Last Updated: September 28 2022

Glycine is an amino acid and neurotransmitter. It can play both stimulatory and depressant roles in the brain. Supplementation can improve sleep quality.

Glycine is most often used for

What is glycine?

Glycine is an amino acid with a number of important functions in the body. Glycine acts as a neurotransmitter, a component of collagen, and as a precursor to various biomolecules (e.g., creatine, heme), among other roles. Glycine is often considered conditionally essential, meaning it can usually be produced in the body in sufficient amounts. However, in certain contexts (e.g., pregnancy) more glycine may be needed from the diet. Glycine is found in most protein sources, meaning common sources of glycine include meat, eggs, soybeans, lentils, and dairy products.

What are glycine’s main benefits?

A few studies have found supplementation with glycine can improve sleep quality, with subsequent benefits to cognitive function. High doses of glycine have been shown to improve symptoms of schizophrenia. Glycine may reduce the blood glucose response to carbohydrate ingestion.

Glycine is a major component of collagen (around 25% by weight) and for this reasons is often taken to improve joint health, but human evidence in this area is currently lacking.

What are glycine’s main drawbacks?

In high amounts, glycine supplementation can cause gastrointestinal symptoms, including nausea and abdominal pain.

How does glycine work?

Glycine supplementation likely works through different mechanisms depending on the outcome of interest.

Glycine is a co-agonist of N-methyl-D-aspartate (NMDA) receptor, meaning glycine plays a role in activating this receptor in the brain. Glycine’s effect on the NMDA receptor has been proposed as underlying the imrpovements in both sleep and symptoms of schizophrenia with supplementation.

Glycine may benefit sleep by lowering core body temperature, as a warm body temperature can adversely affect sleep quality.

What else is Glycine known as?
Note that Glycine is also known as:
  • 2-Aminoacetic acid
Dosage information

For glycemic and sleep benefits, doses of 3-5 grams with meals and before bed, respectively, have been used successfully in clinical research.

