L-Glutamine
Also sold as: Glutamine · L-glutamine · Free-form glutamine
A conditionally essential amino acid used by intestinal and immune cells. Clinical benefits are specific to certain diseases and do not establish universal gut repair, muscle growth or anxiety treatment.
Anxiety
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Research
- Anxiety: No established anxiety benefit in this dossier. The automatic anxiety mapping came from sickle-cell pain crises, a distinct clinical outcome; this is unestablished evidence, not a negative anxiety RCT.
REALITY CHECK // Gut-barrier physiology is real, but a single selected postinfectious-IBS trial does not validate universal leaky-gut treatment. Glutamine did not add strength or lean mass in the cited training trial, while high-dose hospital supplementation increased mortality in metabolically unstable patients. Benefits in sickle-cell disease or combined short-bowel therapy belong to distinct supervised treatments.
Levels: how we grade evidence. Grey = evidence of no benefit; amber = evidence it makes this goal worse.
Ratings are self-reported by a self-selected group of users: how it felt, not proof that it works.
Check your bottle
Compare what your label says with what was used in trials. This is a trial range, not a personal prescription.
Enter the amount from your label to see the result.
How it was studied
UPPER LIMIT // No EFSA or NIH numerical UL is established in the dossier. Oral amounts around 20-30 g/day have been studied in selected adults with normal kidney/liver function, but this is not an official safe ceiling. Gastrointestinal tolerance and the clinical metabolic context matter.
Summary
The strongest gut signal is one trial in postinfectious IBS with documented increased permeability, not every person with bloating or IBS. Resistance-training gains and athlete infection prevention were not supported. Critical-illness trials show that route, dose and patient state can turn a seemingly ordinary amino acid into a harmful intervention.
Mechanism
Glutamine supplies nitrogen and fuel to enterocytes and other cells and participates in barrier-protein regulation. Conversion through glutaminase also produces ammonia; liver dysfunction changes that risk. Tumor glutamine dependence is mechanistic biology, not proof that an oral supplement accelerates a human tumor.
Typical studied dose
The postinfectious IBS trial used oral L-glutamine 5 g three times daily (15 g/day) for eight weeks. A small soreness trial used about 0.3 g/kg after eccentric exercise. The null resistance-training trial used 0.9 g/kg fat-free mass for six weeks. REDOXS used a different hospital regimen: 0.35 g/kg IV plus 30 g enteral, with a mortality signal; these routes and populations are not consumer dosing targets.
Upper limit
No EFSA or NIH numerical UL is established in the dossier. Oral amounts around 20-30 g/day have been studied in selected adults with normal kidney/liver function, but this is not an official safe ceiling. Gastrointestinal tolerance and the clinical metabolic context matter.
Popular stacks with L-Glutamine
Not enough stack data yet. A combination with L-Glutamine appears here once 5 people rate the same set.
Forms and label traps
| Form on label | Active content | Studied range / day | Absorption & GI tolerance | Verdict |
|---|---|---|---|---|
| Free L-glutamine powder Best for: Checking the total daily L-glutamine mass against the selected PI-IBS study, not a general gut-repair claim. |
Extract weight · ~100% marker | 15000–15000 mg | Absorbed from the small intestine with substantial first-pass use by the gut and liver. Generally tolerated around 10-15 g/day in the dossier; larger individual amounts may cause loose stools. |
Studied standard [REFERENCE // STUDIED_FORM] 100% describes pure amino-acid mass, not an elemental mineral fraction. The 15 g/day reference belongs only to the selected eight-week PI-IBS study. |
| Micronized / instant L-glutamine Best for: Readers comparing premium instant powder with the same free amino acid. |
Extract weight · ~100% marker | 15000–15000 mg | Particle size changes mixing convenience, not an established clinical absorption advantage. Similar to ordinary powder. |
Good option [FORM // CHECK_LABEL] The same-molecule trial reference is not a separate micronized-product efficacy trial; no superior outcomes have been established. |
| Alanyl-L-glutamine dipeptide Best for: Recognizing a different compound whose mass is not identical to free glutamine mass. |
Unstandardized: active content unknown | no comparable trial range | More soluble and stable than free glutamine; the practical advantage mainly concerns clinical parenteral nutrition. An oral HIV trial is distinct. Clinical context and route determine tolerance. |
Caution [CAUTION // CHECK_BASIS] The dossier lacks a usable oral trial interval and verified conversion fraction here. Do not compare the entire dipeptide mass directly with free L-glutamine or treat IV formulations as consumer supplements. |
| Prescription pharmaceutical L-glutamine for sickle-cell disease Best for: Distinguishing a studied medical treatment from an OTC muscle/gut claim. |
Unstandardized: active content unknown | no comparable trial range | The same amino acid with pharmaceutical quality controls and a disease-specific clinical context. High-dose supervised therapy; not a consumer comparison. |
Caution [CAUTION // CHECK_BASIS] No consumer target is calculated from a prescription indication. The trial supports sickle-cell outcomes, not anxiety or general performance. |
Common label traps
- TRAP_01 // Repairs every leaky gut
Permeability effects depend on disease and baseline barrier damage. The PI-IBS trial selected patients with increased permeability; it does not validate a stand-alone diagnosis for every healthy person with symptoms. - TRAP_02 // Builds muscle and prevents post-training colds
The training RCT found no added strength or lean mass. Restoring plasma glutamine after exercise did not establish fewer respiratory infections. - TRAP_03 // Harmless amino acid: more stress means more glutamine
REDOXS found increased six-month mortality with high-dose combined IV/enteral glutamine in multiorgan failure. This hospital finding cannot be converted into an OTC risk estimate, but refutes universal safety. - TRAP_04 // Peptide or instant powder works better orally
Dipeptide stability is a real formulation property, especially in IV nutrition. A superior consumer clinical outcome over ordinary oral powder is unproven.
