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L-Glutamine
Most abundant free amino acid in plasma and skeletal muscle; conditionally essential during catabolic stress.
Aliases (6)
Overview
What is L-Glutamine?
L-glutamine is the most abundant free amino acid in the body, conditionally essential during illness and stress. Sold as a supplement for gut health, immune support, and recovery.
Key Benefits
Supports gut mucosal integrity (primary fuel for enterocytes), immune cell function during illness or heavy training, and may aid recovery from intense exercise or critical illness. Modest evidence for IBS/leaky gut symptoms.
Mechanism of Action
Primary fuel for rapidly dividing cells (enterocytes, lymphocytes), substrate for glutathione synthesis, and nitrogen carrier for amino acid metabolism. Replenishes depleted plasma glutamine in catabolic states.
Pharmacokinetics
▸ Mixing & scoop math Powder
- • Mix into 8-16 oz cold water (or sports drink / protein shake). Most powders dissolve in < 30 sec with a brisk stir.
- • If using a shaker, add liquid first, then powder, then shake — minimizes foam and clumps.
- • Hot water is fine for most amino acids and creatine; avoid for heat-sensitive compounds (NAC degrades above ~60 °C).
- • Drink within 5-10 min of mixing — most powders are stable in solution but taste degrades.
Peptide Interactions
Both contribute to glutathione synthesis (NAC = cysteine donor; glutamine = glutamate donor; glycine = the third amino acid in GSH). NAC is rate-limiting; gl…
Both are gut-barrier supportive amino acids and both feed into GSH synthesis. Glycine has additional sleep, collagen, and methylation roles. Stack-safe; comm…
Both osmolyte / cell-volume / mitochondrial-support amino acids. Both daily-safe. Stack-safe. Dylan's V4 stack already includes taurine; glutamine slots in c…
Mitochondrial energy support; ALCAR provides acetyl + carnitine for fatty-acid oxidation; glutamine provides anaplerotic alpha-ketoglutarate to refill TCA in…
Both are intracellular osmolytes; both are cheap, daily-safe, well-characterized. The community-data block shows creatine as the most-combined-with substance…
Standard "gut healing" stack. Glutamine is the foundational amino acid in this protocol; the others are complementary mucosal protectants.
Glutamine is technically not in BCAA (leucine, isoleucine, valine), but is included in some "fermented EAA" formulas. No antagonism. Stack-safe. If Dylan is …
All anti-inflammatory adjuncts; stack-safe; no antagonism.
Glutamine is used clinically for chemo-mucositis with mortality benefit in some trials. The simultaneous theoretical concern about feeding glutamine-addicted…
No documented direct interaction, but in seizure-prone or psychiatrically unstable individuals the glutamate-precursor mechanism is a theoretical concern. Co…
Avoid — ammonia load via impaired urea cycle.
Theoretical pharmacological antagonism. Avoid co-administration.
Quality Indicators
Single-ingredient, COA-backed
Look for single-ingredient powders from vendors who publish a Certificate of Analysis.
Mixes cleanly
Should dissolve or suspend cleanly in water without large clumps once stirred.
Off taste or smell
Strong rancid, fishy, or chemical odors can indicate oxidation or contamination.
Color or texture change over time
A powder that yellows, clumps, or hardens over time may be hygroscopic and degraded.
What to Expect
- First doseFor stim-class powders: acute effect within 30-60 min.
- Week 1-2For volumizers (creatine, betaine): muscle fullness builds.
- Week 2-4Performance gains plateau into a new baseline.
- OngoingMaintenance dose continuous; cycle off only if specific indication.
Side Effects & Safety
- Common (>10%): None reliably. Most users report nothing. dopamine.club has digestive-upset (17), anxiety (15), insomnia (15) as top reported side effects — likely baseline noise across the report set.
- Less common (1–10%):
- Mild GI discomfort, bloating, gas at single doses >10 g, especially empty stomach. Resolves with smaller doses or food.
- Headache / mild restlessness in a small fraction; speculative mechanism via glutamate elevation; resolves on stopping.
- Rare-serious (<1%):
- Theoretical cancer risk. Tumor glutaminolysis confirmed in 2025 Nan review (PMID 39856712); CB-839 in Phase 1b/2. The review warns against supplementation in advanced/metastatic disease while noting potential post-curative use for side-effect mitigation. Healthy adults: no human evidence of increased cancer incidence with chronic supplementation. File but not contraindication.
- Hepatic encephalopathy / cirrhosis. Avoid — impaired urea cycle → ammonia load.
- Bipolar / seizure disorders (theoretical). Marginal CNS glutamate elevation; flag for those populations.
- REDOXS 2013 mortality signal. Parenteral MOF context only; explains clinical caution at megadoses.
- MSG-sensitive individuals. Anecdotal cross-reaction reports; not in controlled trials.
- Specific watch periods: None standard at 5 g/day. At 15–21 g/day: GI tolerance week 1, reassess at week 4.
Upper safe intake: Shao & Hathcock 2008 Observed Safe Level 14 g/day; up to 40 g/day tolerated in research with no harm signal. Highest tested chronic dose: 40 g/day for several weeks (well-tolerated). Practical ceiling: 10 g daily-driver, 20–30 g for clinical windows.
Drug-testing: Not on WADA Prohibited List. Permitted across all tested categories. No false-positive risk on standard tox screens.
