Glutamine supplement with parenteral nutrition decreases whole body proteolysis in low birth weight infants

Objectives: To examine the effect of supplemental glutamine (0.6 g.kg ^-1.d^-1) on whole body protein/nitrogen and glutamine kinetics in low birth weight (LBW) infants receiving parenteral nutrition in the immediate neonatal period. Study design: Premature infants ≤32 weeks gestation with a birth weight from 694 to 1590 g were randomly assigned to either a glutamine-supplemented group (n = 10) or to a control group (n = 10). Tracer isotope studies were performed when the infants were 6 to 7 days old and had been receiving an amino acid intake of approximately 3.0 g.kg ^-1.d^-1 for at least 3 days. Whole body glutamine and nitrogen kinetics were measured with [5-¹⁵N]glutamine, [ ²H₅]phenylalanine, [1-¹³C, ¹⁵N] leucine, [¹⁵N₂]urea, and GC-mass spectrometry. Results: Supplemental glutamine was associated with a lower rate of appearance of glutamine (P = .003), phenylalanine (P = .001), and leucine C (P = .003). There was no significant difference in leucine N turnover, urea turnover and plasma cortisol, and C-reactive protein levels in the 2 groups. Conclusion: Parenteral glutamine supplement in LBW infants was associated with lower whole-body protein breakdown. Because the decrease in whole body proteolysis is associated with protein accretion, parenteral glutamine supplement may be beneficial in selected populations of LBW infants.