Glutamine for IBS: Four Checks on the Postinfection Trial

If someone quotes a glutamine success percentage, ask them to show you the study behind it. These four checks help turn that figure into questions you can discuss with the clinician treating your IBS.

Check who qualified

The postinfection trial required diarrhea-predominant IBS and increased intestinal permeability, measured by a urinary lactulose/mannitol ratio of at least 0.07. Stool cultures had not confirmed the original infection.¹

Ask whether the study population resembles your diagnosis. Take a timeline of when the bowel symptoms began and what investigations you have already had. The study’s selection test is a detail to discuss, rather than a reason to order a commercial test yourself.

Check the response and denominator

The regimen was glutamine 5 g three times daily versus whey-protein placebo for eight weeks. A response meant an IBS severity-score reduction of at least 50 points: 43/54 (79.6%) versus 3/52 (5.8%). This measured symptom improvement, not cure.¹

The paper reports 115 randomized and 106 completers analyzed; the registry lists enrollment as 106.¹² That reporting difference remains unresolved here.

Write down the denominator beside any percentage you bring to an appointment. Ask what improvement you would track, how long an agreed trial would last, and what would make you stop. The published regimen describes the experiment; it is not a personal dosing recommendation.

Check what the later trial tested

A separate 2021 trial randomized 50 adults with IBS to glutamine or placebo for six weeks; both groups received a low-FODMAP diet. Twenty-two per group completed treatment, with missing outcomes imputed for analysis. The study reported greater symptom-severity improvement with glutamine, while the between-group quality-of-life difference was not significant. It did not select the same postinfection, abnormal-permeability population or follow participants after treatment ended.³

The later evidence addresses adding glutamine to a diet program; direct replication would need the earlier selection rules. If you are considering dietary treatment, our low-FODMAP guide explains restriction, reintroduction and personalization.

Check safety and the product

The postinfection trial excluded pregnancy, breastfeeding and significant kidney or liver impairment. It reported no serious adverse events over eight weeks.¹

NCCIH advises discussing supplements with your healthcare provider because interactions and unlisted ingredients are possible; pregnancy and breastfeeding need particular attention.⁴

For US supplements, FDA approval for safety and effectiveness is not required before sale. The NIH Office of Dietary Supplements⁵ also cautions that a label alone makes product quality difficult to judge.⁵ Photograph the complete ingredient list and serving information for your pharmacist or clinician, including any other gut products you take.

Bring the evidence beside your symptom record

Bloated by Dinner includes “The Test It Visit,” which asks you to bring your symptom log, list medicines and supplements, and ask what has been ruled out and what comes next. Use it to prepare a discussion about whether glutamine fits your situation. See the book.