It is generally recognized that at any given time, deployed soldiers and those in field training face a combination of stressors that may include energy imbalance (secondary to undereating, intense physical activity, or both), severe injury, systemic infection, climatic extremes, and changes in altitude. As described above, attempts to identify the effects of such stressors, alone or in combination, on protein requirements have thus far been inconclusive. Additional stressors, such as exposure to unidentified environmental contaminants and the emotional consequences of the battlefield and of separation from a familiar environment, have also been recognized, but far less is understood about their impact on physiology and nutritional status and how this might influence protein requirements (Friedl, 1997; IOM, 1995).
The protein (and energy) content of military operational rations was formulated during World War II on the basis of Food and Nutrition Board recommendations (NRC, 1941). Based on data for energy consumption and expenditure of soldiers during the war, the initial standard of 70 g protein per 3000 kcal for the 70 kg reference man was increased in 1947 to 100 g protein per day (based on 3600-kcal total energy intake) for physically active military men in temperate climates. The protein MRDA for women is 80 g/d based on a daily energy intake of 2000-2800 kcal (AR40-250, 1947). This amount of protein is equivalent to 11 percent of total recommended energy intake (results of recent national nutritional surveys, including the National Health and Nutrition Examination Survey (NHANES) III, have shown that protein intake in the U.S. population averages 14 to 16 percent of total food energy for both males and females).
Since the 1940s, the mean weight of male soldiers has increased from 68 to 78 kg; similarly, the mean weight of female soldiers has increased from 61 to 63 kg. Thus, the MRDA for protein expressed on a g/kg BW basis is 1.3 for both men and women. Based on observations suggesting that protein requirements may be increased for individuals engaged in specific types of exercise, the question arises whether recommendations established for protein intake by soldiers during World War II are still appropriate for military personnel today.
Studies conducted in the 1940s and over the past decade have shown that military personnel maintain relatively high protein intakes during field operations as well as in garrison. Table 1-2 summarizes the average and range