Difference between revisions of "Theanine"

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'''Theanine''', also '''gamma-glutamylethylamide''' or '''5-N-ethyl-glutamine''', is an amino acid and a glutamic acid analog commonly found in [[tea]] (infusions of ''[[Camellia sinensis]]''), primarily in [[black tea]], and also in the basidiomycete mushroom ''Boletus badius'' and in guayusa. More specifically, this compound is called '''<small>L</small>-theanine''', being the L- amino acid (not to be confused with a levorotatory enantiomer). In 1950, the tea laboratory of Kyoto successfully separated theanine from [[gyokuro]] leaf, which has high theanine content. Theanine is an analog to glutamine and glutamate, and can cross the blood–brain barrier. It is sold in the US as a dietary supplement, and is classified by the FDA as a generally recognized as safe (GRAS) ingredient. However, the German Federal Institute for Risk Assessment (Bundesinstitut für Risikobewertung, BfR) has objected to the addition of isolated theanine to beverages.
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| ImageFile = Theanine.png
 
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| ImageFile_Ref = {{chemboximage|correct|??}}
 
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| ImageSize = 160
 
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| ImageName = Stereo, skeletal formula of theanine (S)
 
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| IUPACName = 2-Amino-4-(ethylcarbamoyl)butyric acid{{citation needed|date=July 2012}}
 
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| OtherNames = ''N''<sup>5</sup>-Ethyl-<small>L</small>-glutamine<ref>{{cite doi|10.1007/BF00231550}}</ref>
 
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| Section1 = {{chembox Identifiers
 
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|  CASNo = 3081-61-6
 
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|  CASNo_Ref = {{cascite|correct|??}}
 
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|  CASNo_Comment = <small>''S''</small>
 
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|  PubChem = 228398
 
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|  PubChem_Ref = {{pubchemcite|correct|pubchem}}
 
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|  PubChem1 = 9964226
 
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|  PubChem1_Ref = {{pubchemcite|correct|pubchem}}
 
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|  PubChem1_Comment = <small>''R''</small>
 
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|  PubChem2 = 439378
 
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|  PubChem2_Ref = {{pubchemcite|correct|pubchem}}
 
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|  PubChem2_Comment = <small>''S''</small>
 
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|  ChemSpiderID = 198778
 
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|  ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
 
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|  ChemSpiderID1 = 8139819
 
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|  ChemSpiderID1_Ref = {{chemspidercite|correct|chemspider}}
 
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|  ChemSpiderID1_Comment = <small>''R''</small>
 
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|  ChemSpiderID2 = 388498
 
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|  ChemSpiderID2_Ref = {{chemspidercite|correct|chemspider}}
 
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|  ChemSpiderID2_Comment = <small>''S''</small>
 
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|  UNII = 8021PR16QO
 
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|  UNII_Ref = {{fdacite|correct|FDA}}
 
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|  EINECS = 3081-61-6
 
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|  MeSHName = theanine
 
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|  ChEBI = 17394
 
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|  ChEBI_Ref = {{ebicite|correct|EBI}}
 
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|  SMILES = CC[nH]:c(:[o])CCC(N)c(:[o]):[oH]
 
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|  SMILES1 = CCNC(=O)CCC(N)C(O)=O
 
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|  StdInChI = 1S/C7H14N2O3/c1-2-9-6(10)4-3-5(8)7(11)12/h5H,2-4,8H2,1H3,(H,9,10)(H,11,12)
 
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|  StdInChI_Ref = {{stdinchicite|correct|chemspider}}
 
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|  StdInChIKey = DATAGRPVKZEWHA-UHFFFAOYSA-N
 
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|  StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
 
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}}
 
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| Section2 = {{chembox Properties
 
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|  C = 7
 
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|  H = 14
 
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|  N = 2
 
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|  O = 3
 
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}}
 
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| Section3 = {{chembox Related
 
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|  Function = alkanoic acids
 
