✓ No active regulatory warningsFDA MedWatch, EMA EudraVigilance, WHO VigiBase, WADA Prohibited List · 2026-05-29
📰Read the full L-Glutamine evidence review on GMJ News →Complete clinical article, references and updates on news.gmj.ge. This page is the structured safety summary.⚠ ICU patient with multi-organ failure — high-dose glutamine INCREASED mortality (REDOXS) [3]
⚠ Hepatic encephalopathy patient — glutamine → glutamate → ammonia worsens HE [1]
⚠ Sickle cell disease — Endari (L-glutamine) is FDA-approved [2]
⚠ Post-marathon athlete with recurrent URIs — glutamine may reduce infection risk [2]
ℹ️ Not obtained from food. Obtained as part of dietary protein rather than tracked individually toward a daily target.
🔬 Lab interpreter
Recommended test
No routine monitoring for oral supplementation
No routine monitoring for oral supplementation
Reference range / target
N/A
N/A
In ICU: plasma glutamine (low <420 µmol/L correlates with mortality) [3].
Full lab monitoring ↓⚕ For professionals — confirm ranges against your local laboratory.
Clinical verdict
Glutamine is the most abundant amino acid and primary fuel for gut and immune cells. CRITICAL: REDOXS trial showed high-dose IV glutamine INCREASED mortality in multi-organ failure — do NOT give to patients with renal/hepatic failure. Oral 5–10 g/day for gut health is reasonable. FDA-approved (Endari) for sickle cell disease. The 'leaky gut' marketing exceeds the evidence [1] [2] [3].
1 How much do I need?
👤 Adults: Specific dosage data under clinical review
👴 Elderly: Specific dosage data under clinical review
🤰 Pregnancy: See guidance
Normal body constituent. No supplementation data. Dietary intake safe [1].
👦 Pediatric: See guidance
Used in pediatric critical care. FDA-approved (Endari) for sickle cell disease in children ≥5 years [2].
🏃 Athletes: Standard dose
⚖️ Obesity: Standard dose
Fat-soluble compounds may require dose adjustment in obesity.
🩺 Renal: Consult specialist
Dose adjustment may be needed in renal impairment.
🌱 Vegan: Standard dose
How to take
🍽 Timing: Any time. Can be split across meals [1].
💊 With food: Dissolves in water/beverages. Unflavored [1].
2 Which form?
| Form | Bioavailability | Vegan | Cost |
|---|---|---|---|
| ['L-Glutamine powder', 'common', 'Pure amino acid. Unflavored. Dissolves in water. 5–30 g/day [1].'] | Standard | Check label | |
| ['L-Glutamine capsules', '', '500–1,000 mg per capsule (need many for therapeutic dose) [1].'] | Standard | Check label | |
| ['Alanyl-glutamine (Sustamine)', 'preferred', 'Dipeptide form. More stable and better absorbed than free glutamine [2].'] | Standard | Check label |
3 Common questions
Does glutamine heal leaky gut? ▼
Glutamine is the primary fuel for enterocytes and supports tight junction integrity — this is established biology [2]. Some studies show reduced intestinal permeability markers. However, 'leaky gut syndrome' as a clinical diagnosis is controversial, and high-quality trials of glutamine for IBS or non-specific GI symptoms are lacking.
Why was the REDOXS trial concerning? ▼
REDOXS showed that high-dose glutamine (IV + enteral, ~40 g/day) INCREASED mortality in ICU patients with multi-organ failure [3]. The mechanism likely involves glutamine → glutamate → ammonia conversion overwhelming failing kidneys/liver. This doesn't apply to oral supplementation in otherwise healthy individuals.
Is glutamine good for athletes? ▼
Intense exercise depletes plasma glutamine by 20–40%. Some evidence supports reduced URI incidence post-marathon with glutamine supplementation [2]. For muscle recovery, the evidence is weaker — BCAAs and protein may be more effective.
What is Endari? ▼
Endari is FDA-approved L-glutamine (pharmaceutical grade) for sickle cell disease — the only FDA-approved amino acid supplement for a specific disease. It reduces acute vaso-occlusive crises [2].
