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L-Glutamine

supporting gut health and immune function

amino_acid
Evidence · Grade BSafety · Generally safe
Meta-analysis availableHuman trial evidenceTraditional useInteraction risk

Amino acid that supports intestinal barrier integrity; studied for post-infectious IBS-D.

L-Glutamine is an amino acid, a building block of protein, and the most abundant free amino acid in the human body. It plays a crucial role in various physiological processes, including immune function, gut health, and muscle repair. While the body can produce L-Glutamine, supplementation is sometimes considered, particularly during periods of stress, illness, or intense physical activity, when the body's demand for glutamine may exceed its production. It is often marketed for its potential to support gastrointestinal integrity and immune system function.

Quick answer

What it is: L-Glutamine is an amino acid, a building block of protein, and the most abundant free amino acid in the human body.

May support:Crohn's Disease, Leaky Gut, Irritable Bowel Syndrome, Leaky Gut Syndrome, Gastritis, Psoriasis, GERD, Ulcerative Colitis, Cancer (Adjunctive Support), Inflammatory Bowel Disease, SIBO

Evidence:Evidence · Grade B

Safety:Safety · Generally safe

Evidence Summary

Evidence · Grade B

There is a general understanding of L-Glutamine's physiological roles based on biochemical and cellular studies. However, for specific health claims, especially regarding its efficacy in treating conditions like Irritable Bowel Syndrome, the current evidence base from human clinical trials is limited or mixed. More robust, well-designed studies are needed to establish definitive therapeutic benefits.

Last reviewed · Jun 2026

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Why It Works

L-Glutamine serves as a primary fuel source for intestinal cells and immune cells, supporting their function and integrity.

How it works in more detail

L-Glutamine is a conditionally essential amino acid that plays a critical role in maintaining the integrity of the intestinal barrier. It is a preferred metabolic fuel for enterocytes (cells lining the small intestine) and colonocytes, supporting their proliferation and function. This helps to maintain tight junctions between intestinal cells, which are crucial for preventing the leakage of undigested food particles and toxins into the bloodstream. Additionally, L-Glutamine is a precursor for glutathione, a powerful antioxidant, and is involved in nucleotide synthesis, which is essential for cell growth and repair. It also supports immune cell function, including lymphocytes and macrophages, by providing energy and influencing cytokine production.

How to use

Always consult a qualified clinician.

Editorial guidance

Suggested dosage
Commonly, consumer dosages range from 500 mg to 10 grams per day, often divided into multiple doses, typically in powder or capsule form. Specific dosages may vary based on individual needs and health goals.
Research dosage range
In studies, dosages have varied widely, from a few grams up to 30 grams per day, depending on the condition being investigated.
Typical onset
Effects may vary, with some individuals reporting improvements in gut comfort or exercise recovery within days to weeks of consistent use.
Typical forms
capsule, powder
Quality markers
Look for products that are third-party tested for purity and potency, free from unnecessary fillers, artificial colors, and sweeteners. Reputable brands often provide certificates of analysis.
Medication interactions
  • Chemotherapy drugs (consult physician)
  • Lactulose (may reduce effectiveness)
Avoid if
  • Severe liver disease
  • Kidney disease
  • Reye's syndrome
  • Monosodium glutamate (MSG) sensitivity (due to metabolic conversion)

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Suggested dosage

Commonly, consumer dosages range from 500 mg to 10 grams per day, often divided into multiple doses, typically in powder or capsule form. Specific dosages may vary based on individual needs and health goals.

General guidance — discuss specifics with a clinician.

Active medicinal compounds

L-Glutamine (an amino acid)

Traditional use

As an amino acid, L-Glutamine itself does not have a history of traditional use as a distinct herbal remedy. Its use in supplementation is a modern practice based on biochemical understanding.

Safety

Safety warnings

L-Glutamine is generally considered safe for most healthy adults when taken at recommended doses. However, individuals with certain medical conditions, such as liver or kidney disease, or Reye's syndrome, should exercise caution and consult a healthcare professional before use. High doses may lead to gastrointestinal upset.

