Pathophysiology of glutamine and glutamate metabolism in premature infants

The potential efficacy of glutamine and glutamate as nutritional supplements for premature infants was originally met with enthusiasm. Despite no evidence of toxicity in the clinical trials, the use of glutamine has not become routine. In certain studies, the benefits seem clear, whereas in others, benefits have not been demonstrated. Specific designs for studies have been difficult, targets based on mechanistic frameworks have been poorly defined, study populations are heterogeneous and putative mechanisms of glutamine action are multifold. Our purpose is to review recent findings pertaining to (1) the action and mechanisms of glutamine and glutamate in the gastrointestinal tract, and (2) the future directions for glutamine and glutamate research with a focus on the premature neonate.

Studies elucidating mechanisms of glutamine action include tissue protection, immune modulation, preservation of glutathione and antioxidant capacity, preservation of metabolism, decreased intestinal apoptosis, and enhancement of heat shock proteins. The ability to decrease gastrointestinal-derived systemic inflammation appears to have especially significant implications for premature infants.

We review recent studies of mechanisms of glutamine and glutamate action, pertinent clinical trials, and suggest areas for future research based on these mechanisms.