The AtlasAmino acidsPolar, uncharged

GlutamineGln · Q

The most abundant free amino acid in the body, the carrier of nitrogen between organs, and a supplement that, given to the critically ill in the largest trial, raised mortality.

Status Reference · not yet an episodeSources 32Reviewed October 2026

Open in the Atlas Find it on the map

Skeletal formula — every corner and every line end is a carbon, and the hydrogens on carbon are left implied.

Molecule · Gln · 10 heavy atoms

Glutamine

C₅H₁₀N₂O₃146.15 g/mol

The most abundant free amino acid in the body, the carrier of nitrogen between organs, and a supplement that, given to the critically ill in the largest trial, raised mortality.

Built fromthe charted ones open their own entry

C5CarbonH10Hydrogen N2Nitrogen O3Oxygen

Codes: Gln · Q
Formula: C₅H₁₀N₂O₃
Molar mass: 146.15 g/mol
Systematic name: (2S)-2,5-diamino-5-oxopentanoic acid
Side chain: 2-Carbamoylethyl: two carbons and an amide; polar and uncharged.
Class: Polar, uncharged
In the diet: Conditionally essential
Carbon skeleton: Glucogenic
pKa: α-COOH 2.17 · α-NH₃⁺ 9.13
Isoelectric point: pH 5.65
Hydropathy: -3.5 (Kyte–Doolittle)
Codons: CAA CAG

pKa and isoelectric point: Nelson and Cox, Lehninger Principles of Biochemistry, table of amino acid properties (free amino acid, 25 °C). Hydropathy: Kyte and Doolittle, J Mol Biol 1982. Essentiality: Reeds, J Nutr 2000. Formula and mass computed from the structure.

In brief

What it is

Glutamate with its side-chain acid turned into an amide, which makes it neutral and gives it a second nitrogen to carry. It is the most abundant and versatile free amino acid in the body ¹.

Why it matters

Glutamine moves nitrogen between tissues, fuels the gut lining and dividing immune cells, lets the kidney excrete acid as ammonium, and keeps the brain’s glutamate and GABA supplies topped up ^2,3. That centrality is why it was proposed as conditionally essential in critical illness ².

Where it runs short

Plasma glutamine falls in acute illness, which led to the idea that the body cannot make enough under stress ^2,4. Inherited inability to make it is catastrophic: two newborns without glutamine synthetase had almost no glutamine in blood, urine or spinal fluid, severe brain malformations and died ⁵.

Where it turns

In the largest trial, 1,223 critically ill adults given glutamine had higher mortality at 28 days, in hospital and at six months than those who were not ⁶.

A low level in illness was taken as a deficiency to correct. The trials said otherwise.

The molecule

Glutamine is glutamate with its side-chain carboxylic acid replaced by an amide, –CONH₂. The change removes the negative charge and adds a second nitrogen, which is the point: glutamine is how the body carries nitrogen in a safe, non-toxic form.

Charge · pHGlutamine carries almost no net charge at the pH of blood.

Move across the chart to read the charge at any pH.

Computed from its pKa values (α-carboxyl 2.17, α-amino 9.13) by the Henderson–Hasselbalch equation, for the free amino acid in water at 25 °C. Inside a folded protein the same groups can shift by a unit or more. The faint lines are the other amino acids.

HydropathyGlutamine scores -3.5: the 4th most water-loving of the twenty.

Kyte–Doolittle hydropathy index: positive values avoid water and tend to be buried inside a folded protein, negative values sit on its surface. Each letter is an amino acid; choose one to open it.

The genetic codeGlutamine has 2 codons. The code is redundant, so most single-letter changes at the third position still write glutamine.

