Role of glutamine in immunologic responses.

Glutamine has traditionally been thought of as a nonessential amino acid, but laboratory and clinical data suggests that it may be essential during certain inflammatory conditions, such as infection and injury. Glutamine is a necessary nutrient for cell proliferation, serves as a specific fuel for inflammatory cells and enterocytes, and, when present in appropriate concentrations, enhances cell function. During inflammatory states, glutamine consumption may outstrip endogenous production and a relative glutamine deficiency state may exist. Animal and clinical studies suggest that improved outcome may be possible by providing the appropriate dose of this nutrient by the appropriate route to achieve adequate tissue concentrations. Such an approach prevents patients from being exposed to some of the inadequacies of present day conventional nutrition. The overall benefit of providing an appropriate glutamine-supplemented diet to all metabolically compromised patients arises from the multiple anabolic and host protective effects of this amino acid, of which immunomodulation is only one important facet of glutamine's essential nature.