American Journal of Clinical Nutrition, Vol 22, 292-299, Copyright © 1969 by The American Society for Clinical Nutrition, Inc.

Intestinal Absorption of Amino Acids

Current Concepts

¹ From the Section of Nuclear Medicine (Radiology), Yale University School of Medicine, New Haven, Connecticut

Intestinal transport of amino acids was reviewed with reference to both in vivo and in vitro studies and their limitations. The principal intestinal active transport system for the neutral amino acids has been characterized as to the stereochemical groupings required; a conceptual model of the transport acceptor site was presented. Active transport of amino acids by the small gut can be inhibited by agents interfering with energy production, by other amino acids ("cross inhibition"), by carbohydrates in some cases, and by low sodium concentrations or alteration of adenosine triphosphatase. Transport also responds to other factors, such as hormone administration. Approaches to determining congenital defects in amino acid absorption by the intestine were pointed out, and some known instances of genetically determined absence of intestinal amino acid transport were summarized.