Other outcomes studied
Outside the five leaderboard goals. Same evidence levels as above.
- GUT PERMEABILITY Limited · benefit
A heterogeneous clinical meta-analysis and a selected HIV alanyl-glutamine trial suggest permeability benefits, especially with baseline barrier damage. Normal-barrier healthy adults do not have an established clinical benefit.
PMID 39397201 PMID 23657308 PMID 27749689 PMID 24965526 - POSTINFECTIOUS IBS / SELECTED SUBGROUP Limited · benefit
In one single-center eight-week RCT using 5 g three times daily, an IBS severity-score reduction of at least 50 points occurred in about 80% versus about 6%. Participants had postinfectious IBS and increased permeability; multicenter replication is needed.
PMID 30108163 - CRITICAL ILLNESS / HIGH-DOSE HOSPITAL REGIMEN Strong · makes it worse
REDOXS enrolled 1,223 critically ill patients with multiorgan failure. Combined IV/enteral glutamine increased six-month mortality (43.7% versus 37.2%, p=0.02). This is not an OTC oral trial in healthy people.
PMID 23594003 - SEVERE BURNS / ENTERAL THERAPY Strong · no benefit
RE-ENERGIZE, with about 1,200 severe-burn patients, did not improve time to live discharge or mortality. Critical-care syntheses do not establish a general recovery benefit.
PMID 36082909 PMID 25199493 PMID 38041938 - STRENGTH / LEAN MASS Limited · no benefit
Young adults receiving 0.9 g/kg fat-free mass during six weeks of resistance training had no additional strength, lean-mass or protein-breakdown-marker benefit.
PMID 11822473 - ATHLETE INFECTION PREVENTION Limited · no benefit
Correcting postexercise plasma glutamine did not establish fewer upper-respiratory infections or reversal of exercise-related immune suppression. Combat-sport data remain mixed.
PMID 17136044 PMID 29511657 - SORENESS / STRENGTH RECOVERY Limited · benefit
A small eccentric-knee-exercise trial at about 0.3 g/kg found less soreness and faster strength recovery, more clearly in men. A leucine-plus-glutamine trial cannot isolate glutamine; this is not hypertrophy evidence.
PMID 25811544 PMID 29770871 - ONCOLOGY ORAL MUCOSITIS Limited · benefit
Several meta-analyses suggest less severe mucositis, but a head-and-neck radiotherapy synthesis found no clinical benefit. Treatment and tumor site affect results; use only within the oncology plan.
PMID 33605813 PMID 33598734 PMID 27045857 PMID 32363198 - SICKLE-CELL PAIN CRISES Moderate · benefit
A phase 3 trial in 230 patients reported a median of 3 versus 4 pain crises over 48 weeks, with fewer hospitalizations and substantial dropout. This disease-specific pharmaceutical treatment does not demonstrate anxiety relief.
PMID 30021096 PMID 31505045 PMID 39028356 - SHORT-BOWEL SYNDROME / COMBINATION THERAPY Limited · benefit
Growth hormone plus glutamine plus an optimized diet reduced parenteral-nutrition requirements in selected patients. Benefit was limited/transient in the Cochrane review, and glutamine cannot be separated from the combination.
PMID 16244538 PMID 20556765
Reader questions
Does glutamine fix IBS or leaky gut?
