Randomised placebo-controlled trial of dietary glutamine supplements for postinfectious irritable bowel syndrome.
Level 2 - randomized trial
Individual randomized, double-blind, placebo-controlled trial
PubMed 30108163 · doi:10.1136/gutjnl-2017-315136
What was done
An 8-week randomized, double-blind, placebo-controlled trial evaluated oral glutamine (5 g three times daily) versus placebo in adults who developed diarrhea-predominant irritable bowel syndrome (IBS-D) with increased intestinal permeability following an enteric infection. The primary endpoint was a reduction of ≥50 points on the Irritable Bowel Syndrome Severity Scoring System (IBS-SS). Secondary endpoints included raw IBS-SS scores, daily bowel movement frequency, Bristol Stool Scale scores, and intestinal permeability assessed via urinary lactulose/mannitol ratio.
What was found
A total of 106 participants completed the 8-week trial (54 glutamine, 52 placebo). The primary endpoint occurred in 43 participants (79.6%) receiving glutamine compared to 3 (5.8%) receiving placebo. Glutamine significantly reduced mean 8-week IBS-SS score (181 vs 301, p<0.0001), daily bowel movement frequency (2.9±1.0 vs 5.4, p<0.0001), Bristol Stool Scale score (3.9 vs 6.5, p<0.0001), and intestinal permeability (0.05 vs 0.11, p<0.0001), normalizing elevated permeability. Adverse events and discontinuation rates were low and similar between groups, with no serious adverse events reported.
Why it matters
This trial demonstrates that oral glutamine can substantially improve clinical symptoms and normalize gut barrier function in postinfectious IBS-D with intestinal hyperpermeability.
Limits
The population was restricted to postinfectious IBS-D with baseline intestinal hyperpermeability, limiting generalizability to other IBS subtypes. The sample size was modest (106 completers; initial randomized number not stated), the intervention lasted only 8 weeks without long-term follow-up, and quality of life was not measured.
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