L-Glutamine
Also known as: Glutamine
Conditionally essential amino acid acting as primary fuel for enterocytes/lymphocytes, nitrogen carrier, and substrate for glutathione synthesis.
Last reviewed: 2026-06-23 · 1 indexed study
Set your location for accurate regulatory status
Saved on this device — no sign-in needed.
Overview
L-Glutamine is the most abundant free amino acid in plasma and muscle, serving as fuel for enterocytes and lymphocytes; supplementation supports gut barrier integrity especially during heavy training or GI stress.
Mechanism & Function
Mechanism of Action
Maintains intestinal tight junctions, supplies enterocytes, supports immune cell function during glutamine demand peaks (sepsis, heavy training, illness).
Physiological Role
Useful for endurance athletes with leaky gut symptoms and during heavy training blocks; ergogenic effects on hypertrophy in healthy trained athletes are weak.
Primary Pathways
Performance / Health Relevance
Strongest evidence is for gut barrier and clinical malnutrition; weaker for ergogenics in trained athletes; useful in immune-stressed contexts.
Evidence Review
Practical Use & Dosage
- Minimum Effective Dose
- 5 g/day
- Optimal Range
- 10–20 g/day in divided doses
- Upper / Caution Level
- ~30 g/day short-term
- Timing
- With meals, post-workout, or pre-bed
- Best Format
- Powder, capsule
- Bioavailability
- ~80% absorbed; first-pass gut utilisation reduces systemic availability.
- Absorption Considerations
- Active intestinal transport; high enterocyte first-pass utilisation.
Safety & Interactions
Side Effects
- •Mild GI upset
- •Bloating at high doses
Contraindications
- Severe hepatic encephalopathy
Drug Interactions
- •Anti-seizure medications (theoretical)
Who Should Avoid
- •Cirrhosis with ammonia issues
Monitoring
None routine.
Frequently Asked Questions
Auto-generated from indexed evidence — dosage, safety, interactions, and more.
When is L-Glutamine typically used or indicated?
L-Glutamine is most commonly used for: Gut barrier support, Recovery, Immune support, Post-exercise. Useful for endurance athletes with leaky gut symptoms and during heavy training blocks; ergogenic effects on hypertrophy in healthy trained athletes are weak.
How does L-Glutamine work?
Maintains intestinal tight junctions, supplies enterocytes, supports immune cell function during glutamine demand peaks (sepsis, heavy training, illness).
What is the recommended dose of L-Glutamine?
The optimal range is 10–20 g/day in divided doses. with a minimum effective dose of 5 g/day. Best taken: With meals, post-workout, or pre-bed. Upper / caution level: ~30 g/day short-term.
What are the side effects of L-Glutamine?
Reported side effects include: Mild GI upset; and Bloating at high doses. Monitoring: None routine.
Does L-Glutamine interact with medications?
Known or theoretical interactions: Anti-seizure medications (theoretical). Always check with a clinician before combining with prescription medication.
Who should avoid L-Glutamine?
L-Glutamine is generally not recommended for: Cirrhosis with ammonia issues; and Severe hepatic encephalopathy.
How strong is the evidence for L-Glutamine?
Evidence level: Moderate (overall score 62/100), based on 1 indexed study on SuppIndex.
Research & References (1)
Glutamine supplementation for intestinal barrier function: systematic review
Glutamine reduced intestinal permeability in athletes and clinical populations.
Related Ingredients
Other top-rated ingredients in Amino Acids.
L-Leucine
82/100Essential BCAA that activates mTORC1 via Sestrin2 sensing, driving phosphorylation of S6K1 and 4E-BP1, initiating cap-dependent translation and muscle protein synthesis.
Beta-Alanine
78/100A rate-limiting precursor to carnosine (β-alanyl-L-histidine) synthesis, enhancing intramuscular pH buffering capacity during high-intensity anaerobic exercise.
EAA Blend
78/100Free-form blend of 9 EAAs (Leu, Ile, Val, Lys, Met, Phe, Thr, Trp, His) at evidence-based ratios; bypasses gastric digestion for rapid plasma aminoacidaemia.
Research Overview
Moderate EvidenceCite this ingredient
One-click citation export in APA, MLA, Chicago, BibTeX, or HTML. The URL below is stable and safe to link.
Stable URL
https://thesuppindex.com/ingredients/l-glutamine
SuppIndex. (2026). L-Glutamine: Evidence summary, dosage and clinical studies. Retrieved October 16, 2026, from https://thesuppindex.com/ingredients/l-glutamine
Based on 1 indexed studies · Evidence level: Moderate.
Goal Ratings
Stack Compatibility
Pair with probiotics, glycine, zinc carnosine for gut support.