Improvement in the Intestinal Absorption of Soy Protein By Enzymatic Digestion to Oligopeptide in Healthy Adult Men

Abstract

In this study, we compared the intestinal absorption from different sources with the same amino acid composition (protein, peptide, and amino acid mixture) by measuring changes in serum concentrations of various amino acids. Peptides used in this study were prepared by enzymatic digestion of 11S globulin (a major component of soy protein). Twelve normal male adults were asked to drink beverages containing 12.5g of the test sample, representing 5% suspension of each of the following three different preparations : 11S globulin, 11S peptide, and an amino acid mixture of equivalent composition. Venous blood samples were collected from 0 to 180min to measure free amino acid concentrations. The early slope of serum concentrations and values of area under the curves for each amino acid calculated from changes in serum amino acid concentrations were significantly greater for 11S peptide than for either 11S globulin or the amino acid mixture. This trend was especially remarkable for branched-chain amino acids and aromatic amino acids. Our results suggest that the ingestion of hydrolyzed soy protein results in faster and more efficient absorption than the consumption of protein or amino acid mixtures in healthy adult men.