Amind Acid Requirements of the Normal Infant

Abstract

If the sole purpose of protein in the diet is to furnish amino acids, the amount needed is that which provides the required quantities of essential amino acids. In these studies the requirement of an essential amino acid is determined by feeding a diet made up of purified amino acids and shown to support normal growth (as evidenced by weight nitrogen retention and plasma protein). The amino acid under study is omitted and then reintroduced in increments until normal growth is resumed; the least amount of the amino acid necessary is considered to be the minimum requirement. Using this technique the minimum requirement for infants between 1 and 6 months of age for threonine was 60 mg./kg./day and for phenylalanine, 90 mg./kg./day. An infant ingesting 200 ml./kg./day of woman's milk would receive approximately 104 mg. of threonine and 106 mg. of phenylalanine/kg./day.