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|  OtherFunctn = {{unbulleted list|[[Arginine]]|[[Pantothenic acid]]|[[Hopantenic acid]]}}
 
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|  OtherCpds = [[Panthenol]]
 
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'''Theanine''' ({{IPAc-en|icon|ˈ|θ|iː|ən|iː|n}}), also '''gamma-glutamylethylamide''' or '''5-N-ethyl-glutamine''', is an [[amino acid]] and a [[glutamic acid]] analog commonly found in [[tea]] (infusions of ''[[Camellia sinensis]]''), primarily in [[black tea]],<ref>{{cite journal|url=http://www.sciencedirect.com/science/article/pii/S0308814610011416|title=How much theanine in a cup of tea? Effects of tea type and method of preparation|date=15 March 2011|doi=10.1016/j.foodchem.2010.08.071|last1=Keenan|first1=Emma K.|last2=Finnie|first2=Mike D.A.|last3=Jones|first3=Paul S.|last4=Rogers|first4=Peter J.|last5=Priestley|first5=Caroline M.|journal=Food Chemistry|volume=125|issue=2|pages=588}}</ref> and also in the basidiomycete mushroom ''[[Boletus badius]]'' and in [[ilex guayusa|guayusa]].<ref name="casimir">{{cite journal |author=Casimir J, Jadot J, Renard M |title=[Separation and characterization of N-ethyl-gamma-glutamine from Xerocomus badius.] |journal=Biochim Biophys Acta |volume=39 |pages=462–8 |year=1960 |pmid=13808157 |doi=10.1016/0006-3002(60)90199-2 |issue=3}}</ref> More specifically, this compound is called '''<small>L</small>-theanine''', being the L- amino acid (not to be confused with a [[levorotatory]] [[enantiomer]]). In 1950, the tea laboratory of Kyoto successfully separated theanine from [[gyokuro]] leaf, which has high theanine content.{{citation needed|date=August 2012}} Theanine is an [[Structural analog|analog]] to [[glutamine]] and [[glutamate]], and can cross the [[blood–brain barrier]].<ref name="yokogoshi">{{cite journal |author=Yokogoshi H, Kobayashi M, Mochizuki M, Terashima T |title=Effect of theanine, r-glutamylethylamide, on brain monoamines and striatal dopamine release in conscious rats |journal=Neurochem Res |volume=23 |issue=5 |pages=667–73 |year=1998 |pmid=9566605 |doi=10.1023/A:1022490806093}}</ref>  It is sold in the US as a dietary supplement, and is classified by the [[FDA]] as a [[generally recognized as safe]] (GRAS) ingredient.<ref>{{cite web|url=http://www.nutraingredients-usa.com/Industry/FDA-confirms-GRAS-status-of-Suntheanine|title=FDA confirms GRAS status of Suntheanine|date=March 22, 2007|publisher=NutraIngredients-USA.com}}</ref> However, the German Federal Institute for Risk Assessment (Bundesinstitut für Risikobewertung, BfR) has objected to the addition of isolated theanine to beverages.<ref name="BfR"/>
 
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==Research==
 
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Early studies of theanine involved much larger doses than are found in an everyday cup of tea. Researchers wonder whether drinking tea might have the same effects found in those studies.<ref name=chicago/> However, one recent study by Unilever found that smaller doses typical of those found in a cup of tea did induce changes in alpha waves as shown by EEG.<ref>{{cite journal|last=Owen|first=GN|coauthors=Rao, Nobre|title=L-theanine, a natural constituent in tea, and its effect on mental state|journal=Asia Pac J Clin Nutr.|year=2008|url=http://www.ncbi.nlm.nih.gov/pubmed/18296328}}</ref> [[Alpha waves]] occur in the brain and are associated with relaxation.
 
