Many of the nutrients, especially the B vitamins, are involved with the production of energy via numerous steps in the Krebs citric acid cycle. Thus, consideration will be given in the construction of the micronutrient intake goal to the estimated intakes of total food energy by those persons engaged in strenuous work in the cold or at high altitudes.

It has been estimated that in the cold, the average energy consumption by U.S. military soldiers who self-selected foods from the RCW was 2,800 kcal/d, and from the Meal, Ready-to-Eat (four meals) was 3,000 kcal/d (Personal communication, R. W. Hoyt, U.S. Army Research Institute of Environmental Medicine, Natick, Mass., 1994). The current MRDA for energy in cold weather is 4,500 kcal/d (AR 40-25, 1985). Jones and Lee (see Chapter 11 in this volume) estimate that energy requirements (expenditure) for soldiers range between 4,200 and 5,000 kcal/d during periods of physical exertion in the cold. The negative difference between energy intakes and expenditures thereby results in loss of body weight.

During the conduct of Operation Everest II with simulated altitudes up to 8,848 m (29,000 ft), subjects consumed between 2,500 and 3,000 kcal/d, with 45 percent of the energy being provided by carbohydrates (Rose et al., 1987). Estimates of energy expenditure between 4,000 and 5,000 kcal/d have been reported for those engaged in strenuous exertion while at high altitudes (Reynolds et al., 1992). Therefore, for the construction of the micronutrient intake goal, an estimated average energy intake of 4,500 kcal/d will be assumed in order to keep the personnel in energy balance. Any deficit between energy intake and expenditure must result in loss of body tissue.

Vitamin A is essential for the visual process, differentiation of epithelial cells, maintenance of the immune system, and integrity of the skin. The normal needs for vitamin A can be met by consumption of either preformed vitamin A or β-carotene, with the latter having a considerably lower toxicity (NRC, 1989).

Front Matter (R1-R16)

I: Committee Summary and Recommendations (1-2)

1 A Review of the Physiology and Nutrition in Cold and in High-Altitude Environments (3-58)

2 Committee on Military Nutrition Research Recommendations and Conclusions (59-80)

II: Background and Introduction to theTopic (81-82)

3 Cold Weather and High-Altitude Nutrition: Overview of the Issues (83-94)

4 Leadership Insights for Military Operations in Cold Weather and at High Altitudes (95-100)

5 Cold-Weather Field Feeding: Military Rations (101-114)

6 Feeding the US Army Sixth Infantry Division (Light) in the Cold (115-122)

Part II Discussion (123-124)

III: The Cold Environment (125-126)

7 The Physiology of Cold Exposure (127-148)

8 Military Schedules vs. Biological Clocks (149-160)

9 Influence of Cold Stress on Human Fluid Balance (161-180)

10 Muscle Metabolism and Shivering During Cold Stress (181-188)

11 Macronutrient Requirements for Work in Cold Environments (189-202)

12 Cold Exposure, Appetite, and Energy Balance (203-214)

13 Effects of Cold and altitude on Vitamin and Mineral Requirements (215-244)

14 Micronutrient Deficiency States and Thermoregulation in the Cold (245-256)

15 Drug-Induced Delay of Hypothermia (257-270)

Part III Discussion (271-292)

IV: The High-Terrestrial Environment (293-294)

16 The Physiology of High-Altitude Exposure (295-318)

17 Physical Performance at High Altitudes (319-330)

18 Fluid Metabolism at High Altitudes (331-356)

19 Maintenance of Body Weight at High Altitudes: In Search of 500 kcal/day (357-378)

20 Energy and Macronutrient Requirements for work at High Altitudes (379-392)

21 Oxidative Stress at High Altitudes and Effects of Vitamin E (393-418)

Part IV Discussion (419-432)

V: Performance in Cold and in High-Altitude Environments (433-434)

22 Effets of Altitue on Cognitive Performance and Mood States (435-452)

23 Food Components and Other Treatments That May Enhance Mental Performance at High Altitudes and in the Cold (453-466)

General Discussion (467-478)

Appendixes (479-480)

A: Environmental Stress Management at High Altitudes by Adaptogens, summary of unpublished manuscript (481-484)

B: Biographical Sketches (485-500)

C: Abbreviations (501-504)

D: Factors Related to Nutritional Needs in Cold and in High-Altitude Environments- A Selected Bibliography (505-554)

Index (555-568)