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perform immediately in a combat situation without a period of heat acclimatization. Furthermore, it should be noted that most of the sodium consumed by troops is derived from the consumption of food. Therefore a reduction in food, which is frequently observed during deployment, will likely result in a significant drop in sodium intake.

The data presented in Chapters 12 to 14 show that soldiers acclimated fairly rapidly to the hot environment and adapted to the lowered salt intake over the 10-day study period. However, there were increased symptoms of heat exhaustion during the first two days, which could be a significant problem for troops involved in military operations. These symptoms might have been even more severe had the subjects not been following a careful fluid intake schedule to maintain hydration during the study. It is also possible that the tendency toward heat illness would have been greater if these subjects had not been adapted to 8 grams per day of sodium chloride rather than the levels found in garrison dietary surveys (approximately 12 to 13 grams per day). Therefore, although the CMNR supports the goals of reducing the sodium intake of the U.S. population as well as military personnel, the committee does not recommend a reduction in the sodium content of operational rations at this time. As stated in the committee's report Military Nutrition Initiatives (IOM, 1991), it is not reasonable to expect the dietary sodium intake of military personnel in garrison to be different from that of the civilian population, which for adults is estimated to range from 1800 to 5000 mg per day in some reports (NRC, 1989a,b), and at a slightly higher level of 4000 to 6000 mg of sodium per day in other reports (U.S. Department of Health and Human Services, 1988). In addition, reducing sodium levels in operational rations must follow the efforts to reduce sodium intake in the general population to minimize the potential for compromising soldier performance in the days following deployment to hot environments.

Macronutrients

Chapter 6 provides a review of the influence of heat on macronutrient needs and soldier performance. A summary of this information is provided below.

Protein

Various authors over the past 40 years have reviewed the protein requirements for individuals working in the heat. Mitchell and Edman (1951) stated that "considering all evidence, it may be concluded that protein requirements may be slightly increased in the tropics by some 5–10 grams daily." They postulated that the slight increase in requirements may be due to a stimulation of tissue catabolism if pyrexia occurs and to compensation



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