NITROGEN BALANCES OF YOUNG MEN FED SELECTED AMINO ACID PATTERNS: I. FAO REFERENCE PATTERN, A MODIFICATION OF THE FAO REFERENCE PATTERN, AND WHEAT FLOUR PATTERN

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Abstract
Nitrogen balances were determined for six young men fed three amino acid patterns: the FAO reference pattern, a modification of the FAO pattern in which methionine was decreased and phenylalanine increased isonitrogenously, and the wheat pattern. Total N intake was approximately 10 g. The lowest intakes of the FAO reference pattern amino acids found to be adequate for the support of N equilibrium or positive N balance contained 320 mg tryptophan in the case of two subjects, 280 mg tryptophan for three subjects, and 240 mg tryptophan for one subject. Comparison of group mean N retentions for the FAO and the modified FAO patterns indicated that the two patterns were of equal value. When the FAO reference and wheat patterns were fed to provide comparable amounts of lysine, the limiting amino acid of wheat protein, group mean N retentions were 0.42 and 0.41 g, respectively. When the same two patterns were fed to provide an equivalent amount of essential amino acid N and the chief source of amino acids was intact wheat protein, group mean N retentions were 0.62 g for the FAO reference pattern, and 0.41 g for the wheat pattern; statistically, this difference is not significant. From 0.63 to 0.84 g essential amino acid N provided as FAO reference pattern was adequate to maintain N equilibrium or a slight positive balance.