The 64 codons of the standard genetic code. Codons for glutamine are marked.
1st ↓ 2nd →	U	C	A	G	3rd
U	UUUPhe	UCUSer	UAUTyr	UGUCys	U
	UUCPhe	UCCSer	UACTyr	UGCCys	C
	UUALeu	UCASer	UAAStop	UGAStop	A
	UUGLeu	UCGSer	UAGStop	UGGTrp	G
C	CUULeu	CCUPro	CAUHis	CGUArg	U
	CUCLeu	CCCPro	CACHis	CGCArg	C
	CUALeu	CCAPro	CAAGln	CGAArg	A
	CUGLeu	CCGPro	CAGGln	CGGArg	G
A	AUUIle	ACUThr	AAUAsn	AGUSer	U
	AUCIle	ACCThr	AACAsn	AGCSer	C
	AUAIle	ACAThr	AAALys	AGAArg	A
	AUGMet	ACGThr	AAGLys	AGGArg	G
G	GUUVal	GCUAla	GAUAsp	GGUGly	U
	GUCVal	GCCAla	GACAsp	GGCGly	C
	GUAVal	GCAAla	GAAGlu	GGAGly	A
	GUGVal	GCGAla	GAGGlu	GGGGly	G

Where it comes from

Glutamine synthetase builds glutamine from glutamate and ammonia, using ATP ⁵. Muscle makes and exports most of the body’s supply, and glutamine is the most abundant free amino acid in blood and tissue ¹.

Much of what is swallowed never reaches the body. In adults given labeled glutamine through a nasogastric tube, 54% was taken up by the gut and liver on first pass ⁷, and in infants oral glutamine is essentially all used by the splanchnic tissues ⁴. It is also unstable in solution, which is why it is not routinely added to intravenous amino acid mixtures ⁴.

Conditionally essentialMade from glutamate and ammonia by glutamine synthetase in most tissues, so it is not needed in the diet; it was proposed as conditionally essential in critical illness, a proposal the largest trials did not support ^2,4,6.

How much

None set; the body makes it ⁴.

Where it is in food

All protein contains it, but most dietary glutamine is used by the gut and liver on first pass ^4,7.

In the bottle · fermentedMade by fermentation in engineered Corynebacterium glutamicum, now at titres above 70 g per liter, for food, medicine and feed ^8,9.

What the body does with it

Rapidly dividing cells use glutamine as a fuel, especially the cells lining the gut and lymphocytes ². Immune cells consume it at rates similar to or greater than glucose, and it is needed for lymphocyte proliferation, macrophage activity and neutrophil killing in laboratory studies ¹.

In the kidney, glutamine is the source of the ammonia that carries acid out as ammonium, and that output rises in acidosis ^2,10.

In the brain, the glutamate–glutamine cycle runs between astrocytes and neurons: astrocytes take up released glutamate, make it into glutamine, and send it back to neurons to rebuild their transmitter stores. The same reaction disposes of ammonia in the brain ³.

Many cancer cells are “addicted” to glutamine, despite being able to make it: they use it to import essential amino acids, keep mTOR active, and fuel their mitochondria and NADPH production ¹¹.

Because the brain runs that cycle, glutamine shows up in every attempt to read a psychiatric diagnosis off a metabolite — and the reading keeps being harder than the hypothesis. A 2026 meta-analysis pooled 51 case-control magnetic resonance spectroscopy studies of the anterior cingulate cortex in schizophrenia to separate glutamate, glutamine and the combined signal the scanner usually reports as one ¹². A second pooled 21 studies of blood glutamate, glutamine and GABA in autism — 804 people with a diagnosis against 721 without — and then did the thing that matters: asked whether the difference could tell one person from another, rather than one group from another ¹³.

In three sentences each

A nitrogen carrier

Glutamine carries two nitrogens, one in its amino group and one in its amide; muscle, gut, liver and kidney trade it to move nitrogen and to build nucleotides, amino sugars and other amino acids ^1,2.

Acid out as ammonium

The kidney splits glutamine to release ammonia, which carries acid into the urine as ammonium, and the proximal tubule steps this up in metabolic acidosis ^2,10.

The brain’s supply line

Astrocytes make large amounts of glutamine and pass it to neurons, which turn it back into glutamate and GABA; diminished astrocyte glutamine synthesis is a common thread in neurological disease ³.

How it is made, moved and broken down

Glutaminase turns glutamine into glutamate and ammonia, the first step towards fuel and the kidney’s ammonium ^2,14. Blocking that enzyme was a long-standing hope in cancer, but the glutamine antagonist DON was stopped for toxicity, and the glutaminase inhibitor telaglenastat did not improve treatment of kidney cancer ^14,15.

Carbon skeleton · glucogenicGlutaminase converts it to glutamate and then 2-oxoglutarate, which enters the Krebs cycle; in many cancer cells it is the main mitochondrial fuel ^11,14.

