Glutamine dipeptide-supplemented parenteral nutrition maintains intestinal function in the critically ill

Long-term total parenteral nutrition is accompanied with mucosal atrophy and subsequent malabsorption syndrome. Current information attests the important role of glutamine in maintaining intestinal structure and function. The aim of this study was to investigate the effect of glutamine dipeptide supplementation on small intestinal absorption capacity during critical illness. Twelve intensive care unit patients were uniformly randomized to receive isonitrogenous (0.26 g nitrogen.kg-1.day-1) and isoenergetic (155 kJ.kg-1.day-1) parenteral nutrition over 9 days. The control group received a conventional amino acid solution (1.5 g amino acids.kg-1.day-1), and the test group received a complete amino acid solution containing the dipeptide L-alanyl-L-glutamine (20 g/L). On days 8 and 9, a modified D-xylose test was performed. Excretion of D-xylose during the 5-hour test period was 7.4 +/- 1.1 g (test) vs. 3.8 +/- 0.9 g (control) (P < 0.05). The 2-hour serum D-xylose concentration was 38.7 +/- 3.0 (test) vs. 27.8 +/- 2.9 mg/100 mL (control) (P < 0.05). Kinetic evaluation showed higher maximum D-xylose blood concentration and higher values for the area under the curve with the peptide. The results strongly suggest that glutamine dipeptide-containing total parenteral nutrition prevents intestinal atrophy and increased permeability associated with glutamine-free parenteral nutrition.