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1.^Wang W, Wu Z, Dai Z, Yang Y, Wang J, Wu GGlycine metabolism in animals and humans: implications for nutrition and healthAmino Acids.(2013 Sep)
2.^Lodish H, Berk A, Zipursky SLSection 22.3, Collagen: The Fibrous Proteins of the MatrixMolecular Cell Biology. 4th edition.(2000)
3.^Shoulders MD, Raines RTCollagen structure and stabilityAnnu Rev Biochem.(2009)
4.^Meléndez-Hevia E, De Paz-Lugo P, Cornish-Bowden A, Cárdenas MLA weak link in metabolism: the metabolic capacity for glycine biosynthesis does not satisfy the need for collagen synthesisJ Biosci.(2009 Dec)
5.^National Center for Biotechnology InformationGlycinePubChem Compound Database.()
8.^Myllyharju J, Kivirikko KICollagens and collagen-related diseasesAnn Med.(2001 Feb)
9.^Layer G, Reichelt J, Jahn D, Heinz DWStructure and function of enzymes in heme biosynthesisProtein Sci.(2010 Jun)
10.^Brosnan JT, da Silva RP, Brosnan METhe metabolic burden of creatine synthesisAmino Acids.(2011 May)
11.^Lu SCGlutathione synthesisBiochim Biophys Acta.(2013 May)
12.^Berg JM, Tymoczko JL, Stryer LSection 25.2, Purine Bases Can Be Synthesized de Novo or Recycled by Salvage PathwaysBiochemistry. 5th edition.(2002)
14.^Zafra F, Giménez CGlycine transporters and synaptic functionIUBMB Life.(2008 Dec)
17.^Gomeza J, Armsen W, Betz H, Eulenburg VLessons from the knocked-out glycine transportersHandb Exp Pharmacol.(2006)
18.^Zhong Z, Wheeler MD, Li X, Froh M, Schemmer P, Yin M, Bunzendaul H, Bradford B, Lemasters JJL-Glycine: a novel antiinflammatory, immunomodulatory, and cytoprotective agentCurr Opin Clin Nutr Metab Care.(2003 Mar)
22.^Gersovitz M, Bier D, Matthews D, Udall J, Munro HN, Young VRDynamic aspects of whole body glycine metabolism: influence of protein intake in young adult and elderly malesMetabolism.(1980 Oct)
23.^Cornish-Bowden A, Pereto J, Cardenas MLBiochemistry and evolutionary biology: two disciplines that need each other?J Biosci.(2014 Mar)
24.^Greer M, Greer JK, Gillingham JOsteoarthritis in selected wild mammalsProc Okla Acad Sci.(1977)
25.^Weissengruber GE, Fuss FK, Egger G, Stanek G, Hittmair KM, Forstenpointner GThe elephant knee joint: morphological and biomechanical considerationsJ Anat.(2006 Jan)
26.^Wallach JDDegenerative arthritis in a black rhinocerosJ Am Vet Med Assoc.(1967 Oct 1)
28.^STRAUS WL Jr, CAVE JEPathology and the posture of Neanderthal manQ Rev Biol.(1957 Dec)
33.^Jackson AA, Badaloo AV, Forrester T, Hibbert JM, Persaud CUrinary excretion of 5-oxoproline (pyroglutamic aciduria) as an index of glycine insufficiency in normal manBr J Nutr.(1987 Sep)
34.^Metges CC, Yu YM, Cai W, Lu XM, Wong S, Regan MM, Ajami A, Young VROxoproline kinetics and oxoproline urinary excretion during glycine- or sulfur amino acid-free diets in humansAm J Physiol Endocrinol Metab.(2000 May)
39.^Jackson AA, Persaud C, Hall M, Smith S, Evans N, Rutter NUrinary excretion of 5-L-oxoproline (pyroglutamic acid) during early life in term and preterm infantsArch Dis Child Fetal Neonatal Ed.(1997 May)
41.^Nair AB, Jacob SA simple practice guide for dose conversion between animals and humanJ Basic Clin Pharm.(2016 Mar)
42.^Shoham S, Javitt DC, Heresco-Levy UHigh dose glycine nutrition affects glial cell morphology in rat hippocampus and cerebellumInt J Neuropsychopharmacol.(1999 Mar)
