Glutamine

The amino acid glutamine is the preferred fuel for small intestinal enterocytes and can decrease intestinal permeability, a potential benefit for Crohns Disease patients. Duodenal biopsies from healthy volunteers were cultured in the presence of the inflammatory cytokine-enhancing IL-1beta and increasing amounts of glutamine. Glutamine inhibited IL-1beta-induced production of pro-inflammatory cytokines IL-6 (found to be high in the serum and mucosa of Crohn's Disease patients83) and IL-8, and enhanced production of the anti-inflammatory IL-10.²⁴⁷

Despite theoretical indications for glutamine supplementation in Crohn's Disease, several small intervention trials have not yielded benefit. In a double-blind study to determine if glutamine decreases gut permeability in Crohn’s disease, 14 Crohn's Disease patients were randomly assigned to receive 7 g glutamine or placebo (glycine) three times daily along with their conventional treatment. There were no significant changes in permeability during the four-week trial in either the glutamine or placebo groups. In addition, no significant changes were seen in CDAI, CRP, or plasma glutamine/ glutamate levels.²⁴⁸

Two studies investigating high-glutamine diets in children with Crohns Disease also found no significant benefit. Eighteen children received either a low-glutamine (4% of amino acid content) polymeric diet or a glutamine-enriched (42% of amino acid content) polymeric diet to determine whether glutamine enhances rate of remission. After four weeks, 5/9 in the low-glutamine group and 4/7 (two patients dropped out of this group due to diet intolerance) in the high-glutamine group achieved remission. Pediatric CDAI was significantly lower in the low-glutamine group, indicating greater response to the low- than high-glutamine diet.²⁴⁹ In a second arm of the study, glutamine did not affect intestinal permeability.²⁵⁰

Growth is often stunted by childhood Crohns Disease and low serum levels of insulin-like growth factor- 1 (IGF-1) have been implicated. In doubleblind fashion, 15 children with Crohn's Disease were assigned to receive one of two diets (same amino acid content as previous study) and the effect on IGF-1 assessed. No significant changes in IGF-1 were noted after four weeks of supplementation.²⁵¹



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