Avoid if

  • Severe liver disease
  • Kidney disease
  • Reye's syndrome
  • Monosodium glutamate (MSG) sensitivity (due to metabolic conversion)

Medication interactions

  • Chemotherapy drugs (consult physician)
  • Lactulose (may reduce effectiveness)

Reported side effects

  • Nausea
  • Stomach upset
  • Gas
  • Bloating

General guidance — discuss specifics with a clinician.

Evidence ecosystem

Scientific literature, clinical guidance, government sources, ongoing research, traditional use, and lived experience — grouped by source type and quality.

Overall grade (B)

There is a general understanding of L-Glutamine's physiological roles based on biochemical and cellular studies. However, for specific health claims, especially regarding its efficacy in treating conditions like Irritable Bowel Syndrome, the current evidence base from human clinical trials is limited or mixed. More robust, well-designed studies are needed to establish definitive therapeutic benefits.

Filter by source type

Meta-Analyses(1)

Pooled analyses across multiple human trials.

Very High Quality
  • Metabolomics in Prediabetes and Diabetes: A Systematic Review and Meta-analysis.

    Guasch-Ferré M, Hruby A, Toledo E, Clish CB, Martínez-González MA, Salas-Salvadó J · Diabetes care · 2016

    To conduct a systematic review of cross-sectional and prospective human studies evaluating metabolite markers identified using high-throughput metabolomics techniques on prediabetes and type 2 diabetes. We searched MEDLINE and EMBASE databases through August 2015. We conducted a qualitative review of cross-sectional and prospective studies. Additionally, meta-analyses of metabolite markers, with data estimates from at least three prospective studies, and type 2 diabetes risk were conducted, and multivariable-adjusted relative risks of type 2 diabetes were calculated per study-specific SD difference in a given metabolite. We identified 27 cross-sectional and 19 prospective publications reporting associations of metabolites and prediabetes and/or type 2 diabetes. Carbohydrate (glucose and fructose), lipid (phospholipids, sphingomyelins, and triglycerides), and amino acid (branched-chain amino acids, aromatic amino acids, glycine, and glutamine) metabolites were higher in individuals wi

    Meta-AnalysisPubMedVery High Quality

Clinical Guidelines(1)

Recommendations from medical societies (NICE, AHA, ADA, ACG, Endocrine Society…).

High Quality
  • ESPEN guideline on clinical nutrition in the intensive care unit.

    Singer P, Blaser AR, Berger MM, Alhazzani W, Calder PC, Casaer MP · Clinical nutrition (Edinburgh, Scotland) · 2019

    Following the new ESPEN Standard Operating Procedures, the previous guidelines to provide best medical nutritional therapy to critically ill patients have been updated. These guidelines define who are the patients at risk, how to assess nutritional status of an ICU patient, how to define the amount of energy to provide, the route to choose and how to adapt according to various clinical conditions. When to start and how to progress in the administration of adequate provision of nutrients is also described. The best determination of amount and nature of carbohydrates, fat and protein are suggested. Special attention is given to glutamine and omega-3 fatty acids. Particular conditions frequently observed in intensive care such as patients with dysphagia, frail patients, multiple trauma patients, abdominal surgery, sepsis, and obesity are discussed to guide the practitioner toward the best evidence based therapy. Monitoring of this nutritional therapy is discussed in a separate document.

    Clinical GuidelinePubMed (Practice Guideline)Very High Quality

Randomized Human Trials(1)

Controlled human studies with random assignment.

High Quality
  • Randomized Trial to Assess the Safety and Tolerability of Daily Intake of an Allulose Amino Acid-Based Hydration Beverage in Men and Women.

