Theanine
•Last Updated: September 28 2022
L-theanine is a naturally occurring, non-protein amino acid found in tea that promotes relaxation by reducing stress and anxiety levels. Although L-theanine is not a sedative and does not cause drowsiness, it may help improve sleep quality by promoting a more relaxed state. L-theanine supplementation has also been shown to have positive effects on aspects of cognitive function, especially when taken with caffeine.
Theanine is most often used for
Last Updated: September 28 2022
L-theanine is a naturally occurring non-proteinogenic amino acid that is found in tea and other natural sources. Unlike the 20 standard proteinogenic amino acids that are encoded in the genetic code and incorporated into proteins in the body, non-proteinogenic amino acids such as L-theanine are not used as building blocks for protein synthesis. Depending on the type of tea, L-theanine content is generally present in amounts under 50 mg per serving. When higher doses are desired, L-theanine is also commonly taken as a dietary supplement.
The main benefits of L-theanine are associated with promoting a relaxed state without causing drowsiness. L-theanine may also have mild cognitive-enhancing effects, especially when taken with caffeine.[1] L-theanine has also been shown to suppress the blood pressure increasing effects of caffeine[2] and may also counteract blood pressure increases under stressful conditions.[3] Though it does not provide any sedative-like effects, L-theanine enhances sleep quality by promoting a more relaxed state in the brain.[4]
L-theanine has remarkably low toxicity, with one rodent study failing to find any toxic effects at 4,000 mg of L-theanine per kg of body weight daily for 13 weeks.[5] Additional animal studies have reported similar results with no observed toxicity at remarkably high doses, and L-theanine seems to be equally well-tolerated in humans, with no known reports of adverse effects or toxicity. Due to the ability of L-theanine to reduce blood pressure in certain contexts, people taking prescription blood pressure medication should consult with their physician before taking L-theanine supplements.
After consumption, L-theanine can cross the blood-brain barrier[6] and affect brain activity by promoting increased alpha-waves,[7] a pattern of brain activity associated with a more relaxed state. The tendency of L-theanine to increase alpha waves may explain its stress and anxiety reducing effects.[8] In animal studies, L-theanine has been shown to affect neurotransmitter signaling in the brain, but these effects have been less explored in humans. The mechanisms behind the synergistic effect of L-theanine and caffeine on cognition are not completely understood, but its relaxation-promoting properties are likely responsible for the reduced anxiousness and jitters associated with caffeine use.
Note that Theanine is also known as:
- L-Theanine
- 5-N-Ethyl-Glutamine
- γ-glutamylethylamide
L-Theanine tends to be taken in the dosage of 100-200mg, usually alongside caffeine
Evidence + Benefits at a glance
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Research feed
1.^Gail N Owen, Holly Parnell, Eveline A De Bruin, Jane A RycroftThe combined effects of L-theanine and caffeine on cognitive performance and moodNutr Neurosci.(2008 Aug)
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7.^Manuel Gomez-Ramirez, Beth A Higgins, Jane A Rycroft, Gail N Owen, Jeannette Mahoney, Marina Shpaner, John J FoxeThe deployment of intersensory selective attention: a high-density electrical mapping study of the effects of theanineClin Neuropharmacol.(Jan-Feb 2007)
8.^Shinsuke Hidese, Shintaro Ogawa, Miho Ota, Ikki Ishida, Zenta Yasukawa, Makoto Ozeki, Hiroshi KunugiEffects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled TrialNutrients.(2019 Oct 3)
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35.^The acute effects of L-theanine in comparison with alprazolam on anticipatory anxiety in humans.()
