Nutritional Needs in Cold and High-Altitude Environments Applications for Military Personnel in Field Operations (1996) / Chapter Skim
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2 Committee on Military Nutrition Research Recommendations and Conclusions
2 Committee on Military Nutrition Research Recommendations and Conclusions
Pages 59-80
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From page 59... ...
70 .......... 70 .71 .72 ..72 ..73 Education md Logistics AREAS FOR FUTURE RESEARCH Water and Dehydration Energy Specific Nutrients Perfonn~ce Ad Medico Conditions 74 Military Ration Development Ad Guidance 75 CONCLUSIONS 75 REFERENCES 77 As stated in Chapter 1, the Committee on Military Nutrition Research (CMNR)
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From page 60... ...
Cold and high-altitude exposure affects muscle strength and endurance through changes in cardiac output and oxygen uptake. Very cold environments that lower body temperature by more than 0.9°F (0.5°C)
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From page 61... ...
Although some studies have reported weight gain in cold environments, other investigations have found that soldiers operating in cold climates may not consume military rations in amounts adequate to meet energy expenditure. Reports from field training exercises have shown decreased intake of energy relative to need in both cold and high-altitude environments.
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From page 62... ...
Cold-weather operations probably require a total energy intake ranging from 45 to 62 kcal/kg body weight/d, but earlier military studies in the Arctic suggested that 4,000 kcal/d or less were actually being consumed (LeBlanc, 1957~. Current projections for energy needs in arctic conditions focus on 58 kcal/kg body weight/d (see Chapter 1 in this volume)
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From page 63... ...
From a metabolic point of view, it is probable that the additional fat calories will be metabolized promptly, to satisfy immediate energy needs, rather than being stored in body fat depots. If extra dietary fat is consumed primarily to meet high daily energy requirements and to prevent weight loss during military operations in cold climates, it will not necessarily have important long-term consequences.
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From page 64... ...
Nutrients of particular concern would be iron, because of its relationship to hemoglobin and hemoglobin synthesis, and vitamin E, because of its relationship to oxidative stress. In addition to prior nutritional status, the body composition, recent losses of body weight or lean body mass, and recent health and training history of individual soldiers should be considered prior to their participation in missions or training in cold and in high-altitude environments.
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From page 65... ...
Thermoregulation involves cardiovascular measures to reduce heat loss (nonshivering thermogenesis) , an increase in metabolic heat production through shivering and an increase in voluntary muscular activity.
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From page 66... ...
Thennoregulation is also affected by a decrease in body water due to the decrease in body heat transfer to the periphery with the decrease in blood volume because it is the blood that carries the body heat to the periphery, where it is given up to the environment through evaporative heat loss. Body fluid losses of greater than 10 percent of total body water are life threatening.
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From page 67... ...
When doubly labeled water techniques were used to determine energy expenditures, mean total energy requirements of 3,400 to 4,300 kcal/d (or 2.5 to 3 times BMR) were recorded in sedentary male military personnel in the cold or at high altitudes.
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From page 68... ...
There is good reason to conduct research on sodium requirements in cold environments especially where hard physical work is required. Excessively high sodium intake can lead to increased diuresis, which is a major concern in cold environments.
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From page 69... ...
, including reduced thirst, inadequate fluid intakes (from both water and foods) , and increased sensible and insensible water losses associated with exercise.
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From page 70... ...
These preliminary findings are worthy of additional future studies. RECOMMENDATIONS On the basis of the papers presented by the invited speakers, discussion at the workshop, and subsequent committee deliberations, the Committee o Military Nutrition Research offers the following recommendations regarding nutrient requirements for work in cold and in high-altitude environments.
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From page 71... ...
When energy expenditures are high and total caloric intake is increased, the CMNR recommends that carbohydrate intake be increased to maintain calories from carbohydrate in the range of at least 40 percent of total caloric intake. This will help provide a palatable diet that is not excessive in fat content.
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From page 72... ...
Individuals who have not yet regained lean body mass lost in prior field operations should not be deployed to cold or high-altitude environments until lean body mass is regained. · Military troops, leaders, and medical personnel being assigned to high-altitude training or missions should be fully instructed on the symptoms and signs of AMS, subacute mountain sickness, high-altitude pulmonary edema (HAPE)
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From page 73... ...
to define energy requirements during military operations in which simultaneous exposures to intense cold and high altitudes occur, by validation of the "free-living" estimation of energy requirement based on Hoyt and Honig's proposed use of body weight, foot strike, and terrain (see Chapter 20 in this volume)
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From page 74... ...
to resolve conflicting data on possible effects of cold exposure on muscle strength and endurance. · to examine the relationship between the aging process and acclimatization.
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From page 75... ...
High energy, palatable rations supplying at least 400 g carbohydrate per day must be provided to insure that energy intake matches energy expenditure. Restriction of fat calories to only 30 percent is not appropriate in these operational rations.
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From page 76... ...
Individuals who have not yet regained lean body mass lost in prior field operations should not be deployed to cold or high-altitude environments until learn body mass is regained. An impressive body of evidence has already been generated to define the nutritional needs of troops required to engage in military operations under environmental conditions of extreme cold and/or high altitudes.
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From page 77... ...
the need to apply to military personnel the recent findings concerning maintenance of body weight and composition at altitude by encouraging the intake of a minimum level of dietary carbohydrate and total calories; (3) the need to determine the optimal ratio of energy sources, micronutrients, arid sodium in the cold; (4)
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From page 78... ...
1994 Food Components to Enhance Performance, An Evaluation of Potential PerformanceEnhancing Food Components for Operational Rations. A report of the Committee on Military Nutrition Research, Food and Nutrition Board.
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From page 79... ...
_ ~ ~~ ~~ ~ ~~ ^~ 79 Ups. Dep~en~ of He Arm, He may, Id He AS Fome 1983 may Regulation 40-23~ Command medical lns~uchon 10110.1 force Regulation 160-95.
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