Made and brokenGlutamine synthetase stores ammonia; glutaminase releases it ^2,5.

Glutamate + NH₄⁺
Glutamine synthetaseGLUL · ATP
Glutamine
GlutaminaseGLS, GLS2
Glutamate + NH₄⁺

The glutamate–glutamine cycleBetween astrocytes and neurons ³.

Glutamate released by neurons
Glutamine synthetaseGLUL · ATP
Glutamine in astrocytes
Glutaminase, then GADGLS, GAD1 · vitamin B6 for GAD
Glutamate, and GABA

Where it matters most

Muscle: Makes and exports most of the body’s glutamine ¹.
Gut: A main consumer, as fuel for the lining ^2,7.
Kidney: Uses it to make ammonium and excrete acid ^2,10.
Brain: The glutamate–glutamine cycle between astrocytes and neurons ³.
Immune cells: Consume it at high rates when active ¹.

When it goes wrong

Drug

Glutamine supplements in critical illness

In REDOXS, 1,223 ventilated adults with multi-organ failure were given glutamine, antioxidants, both or neither; glutamine raised in-hospital and six-month mortality and did nothing for organ failure or infection ⁶. In MetaPlus, a feed enriched with glutamine, fish oil, selenium and antioxidants did not reduce infections, and six-month mortality in medical patients was 54% against 35% ¹⁶.

Drug

Sickle cell disease

HBB

In a phase 3 trial of 230 patients, pharmaceutical-grade L-glutamine twice daily cut the median number of pain crises over 48 weeks from 4.0 to 3.0 and hospitalizations from 3.0 to 2.0 ¹⁷. A systematic review found the three eligible studies supportive but with conflicting results and limitations ¹⁸.

Inherited

Congenital glutamine synthetase deficiency

GLUL · autosomal recessive

Two unrelated newborns with homozygous GLUL mutations had virtually no glutamine in serum, urine and cerebrospinal fluid, severe brain malformations and multi-organ failure, and died in the neonatal period ⁵.

How it is foundPlasma, urine and CSF amino acids; GLUL sequencing ⁵.

Drug

Cancer and glutamine

GLS

Many cancer cells consume glutamine heavily ¹¹. The glutamine antagonist DON worked in early studies but was halted for toxicity; prodrugs designed to reach the brain are in preclinical work ¹⁵. The glutaminase inhibitor telaglenastat did not add to cabozantinib in 444 people with kidney cancer ¹⁴.

Drug

Mucositis during cancer treatment

The one supportive-care use with trials behind it rather than theory. The mouth and gut lining turns over fast, lives on glutamine, and is what chemotherapy and radiotherapy damage first. In children on high-dose methotrexate the incidence of mucositis overall barely moved — 71.8% against 81.2%, P = 0.08 — but severe mucositis fell from 44% of courses to 3.1%, and the median duration from five days to two ¹⁹. In head and neck radiotherapy, glutamine and arginine each reduced severity, pain and weight loss against maltodextrin alone ²⁰.

How it is foundClinical grading, usually the WHO oral mucositis scale, alongside a pain score ^19,20.

Drug

Glutamine around surgery

A large, repetitive and almost entirely single-center literature reporting fewer complications and shorter stays after colorectal and hepatic surgery ^21,22,23. The effects are consistent, which is reassuring, and consistently from small trials run in one place at a time, which is not. The authors of the colorectal analyses rate their own certainty low to moderate; the honest summary is that this is where glutamine might turn out to work, not where it has been shown to.

How it is foundPostoperative complication rates and length of stay — endpoints that reward a trial's own standard of care as much as its intervention ²².

How it is measured

Plasma glutamine is routinely measured but hard to measure well. It breaks down in solution, and in electrospray mass spectrometry it cyclizes to pyroglutamate inside the instrument; separating glutamine, glutamate and pyroglutamate and using isotope-labeled standards corrects the error ^4,24.

Plasma glutaminePart of the amino acid panel; low in critical illness and very low in glutamine synthetase deficiency ^4,5.A low plasma level was not a reliable guide to who would benefit from supplements ¹. In electrospray mass spectrometry, a third to nearly all of the glutamine can cyclize to pyroglutamate inside the instrument unless the method corrects for it ²⁴.

