L-Glutamine for Irritable Bowel Syndrome (IBS)
CPilot RCTs suggest glutamine (5 g TID) reduces intestinal permeability and IBS-D symptoms in post-infectious IBS. Promising but needs larger trials.
The Bottom Line
Pilot RCTs suggest glutamine (5 g TID) reduces intestinal permeability and IBS-D symptoms in post-infectious IBS. Promising but needs larger trials.
Key Study Findings
Population: animal model of IBS with diarrhea
Population: female rats with water avoidance stress-induced IBS-D model
Population: Male C57BL/6 mice (IBS-D model)
Population: IBD and IBS patients (review)
Population: Mouse model
Population: Mice
Key Statistics
2
Studies
150
Participants
Positive
Grade
Referenced Papers
Dosage & Usage
mg = milligrams · mcg = micrograms (1,000× smaller) · IU = International Units
Commonly Used Dosages
- general:
- 5-15 g/day
- ibsdsupport:
- 5 g three times daily (15 g/day total)
- postexercisegut:
- 0.25-0.9 g/kg before intense exercise
- gutbarriersupport:
- 0.5 g/kg/day (approximately 30-40 g/day for adults)
Upper limit: Generally well-tolerated up to 0.5 g/kg/day; caution above 40 g/day
Dosages Studied in Research
| Dosage | Duration | Effect | N |
|---|---|---|---|
| None | -- | Positive | -- |
| Bifidobacterium animalis subsp. lactis BB-12 and Lactiplantibacillus plantarum ATCC 14917 | 4 weeks | Positive | 25 |
| None | -- | Mixed | 62 |
| None | -- | Positive | -- |
| None | -- | Positive | -- |
| None | -- | Mixed | -- |
| None | -- | Mixed | -- |
| None | -- | Negative | 75 |
Best taken: Between meals or before exercise; divide doses throughout the day
Safety & Side Effects
Reported Side Effects
- ⚠ Mild gastrointestinal discomfort at high doses
- ⚠ Headache
- ⚠ Dizziness at very high doses
- ⚠ Potential glutamate excitotoxicity concerns in neurological conditions (theoretical)
Known Interactions
- ● Lactulose (glutamine may reduce the efficacy of lactulose for hepatic encephalopathy)
- ● Anti-seizure medications (glutamine converts to glutamate; theoretical concern)
- ● Chemotherapy agents (glutamine may protect cancer cells; discuss with oncologist)
Tolerable upper intake: Generally well-tolerated up to 0.5 g/kg/day; caution above 40 g/day
Always consult your healthcare provider before starting any supplement.
Frequently Asked Questions
Does L-Glutamine help with Irritable Bowel Syndrome (IBS)?
How much L-Glutamine should I take for Irritable Bowel Syndrome (IBS)?
Are there side effects of L-Glutamine?
How strong is the evidence for L-Glutamine and Irritable Bowel Syndrome (IBS)?
Related Evidence
Other ingredients for Irritable Bowel Syndrome (IBS)
L-Glutamine for other conditions
FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. The products and information on this website are not intended to diagnose, treat, cure, or prevent any disease. The evidence grades presented are based on our analysis of published peer-reviewed research and do not constitute medical advice. Always consult your healthcare provider before starting any supplement regimen.