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Systematic (IUPAC) name
2-Amino-4-(ethylcarbamoyl)butyric acid
CAS number 3081-61-6
ATC code none
PubChem 228398
ChemSpider 388498
Chemical data
Formula C7H14N2O3 
Mol. mass 174.20 g/mol
SMILES eMolecules & PubChem
Synonyms L-theanine, N-ethyl-L-glutamine
Physical data
Melt. point 117 °C (243 °F)
Therapeutic considerations
Pregnancy cat.  ?
Legal status legal
Routes oral

Theanine (pronounced /ˈθiənin/) (gamma-glutamylethylamide, or 5-N-ethyl-glutamine) is a glutamic acid analog or amino acid derivative commonly found in tea (infusions of Camellia sinensis), and also in the basidiomycete mushroom Boletus badius.[1] In 1950 the Tea laboratory of Kyoto successfully separated theanine from Gyokuro leaf, which has the highest theanine content among all teas. Theanine is an analog to glutamine and glutamate, and can cross the blood-brain barrier.[2] It is sold in the US as a dietary supplement and is FDA confirmed as Generally recognized as safe (GRAS).[3] The Japanese Ministry of Health and Welfare approved the use of L-theanine (the levorotary enantiomer of theanine) in 1964.[4]


Effects on the brain

Able to cross the blood-brain barrier, theanine has psychoactive properties.[5] Theanine has been shown to reduce mental and physical stress[6], and improves cognition and mood in a synergistic manner with caffeine.[7]

While structurally related to the excitatory neurotransmitter glutamate, theanine only has weak affinity for the glutamate receptor on post-synaptic cells.[8] Rather, its primary effect seems to increase the overall level of the brain inhibitory transmitter GABA. Theanine also increases brain dopamine levels and has micromolar affinities for AMPA, kainate and NMDA receptors.[9] Its effect on serotonin is still a matter of debate in the scientific community, with studies showing increases and decreases in brain serotonin levels using similar experimental protocols.[10][11] It has also been found that injecting spontaneously hypertensive mice with theanine significantly lowered levels of 5-hydroxyindoles in the brain.[12] Researchers also speculate that it may inhibit glutamic acid excitotoxicity.[9] Theanine also promotes alpha wave production in the brain.[5]

Studies on test rats have shown that even repeated, extremely high doses of theanine cause little to no harmful psychological or physical effects.[13] Theanine showed neuroprotective effects in one rat study.[14]

Several beverage manufacturers are selling drinks containing theanine and are marketing them as drinks that help people focus and concentrate.[15]

Immune system benefits

L-Theanine may help the body's immune response to infection by boosting the disease-fighting capacity of gamma delta T cells. The study, published in 2003 by the Brigham and Women's Hospital, included a four-week trial with 11 coffee drinkers and 10 tea drinkers, who consumed 600 milliliters of coffee or black tea daily. Blood sample analysis found that the production of anti-bacterial proteins was up to five times higher in the tea-drinkers, an indicator of a stronger immune response.[16]

According to a study conducted by researchers at Johns Hopkins University, when gophers were given 25 milligrams of theanine twice daily for three weeks there were increased levels of theta waves within the hypothalamus, indicating improved cognition and memory versus placebo.[17]