Food, supplements and the evidence

Establishedreplicated in people, for a named outcome

Pharmaceutical L-glutamine reduces pain crises modestly in sickle cell disease ¹⁷.
Glutamine reduces the severity of mucositis during cancer treatment. In children receiving high-dose methotrexate for leukemia, a swish-and-swallow mouthwash cut severe mucositis from 44% of courses to 3.1%, halved its duration and lowered pain scores, in a cross-over trial where each child was their own control ¹⁹. In head and neck radiotherapy, both L-glutamine and L-arginine reduced mucositis severity, pain and weight loss against maltodextrin, and did not differ from each other ²⁰. Five trials in 311 colorectal cancer patients also found less chemotherapy-associated diarrhea ²⁵.

Uncertainsmall, short, mixed, surrogate or preclinical

Glutamine for post-infectious, diarrhea-predominant irritable bowel syndrome: a single-center trial of 5 g three times a day in 106 completers reported responses in 80% against 6% on placebo, an effect large enough to need replication ²⁶.
Glutamine for athletes and immune support: laboratory roles in immune cells are clear, but whether supplements help is difficult to determine ¹.
Glutamine around surgery, where the evidence is abundant and thin at the same time. Two meta-analyses from one group — 17 trials and 950 patients, then 27 studies and 1,643 — report fewer infectious and non-infectious complications and about two days less in hospital after colorectal resection, and grade their own certainty low to moderate; every included trial was single-center ^21,22. A third, in 1,198 patients after hepatectomy or liver transplantation, reports improvements across immune markers, inflammatory markers, liver enzymes and serum proteins all at once, which is a pattern worth being careful with ²³. In cardiac surgery, amino acid MIXTURES reduced stage 1 and stage 3 acute kidney injury across six trials and 4,501 patients, while glutamine on its own was rated very-low-certainty evidence and changed neither mortality nor dialysis ²⁷.
Glutamine for inflammation and oxidative stress in chronic disease. A systematic review searching to May 2025 found six randomized trials across the whole of chronic disease to answer that question — which is the finding, more than anything in them ²⁸.

Sold asthe claim on the label, against the evidence

“Glutamine heals the gut and boosts immunity in illness.” Given to critically ill patients, it raised mortality in the largest trial, and an immune-nutrient feed containing it did not reduce infections ^6,16.
“Glutamine protects the gut and the immune system in hard training.” Four weeks of supplementation in 19 collegiate cross-country skiers, each on both arms, did not establish an effect on gut microbiota composition or gastrointestinal symptoms across a training period ²⁹. Six hours of hypoxia at a simulated 4,500 m did not move mood or cognition either, with or without 20 g of glutamine a day ³⁰.

What is strange about it

Glutamine’s reputation in intensive care was built on the logic that low levels in illness meant a shortage ². The REDOXS trial, the largest test of it, found a trend to higher 28-day mortality, 32.4% against 27.2%, and significantly higher mortality in hospital and at six months ⁶.

The only drug use of glutamine with regulatory approval is in sickle cell disease, approved by the FDA in 2017 on a trial in which the median number of pain crises over 48 weeks fell from four to three ^17,18.

Tumors that depend on glutamine made glutaminase an obvious target; in 444 people with kidney cancer, adding the glutaminase inhibitor telaglenastat changed median progression-free survival from 9.3 to 9.2 months ¹⁴.

The intensive-care story did not stop with REDOXS. RE-ENERGIZE gave enteral glutamine at 0.5 g per kilogram per day to patients with deep second- or third-degree burns within 72 hours of admission, in a double-blind, placebo-controlled trial — the population with the strongest theoretical case for it, since burns are where the metabolic argument began. It found no benefit ³¹. Two large, well-run trials have now looked for the effect the biochemistry predicts, in the two groups most likely to show it, and come back empty.

And the cancer argument now runs in both directions at once. Blocking glutamine was the obvious move, and the glutaminase inhibitor failed its trial. Giving it is the opposite move, and it has just been tried: GlutaPanc, an open-label single-arm phase 1 study, added FDA-approved clinical-grade oral L-glutamine at 0.1 to 0.3 g per kilogram twice daily to gemcitabine and nab-paclitaxel in 16 people with untreated advanced pancreatic cancer, to find a dose ³². Sixteen patients and no control arm is a dose-finding study and nothing more — but after thirty years of preclinical antitumor activity that nobody had taken into a person, it is the first time the question was asked of the disease rather than of a cell line.