The most striking RCT selected postinfectious IBS with objectively increased permeability. At 15 g/day for eight weeks it found a large symptom signal, but one center and a narrow population limit generalization. Ordinary bloating does not establish that same condition.
Is an expensive peptide or instant form better?
Micronization helps mixing. Dipeptides are more soluble and stable, useful in clinical nutrition, but superior hard outcomes from an oral consumer product have not been demonstrated.
Can glutamine cause anxiety or insomnia?
These are repeated user reports, not proof that oral glutamine causes excess brain glutamate. Persistent new symptoms warrant stopping and clinical review, especially with seizure or psychiatric treatment.
Is it safe with cancer or liver disease?
Do not self-prescribe in these settings. Advanced liver disease changes ammonia handling; oncology use requires the treating team because supportive-care results and tumor biology are different questions.
Should it be added to hot coffee?
The dossier notes lower stability of free glutamine in hot solutions. Cool or lukewarm preparation and prompt consumption concern formulation stability, not proof that a hot drink is toxic.
Stack interactions
- Danger Cirrhosis, hepatic encephalopathy and ammonia-lowering treatment [CAUTION // CLINICAL_REVIEW]
Glutamine can increase ammonia load through its metabolism. This may conflict with the therapeutic goal in advanced liver disease; specialist supervision is necessary.
PMID 26195206 - Danger Cancer therapy / mucositis protocols [CAUTION // CLINICAL_REVIEW]
Some mucositis meta-analyses are favorable and others null. Tumor glutamine metabolism creates a mechanistic concern, but clinical tumor acceleration from oral glutamine has not been proved. The oncology team decides whether to use it.
PMID 33605813 PMID 32363198 PMID 20570523 - Caution Antiseizure medicines / glutamatergic stacks [CAUTION // CLINICAL_REVIEW]
Precaution based on glutamine-to-glutamate biology and user reports of agitation. No controlled interaction evidence in healthy supplement users establishes causation. - Caution Probiotics, fiber and gut-support stacks [CAUTION // CLINICAL_REVIEW]
No specific adverse pharmacological interaction is established here, but introducing many ingredients together obscures the cause of bloating or intolerance. The stack itself has not been validated by the glutamine trial.
Red flags: interactions and who should avoid it
Interactions
Cancer-treatment use, including mucositis support, belongs to the oncology team. Advanced liver disease and ammonia-lowering therapy require clinical review because glutamine metabolism can add ammonia. Seizure/antiseizure cautions and anxiety after stacking glutamatergic agents are theoretical or anecdotal, not proven controlled interactions.
Avoid or ask a doctor first if
Avoid unsupervised use with cirrhosis or hepatic encephalopathy, severe kidney impairment, critical illness or multiorgan failure, and active cancer treatment. Pregnancy, breastfeeding and nonclinical use in children lack safety data. New agitation, anxiety or insomnia warrants stopping and review; causation through glutamate has not been demonstrated in healthy users. Larger single amounts may cause gastrointestinal discomfort or loose stools.
Sources (PubMed, 25)
- A systematic review and meta-analysis of clinical trials on the effects of glutamine supplementation on gut permeability in adults.
PMID 39397201 · 2024 · systematic review / meta-analysisHeterogeneous clinical-trial synthesis on adult gut permeability; effects depend on baseline disease and barrier damage.
- Improvement of intestinal permeability with alanyl-glutamine in HIV patients: a randomized, double blinded, placebo-controlled clinical trial.
PMID 23657308 · 2013 · randomized controlled trialAlanyl-glutamine in HIV patients improved intestinal permeability in a selected clinical population.
- Glutamine and the regulation of intestinal permeability: from bench to bedside.
PMID 27749689 · 2017 · narrative reviewBench-to-bedside barrier-regulation mechanisms and clinical translation limits.
- Glutamine and intestinal barrier function.
PMID 24965526 · 2015 · narrative reviewReview of glutamine and intestinal barrier function; mechanism is not general healthy-user efficacy.
- Randomised placebo-controlled trial of dietary glutamine supplements for postinfectious irritable bowel syndrome.
PMID 30108163 · 2019 · randomized controlled trialSelected PI-IBS RCT: 5 g three times daily for eight weeks with a large symptom response, requiring replication.
- A randomized trial of glutamine and antioxidants in critically ill patients.
PMID 23594003 · 2013 · randomized controlled trialREDOXS: increased mortality with high-dose combined IV/enteral glutamine in multiorgan failure.
- A Randomized Trial of Enteral Glutamine for Treatment of Burn Injuries.
PMID 36082909 · 2022 · randomized controlled trialLarge severe-burn RCT: no improvement in time to live discharge or mortality.
