PROTEIN, AMINO ACID METABOLISM AND THERAPY: Edited by Sidney M. Morris Jr. and Alessandro LavianoInterrelationships between glutamine and citrulline metabolismMarini, Juan C.a,b Author Information aSection of Critical Care Medicine bUnited States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA Correspondence to Juan C. Marini, Section of Critical Care Medicine, Baylor College of Medicine, Houston, TX, USA. E-mail: [email protected] Current Opinion in Clinical Nutrition and Metabolic Care: January 2016 - Volume 19 - Issue 1 - p 62-66 doi: 10.1097/MCO.0000000000000233 Buy Metrics Abstract Purpose of review This article analyzes the contribution of glutamine to the synthesis of citrulline and reviews the evidence that glutamine supplementation increases citrulline production. Recent findings Glutamine supplementation has been proposed in the treatment of critically ill patients; however, a recent large multicenter randomized controlled trial resulted in increased mortality in the glutamine-supplemented group. Within this context, defining the contribution of glutamine to the production of citrulline, and thus to de-novo arginine synthesis, has become a pressing issue. Summary The beneficial effects of glutamine supplementation may be partially mediated by the effects of glutamine on citrulline synthesis by the gut and the de-novo synthesis of arginine by the kidney and other tissues. Although there is no strong evidence to support that glutamine is a major precursor for citrulline synthesis in humans, glutamine has the potential to increase overall gut function and in this way increase citrulline production. Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.