Nitrogen Balance as Related to Caloric and Protein Intake in Active Young Men

Based on an intensive review of published observations on protein intake in the presence of a reduced caloric intake, certain conclusions seem clear. For young, essentially normal active men, when no protein is fed the protein deficit (negative nitrogen balance) can be maximally reduced by supplying about 700 nonprotein calories. No significant protein-sparing is achieved by intake as high as 2800 calories in the absence of protein. When the caloric intake is approximately 1000, 3 Gm. of nitrogen will produce as much protein sparing as higher quantities of nitrogen. When full caloric requirement is met, 8.5 Gm. of nitrogen promotes balance and little additional storage results even from much larger protein intakes. These findings, plus others cited from the literature, suggest that a versatile food unit of 500 calories (7 to 8 per cent of which are derived from protein) would be most practical and physiological in the development of a military survival ration, or a short-term civilian emergency feeding.