43.^Shoham S, Javitt DC, Heresco-Levy UChronic high-dose glycine nutrition: effects on rat brain cell morphologyBiol Psychiatry.(2001 May 15)
44.^Bacci G, Toni A, Avella M, Manfrini M, Sudanese A, Ciaroni D, Boriani S, Emiliani E, Campanacci MLong-term results in 144 localized Ewing's sarcoma patients treated with combined therapyCancer.(1989 Apr 15)
45.^Heresco-Levy U, Javitt DC, Ermilov M, Mordel C, Horowitz A, Kelly DDouble-blind, placebo-controlled, crossover trial of glycine adjuvant therapy for treatment-resistant schizophreniaBr J Psychiatry.(1996 Nov)
46.^Heresco-Levy U, Javitt DC, Ermilov M, Mordel C, Silipo G, Lichtenstein MEfficacy of high-dose glycine in the treatment of enduring negative symptoms of schizophreniaArch Gen Psychiatry.(1999 Jan)
47.^Javitt DC, Silipo G, Cienfuegos A, Shelley AM, Bark N, Park M, Lindenmayer JP, Suckow R, Zukin SRAdjunctive high-dose glycine in the treatment of schizophreniaInt J Neuropsychopharmacol.(2001 Dec)
49.^Attobla MHBEGlycine supplementation to improve insulin sensitivity in humansPhD diss., University of Alabama at Birmingham.(2014)
50.^Inagawa K, Nobuhiro K, Ono K, Sukegawa E, Tsubuku S, Takahashi MAssessment of acute adverse events of glycine ingestion at a high dose in human volunteersSEIKATSU EISEI (Journal of Urban Living and Health Association).(2006)
51.^Silk DB, Grimble GK, Rees RGProtein digestion and amino acid and peptide absorptionProc Nutr Soc.(1985 Feb)
56.^Adibi SA, Soleimanpour MRFunctional characterization of dipeptide transport system in human jejunumJ Clin Invest.(1974 May)
57.^Rajendran VM, Ansari SA, Harig JM, Adams MB, Khan AH, Ramaswamy KTransport of glycyl-L-proline by human intestinal brush border membrane vesiclesGastroenterology.(1985 Dec)
59.^Craft IL, Geddes D, Hyde CW, Wise IJ, Matthews DMAbsorption and malabsorption of glycine and glycine peptides in manGut.(1968 Aug)
60.^Gannon MC, Nuttall JA, Nuttall FQThe metabolic response to ingested glycineAm J Clin Nutr.(2002 Dec)
61.^Gulliford MC, Bicknell EJ, Pover GG, Scarpello JHIntestinal glucose and amino acid absorption in healthy volunteers and noninsulin-dependent diabetic subjectsAm J Clin Nutr.(1989 Jun)
69.^Matthews DE, Conway JM, Young VR, Bier DMGlycine nitrogen metabolism in manMetabolism.(1981 Sep)
70.^Kikuchi G, Motokawa Y, Yoshida T, Hiraga KGlycine cleavage system: reaction mechanism, physiological significance, and hyperglycinemiaProc Jpn Acad Ser B Phys Biol Sci.(2008)
71.^Conter C, Rolland MO, Cheillan D, Bonnet V, Maire I, Froissart RGenetic heterogeneity of the GLDC gene in 28 unrelated patients with glycine encephalopathyJ Inherit Metab Dis.(2006 Feb)
72.^Jois M, Hall B, Fewer K, Brosnan JTRegulation of hepatic glycine catabolism by glucagonJ Biol Chem.(1989 Feb 25)
74.^Aragón C, López-Corcuera BGlycine transporters: crucial roles of pharmacological interest revealed by gene deletionTrends Pharmacol Sci.(2005 Jun)
75.^Betz H, Gomeza J, Armsen W, Scholze P, Eulenburg VGlycine transporters: essential regulators of synaptic transmissionBiochem Soc Trans.(2006 Feb)
76.^D'Souza DC, Singh N, Elander J, Carbuto M, Pittman B, Udo de Haes J, Sjogren M, Peeters P, Ranganathan M, Schipper JGlycine transporter inhibitor attenuates the psychotomimetic effects of ketamine in healthy males: preliminary evidenceNeuropsychopharmacology.(2012 Mar)
77.^Ribeiro CS, Reis M, Panizzutti R, de Miranda J, Wolosker HGlial transport of the neuromodulator D-serineBrain Res.(2002 Mar 8)