Where it connects

In the Atlas

GluGlutamateNegatively charged AsnAsparaginePolar, uncharged ArgArgininePositively charged NNitrogenElement

Topics on the map

On the map

A star in Conditional amino acids, one of 14. The most abundant free amino acid in the body and conditionally essential in critical illness — where giving extra of it, in the largest trial, increased mortality.

Find it on the map

Sources

32 sources, numbered as they are cited. Every one was checked against PubMed or its publisher before it was cited here; the note under each says what it shows and what it does not.

1
Cruzat V, Macedo Rogero M, Noel Keane K, et al. Glutamine: metabolism and immune function, supplementation and clinical translation.Nutrients · 2018 · 10(11):1564doi:10.3390/nu10111564 · PMID 30360490
Review; the most abundant free amino acid; immune roles.
2
Lacey JM, Wilmore DW. Is glutamine a conditionally essential amino acid?Nutr Rev · 1990 · 48(8):297–309doi:10.1111/j.1753-4887.1990.tb02967.x · PMID 2080048
The original argument for conditional essentiality.
3
Andersen JV, Schousboe A. Glial glutamine homeostasis in health and disease.Neurochem Res · 2023 · 48(4):1100–1128doi:10.1007/s11064-022-03771-1 · PMID 36322369
Astrocyte glutamine and the glutamate–glutamine cycle.
4
Parimi PS, Kalhan SC. Glutamine supplementation in the newborn infant.Semin Fetal Neonatal Med · 2007 · 12(1):19–25doi:10.1016/j.siny.2006.10.003 · PMID 17142118
Oral glutamine used by splanchnic tissues; unstable in solution.
5
Häberle J, Görg B, Rutsch F, et al. Congenital glutamine deficiency with glutamine synthetase mutations.N Engl J Med · 2005 · 353(18):1926–1933doi:10.1056/NEJMoa050456 · PMID 16267323
Two newborns.
6
Heyland D, Muscedere J, Wischmeyer PE, et al. A randomized trial of glutamine and antioxidants in critically ill patients.N Engl J Med · 2013 · 368(16):1489–1497doi:10.1056/NEJMoa1212722 · PMID 23594003
REDOXS: 1,223 patients; harm with glutamine.
7
Matthews DE, Marano MA, Campbell RG. Splanchnic bed utilization of glutamine and glutamic acid in humans.Am J Physiol · 1993 · 264(6 Pt 1):E848–E854doi:10.1152/ajpendo.1993.264.6.E848 · PMID 8101428
54% of enteral glutamine retained on first pass.
8
Lv Q, Hu M, Tian L, et al. Enhancing L-glutamine production in Corynebacterium glutamicum by rational metabolic engineering combined with a two-stage pH control strategy.Bioresour Technol · 2021 · 341:125799doi:10.1016/j.biortech.2021.125799 · PMID 34425465
73.5 g/L.
9
EFSA FEEDAP Panel; Bampidis V, Azimonti G, et al. Safety and efficacy of L-glutamine produced using Corynebacterium glutamicum NITE BP-02524 for all animal species.EFSA J · 2020 · 18(4):e06075doi:10.2903/j.efsa.2020.6075 · PMID 32874286
Fermentation with a genetically modified strain; no viable cells in product.
10
Curthoys NP, Moe OW. Proximal tubule function and response to acidosis.Clin J Am Soc Nephrol · 2014 · 9(9):1627–1638doi:10.2215/CJN.10391012 · PMID 23908456
The proximal tubule’s response to acidosis.
11
Wise DR, Thompson CB. Glutamine addiction: a new therapeutic target in cancer.Trends Biochem Sci · 2010 · 35(8):427–433doi:10.1016/j.tibs.2010.05.003 · PMID 20570523
Why cancer cells consume glutamine.
12
Chan MS, Tang PY, Chua ZK, et al. Insights into changes in glutaminergic metabolites in the anterior cingulate cortex: a systematic review and meta-analysis of magnetic resonance spectroscopy in schizophrenia.Psychiatry Res Neuroimaging · 2026 · 358:112175doi:10.1016/j.pscychresns.2026.112175 · PMID 41702060
Fifty-one case-control studies of one brain region, pooled.
13
