We use essential cookies (authentication, your saved goals/stack) by default. With your permission we'll also enable privacy-respecting analytics (Vercel Web Analytics, anonymous load-time metrics) and error-replay diagnostics (Sentry — DOM snapshots only when an error fires) so we can fix bugs faster. Learn more
L-Glutamine
Primary fuel for intestinal and immune cells — becomes conditionally essential during stress, illness, or intense training.
What the evidence says
L-Glutamine appears to help in 3 of 3 studies with measurable effects — the evidence leans clearly favourable.
Most evidence is from high-quality meta-analyses and randomised trials published 1999–2025 with a typical study size of 46 participants.
Based on 16 studies · 2 meta-analyses · 7 RCTs · 3,072 total participants
Confidence
HighWhat the studies found
By outcome
See full supplement plans that include L-Glutamine.
L-Glutamine has an evidence score of 9/10 — very strong evidence based on 16 indexed studies, including 6 meta-analyses. Primary fuel for intestinal and immune cells — becomes conditionally essential during stress, illness, or intense training.
The commonly studied dose of L-Glutamine is 5-10g. Research points to an estimated optimal dose around 15g, with a minimum effective dose near 5g. Individual response varies — start low and adjust.
Timing is flexible for L-Glutamine — consistent daily use matters more than the time of day. L-glutamine is the most abundant amino acid in the body and serves as a primary fuel source for enterocytes (intestinal cells) and immune cells.
Colostrum
Mostly mechanism / observationalFirst milk rich in immunoglobulins, growth factors, and antimicrobial compounds that supports gut health, immunity, and recovery.
Arginine
Probably helpsPrimary substrate for nitric oxide production — dilates blood vessels to improve circulation, exercise performance, and cardiovascular health.
Last reviewed May 2026 · evidence from 40 studies · how we score
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
L-Glutamine is a conditionally essential amino acid that becomes crucial during stress, illness, or intense training. It's the primary fuel source for intestinal cells and immune cells. Supplementation is most beneficial during periods of high physical stress, gut issues, or immune challenges. Healthy individuals on adequate protein may not need it.
Primary energy source for gut cells
Fuels rapidly dividing immune cells
Carries nitrogen between tissues
How L-Glutamine works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
5-10g
Can be taken without food
| Form | Type |
|---|---|
| 🧪L-Glutamine powder | Recommended |
| 💊Capsules (but need many for effective dose) | Alternative |
Powder is most practical due to large doses needed. Tasteless and mixes easily.
Minimum: 2 weeks
Optimal: 4 weeks
Cycling: Not required
Note: Can be taken with or without food. For gut health, some prefer taking on empty stomach. Split doses may be easier on digestion.
Based on RCT showing reduced URTI incidence in combat athletes (n=21) and enhanced IgA levels. Limited sample size and specific population studied. Effect may be primarily in high-stress/training conditions.
Supports intestinal lining integrity
May reduce infection risk during heavy training
May reduce soreness after intense exercise
Likely safe at moderate doses; consult doctor
Consult oncologist; glutamine feeding of tumors is debated
May reduce lactulose effectiveness
May affect seizure control in some
Tip: Start with lower dose
Tip: Split doses throughout day
Glutamine supports gut lining while probiotics improve microbiome
Comprehensive gut health support
Both support gut barrier function
Enhanced intestinal integrity
Both support gut lining
Enhanced gut healing
Both support gut barrier integrity
Enhanced gut healing
Both support gut lining integrity
Enhanced gut healing
Slippery elm coats; glutamine feeds gut cells
Comprehensive gut repair
Both support gut barrier integrity
Enhanced gut healing and barrier repair
L-Glutamine is generally well-tolerated and considered safe for most healthy adults at recommended doses. The most commonly reported side effects are bloating, GI discomfort. Use caution if any of these apply to you: Liver disease (impaired glutamine metabolism); Reye's syndrome; Sensitivity to MSG (glutamine converts to glutamate).
NAC
Likely helpsRate-limiting precursor to glutathione, the body's master antioxidant — supports mood, respiratory health, and liver protection.
Tap node to isolate • Pinch to zoom • Tap edge for research