78.^Hayashi F, Takahashi K, Nishikawa TUptake of D- and L-serine in C6 glioma cellsNeurosci Lett.(1997 Dec 19)
81.^O'Brien JA, Berger AJCotransmission of GABA and glycine to brain stem motoneuronsJ Neurophysiol.(1999 Sep)
83.^Ghavanini AA, Mathers DA, Kim HS, Puil EDistinctive glycinergic currents with fast and slow kinetics in thalamusJ Neurophysiol.(2006 Jun)
85.^Muller E, Bakkar W, Martina M, Sokolovski A, Wong AY, Legendre P, Bergeron RVesicular storage of glycine in glutamatergic terminals in mouse hippocampusNeuroscience.(2013 Jul 9)
87.^Young AB, Snyder SHStrychnine binding associated with glycine receptors of the central nervous systemProc Natl Acad Sci U S A.(1973 Oct)
89.^Monyer H, Burnashev N, Laurie DJ, Sakmann B, Seeburg PHDevelopmental and regional expression in the rat brain and functional properties of four NMDA receptorsNeuron.(1994 Mar)
92.^Traynelis SF, Wollmuth LP, McBain CJ, Menniti FS, Vance KM, Ogden KK, Hansen KB, Yuan H, Myers SJ, Dingledine RGlutamate receptor ion channels: structure, regulation, and functionPharmacol Rev.(2010 Sep)
93.^Hollmann M, Boulter J, Maron C, Beasley L, Sullivan J, Pecht G, Heinemann SZinc potentiates agonist-induced currents at certain splice variants of the NMDA receptorNeuron.(1993 May)
95.^Dingledine R, Kleckner NW, McBain CJThe glycine coagonist site of the NMDA receptorAdv Exp Med Biol.(1990)
96.^Berger AJ, Dieudonné S, Ascher PGlycine uptake governs glycine site occupancy at NMDA receptors of excitatory synapsesJ Neurophysiol.(1998 Dec)
97.^Javitt DC, Heresco-Levy UAre glycine sites saturated in vivoArch Gen Psychiatry.(2000 Dec)
100.^Song W, Chattipakorn SC, McMahon LLGlycine-gated chloride channels depress synaptic transmission in rat hippocampusJ Neurophysiol.(2006 Apr)
101.^Danglot L, Rostaing P, Triller A, Bessis AMorphologically identified glycinergic synapses in the hippocampusMol Cell Neurosci.(2004 Dec)
102.^Brackmann M, Zhao C, Schmieden V, Braunewell KHCellular and subcellular localization of the inhibitory glycine receptor in hippocampal neuronsBiochem Biophys Res Commun.(2004 Nov 19)
103.^Galli A, Mori F, Bargellini M, Coppini LSodium-dependent release of exogenous glycine from preloaded rat hippocampal synaptosomesJ Neural Transm Gen Sect.(1993)
105.^Moura AP, Grings M, Dos Santos Parmeggiani B, Marcowich GF, Tonin AM, Viegas CM, Zanatta A, Ribeiro CA, Wajner M, Leipnitz GGlycine Intracerebroventricular Administration Disrupts Mitochondrial Energy Homeostasis in Cerebral Cortex and Striatum of Young RatsNeurotox Res.(2013 May 3)
106.^Busanello EN, Moura AP, Viegas CM, Zanatta A, da Costa Ferreira G, Schuck PF, Wajner MNeurochemical evidence that glycine induces bioenergetical dysfunctionNeurochem Int.(2010 Jul)
107.^Zanatta A, Schuck PF, Viegas CM, Knebel LA, Busanello EN, Moura AP, Wajner MIn vitro evidence that D-serine disturbs the citric acid cycle through inhibition of citrate synthase activity in rat cerebral cortexBrain Res.(2009 Nov 17)
109.^Heresco-Levy U, Ermilov M, Lichtenberg P, Bar G, Javitt DCHigh-dose glycine added to olanzapine and risperidone for the treatment of schizophreniaBiol Psychiatry.(2004 Jan 15)
113.^Bannai M, Kawai N, Ono K, Nakahara K, Murakami NThe effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteersFront Neurol.(2012 Apr 18)