References
Cruzat et al. 2018 — Glutamine: Metabolism and Immune Function, Supplementation and Clinical Translation (Nutrients), PMID 30360490
comprehensive review of mechanism, immune function, and clinical use
View StudyNewsholme 2001 — Why is L-glutamine metabolism important to cells of the immune system? (J Nutr), PMID 11533293
foundational immune metabolism paper
View StudyAchamrah et al. 2017 — Glutamine and the regulation of intestinal permeability (Curr Opin Clin Nutr Metab Care), PMID 27749689
gut permeability mechanism review
View StudyWang et al. 2015 — Glutamine and intestinal barrier function (Amino Acids), PMID 25618482
gut barrier review
View StudyLu et al. 2024 — Supplementation of L-glutamine enhanced mucosal immunity and improved hormonal status of combat-sport athletes (J Int Soc Sports Nutr), PMID 38193521
direct combat-sport RCT, 21 g/day × 3 weeks; the most archetype-relevant trial
View StudyCastell et al. 1996 — Does glutamine have a role in reducing infections in athletes? (Eur J Appl Physiol), PMID 8954294
original athlete-immunity evidence
View StudyCastell & Newsholme 1997 — The effects of oral glutamine supplementation on athletes after prolonged, exhaustive exercise (Nutrition), PMID 9263285
followup on URTI reduction
View StudyCandow et al. 2001 — Effect of glutamine supplementation combined with resistance training in young adults (Eur J Appl Physiol), PMID 11822473
foundational null on strength + hypertrophy
View StudyLegault et al. 2015 — Influence of Oral L-Glutamine on Muscle Strength Recovery + Soreness (Int J Sport Nutr Exerc Metab), PMID 25811544
modest recovery + soreness signal post-eccentric exercise (note: original prompt PMID 25811346 was a typo for 25811544)
View StudyBowtell et al. 1999 — Effect of oral glutamine on whole body carbohydrate storage during recovery from exhaustive exercise (J Appl Physiol), PMID 10484584
glycogen resynthesis evidence
View StudyRamezani Ahmadi et al. 2019 — Glutamine supplementation on athletic performance, body composition, and immune function: systematic review + meta-analysis (Clin Nutr), PMID 29784526
pooled null on performance + body composition
View StudyCordova-Martinez et al. 2021 — Effect of glutamine supplementation on muscular damage biomarkers in professional basketball players (Nutrients), PMID 34204359
null on muscle damage markers
View StudyCoqueiro et al. 2019 — Glutamine as an anti-fatigue amino acid in sports nutrition (Nutrients)
modern athletic-recovery review
View StudyDjordjevic et al. 2026 — Glutamine Supplementation and Exercise: A Narrative Review of Biochemical Mechanisms and Timing Strategies (Medicina), PMID 41752728
most recent timing-strategies review
View StudyAbbasi et al. 2024 — Systematic review and meta-analysis of glutamine supplementation on gut permeability in adults (Amino Acids), PMID 39397201
pooled null overall; signal only at >30 g/day or <2 weeks
View StudyZhou et al. 2019 — Randomised placebo-controlled trial of dietary glutamine supplements for postinfectious irritable bowel syndrome (Gut), PMID 30108163
landmark positive RCT in PI-IBS-D, 15 g/day × 8 weeks
View Studyvan der Hulst et al. 1993 — Glutamine and the preservation of gut integrity (Lancet), PMID 8098788
foundational gut-integrity TPN RCT
View StudyHeyland et al. 2013 — REDOXS trial: Glutamine and antioxidants in critically ill patients (NEJM)
the parenteral mortality signal
View StudyLiang et al. 2024 — Glutamine enteral therapy for critically ill adult patients: updated meta-analysis (Clin Nutr), PMID 38041938
current consensus retiring the routine-ICU recommendation
View Studyvan Zanten et al. 2014 — Enteral Glutamine Supplementation in Critically Ill Patients (Crit Care), PMID 25539571
enteral vs parenteral distinction
View StudyTao et al. 2014 — Glutamine for chemotherapy-induced oral mucositis meta-analysis, PMID 24433618
chemo-mucositis evidence
View StudyCochrane 2017 — Glutamine supplementation for critically ill adults
Cochrane systematic review (now superseded by Liang 2024)
View StudyNan et al. 2025 — Glutamine and cancer: metabolism, immune microenvironment, and therapeutic targets (Cell Commun Signal), PMID 39856712
current oncology synthesis with explicit supplementation guidance
View StudyShao & Hathcock 2008 — Risk assessment for taurine, glutamine, arginine, PMID 18325648
safety / upper-intake review
View StudyExamine.com — Glutamine reference
practical reference with summary of clinical evidence
View StudyLatest research
- reviewGlutamine supplementation and exercise — biochemical mechanisms and timing strategies (narrative review)Reaffirms multi-pathway mechanisms (GSH, mTOR, intestinal barrier, anaplerosis) and notes preclinical preference for post-exercise dosing; concedes that human-side timing evidence is still insufficient to define an optimal protocol.
- reviewGlutamine and cancer — metabolism, immune microenvironment, and therapeutic targetsConfirms the glutaminolysis-addicted phenotype of many tumors; explicitly cautions against supplementation in advanced/metastatic cancer but suggests post-curative early-stage use may reduce treatment side effects. Adds nuance to the cancer paradox without changing the healthy-adult risk picture.
- metaSystematic review and meta-analysis of glutamine supplementation on gut permeability in adultsAcross 10 RCTs (n=352), pooled effect on gut permeability was null overall; subgroup signal only emerged at doses >30 g/day or in courses <2 weeks. Recreational 5g protocols sit below the threshold where the meta-analysis sees a signal.
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