Glutamine for IBS: Does it Really Help?

randomized-controlled-trial PMID: 30108163

Quick Summary: A study found that taking glutamine supplements significantly improved symptoms for people with diarrhea-predominant IBS (IBS-D) that started after a gut infection. The glutamine group saw a big reduction in IBS symptoms compared to those who took a placebo.

What The Research Found

This research looked at how glutamine, an amino acid, affects people with IBS-D who also had increased "leaky gut" (intestinal permeability) after a gut infection. The study showed that glutamine:

Significantly reduced IBS symptoms: Most people taking glutamine had a big improvement in their IBS symptoms.

Reduced diarrhea: People taking glutamine had fewer daily bowel movements.

Improved stool consistency: Glutamine helped improve stool form.

Improved "leaky gut": Glutamine helped to normalize intestinal permeability.

Study Details

Who was studied: Adults with IBS-D who had increased intestinal permeability after a gut infection.

How long: The study lasted 8 weeks.

What they took: Participants took either 5 grams of glutamine powder three times a day or a placebo (a dummy treatment).

What This Means For You

If you have IBS-D that started after a gut infection, and you have "leaky gut", glutamine might help reduce your symptoms. This study suggests that glutamine could help with diarrhea, improve stool consistency, and reduce overall IBS discomfort. Always talk to your doctor before starting any new supplement. They can help you determine if glutamine is right for you and monitor your progress.

Study Limitations

Specific Group: This study only looked at people with a specific type of IBS (IBS-D after an infection) and "leaky gut."

Short-Term: The study only lasted 8 weeks, so we don't know if the benefits last long-term.

More Research Needed: Larger studies are needed to confirm these findings and see if glutamine improves quality of life.

Key Findings

This study found that oral glutamine supplementation (5g three times daily) significantly improved symptoms in patients with postinfectious irritable bowel syndrome-diarrhea-predominant (IBS-D). The primary endpoint—a ≥50-point reduction in IBS Severity Scoring System (IBS-SS) scores—was achieved by 79.6% of glutamine recipients versus 5.8% in the placebo group (p<0.0001). Glutamine also reduced daily bowel movements, improved stool consistency (Bristol Stool Scale), and normalized intestinal permeability (urinary lactulose/mannitol ratios), with no serious adverse events reported.

Study Design

A randomized, double-blind, placebo-controlled trial conducted over 8 weeks. Participants (n=106 total: 54 glutamine, 52 placebo) were adults diagnosed with postinfectious IBS-D and confirmed intestinal hyperpermeability. The study was registered (NCT01414244) and focused on short-term outcomes.

Dosage & Administration

Subjects received 5g of glutamine powder three times daily (t.i.d.), mixed with water. Placebo participants consumed identical-looking non-caloric powder. Compliance was monitored via pill counts and daily diaries.

Results & Efficacy

Primary Endpoint: 43/54 (79.6%) glutamine vs. 3/52 (5.8%) placebo achieved ≥50-point IBS-SS reduction (p<0.0001; 14-fold difference).
Secondary Endpoints:
Mean IBS-SS score at week 8: 301 (placebo) vs. 181 (glutamine) (p<0.0001).
Daily bowel movements: 5.4 (placebo) vs. 2.9 ± 1.0 (glutamine) (p<0.0001).
Bristol Stool Scale: 6.5 (placebo) vs. 3.9 (glutamine) (p<0.0001).
Intestinal permeability (urinary lactulose/mannitol ratio): 0.11 (placebo) vs. 0.05 (glutamine) (p<0.0001).
Safety: Adverse events (e.g., mild gastrointestinal discomfort) occurred in 11.3% of glutamine vs. 9.6% placebo (p=NS), with low discontinuation rates (3.7% vs. 5.8%).

Limitations

Blinding Uncertainty: The study did not specify whether participants were blinded to treatment allocation.
Sample Specificity: Results apply only to postinfectious IBS-D patients with confirmed intestinal hyperpermeability, limiting generalizability.
Short Duration: Long-term efficacy and safety beyond 8 weeks remain unknown.
Mechanistic Gaps: The study did not explore molecular pathways linking glutamine to symptom improvement.
Need for Larger Trials: A larger RCT is required to confirm findings and assess quality of life impacts.

Clinical Relevance

For individuals with postinfectious IBS-D and intestinal hyperpermeability, glutamine (5g thrice daily) may offer rapid, safe symptom relief, including reduced diarrhea frequency and improved gut barrier function. However, the lack of long-term data and the need for replication in broader populations mean clinicians should consider glutamine as an adjunct, not first-line, therapy. Supplement users should consult healthcare providers to confirm suitability for their IBS subtype and monitor response. These findings support glutamine’s potential role in managing gut barrier dysfunction but emphasize the importance of targeted use.

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Source: PubMed (NCT01414244), 2019 RCT.

Glutamine for IBS: Does it Really Help?