114.^Zhong X, Li X, Qian L, Xu Y, Lu Y, Zhang J, Li N, Zhu X, Ben J, Yang Q, Chen QGlycine attenuates myocardial ischemia-reperfusion injury by inhibiting myocardial apoptosis in ratsJ Biomed Res.(2012 Sep)
115.^Schemmer P, Zhong Z, Galli U, Wheeler MD, Xiangli L, Bradford BU, Conzelmann LO, Forman D, Boyer J, Thurman RGGlycine reduces platelet aggregationAmino Acids.(2013 Mar)
116.^Ding Y, Svingen GF, Pedersen ER, Gregory JF, Ueland PM, Tell GS, Nygård OKPlasma Glycine and Risk of Acute Myocardial Infarction in Patients With Suspected Stable Angina PectorisJ Am Heart Assoc.(2015 Dec 31)
118.^Chen CY, Ching LC, Liao YJ, Yu YB, Tsou CY, Shyue SK, Chen YM, Lee TSDeficiency of glycine N-methyltransferase aggravates atherosclerosis in apolipoprotein E-null miceMol Med.(2012 Jul 18)
119.^Gall WE, Beebe K, Lawton KA, Adam KP, Mitchell MW, Nakhle PJ, Ryals JA, Milburn MV, Nannipieri M, Camastra S, Natali A, Ferrannini E, RISC Study Groupalpha-hydroxybutyrate is an early biomarker of insulin resistance and glucose intolerance in a nondiabetic populationPLoS One.(2010 May 28)
120.^Thalacker-Mercer AE, Ingram KH, Guo F, Ilkayeva O, Newgard CB, Garvey WTBMI, RQ, diabetes, and sex affect the relationships between amino acids and clamp measures of insulin action in humansDiabetes.(2014 Feb)
121.^Cheng S, Rhee EP, Larson MG, Lewis GD, McCabe EL, Shen D, Palma MJ, Roberts LD, Dejam A, Souza AL, Deik AA, Magnusson M, Fox CS, O'Donnell CJ, Vasan RS, Melander O, Clish CB, Gerszten RE, Wang TJMetabolite profiling identifies pathways associated with metabolic risk in humansCirculation.(2012 May 8)
122.^Lustgarten MS, Price LL, Phillips EM, Fielding RASerum glycine is associated with regional body fat and insulin resistance in functionally-limited older adultsPLoS One.(2013 Dec 31)
124.^Floegel A, Stefan N, Yu Z, Mühlenbruch K, Drogan D, Joost HG, Fritsche A, Häring HU, Hrabě de Angelis M, Peters A, Roden M, Prehn C, Wang-Sattler R, Illig T, Schulze MB, Adamski J, Boeing H, Pischon TIdentification of serum metabolites associated with risk of type 2 diabetes using a targeted metabolomic approachDiabetes.(2013 Feb)
125.^Seibert R, Abbasi F, Hantash FM, Caulfield MP, Reaven G, Kim SHRelationship between insulin resistance and amino acids in women and menPhysiol Rep.(2015 May)
126.^Xie W, Wood AR, Lyssenko V, Weedon MN, Knowles JW, Alkayyali S, Assimes TL, Quertermous T, Abbasi F, Paananen J, Häring H, Hansen T, Pedersen O, Smith U, Laakso M, MAGIC Investigators, DIAGRAM Consortium, GENESIS Consortium, RISC Consortium, Dekker JM, Nolan JJ, Groop L, Ferrannini E, Adam KP, Gall WE, Frayling TM, Walker MGenetic variants associated with glycine metabolism and their role in insulin sensitivity and type 2 diabetesDiabetes.(2013 Jun)
127.^Magnusson M, Wang TJ, Clish C, Engström G, Nilsson P, Gerszten RE, Melander ODimethylglycine Deficiency and the Development of DiabetesDiabetes.(2015 Aug)
128.^Irving BA, Carter RE, Soop M, Weymiller A, Syed H, Karakelides H, Bhagra S, Short KR, Tatpati L, Barazzoni R, Nair KSEffect of insulin sensitizer therapy on amino acids and their metabolitesMetabolism.(2015 Jun)
129.^Attobla MHBEGlycine supplementation to improve insulin sensitivity in humansMaster’s Thesis, University of Alabama at Birmingham.(2014)