Shi Y, Yin X, Luo J, et al. Peripheral blood glutamate, glutamine, and GABA in autism spectrum disorder: a systematic review and meta-analysis of group differences with an exploratory assessment of diagnostic accuracy.Prog Neuropsychopharmacol Biol Psychiatry · 2026 · 150:111926doi:10.1016/j.pnpbp.2026.111926 · PMID 42727811
A group difference is not a test, and the paper says so in its own title.
14
Tannir NM, Agarwal N, Porta C, et al. Efficacy and safety of telaglenastat plus cabozantinib vs placebo plus cabozantinib in patients with advanced renal cell carcinoma: the CANTATA randomized clinical trial.JAMA Oncol · 2022 · 8(10):1411–1418doi:10.1001/jamaoncol.2022.3511 · PMID 36048457
444 patients; no benefit. Manufacturer-sponsored.
15
Rais R, Jančařík A, Tenora L, et al. Discovery of 6-diazo-5-oxo-L-norleucine (DON) prodrugs with enhanced CSF delivery in monkeys: a potential treatment for glioblastoma.J Med Chem · 2016 · 59(18):8621–8633doi:10.1021/acs.jmedchem.6b01069 · PMID 27560860
DON halted for toxicity; prodrugs preclinical.
16
van Zanten AR, Sztark F, Kaisers UX, et al. High-protein enteral nutrition enriched with immune-modulating nutrients vs standard high-protein enteral nutrition and nosocomial infections in the ICU: a randomized clinical trial.JAMA · 2014 · 312(5):514–524doi:10.1001/jama.2014.7698 · PMID 25096691
MetaPlus: 301 patients; no fewer infections; higher six-month mortality in medical patients. Manufacturer co-authors.
17
Niihara Y, Miller ST, Kanter J, et al. A phase 3 trial of L-glutamine in sickle cell disease.N Engl J Med · 2018 · 379(3):226–235doi:10.1056/NEJMoa1715971 · PMID 30021096
230 patients, 48 weeks.
18
Cieri-Hutcherson NE, Hutcherson TC, Conway-Habes EE, et al. Systematic review of L-glutamine for prevention of vaso-occlusive pain crisis in patients with sickle cell disease.Pharmacotherapy · 2019 · 39(11):1095–1104doi:10.1002/phar.2329 · PMID 31505045
FDA approval in 2017; three eligible studies.
19
Sankaran SS, Dewan P, Malhotra RK, et al. Glutamine mouthwash for preventing methotrexate-induced mucositis in children with acute lymphoblastic leukemia: a randomized cross-over trial.Indian Pediatr · 2025 · 62(4):269–275doi:10.1007/s13312-025-00042-4 · PMID 40198535
Severe mucositis 3.1% against 44%, in children who each served as their own control.
20
Hassanein FEA, Mikhail C, Elkot S, Abou-Bakr A. L-arginine vs. L-glutamine oral suspensions for radiation-induced oral mucositis: a triple-blind randomized trial.J Cancer Res Clin Oncol · 2025 · 151(7):198doi:10.1007/s00432-025-06213-x · PMID 40603739
Both amino acids beat maltodextrin; neither beat the other.
21
Huang Y, Yang X, Qin S, et al. Effect of perioperative glutamine-enhanced parenteral nutrition on short-term outcomes in colorectal cancer patients undergoing radical resection: a systematic review and meta-analysis of randomized controlled trials.Technol Cancer Res Treat · 2026 · 25:15330338261438204doi:10.1177/15330338261438204 · PMID 41891764
Seventeen single-center trials, 950 patients, low-to-moderate certainty by the authors' own grading.
22
Huang Y, Yang XZ, Qin SH, et al. Effect of perioperative glutamine-enriched nutritional support on patients with colorectal cancer: a systematic review and meta-analysis.World J Gastrointest Surg · 2025 · 17(12):112256doi:10.4240/wjgs.v17.i12.112256 · PMID 41479717
The same group, the same question, a wider net: 27 studies and 1,643 patients, six months earlier.
23
Meng X, Zhang M, Wang X. Efficacy of glutamine supplementation in postoperative patients undergoing hepatic surgery: a systematic review and meta-analysis of randomized controlled trials.Clinics (Sao Paulo) · 2026 · 81:101086doi:10.1016/j.clinsp.2026.101086 · PMID 42679488
Eighteen studies, 1,198 patients: fewer complications, and effect sizes large enough to be worth asking where they came from.
