A study of the protein metabolism of a two-year old on two levels of plant protein intake

Abstract

A fifteen day balance study was conducted to test the value of two diets providing 24 and 16 gm. of plant-protein daily and to approach the approximate minimum protein requirement using plant proteins for a 23-month old Chinese girl weighing 12 kg. The diets were supplemented to bring nutrients to the NRC recommended allowances except for protein and calories. Essential amino acids were planned to approximate the FAO provisional pattern.

Nitrogen determinations were made on food, urine and feces. Food composites for each diet were analyzed for nine of the essential amino acids using a Beckman/Spince Model 120 Amino Acid Analyzer. Tryptophan was determined by microbiological assay.

Nitrogen in the diets averaged 3.96 and 2.69 gm. respectively for the two protein levels of 24 and 16 gm. daily with retention of 0.33 gm. daily for all periods, or 0.48 gm. and 0.44 gm. for the test periods.

The essential amino acids as analyzed represent 59 per cent and 34 per eent of the total protein in the moderate and low protein diets. The analyzed amino acid patterns were as follows: tryptophan 1.0 and 1.0; threonine 2.8 and 2.2; isoleucine 5.8 and 3.5; leucine 9.4 and 5.5; lysine 3.1 and 3.7; methionine 1.2 and 0.8; phenylalanine 6.1 and 3.6; valine 6.7 and 3.9; arginine 4.4 and 4.5; and histidine 1.3 and 2.0.

A positive nitrogen retention of better than 0.4 gm. daily (0.033 gm./kg.) was obtained with daily nitrogen intake of 0.33 and 0.22 gm. per kg. of body weight for this 23-month old girl with approximately 90 and 84 calories per kg. per day.