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===Effects on the brain===
 
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Able to cross the [[blood–brain barrier]], theanine has [[psychoactive drug|psychoactive]] properties.<ref name="gomez">{{cite journal |author=Gomez-Ramirez M |title=The Deployment of Intersensory Selective Attention: A High-density Electrical Mapping Study of the Effects of Theanine |journal=Clin Neuropharmacol |volume=30 |issue=1 |pages=25–38 |year= 2007|pmid=17272967 |doi=10.1097/01.WNF.0000240940.13876.17 |last2=Higgins |first2=BA |last3=Rycroft |first3=JA |last4=Owen |first4=GN |last5=Mahoney |first5=J |last6=Shpaner |first6=M |last7=Foxe |first7=JJ}}</ref> Theanine has been studied for its potential ability to reduce mental and physical [[Stress (medicine)|stress]],<ref name="kimura">{{cite journal |author=Kimura K, Ozeki M, Juneja L, Ohira H |title=L-Theanine reduces psychological and physiological stress responses |journal=Biol Psychol |volume=74 |issue=1 |pages=39–45 |year=2007 |pmid=16930802 |doi=10.1016/j.biopsycho.2006.06.006}}</ref> improve cognition<ref>{{Cite journal | author = Park SK. Jung IC. Lee WK. Lee YS. Park HK. Go HJ. Kim K. Lim NK. Hong JT. Ly SY. Rho SS.  | title = A combination of green tea extract and l-theanine improves memory and attention in subjects with mild cognitive impairment: a double-blind placebo-controlled study | journal = Journal of Medicinal Food | volume = 14 | issue = 4 | pages = 334–343 | year = 2011 | doi = 10.1089/jmf.2009.1374 | pmid = 21303262}}</ref> and boost mood in a synergistic manner with [[caffeine]].<ref name="pmid18006208">{{cite journal |author=Haskell CF, Kennedy DO, Milne AL, Wesnes KA, Scholey AB |title=The effects of l-theanine, caffeine and their combination on cognition and mood |journal=Biol Psychol |volume=77 |issue=2 |pages=113–22 |year=2008 |pmid=18006208 |doi=10.1016/j.biopsycho.2007.09.008}}</ref><ref>{{cite web | url = http://www.sciencenews.org/view/generic/id/8965/title/Distracted%3F_Tea_might_help_your_focus | title = Distracted? Tea might help your focus | date = September 29th, 2007 | publisher = sciencenews.org | quote = John J. Foxe of the Nathan S. Kline Institute for Psychiatric Research in Orangeburg, N.Y., and his colleagues recruited 16 people for tests of attentiveness on four days. Before testing, each individual drank a glass of water. On 3 days, the drink was spiked with 100 milligrams of theanine, 60 mg of caffeine, or both. The theanine dose was equivalent to that in 4 to 5 cups of tea, and the caffeine translated to about 2.5 cups of tea. In the difficult tests, participants watched a computer screen and pressed a button when a designated shape appeared on the side of a busy visual field to which an arrow had previously pointed. Participants' accuracy differed little between days when they got water alone or with only one additive. Accuracy improved dramatically, however, on the day that they got the theanine-caffeine combination. The attention benefit lasted throughout the 3 hours of testing.}}</ref>
 
