Glutamine: From basic science to clinical applications

Glutamine (Gin) has been one of the most intensively studied nutrients in the field of nutrition support in recent years. Interest in provision of Gin derives from animal studies in models of catabolic stress, primarily in rats. Enteral or parenteral Gin supplementation improved organ function and/or survival in most of these investigations. These studies have also supported the concept that Gin is a critical nutrient for the gut mucosa and immune cells. Recent molecular and protein chemistry studies are beginning to define the basic mechanism involved in Gin action in the gut, liver and other cells and organs. Double-blind prospective clinical investigations to date suggest that Gin-enriched parenteral or enteral feedings are generally safe and effective in catabolic patients. intravenous Gin (either as the L-amino acid or as Gln-dipeptides) has been shown to increase plasma Gin levels, exert protein anabolic effects, improve gut structure and/or function and reduce important indices of morbidity, including infection rates and length of hospital stay in selected patients subgroups. Additional blinded studies of Gin administration in catabolic patients and increasing clinical experience with Gin-enriched nutrient products will determine whether routine Gin supplementation should be given in nutrition support, and to whom. Taken together, the data obtained over the past decade or so of intensive research on Gin nutrition demonstrate that this amino acid is an important dietary nutrient and is probably conditionally essential in humans in certain catabolic conditions.