Effect of long-term oral glutamine supplements on small intestinal permeability in patients with Crohn's disease

Background: Glutamine is a major fuel and an important nitrogen source for the small intestinal cell. It plays a key role in maintaining mucosal cell integrity and gut barrier function. Increased permeability may be a factor in the pathogenesis of Crohn's disease and may be an interesting parameter in the follow-up of the disease. Therefore, the aim of this study was to examine whether oral glutamine supplements are able to restore an increased intestinal permeability in patients with Crohn's disease. Methods: The inclusion criteria for the study were Crohn's disease and a disturbed small intestinal permeability for Cr-51-EDTA. Of 38 patients screened, 18 had an increased permeability (6 hours urinary excretion >1.1% of label recovered in urine). Four teen patients were included in the study and were randomized to receive either oral glutamine (7 g three times per day; n = 7) or placebo (7 g glycine three times per day; n = 7) in addition to their normal treatment during a 4-week period. The study was performed in a double-blind manner. Results: Baseline permeability (mean +/- SD) was 2.32% +/- 0.77%; dose in the glutamine group and 2.29% +/- 0.67% dose in the placebo group. Permeability did not change significantly after glutamine (3.26% +/- 2.15% dose) or after placebo (2.27% +/- 1.32% dose). There was no significant effect on plasma glutamine, plasma glutamate, plasma ammonium, Crohn's disease activity index, C-reactive protein, or nutritional status. Conclusions: Oral glutamine supplements, in the dose administered, do not seem to restore impaired permeability in patients with Crohn's disease.