L-Glutamine for Irritable Bowel Syndrome (IBS)
C Some Evidence Limited evidence from small studies, but some positive signals exist.Pilot RCTs suggest glutamine (5 g TID) reduces intestinal permeability and IBS-D symptoms in post-infectious IBS. Promising but needs larger trials.
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C
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
Other
Unraveling the active ingredients and molecular mechanisms of Qinghua Changyan granule against irritable bowel syndrome …
Dose: None
vs: None
Outcome: IBS-D symptom relief via gut microbiota and glutamine …
Effect: None
None
Population: animal model of IBS with diarrhea
Other
n=25
4 weeks
Effect of probiotic administration of Bifidobacterium animalis subsp. lactis BB-12 and Lactiplantibacillus plantarum ATCC 14917 …
Dose: Bifidobacterium animalis subsp. lactis BB-12 and Lactiplantibacillus plantarum ATCC 14917
vs: phosphate-buffered saline (PBS)
Outcome: visceral hypersensitivity (abdominal withdrawal reflex scores)
Effect: None
p<0.05
Population: female rats with water avoidance stress-induced IBS-D model
Other
n=62
[Study on activation mechanism of SGCs in representation along the distribution of stomach meridian in …
Dose: None
vs: Control group (no citrobacter)
Outcome: SGC activation in DRG segments
Effect: None
P<0.05 to P<0.01
Population: Male C57BL/6 mice (IBS-D model)
Review
Intestinal Barrier Impairment, Preservation, and Repair: An Update.
Dose: None
vs: None
Outcome: Intestinal barrier preservation and repair
Effect: None
None
Population: IBD and IBS patients (review)
Other
Multi-Omics Reveals the Effects of Cannabidiol on Gut Microbiota and Metabolic Phenotypes.
Dose: None
vs: None
Outcome: Cholesterol levels
Effect: None
None
Population: Mouse model
In Vitro
Effects of Glutamine, Curcumin and Fish Bioactive Peptides Alone or in Combination on Intestinal Permeability …
Dose: None
vs: None
Outcome: inflammation markers
Effect: None
None
Population: Mice
Key Statistics
2
Studies
150
Participants
↑
Positive
C
Grade
Referenced Papers
Fitoterapia
2026
1 citations
Journal of the …
2026
Zhongguo zhen jiu …
2025
Nutrients
2024
47 citations
Cannabis and cannabinoid …
2024
10 citations
International journal of …
2023
9 citations
Journal of gastroenterology
2022
23 citations
NeuroImage. Clinical
2022
8 citations
Digestion
2021
29 citations
Frontiers in nutrition
2021
17 citations
Medicine
2021
Nutrition research (New …
2020
42 citations
World journal of …
2020
11 citations
Gut
2019
148 citations
Metabolomics : Official …
2019
41 citations
Pain
2019
23 citations
Scientific reports
2019
14 citations
Gut
2019
5 citations
[Not Available].
RCT
Praxis
2018
Current opinion in …
2017
71 citations
JPEN. Journal of …
2016
44 citations
Gastroenterology
2015
17 citations
Frontline gastroenterology
2012
20 citations
The American journal …
2011
48 citations
Clinical nutrition (Edinburgh, …
2011
12 citations
MicroRNA-29a regulates intestinal membrane permeability in patients with irritable bowel syndrome.
Other
Gut
2010
263 citations
Clinics (Sao Paulo, …
2010
47 citations
Zhong xi yi …
2009
6 citations
Journal of clinical …
2008
73 citations
Nutrition in clinical …
2008
42 citations
Journal of proteome …
2006
80 citations
Medycyna wieku rozwojowego
2004
1 citations
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)?
Based on 2 studies with 150 participants, there is limited but promising evidence that L-Glutamine may support Irritable Bowel Syndrome (IBS) management. Our evidence grade is C (Some Evidence).
How much L-Glutamine should I take for Irritable Bowel Syndrome (IBS)?
Studies have used various dosages. A commonly studied range is 5-15 g/day. Always consult your healthcare provider before starting any supplement regimen.
Are there side effects of L-Glutamine?
Reported side effects may include Mild gastrointestinal discomfort at high doses, Headache, Dizziness at very high doses, Potential glutamate excitotoxicity concerns in neurological conditions (theoretical). Most side effects are mild and dose-dependent. Consult your doctor if you experience any adverse reactions.
How strong is the evidence for L-Glutamine and Irritable Bowel Syndrome (IBS)?
We rate the evidence as Grade C (Some Evidence). This rating is based on 2 peer-reviewed studies with 150 total participants. The overall direction of effect is positive.
Related Evidence
Other ingredients for Irritable Bowel Syndrome (IBS)
L-Glutamine for other conditions
References
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- [2] Nazila Dardmeh et al.. J Sci Food Agric. 2026. Effect of probiotic administration of Bifidobacterium animalis subsp. lactis BB-12 and Lactiplantibacillus plantarum ATCC 14917 on metabolic profiles in an … doi:10.1002/jsfa.70190 PubMed
- [3] Na Li et al.. Zhongguo Zhen Jiu. 2025. [Study on activation mechanism of SGCs in representation along the distribution of stomach meridian in IBS-D mice]. doi:10.13703/j.0255-2930.20241126-0001 PubMed
- [4] Ayah Matar et al.. Nutrients. 2024. Intestinal Barrier Impairment, Preservation, and Repair: An Update. doi:10.3390/nu16203494 PubMed
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- [27] Jean Robert Rapin et al.. Clinics (Sao Paulo). 2010. Possible links between intestinal permeability and food processing: A potential therapeutic niche for glutamine. doi:10.1590/S1807-59322010000600012 PubMed
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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.