Glutamine supplementation in neonates: is there a future?

Over the past couple of decades, glutamine (GLN) has emerged as important metabolic intermediate, signaling molecule and nutrient that becomes rapidly depleted and therefore critically important during stress. In very low-birthweight (VLBW) infants, a population of patients in whom supplementation of GLN should provide major benefits, GLN is provided in subnutritional quantities because standard parenteral nutrition solutions do not contain GLN and most of these babies do not receive full enteral feedings until several weeks after birth. No evidence of toxicity of GLN supplementation was found in these clinical trials, but the results for efficacy on a limited number of outcomes have been mixed. The use of GLN supplementation in VLBW infants has therefore not become routine. Some authors suggest that further study in this area is no longer warranted. The purpose of this review is to provide an update in the area of GLN supplementation for preterm infants in order to determine whether GLN supplementation is unwarranted and/or additional investigations are needed. Evidence is presented and an argument is made that thoughtful reevaluation of future applications and trials of GLN in premature infants is warranted.