130.^Cobb J, Eckhart A, Perichon R, Wulff J, Mitchell M, Adam KP, Wolfert R, Button E, Lawton K, Elverson R, Carr B, Sinnott M, Ferrannini EA novel test for IGT utilizing metabolite markers of glucose toleranceJ Diabetes Sci Technol.(2015 Jan)
131.^Sekhar RV, Patel SG, Guthikonda AP, Reid M, Balasubramanyam A, Taffet GE, Jahoor FDeficient synthesis of glutathione underlies oxidative stress in aging and can be corrected by dietary cysteine and glycine supplementationAm J Clin Nutr.(2011 Sep)
132.^Iverson JF, Gannon MC, Nuttall FQInteraction of ingested leucine with glycine on insulin and glucose concentrationsJ Amino Acids.(2014)
133.^Gameiro A, Reimann F, Habib AM, O'Malley D, Williams L, Simpson AK, Gribble FMThe neurotransmitters glycine and GABA stimulate glucagon-like peptide-1 release from the GLUTag cell lineJ Physiol.(2005 Dec 15)
134.^González-Ortiz M, Medina-Santillán R, Martínez-Abundis E, von Drateln CREffect of glycine on insulin secretion and action in healthy first-degree relatives of type 2 diabetes mellitus patientsHorm Metab Res.(2001 Jun)
135.^Bahmani F, Bathaie SZ, Aldavood SJ, Ghahghaei AGlycine therapy inhibits the progression of cataract in streptozotocin-induced diabetic ratsMol Vis.(2012)
139.^Labonte CC, Farsijani S, Marliss EB, Gougeon R, Morais JA, Pereira S, Bassil M, Winter A, Murphy J, Combs TP, Chevalier SPlasma Amino Acids vs Conventional Predictors of Insulin Resistance Measured by the Hyperinsulinemic ClampJ Endocr Soc.(2017 Apr 26)
140.^Wang-Sattler R, Yu Z, Herder C, Messias AC, Floegel A, He Y, Heim K, Campillos M, Holzapfel C, Thorand B, Grallert H, Xu T, Bader E, Huth C, Mittelstrass K, Döring A, Meisinger C, Gieger C, Prehn C, Roemisch-Margl W, Carstensen M, Xie L, Yamanaka-Okumura H, Xing G, Ceglarek U, Thiery J, Giani G, Lickert H, Lin X, Li Y, Boeing H, Joost HG, de Angelis MH, Rathmann W, Suhre K, Prokisch H, Peters A, Meitinger T, Roden M, Wichmann HE, Pischon T, Adamski J, Illig TNovel biomarkers for pre-diabetes identified by metabolomicsMol Syst Biol.(2012)
141.^Sekhar RV, McKay SV, Patel SG, Guthikonda AP, Reddy VT, Balasubramanyam A, Jahoor FGlutathione synthesis is diminished in patients with uncontrolled diabetes and restored by dietary supplementation with cysteine and glycineDiabetes Care.(2011 Jan)
142.^Cruz M, Maldonado-Bernal C, Mondragón-Gonzalez R, Sanchez-Barrera R, Wacher NH, Carvajal-Sandoval G, Kumate JGlycine treatment decreases proinflammatory cytokines and increases interferon-gamma in patients with type 2 diabetesJ Endocrinol Invest.(2008 Aug)
143.^Kasai K, Kobayashi M, Shimoda SIStimulatory effect of glycine on human growth hormone secretionMetabolism.(1978 Feb)
144.^Gromada J, Franklin I, Wollheim CBAlpha-cells of the endocrine pancreas: 35 years of research but the enigma remainsEndocr Rev.(2007 Feb)
145.^Li C, Liu C, Nissim I, Chen J, Chen P, Doliba N, Zhang T, Nissim I, Daikhin Y, Stokes D, Yudkoff M, Bennett MJ, Stanley CA, Matschinsky FM, Naji ARegulation of glucagon secretion in normal and diabetic human islets by γ-hydroxybutyrate and glycineJ Biol Chem.(2013 Feb 8)
148.^Schuette SA, Lashner BA, Janghorbani MBioavailability of magnesium diglycinate vs magnesium oxide in patients with ileal resectionJPEN J Parenter Enteral Nutr.(1994 Sep-Oct)
151.^Versiane O, Rodrigues BL, Ramos JM, Téllez CA, Felcman JSynthesis, molecular structure and vibrational spectra of a dimeric complex formed by cobalt and glycineSpectrochim Acta A Mol Biomol Spectrosc.(2006 Dec)