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What is Glutamine?

3452 Views Posted on: 2024-04-12
Posted by: Matylda Bestyńska

glutamine LEmag2021-5There are 20 amino acids utilized by our genetic code to manufacture proteins. Glutamine is the most abundant and versatile.1

Research shows that it may improve digestive and gut health and enhance the body’s response to exercise.1,2

Researchers consider glutamine to be semi-essential because the body often doesn’t produce enough.3 The difference needs to be made up by oral intake.

Many people take whey or vegan protein, which already contains glutamine. For some individuals, however, this might not be sufficient.

While glutamine is found throughout the body, about 30% of total glutamine is used just in the intestines.4 Because of this, a depletion of glutamine can be especially consequential to gut health.

Three randomized, controlled studies have shown that glutamine use benefits intestinal health:

  • Thirty-three obese or overweight adults received either glutamine or the amino acid L-alanine for two weeks to analyze changes in gut microbiota.5 Those who received glutamine had a decreased ratio of Firmicutes bacteria to Bacteroidetes bacteria. Imbalance of this ratio is considered dysbiosis. Higher ratios are usually seen in obesity and in inflammatory bowel disease (IBD).6 The improved gut microbiota balance with the use of glutamine suggests it is a good candidate to help restore gut flora balance.
  • Ten active men received glutamine or a placebo before intense exercise, to study gastrointestinal permeability differences post-exercise.7 Increased intestinal permeability, also known as "leaky gut," is related to multiple digestive disorders. Those taking glutamine had decreased gastrointestinal permeability compared to those in the placebo group.
  • In a larger study, 106 participants with irritable bowel syndrome took glutamine or a placebo for eight weeks.8 Irritable bowel syndrome severity scores were reduced by 50 points or more in 79.6% of the glutamine group but in only 5.8% of the placebo group.

2-glutamine LEmag2021-5Additional studies have shown that glutamine may:

  • Improve immune function in heavy-load-training athletes,9
  • Reduce the accumulation of blood ammonia (believed to be a cause of fatigue) in high-level endurance athletes,10
  • Decrease muscle soreness following eccentric exercise (a workout in which the muscles get longer in response to a force, for instance, the downward phase of a biceps curl),11
  • Reduce symptoms for sickle cell anemia patients,12 and
  • Reduce chemotherapy- and radiation-induced mucositis (inflammation of the mucous membrane) in cancer patients.13

To summarize, research has shown that glutamine can improve intestinal health and exercise response. 

Material used with permission of Life Extension. All rights reserved.

  1. Cruzat V, Macedo Rogero M, Noel Keane K, et al. Glutamine: Metabolism and Immune Function, Supplementation and Clinical Translation. Nutrients. 2018 Oct 23;10(11).
  2. Kim MH, Kim H. The Roles of Glutamine in the Intestine and Its Implication in Intestinal Diseases. Int J Mol Sci. 2017 May 12;18(5).
  3. Xiao D, Zeng L, Yao K, et al. The glutamine-alpha-ketoglutarate (AKG) metabolism and its nutritional implications. Amino Acids. 2016 Sep;48(9):2067-80.
  4. Kim MH, Kim H. The Roles of Glutamine in the Intestine and Its Implication in Intestinal Diseases. Int J Mol Sci. 2017 May 12;18(5):1051.
  5. de Souza AZ, Zambom AZ, Abboud KY, et al. Oral supplementation with L-glutamine alters gut microbiota of obese and overweight adults: A pilot study. Nutrition. 2015 Jun;31(6):884-9.
  6. Stojanov S, Berlec A, Štrukelj B. The Influence of Probiotics on the Firmicutes/Bacteroidetes Ratio in the Treatment of Obesity and Inflammatory Bowel disease. Microorganisms. 2020 Nov 1;8(11).
  7. Pugh JN, Sage S, Hutson M, et al. Glutamine supplementation reduces markers of intestinal permeability during running in the heat in a dose-dependent manner. Eur J Appl Physiol. 2017 Dec;117(12):2569-77.
  8. Zhou Q, Verne ML, Fields JZ, et al. Randomised placebo-controlled trial of dietary glutamine supplements for postinfectious irritable bowel syndrome. Gut. 2019 Jun;68(6):996-1002.
  9. Song QH, Xu RM, Zhang QH, et al. Glutamine supplementation and immune function during heavy load training. Int J Clin Pharmacol Ther. 2015 May;53(5):372-6.
  10. Carvalho-Peixoto J, Alves RC, Cameron LC. Glutamine and carbohydrate supplements reduce ammonemia increase during endurance field exercise. Appl Physiol Nutr Metab. 2007 Dec;32(6):1186-90.
  11. Legault Z, Bagnall N, Kimmerly DS. The Influence of Oral L-Glutamine Supplementation on Muscle Strength Recovery and Soreness Following Unilateral Knee Extension Eccentric Exercise. Int J Sport Nutr Exerc Metab. 2015 Oct;25(5):417-26.
  12. Niihara Y, Miller ST, Kanter J, et al. A Phase 3 Trial of l-Glutamine in Sickle Cell Disease. N Engl J Med. 2018 Jul 19;379(3):226-35.
  13. Sayles C, Hickerson SC, Bhat RR, et al. Oral Glutamine in Preventing Treatment-Related Mucositis in Adult Patients With Cancer: A Systematic Review. Nutr Clin Pract. 2016 Apr;31(2):171-9.
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Posted in: Probiotics, Glutamine, Digestive system, Muscles

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Scientific Sources

What is glutamine and why is it important?

Glutamine is the most abundant amino acid in the body, classified as "conditionally essential" - the body produces it, but during stress, illness, or intense exercise, demand may exceed production requiring dietary intake. Glutamine is crucial fuel for rapidly dividing cells (intestinal cells, immune cells), supports protein synthesis, aids nitrogen transport, serves as precursor for other compounds, and plays vital roles in gut health, immune function, and muscle recovery.