4 Clinical evidence
Strong
Primary fuel for enterocytes and lymphocytes — well-established biochemistry [2]. REDOXS trial (n=1,223): high-dose IV glutamine in multi-organ failure INCREASED 28-day mortality (OR 1.09 per 0.1 g/kg increase). Critical safety finding [3]. Conditionally essential in critical illness, burns, trauma [1]. HIGH
Moderate
Gut barrier integrity: glutamine supports tight junctions and reduces intestinal permeability in some trials [2]. Exercise-induced immune suppression: some evidence that glutamine reduces URI incidence after intense exercise [2]. Sickle cell disease: 0.3 g/kg BID (Endari/L-glutamine) is FDA-approved for reducing acute complications [2]. Mucositis (chemo-induced): some positive trials for oral mucositis prevention [2]. MODERATE
Insufficient
5 Safety, toxicity & adverse events
Absolute contraindications
✕ Hepatic encephalopathy — glutamine → glutamate → ammonia; worsens hyperammonemia in liver failure
Relative
⚠ Reye syndrome
⚠ Concurrent anti-epileptics — glutamine converts to glutamate (excitatory); theoretical concern
⚠ Cancer — some tumors are glutamine-dependent ("glutamine addiction"); discuss with oncologist
🚩 Red flags
● ICU patient with organ failure — do NOT give high-dose glutamine (REDOXS) [3]
● Hepatic encephalopathy patient on lactulose + glutamine — counterproductive [1]
6 Interactions
Drug interactions
Lactulose (hepatic encephalopathy) Major
Mechanism: Glutamine is metabolized to glutamate then ammonia. In hepatic failure, ammonia cannot be cleared. [1]
Effect: May worsen hepatic encephalopathy. [1]
Action: Avoid glutamine in hepatic encephalopathy [1].
Supplement synergies
Zinc · 15–30 mg zinc
Both support gut barrier integrity. Complementary mechanisms [2].
Both support gut barrier integrity. Complementary mechanisms [2].
NAC + Glycine · 600 mg NAC + 1–3 g glycine
Glutamine + cysteine (NAC) + glycine = complete glutathione precursor set [2].
Glutamine + cysteine (NAC) + glycine = complete glutathione precursor set [2].
7 Regulatory
United States (FDA): GRAS. Endari (L-glutamine): FDA-approved for sickle cell disease (2017) [2].
European Union: Food supplement [1].
South Korea: Dietary supplement.
8 US supplement products
13
on-market products containing L-Glutamine (NIH DSLD)
Brands carrying L-Glutamine (4)
Click a brand to see its L-Glutamine products.
9 Frequently paired with
10 Cite this page
Vancouver: Pkhakadze G. L-Glutamine — safety profile [Internet]. Tbilisi: PHIG; 2026 [cited 2026 Aug 15]. Available from: https://supplement.ge/ingredients/l-glutamine/
APA 7th: Pkhakadze, G. (2026). L-Glutamine — Safety profile. Public Health Institute of Georgia. https://supplement.ge/ingredients/l-glutamine/
📋 Editorial information
Author: Prof. G. Pkhakadze, MD, MPH, PhD
Institution: Public Health Institute of Georgia (PHIG)
Affiliation: David Tvildiani Medical University (DTMU)
First published: January 2026
Last reviewed: 2026-05-29
Next review: February 2027
References: 3 cited sources
COI: SupplementIndex receives no funding from supplement manufacturers. All content independently authored by PHIG.
Process: Systematic literature review
📄 License & reuse
Published under Creative Commons Attribution 4.0 International (CC BY 4.0). You may share and adapt for any purpose with attribution.
Pkhakadze G. "L-Glutamine — Safety Profile." SupplementIndex, PHIG, 2026. https://supplement.ge/ingredients/l-glutamine/ CC BY 4.0.
GP
Prof. G. Pkhakadze, MD, MPH, PhD
Professor of Public Health · Head of Department, DTMU
Editor-in-Chief, Georgian Medical Journal (ISSN 3088-4322)
Chair, Public Health Institute of Georgia · UEMS Public Health Section
Educational and public health purposes. CC BY 4.0. Consult your healthcare provider before starting any supplement. Corrections: info@accreditation.ge. Publisher: PHIG