    Bloomer RJ, Pence J, Hellenbrand J, Davis A, Davis S, Stockton M · Nutrients · 2024 · n=40

    Maintaining adequate hydration is critical to optimal health, well-being, and performance. Those who are physically active in stressful environments, such as warm and/or humid scenarios, may be at particular risk for dehydration with ensuing loss of electrolytes, leading to sluggishness and impaired physical performance. We evaluated an electrolyte and amino acid product containing L-alanine and L-glutamine, as well as select vitamins [B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B12 (cobalamin), and vitamin C (ascorbic acid)]. Subjects (n = 40; four groups, n = 10) were randomized to consume either a placebo packet or one, two, or three packets daily of the test product for 4 weeks with site visits at 0, 2, and 4 weeks. We tested safety and tolerability by analyzing hematological parameters (complete blood counts), metabolic parameters (hepatic, renal, acid-base balance), urinalysis end products, thyroid status [T3 (triiodothyronine), T4 (thyroxine), TSH (thyroid-stimulating

    Randomized TrialPubMedHigh Quality

Clinical Trial Registries(2)

Registered ongoing or completed trials (ClinicalTrials.gov).

Moderate Quality
  • XIGO Effectiveness Study: An Investigation of the Safety and Efficacy of Oral XIGO Tablets on Patients Diagnosed With the Common Cold

    n=140 · NCT01092039 · COMPLETED · COMPLETED

    The purpose of the study will be to assess the efficacy and safety of XIGO administered orally, three times a day, compared with placebo in patients with the common cold.

    Clinical TrialClinicalTrials.govModerate Quality
  • Glutamate, Hyperarousal and Restless Legs Syndrome

    n=77 · NCT01675323 · COMPLETED · COMPLETED

    Restless Legs Syndrome (RLS) research has focused on the sensory features and failed to address an important aspect of RLS; i.e. a 'hyperarousal' or profound chronic sleep loss without significant excessive daytime sleepiness. This hyperarousal produces RLS symptoms by overwhelming the normal inhibitory processes needed to decrease sensory and motor cortical activity for resting and sleep. Thus the hyperarousal produces both the RLS need to move when trying to rest and the inability to maintain sleep. The biological consequences of this hyperarousal process on sleep (increased wake time) and cortical excitability (as demonstrated by transcranial magnetic stimulation (TMS)) are postulated to reflect increased degree of excitatory glutamatergic activity, and therefore affected brain regions will show relatively increased glutamate (Glu) and glutamine (Gln) on MR spectroscopy (MRS). Changes in inhibitory activity and GABA may also occur, but less significantly than the increase in Glu/Gln. Our pilot MRS data discovered a new abnormality in RLS: increased Thalamic Glx (Glu + Gln) that correlated well with sleep measures of hyperarousal. Glx levels are not specific for the neurotransmitter role of Glu. In this project RLS and matching controls subjects will be studied using polysomnograms (PSG) and TMS and 7T MRI for MRS that provides accurate measurement of Gln levels, which reflect mostly neurotransmitter Glu activity. The first aim is to confirm that Gln is increased in the thalamus and to determine if this also occurs in the motor and sensory cortices. The relation between Glu, Gln and GABA will also be evaluated. Second, assessments will be made of the degree of relation between Gln increase and the hyperarousal effects on sleep and cortical excitability (TMS). This would demonstrate that abnormally increased Glu activity is primary to RLS hyperarousal and radically changes the emphasis in RLS to be less on dopamine and more on Glu-hyperarousal as a major feature of RLS.This is an entirely new direction for RLS research and treatment development. The new concept of hyperarousal adds a missing dimension to understanding RLS, namely the discovery of the Glu abnormality and its central relation to the other hyperarousal features.

    Clinical TrialClinicalTrials.govModerate Quality

Limitations: The primary limitation is the lack of extensive, high-quality human clinical trials, particularly large-scale, double-blind, placebo-controlled studies, to conclusively demonstrate efficacy for many of its purported benefits. Existing studies may suffer from small sample sizes, heterogeneous patient populations, and varying methodologies, making it difficult to draw firm conclusions.

This page is educational. Statements use phrases like "may support" and "has been studied for"because no remedy here is approved to cure, treat, or reverse any condition. Discussion happens on the ailment pages — community statistics here are derived from those reports. Always consult a qualified clinician.

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