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While structurally related to the excitatory neurotransmitter glutamate, theanine only has weak affinity for the glutamate receptor on postsynaptic cells.<ref>{{cite journal | author = 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 | journal = Biosci Biotechnol Biochem | year = 2002 | volume = 66 | issue = 12 | pages = 2683–2686 | doi = 10.1271/bbb.66.2683 | pmid = 12596867 | title = Inhibition by theanine of binding of 3HAMPA, 3Hkainate, and 3HMDL 105,519 to glutamate receptors}}</ref> Rather, its primary effect seems to increase the overall level of the brain inhibitory transmitter [[GABA]]{{fact|date=October 2012}}. Theanine also increases brain [[dopamine]] levels and has a low affinity for [[AMPA receptor|AMPA]], [[Kainate receptor|kainate]] and [[NMDA receptor]]s.<ref name="nathan">{{cite journal |author=Nathan P, Lu K, Gray M, Oliver C |title=The neuropharmacology of L-theanine(N-ethyl-L-glutamine): a possible [[neuroprotective]] and cognitive enhancing agent |journal=J Herb Pharmacother |volume=6 |issue=2 |pages=21–30 |year=2006 |pmid=17182482 |doi=10.1300/J157v06n02_02}}</ref> 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.<ref>{{cite journal | author = Yokogoshi H, Mochizuki M, Saitoh K | title = Theanine-induced reduction of brain serotonin concentration in rats | journal = Biosci Biotechnol Biochem | year = 1998 | volume = 62 | issue = 4 | pages = 816–817 | doi = 10.1271/bbb.62.816 | pmid = 9614715}}</ref><ref>{{cite journal | author = Yokogoshi H, Kobayashi M, Mochizuki M, Terashima T | title = Effect of theanine, γ-glutamylethylamide, on brain monoamines and striatal dopamine release in conscious rats | journal = Neurochem Res | year = 1998 | volume = 23 | issue = 5 | pages = 667–673 | doi = 10.1023/A:1022490806093 | pmid = 9566605}}</ref> It has also been found that injecting spontaneously hypertensive mice with theanine significantly lowered levels of [[5-hydroxyindole]]s in the brain.<ref name="yokogoshi-5hydroxyindoles">{{cite journal |author=Yokogoshi H, Kato Y, Sagesaka YM, Takihara-Matsuura T, Kakuda T, Takeuchi N |title=Reduction effect of theanine on blood pressure and brain 5-hydroxyindoles in spontaneously hypertensive rats |journal=Biosci Biotechnol Biochem. |volume=59 |issue=4 |pages=615–618 |year=1995 |pmid=7539642 |doi=10.1271/bbb.59.615}}</ref>  Researchers also speculate it may inhibit [[glutamic acid]] [[excitotoxicity]].<ref name="nathan" /> Theanine also promotes [[alpha wave]] production in the brain.<ref name="gomez" />
 
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Studies on test rats have shown even repeated, extremely high doses of theanine cause little to no harmful psychological or physical effects.<ref name="borzelleca">{{cite journal |author=Borzelleca J, Peters D, Hall W |title=A 13-week dietary toxicity and toxicokinetic study with L-theanine in rats |journal=Food Chem Toxicol |volume=44 |issue=7 |pages=1158–66 |year=2006 |pmid=16759779 |doi=10.1016/j.fct.2006.03.014}}</ref> Theanine showed neuroprotective effects in one rat study.<ref name="pmid17705146">{{cite journal |author=Egashira N |title=Theanine prevents memory impairment induced by repeated cerebral ischemia in rats |journal=Phytother Res |volume=22 |issue=1 |pages=65–8 |year=2008 |pmid=17705146 |doi=10.1002/ptr.2261 |author-separator=, |author2=Ishigami N |author3=Pu F |display-authors=3 |last4=Mishima |first4=Kenichi |last5=Iwasaki |first5=Katsunori |last6=Orito |first6=Kensuke |last7=Oishi |first7=Ryozo |last8=Fujiwara |first8=Michihiro}}</ref>
 
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A placebo-controlled trial has shown adding theanine to ongoing [[antipsychotic]] medication is helpful in reducing some symptoms of [[schizophrenia]].<ref name="BfR">{{cite | author=Egashira N, Ishigami N, Pu F, ''et al.'' |web|url=http://www.stanleyresearch.org/Trial/Drug/awardedtrialdetail.aspx?id=252|title=L-Theanine relieves positive, activation, and anxiety symptoms in patients with schizophrenia and schizoaffective disorder: an 8-week, randomized, double-blind, placebo-controlled, 2-center study, J Clin Psychiatry 2010;71:1-9.|publisher=Stanley Research}}</ref>
 