How does glutamine support intestinal and gut health?

Glutamine is primary fuel source for enterocytes (intestinal lining cells), maintaining gut barrier integrity and preventing leaky gut. It supports tight junction proteins, reduces intestinal permeability, promotes intestinal cell regeneration, modulates gut inflammation, and supports healthy gut microbiome. Research shows glutamine supplementation benefits inflammatory bowel disease, chemotherapy-induced mucositis, and gut dysfunction from stress or critical illness. Gut barrier health is fundamental to overall health.

What role does glutamine play in immune function?

Glutamine is essential fuel for immune cells (lymphocytes, macrophages, neutrophils), required for their proliferation and function. During infection, injury, or intense exercise, immune cells consume glutamine rapidly. Supplementation supports immune cell activity, maintains lymphocyte function, supports antibody production, and may reduce infection risk in athletes or stressed individuals. Glutamine depletion impairs immune responses, while adequate levels support optimal immunity.

Can glutamine help with exercise recovery and muscle maintenance?

Intense exercise depletes muscle glutamine stores. Supplementation may support muscle recovery, reduce exercise-induced immune suppression (common in endurance athletes), decrease muscle soreness, support protein synthesis, and prevent muscle breakdown during caloric restriction. While evidence is mixed, many athletes use glutamine for recovery. Benefits appear strongest during periods of high training volume, stress, or when immune system challenged.

What is the recommended glutamine dosage?

For gut health support, 5-15g daily in divided doses. For immune support during stress or training, 5-10g daily. For clinical conditions (IBD, chemotherapy mucositis), higher doses up to 20-30g daily under medical supervision. Glutamine is remarkably safe with no established upper limit. Take between meals for best absorption, or post-workout for athletes. L-glutamine (not glutamic acid) is the form used in supplements. Powder form allows flexible dosing.

  • Glutamine is most abundant amino acid and primary fuel for rapidly dividing intestinal and immune cells
  • Glutamine maintains gut barrier integrity preventing intestinal permeability (leaky gut)
  • Glutamine supports intestinal healing in inflammatory bowel disease and chemotherapy-induced damage
  • Glutamine is essential fuel for immune cells supporting lymphocyte function and antibody production
  • Glutamine supplementation may reduce infection risk in athletes and stressed individuals
  • Glutamine supports muscle recovery and prevents breakdown during intense training or caloric restriction
  • Glutamine modulates gut microbiome supporting beneficial bacterial populations
  • Glutamine is remarkably safe even at high doses (20-30g daily) with excellent tolerability
  1. For gut health: Take 5-15g L-glutamine daily in 2-3 divided doses
  2. For immune support: Use 5-10g daily during periods of stress or heavy training
  3. For clinical conditions: Higher doses (20-30g daily) under medical supervision for IBD or chemotherapy support
  4. Timing: Take between meals on empty stomach for best absorption
  5. Post-workout option: Athletes can take 5-10g immediately after training for recovery
  6. Powder form preferred: Allows flexible dosing; mix in water or non-acidic beverage
  7. Start lower, increase gradually: Begin with 5g daily, increase to target dose over 1-2 weeks
  8. Consistency important: Daily use provides sustained benefits for gut and immune health
  9. With probiotics: Can combine with probiotics for comprehensive gut health support
  10. Long-term safety: Safe for extended use; many use continuously for chronic gut issues
  11. Quality matters: Choose pharmaceutical-grade L-glutamine from reputable manufacturers
  • People with gut issues including leaky gut, IBS, or inflammatory bowel disease
  • Individuals undergoing chemotherapy experiencing mucositis or gut damage
  • Athletes in heavy training experiencing immune suppression or frequent infections
  • Those recovering from illness or surgery with increased metabolic demands
  • People under chronic stress depleting glutamine stores
  • Individuals wanting to support gut barrier health and intestinal integrity
  • Those seeking immune system support during high-stress periods
  • People on calorie-restricted diets wanting to preserve muscle mass
  • People with liver disease - glutamine metabolism affected; requires medical supervision
  • Those with kidney disease - discuss with nephrologist before high-dose supplementation
  • Individuals with seizure disorders - glutamine converts to glutamate (excitatory neurotransmitter); use with caution
  • People sensitive to MSG - may have sensitivity to glutamine though uncommon
  • Those with Reye's syndrome history - theoretical concerns about ammonia metabolism
  • Pregnant or breastfeeding women taking high doses - safety data limited; discuss with healthcare provider

Results: Comprehensive review shows glutamine plays crucial roles in metabolism, immune function, and clinical translation. Glutamine is essential for rapidly dividing cells and has therapeutic applications in various clinical conditions.

Citation: Cruzat V, et al. [Glutamine: Metabolism and Immune Function, Supplementation and Clinical Translation]

Results: Research demonstrates critical roles of glutamine in intestine including maintaining barrier function, supporting enterocyte metabolism, and preventing intestinal permeability. Glutamine has important implications for intestinal diseases.

Citation: Kim MH, Kim H. Int J Mol Sci. 2017 [Roles of Glutamine in Intestine and Intestinal Diseases]

Results: Studies show glutamine-alpha-ketoglutarate metabolism has important nutritional implications. Glutamine serves as precursor for multiple metabolic pathways critical for health.

Citation: Xiao D, et al. Amino Acids [Glutamine-AKG metabolism and nutritional implications]

Results: Research demonstrates oral L-glutamine supplementation alters gut microbiota composition in obese and overweight individuals, suggesting potential for microbiome modulation through glutamine.

Citation: de Souza AZ, et al. [Oral L-glutamine supplementation alters gut microbiota]