L-Glutamine for Gut Barrier Integrity
Glutamine plausibly supports intestinal barrier function, with best evidence in critical illness and specific IBS subgroups.
Overview
Verdict
How It Works
Dosing & Protocol
Typical dose
- Recommended dose
- 5 g glutamine powder three to six times daily (15-30 g/day) dissolved in water, taken between meals, for 4-8 weeks
- Expected timeframe
- 4-8 weeks
Protocol
- form
- L-glutamine powder, which is cheaper and easier to dose than capsules at these quantities
- duration
- 4-8 weeks, then reassess
- co factor
- Take between meals, dissolved in water, not with hot liquids which degrade it. Evidence is mixed. Glutamine is the primary fuel for enterocytes and its supply becomes limiting in catabolic states, and this is where the evidence is strongest: in critical illness, burns, chemotherapy-induced mucositis and short bowel syndrome, glutamine has reduced markers of intestinal permeability and improved mucosal outcomes in several trials. There is also a positive randomised trial in post-infectious IBS with increased permeability, where 15 g/day reduced symptoms and normalised permeability. In healthy people or those without demonstrated barrier dysfunction, evidence of benefit is absent, and the popular leaky gut framing outruns the data considerably.
- titration
- Increase by 5 g every few days to 15-30 g/day in divided doses as tolerated; reduce if bloating or nausea occurs
- starting dose
- 5 g dissolved in water twice daily between meals
Evidence
What the studies say
Randomised clinical trial: oral glutamine reduces intestinal permeability and IBS symptoms in postinfectious IBS with diarrhoea
Zhou Q, Verne ML, Fields JZ +4 more
Oral dietary glutamine supplements dramatically reduced all major IBS-related endpoints in patients with IBS-D and increased intestinal permeability.
Glutamine supplementation and exercise-induced immune and gut permeability changes: a systematic review
Ramezani Ahmadi A, Rayyani E, Bahreini M +1 more
Glutamine supplementation attenuated exercise-induced increases in intestinal permeability, while effects on immune outcomes were inconsistent.
Safety
Caveats
Persistent gut symptoms need a diagnosis before a supplement: coeliac disease, inflammatory bowel disease, bile acid diarrhoea, pancreatic insufficiency and microscopic colitis are all treatable and commonly missed. Blood in the stool, weight loss, nocturnal symptoms, anaemia or a change in habit after 50 warrant urgent assessment. Safety ceiling: glutamine is contraindicated in hepatic encephalopathy and should be avoided in cirrhosis or significant liver disease, because its metabolism generates ammonia - this is the most important limit. Use caution in renal impairment, where nitrogen load matters. Avoid without medical advice if you have a seizure disorder, given theoretical glutamate-related effects, and note that glutamine may interact with anticonvulsants. Trials have used up to 30 g/day safely for weeks, but long-term safety at high doses is not established. No safety data in pregnancy or breastfeeding - avoid in both. Avoid in active cancer without oncology advice, since tumour cells also consume glutamine.
Less likely to help if
Medical Disclaimer
The information provided on this website is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any supplement regimen.
Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.