- Glutamine supplementation for critically ill adults.
PMID 25199493 · 2014 · systematic review / meta-analysisCritical-care Cochrane review; no general survival-benefit assurance.
- Glutamine enteral therapy for critically ill adult patients: An updated meta-analysis of randomized controlled trials and trial sequential analysis.
PMID 38041938 · 2024 · systematic review / meta-analysisUpdated critical-care meta-analysis/trial-sequential analysis: no convincing overall clinical benefit.
- Effect of glutamine supplementation combined with resistance training in young adults.
PMID 11822473 · 2001 · randomized controlled trialSix-week resistance-training trial: no added lean-mass or strength benefit.
- Nutritional modulation of exercise-induced immunodepression in athletes: a systematic review and meta-analysis.
PMID 17136044 · 2007 · systematic review / meta-analysisAthlete immune review: restoring glutamine concentration did not establish infection prevention.
- Effect of rapid weight loss and glutamine supplementation on immunosuppression of combat athletes: a double-blind, placebo-controlled study.
PMID 29511657 · 2018 · randomized controlled trialCombat-athlete rapid-weight-loss study; does not establish a robust clinical infection-prevention effect.
- The Influence of Oral L-Glutamine Supplementation on Muscle Strength Recovery and Soreness Following Unilateral Knee Extension Eccentric Exercise.
PMID 25811544 · 2015 · randomized controlled trialSmall eccentric-exercise RCT: soreness/strength-recovery signal, about 0.3 g/kg.
- The effects of acute leucine or leucine-glutamine co-ingestion on recovery from eccentrically biased exercise.
PMID 29770871 · 2018 · randomized controlled trialLeucine-glutamine combination recovery study; attribution to glutamine alone is limited.
- Role of Glutamine in the Management of Oral Mucositis in Patients with Cancer: A Meta-Analysis of Randomized Controlled Trials.
PMID 33605813 · 2022 · systematic review / meta-analysisCancer mucositis meta-analysis with favorable signals that require treatment-specific interpretation.
- Effectiveness of glutamine in the management of oral mucositis in cancer patients: a meta-analysis of randomized controlled trials.
PMID 33598734 · 2021 · systematic review / meta-analysisMucositis meta-analysis: selected cancer supportive-care signal.
- Glutamine in Alleviation of Radiation-Induced Severe Oral Mucositis: A Meta-Analysis.
PMID 27045857 · 2016 · systematic review / meta-analysisSevere radiation-induced mucositis synthesis with favorable signal.
- Oral Glutamine May Have No Clinical Benefits to Prevent Radiation-Induced Oral Mucositis in Adult Patients With Head and Neck Cancer: A Meta-Analysis of Randomized Controlled Trials.
PMID 32363198 · 2020 · systematic review / meta-analysisConflicting head-and-neck radiotherapy synthesis: no clinical benefit.
- A Phase 3 Trial of l-Glutamine in Sickle Cell Disease.
PMID 30021096 · 2018 · randomized controlled trialPhase 3 sickle-cell trial: fewer pain crises and hospitalizations in a disease-specific treatment context.
- Systematic Review of l-glutamine for Prevention of Vaso-occlusive Pain Crisis in Patients with Sickle Cell Disease.
PMID 31505045 · 2019 · systematic review / meta-analysisSickle-cell crisis-prevention systematic review; moderate, indication-specific evidence.
- Safety and efficacy of L-Glutamine in reducing the frequency of acute complications among patients with sickle cell disease: A randomized controlled study.
PMID 39028356 · 2024 · randomized controlled trialFurther randomized sickle-cell complication evidence in the supplied dossier.
- Growth hormone, glutamine, and an optimal diet reduces parenteral nutrition in patients with short bowel syndrome: a prospective, randomized, placebo-controlled, double-blind clinical trial.
PMID 16244538 · 2005 · randomized controlled trialCombined growth hormone, glutamine and optimized diet in short-bowel syndrome; cannot isolate glutamine.
- Human growth hormone and glutamine for patients with short bowel syndrome.
PMID 20556765 · 2010 · systematic review / meta-analysisCochrane short-bowel review: limited/transient combination-therapy evidence.
- Glutamine addiction: a new therapeutic target in cancer.
PMID 20570523 · 2010 · narrative reviewReview of tumor glutamine dependence; mechanistic concern, not proof of tumor growth from oral supplementation.
- Ammonia and Its Role in the Pathogenesis of Hepatic Encephalopathy.
PMID 26195206 · 2015 · narrative reviewAmmonia biology in hepatic encephalopathy supports liver-disease caution.
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