Effects of glutamine supplementation on inflammatory bowel disease: A systematic review of clinical trials.

Context: Glutamine supplementation has been applied clinical practice to treat inflammatory bowel disease (IBD). However, scientific evidence about this is still controversial.

Objective: In this review, we systematically evaluated the effects of glutamine supplementation on IBD, based on evidence from randomized clinical trials.

Data Source: This review was conducted in accordance with the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We used the PubMed and SciVerse Scopus databases. The Cochrane collaboration tool was used to assess the risk of bias in clinical trials.

Data Extraction: The review was carried out by two independent researchers according to the established inclusion criteria. The PICO (patient, intervention, comparison, and outcomes) strategy was used, with the descriptors: "glutamine," "supplementation," "inflammatory bowel diseases," "Crohn's disease," and "ulcerative colitis".

Data Synthesis: Seven research articles were selected for this systematic review. In these studies, glutamine was administered to the participants through oral (21-30g or 0.5g per kg of participant's body weight), enteral (7.87g-8.3 g/100g of the enteral formula), and/or parenteral (0.3  g/kg of the participant's body weight) routes. No changes in anthropometry or biochemical parameters were observed. However, in one study reduced intestinal permeability and morphometry were reported. In two other studies, a slight effect of glutamine on inflammation and oxidative stress was observed. Additionally, two other studies reported an effect of glutamine supplementation on disease activity.

Conclusions: The findings obtained through this systematic review indicate that glutamine supplementation has no effect on disease course, anthropometric measurements, intestinal permeability and morphology, disease activity, intestinal symptoms, biochemical parameters, oxidative stress and inflammation markers in patients with IBD, regardless of the route of administration, either treated at a hospital or as outpatients.