24
Purwaha P, Silva LP, Hawke DH, et al. An artifact in LC-MS/MS measurement of glutamine and glutamic acid: in-source cyclization to pyroglutamic acid.Anal Chem · 2014 · 86(12):5633–5637doi:10.1021/ac501451v · PMID 24892977
In-source conversion to pyroglutamate.
25
Chen L, Wang D, Meng C, et al. Glutamine prevents diarrhea in colorectal cancer patients undergoing chemotherapy or chemoradiotherapy: a meta-analysis.BMC Gastroenterol · 2025 · 25(1):697doi:10.1186/s12876-025-04308-w · PMID 41053591
Five trials, 311 patients.
26
Zhou Q, Verne ML, Fields JZ, et al. Randomised placebo-controlled trial of dietary glutamine supplements for postinfectious irritable bowel syndrome.Gut · 2019 · 68(6):996–1002doi:10.1136/gutjnl-2017-315136 · PMID 30108163
Single center; 79.6% against 5.8% responders.
27
Majeed MW, Finnegan E, Gallo Ruelas M, et al. Effectiveness of amino acid supplementation in preventing acute kidney injury following cardiac surgery: a systematic review and meta-analysis of randomized controlled trials.Acta Anaesthesiol Scand · 2025 · 69(6):e70037doi:10.1111/aas.70037 · PMID 40411139
Six trials, 4,501 patients. The mixtures worked; glutamine alone was rated very low certainty.
28
Movahed S, Bahadorkhan A, Malov V, et al. The effects of glutamine supplementation on inflammatory and oxidative stress indices in chronic diseases: a systematic review.Amino Acids · 2026 · 58(1)doi:10.1007/s00726-026-03543-z · PMID 42366260
Searched to May 2025 across three databases and found six randomized trials in the whole of chronic disease.
29
Lu TL, Tanisawa K, Fujita Z, et al. Influence of four-week glutamine supplementation on gut microbiota across a training period in cross-country skiers.Sports (Basel) · 2026 · 14(9):375doi:10.3390/sports14090375 · PMID 42784371
Nineteen athletes, each on both arms, four weeks.
30
Souza WY, Lemos VA, Quaresma MVDS, et al. Six hours of hypoxia at 4500 m does not affect psychobiological parameters, regardless of glutamine supplementation: a randomized, double-masked, placebo-controlled clinical trial.Nutr Health · 2026 · 2601060261480418doi:10.1177/02601060261480418 · PMID 42640731
The title is the result.
31
Heyland DK, Wibbenmeyer L, Pollack JA, et al. A randomized trial of enteral glutamine for treatment of burn injuries.N Engl J Med · 2022 · 387(11):1001–1010doi:10.1056/NEJMoa2203364 · PMID 36082909
RE-ENERGIZE. The second large trial to look for the benefit the theory predicted, and not find it.
32
Gong J, Muranaka H, Choi SY, et al. L-glutamine in combination with first-line gemcitabine and nab-paclitaxel in advanced pancreatic ductal adenocarcinoma: an open-label, single-arm, phase 1 GlutaPanc trial.Nat Cancer · 2026 · 7(9):1406–1418doi:10.1038/s43018-026-01225-z · PMID 42675216
Sixteen patients, a dose-finding design, and the first time the preclinical antitumor story was tested in people.

This is education, not medical advice. Nothing on this page is written with knowledge of your history, your medications or your risks, and nothing here is a dose. Do not start or stop any treatment on the basis of it — talk to your own physician. Read the full medical disclaimer.

In brief

The molecule

Where it comes from

What the body does with it

A nitrogen carrier

Acid out as ammonium

The brain’s supply line

How it is made, moved and broken down

Where it matters most

When it goes wrong

Glutamine supplements in critical illness

Sickle cell disease

Congenital glutamine synthetase deficiency

Cancer and glutamine

Mucositis during cancer treatment

Glutamine around surgery

How it is measured

Food, supplements and the evidence

What is strange about it

Where it connects

Sources

Every source, in your inbox.