Protein digestion in human intestine as reflected in luminal, mucosal, and plasma amino acid concentrations after meals

Abstract

It is concluded that after the ingestion of a test meal containing a substantial amount of protein which is within the usual range of dietary intake: the exogenous protein is the principal source of the increased free and peptide amino acids in the intraluminal contents and in the plasma; there are greater amounts of amino acids present as small peptides than in the free form in the gut lumen; and the ingested protein can be recovered as late as 4 h both in the jejunum and in the ileum.