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Several beverage manufacturers are selling drinks containing theanine and are marketing them as drinks to help people focus and concentrate,<ref name=chicago>{{cite news|url=http://articles.chicagotribune.com/2009-05-17/features/0905130394_1_theanine-caffeine-content-dr-jack-f-bukowski|title=L-theanine: New drinks promise focus, but more research attention needed|first=Shari|last=Roan|date=May 17, 2009|publisher=Chicago Tribune}}</ref> while other manufacturers claim relaxing and tranquillizing properties.<ref name="BfR" />
 
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===Immune system effects===
 
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<small>L</small>-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, 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 the production of antibacterial proteins was up to five times higher in the tea drinkers, an indicator of a stronger immune response.<ref>{{cite journal |author=Kamath A, Wang L, Das H, Li L, Reinhold V, Bukowski J |title=Antigens in tea-beverage prime human Vgamma 2Vdelta 2 T cells in vitro and in vivo for memory and nonmemory antibacterial cytokine responses |journal=Proc Natl Acad Sci USA |volume=100 |issue=10 |pages=6009–14 |year=2003 |pmid=12719524 |doi=10.1073/pnas.1035603100 |pmc=156317}}</ref>
 
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==As a supplement==
 
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In 2003, the German Federal Institute for Risk Assessment (''Bundesinstitut für Risikobewertung'', BfR) objected to the addition of isolated theanine to beverages. The institute stated the amount of theanine consumed by regular drinkers of tea or coffee is virtually impossible to determine. While it was estimated the quantity of [[green tea]] consumed by the average Japanese tea drinker per day contains about 20&nbsp;mg of the substance, there are no studies measuring the amount of theanine being extracted by typical preparation methods, or the percentage lost by discarding the first infusion. Therefore, with the Japanese being exposed to possibly much less than 20&nbsp;mg per day, and Europeans presumably even less, [[pharmacological]] reactions to drinks typically containing 50&nbsp;mg of theanine per 500 millilitres cannot be excluded, in the opinion of the BfR. Such reactions could include impairment of [[psychomotor]] skills and amplification of the [[sedating]] effects of alcohol and [[hypnotics]].<ref name="BfR">{{cite web|url=http://www.bfr.bund.de/cm/208/getraenke_mit_isoliertem_l_theanin.pdf|title=Getränke mit isoliertem L-Theanin|trans_title=Beverages with isolated L-theanine|publisher=Bundesinstitut für Risikobewertung|language=German|date=August 2003}}</ref>
 
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In 2006, a study found no consistent, statistically significant treatment-related adverse effects on behavior, morbidity, mortality, body weight, food consumption and efficiency, clinical chemistry, [[hematology]], or [[urinalysis]] in rats fed high doses of theanine for 13 weeks.<ref name="borzelleca"/> Large studies in humans have not been undertaken.
 
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Theanine has also been found to have [[mast cell]]-stabilizing properties in an animal model.<ref>{{cite journal|pmid=21344174|year=2012|last1=Kim|first1=NH|last2=Jeong|first2=HJ|last3=Kim|first3=HM|title=Theanine is a candidate amino acid for pharmacological stabilization of mast cells|volume=42|issue=5|pages=1609–18|doi=10.1007/s00726-011-0847-9|journal=Amino acids}}</ref>
 
  
 
==See also==
 
==See also==
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Latest revision as of 06:17, 8 November 2013

Theanine, also gamma-glutamylethylamide or 5-N-ethyl-glutamine, is an amino acid and a glutamic acid analog commonly found in tea (infusions of Camellia sinensis), primarily in black tea, and also in the basidiomycete mushroom Boletus badius and in guayusa. More specifically, this compound is called L-theanine, being the L- amino acid (not to be confused with a levorotatory enantiomer). In 1950, the tea laboratory of Kyoto successfully separated theanine from gyokuro leaf, which has high theanine content. Theanine is an analog to glutamine and glutamate, and can cross the blood–brain barrier. It is sold in the US as a dietary supplement, and is classified by the FDA as a generally recognized as safe (GRAS) ingredient. However, the German Federal Institute for Risk Assessment (Bundesinstitut für Risikobewertung, BfR) has objected to the addition of isolated theanine to beverages.

See also

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