Effects of glutamine on markers of intestinal inflammatory response and mucosal permeability in abdominal surgery patients: A meta-analysis

The present meta-analysis was carried out to determine whether supplementation with glutamine (Gln) would reduce the intestinal inflammatory response and mucosal permeability in patients undergoing abdominal surgery. The PubMed, EMBASE, Web of Science, and The Cochrane Library databases were searched for randomized controlled trials on the effects of supplementation with Gln, and published from August, 1966 to June 2014. Inclusion criteria for the meta-analysis were: i) Study design was a randomized controlled trial, ii) study included patients undergoing abdominal surgery, iii) study patients received a supplementation with Gln peptide (Ala-Gln or Gly-Gln) whereas control patients did not use any supplements, and iv) study outcomes included inflammatory markers [C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), and interleukin (IL)-6, and IL-2 receptor] and markers of intestinal permeability [lactulose/mannitol, diamine oxidase, D(-)lactic acid, and endotoxin]. Qualities of controlled trials were assessed using the Jadad score. Meta-analyses were performed with fixed- or random-effect models depending on the heterogeneity of studies. There were 21 trials meeting the inclusion criteria. The meta-analysis revealed that the levels of CRP, TNF-α, and IL-6 in patients supplemented with Gln were significantly lower than those in control patients, whereas the levels of IL-2 receptor were increased by Gln supplementation. Gln also significantly decreased the lactulose/mannitol ratio, the levels of diamine oxidase and endotoxin, and tended to decrease the levels of cyclic D-lactic acid. In conclusion, Gln appears to effectively reduce the inflammatory response and intestinal mucosal permeability in patients after abdominal surgery.