to 23 days of moderate to high physical activity in a hot tropical environment but fails to provide sufficient iron, folic acid, antioxidants and vitamin B6 to prevent a decline in storage of these nutrients. Further study is required to determine the implications of operational anorexia (ie decreased appetite), declining vitamin and mineral storage (particularly iron), weight loss and suppressed immune function on redeployment. To achieve this, the causes of operational anorexia need to be better understood and the effects of long-term feeding with CRP under operational conditions need to be better assessed.

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