Effect of Level and Pattern of Essential Amino Acids on Nitrogen Retention of Adult Man

Abstract

Two studies were conducted to determine the effect on nitrogen retention of increasing the dietary intake of essential and semiessential amino acids, patterned as in the poorly balanced protein of corn, when total nitrogen was held constant. Men were fed diets containing approximately 6.00 g nitrogen daily of which crystalline amino acids and diammonium citrate provided 5.50 g and ordinary foods, the remainder. During five experimental periods of study 1, the eight essential and four semiessential amino acids patterned as in corn protein provided 1.10, 2.20, 3.30, 4.40 and 5.50 g nitrogen daily. During the sixth experimental period, 2.20 g nitrogen was also provided by the essential and semiessential amino acids, but the level of isoleucine was increased to that in the FAO provisional pattern. Each increase in the intake of essential and semiessential amino acids was accompanied by an increase in nitrogen retention. Increasing the level of isoleucine to that in the FAO pattern had no effect on nitrogen retention. In the second study, nitrogen balance responses of men fed the corn and egg pattern were compared; equivalent amounts of nitrogen, 2.20, 3.30, or 5.50 g, were supplied by the essential and semiessential amino acids of the two patterns. When the essential nitrogen provided 3.30 or 5.50 g, more highly positive nitrogen balances were obtained when subjects were fed the egg pattern than when they were fed the corn pattern of amino acids.