See also


  1. ^ Casimir J, Jadot J, Renard M (1960). "[Separation and characterization of N-ethyl-gamma-glutamine from Xerocomus badius.]". Biochim Biophys Acta 39: 462–8. doi:10.1016/0006-3002(60)90199-2. PMID 13808157. 
  2. ^ Yokogoshi H, Kobayashi M, Mochizuki M, Terashima T (1998). "Effect of theanine, r-glutamylethylamide, on brain monoamines and striatal dopamine release in conscious rats". Neurochem Res 23 (5): 667–73. doi:10.1023/A:1022490806093. PMID 9566605. 
  3. ^ "FDA confirms GRAS status of Suntheanine". March 22, 2007. 
  4. ^ Perrini, Carolyn. "L-Theanine: How a Unique Anxiety Reducer and Mood Enhancer Increases Alpha Waves and Alertness". Okinawa Tea Company. 
  5. ^ a b Gomez-Ramirez M; Higgins, BA; Rycroft, JA; Owen, GN; Mahoney, J; Shpaner, M; Foxe, JJ (2007). "The Deployment of Intersensory Selective Attention: A High-density Electrical Mapping Study of the Effects of Theanine". Clin Neuropharmacol 30 (1): 25–38. doi:10.1097/01.WNF.0000240940.13876.17. PMID 17272967. 
  6. ^ Kimura K, Ozeki M, Juneja L, Ohira H (2007). "L-Theanine reduces psychological and physiological stress responses". Biol Psychol 74 (1): 39–45. doi:10.1016/j.biopsycho.2006.06.006. PMID 16930802. 
  7. ^ Haskell CF, Kennedy DO, Milne AL, Wesnes KA, Scholey AB (2008). "The effects of l-theanine, caffeine and their combination on cognition and mood". Biol Psychol 77 (2): 113–22. doi:10.1016/j.biopsycho.2007.09.008. PMID 18006208. 
  8. ^ Kakuda T, Nozawa A, Sugimoto A, Niino H. Inhibition by theanine of binding of [3H] AMPA, [3H] kainate, and [3H]MDL 105,519 to glutamate receptors. Biosci Biotechnol Biochem. 2002;66(12):2683-6.
  9. ^ a b Nathan P, Lu K, Gray M, Oliver C (2006). "The neuropharmacology of L-theanine(N-ethyl-L-glutamine): a possible neuroprotective and cognitive enhancing agent". J Herb Pharmacother 6 (2): 21–30. doi:10.1300/J157v06n02_02. PMID 17182482. 
  10. ^ Yokogoshi H, Mochizuki M, Saitoh K. Theanine-induced reduction of brain serotonin concentration in rats. Biosci Biotechnol Biochem. 1998;62(4):816-7.
  11. ^ Yokogoshi H, Kobayashi M, Mochizuki M, Terashima T. Effect of theanine, γ-glutamylethylamide, on brain monoamines and striatal dopamine release in conscious rats. Neurochem Res. 1998;23(5):667-73.
  12. ^ Yokogoshi H, Kato Y, Sagesaka YM, Takihara-Matsuura T, Kakuda T, Takeuchi N (1995). "Reduction effect of theanine on blood pressure and brain 5-hydroxyindoles in spontaneously hypertensive rats.". Biosci Biotechnol Biochem. 59 (4): 615–618. doi:10.1271/bbb.59.615. PMID 7539642. 
  13. ^ Borzelleca J, Peters D, Hall W (2006). "A 13-week dietary toxicity and toxicokinetic study with L-theanine in rats". Food Chem Toxicol 44 (7): 1158–66. doi:10.1016/j.fct.2006.03.014. PMID 16759779. 
  14. ^ Egashira N, Ishigami N, Pu F, et al. (2008). "Theanine prevents memory impairment induced by repeated cerebral ischemia in rats". Phytother Res 22 (1): 65–8. doi:10.1002/ptr.2261. PMID 17705146. 
  15. ^ Roan, Shari (May 17, 2009). "L-theanine: New drinks promise focus, but more research attention needed". Chicago Tribune.,0,2196283.story. 
  16. ^ Kamath A, Wang L, Das H, Li L, Reinhold V, Bukowski J (2003). "Antigens in tea-beverage prime human Vgamma 2Vdelta 2 T cells in vitro and in vivo for memory and nonmemory antibacterial cytokine responses". Proc Natl Acad Sci USA 100 (10): 6009–14. doi:10.1073/pnas.1035603100. PMID 12719524. 
  17. ^ Kamath, AB; Wang, L; Das, H; Li, L; Reinhold, VN; Bukowski, JF (2003). "Antigens in tea-beverage prime human Vgamma 2Vdelta 2 T cells in vitro and in vivo for memory and nonmemory antibacterial cytokine responses.". Proc Natl Acad Sci USA 100 (10): 6009–14. doi:10.1073/pnas.1035603100. PMID 12719524. 


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