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however, that "no allowance has been included for large, prolonged losses from the skin through sweat."

The military has endeavored to reduce the sodium intake of its personnel through modifications of garrison and operational ration guidelines. Dietary surveys conducted at various military facilities have documented changes in the dietary intakes of several nutrients, but the sodium intake of personnel eating in military dining halls has remained relatively stable at 1500 to 1850 mg of sodium per 1000 kcal of diet (IOM, 1991). The MRDAs set forth a goal of 1700 mg of sodium per 1000 kcal of diet for foods served in military dining halls. This level is estimated to equal a daily sodium intake of approximately 5500 mg for men and 4100 mg for women. For operational rations4 the MRDAs specify a range of 5000 to 7000 mg of sodium per day, excluding the additional salt packets that are packed with the rations. Restricted rations5 have sodium levels, as established by the MRDAs, of 2500 to 3500 mg of sodium per day.

In an earlier report (IOM, 1991), the CMNR evaluated the sodium content of military rations. The committee urged caution in arbitrarily reducing sodium intake drastically from current levels and noted that studies were needed to evaluate the impact of reductions on personnel who might not be heat acclimatized and who were routinely consuming diets that provided sodium in the range of 1700 to 1850 mg per 1000 kcal of diet. The committee recommended that the "total daily intake of salt should be limited to 10 grams or less (4000 mg sodium) except under conditions in which salt requirements exceed values due to large salt losses such as those associated with heavy physical work in hot environments."

Chapters 12 through 14 in Part III summarize the details of studies by researchers from the USARIEM who investigated the impact of reducing intake from 8 grams to 4 grams of sodium chloride per day (3200 to 1600 mg sodium) for individuals working in a hot environment. The primary concern of the CMNR in including this study as part of this report was a consideration of the possible detrimental effects on troops of being suddenly deployed from a temperate environment to a desert or a jungle without an opportunity for acclimatizing to the heat. A mobilization of this kind would also result in soldiers' consuming combat rations that would provide significantly lower levels of sodium than they had been consuming prior to deployment. The committee's concern centers on the ability of troops to


Operational rations typically are composed of nonperishable items that are designed for use under actual or simulated combat conditions.


Restricted rations are designed for use under more specific operational scenarios such as long-range patrol, assault, and reconnaissance when troops are required to subsist for short periods (up to 10 days) on an energy-restricted ration. These rations require no further preparation; because they are intended for short-range patrols, they provide suboptimal levels of energy and nutrients.

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