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37.^Gomez-Ramirez M, Higgins BA, Rycroft JA, Owen GN, Mahoney J, Shpaner M, Foxe JJThe deployment of intersensory selective attention: a high-density electrical mapping study of the effects of theanineClin Neuropharmacol.(2007 Jan-Feb)
38.^Visual spatial attention tracking using high-density SSVEP data for independent brain-computer communication.()
39.^Kelly SP, Lalor EC, Reilly RB, Foxe JJIncreases in alpha oscillatory power reflect an active retinotopic mechanism for distracter suppression during sustained visuospatial attentionJ Neurophysiol.(2006 Jun)
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41.^Kimura R, Murata TEffect of theanine on norepinephrine and serotonin levels in rat brainChem Pharm Bull (Tokyo).(1986 Jul)
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48.^Kim TI, Lee YK, Park SG, Choi IS, Ban JO, Park HK, Nam SY, Yun YW, Han SB, Oh KW, Hong JTl-Theanine, an amino acid in green tea, attenuates beta-amyloid-induced cognitive dysfunction and neurotoxicity: reduction in oxidative damage and inactivation of ERK/p38 kinase and NF-kappaB pathwaysFree Radic Biol Med.(2009 Dec 1)
49.^Schallier A, Vermoesen K, Loyens E, Van Liefferinge J, Michotte Y, Smolders I, Massie AL-Theanine intake increases threshold for limbic seizures but decreases threshold for generalized seizuresNutr Neurosci.(2013 Mar)
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52.^Takeda A, Tamano H, Suzuki M, Sakamoto K, Oku N, Yokogoshi HUnique induction of CA1 LTP components after intake of theanine, an amino acid in tea leaves and its effect on stress responseCell Mol Neurobiol.(2012 Jan)
53.^Tian X, Sun L, Gou L, Ling X, Feng Y, Wang L, Yin X, Liu YProtective effect of l-theanine on chronic restraint stress-induced cognitive impairments in miceBrain Res.(2013 Mar 29)
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61.^Owen GN, Parnell H, De Bruin EA, Rycroft JAThe combined effects of L-theanine and caffeine on cognitive performance and moodNutr Neurosci.(2008 Aug)
62.^Giesbrecht T, Rycroft JA, Rowson MJ, De Bruin EAThe combination of L-theanine and caffeine improves cognitive performance and increases subjective alertnessNutr Neurosci.(2010 Dec)
63.^Foxe JJ, Morie KP, Laud PJ, Rowson MJ, de Bruin EA, Kelly SPAssessing the effects of caffeine and theanine on the maintenance of vigilance during a sustained attention taskNeuropharmacology.(2012 Jun)
64.^Haskell CF, Kennedy DO, Milne AL, Wesnes KA, Scholey ABThe effects of L-theanine, caffeine and their combination on cognition and moodBiol Psychol.(2008 Feb)
65.^Einöther SJ, Martens VE, Rycroft JA, De Bruin EAL-theanine and caffeine improve task switching but not intersensory attention or subjective alertnessAppetite.(2010 Apr)
66.^Intestinal transport of pure theanine and theanine in green tea extract: Green tea components inhibit theanine absorption and promote theanine excretion.()
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74.^Reo Hamaguchi, Takashi Tsuchiya, Go Miyata, Toshihiko Sato, Kenichi Takahashi, Koh Miura, Hiroshi Oshio, Hisatsugu Ohori, Keisuke Ariyoshi, Shunsuke Oyamada, Satoru IwaseEfficacy of oral administration of cystine and theanine in colorectal cancer patients undergoing capecitabine-based adjuvant chemotherapy after surgery: a multi-institutional, randomized, double-blinded, placebo-controlled, phase II trial (JORTC-CAM03)Support Care Cancer.(2020 Aug)
75.^Javier Zaragoza, Grant Tinsley, Stacie Urbina, Katelyn Villa, Emily Santos, Angelie Juaneza, Matthias Tinnin, Cory Davidson, Susan Mitmesser, Zhiying Zhang, Lem TaylorEffects of acute caffeine, theanine and tyrosine supplementation on mental and physical performance in athletesJ Int Soc Sports Nutr.(2019 Nov 26)
76.^Takashi Tsuchiya, Hiroshi Honda, Masaya Oikawa, Tetsuya Kakita, Atsushi Oyama, Hidekazu Oishi, Katsuyuki Tochikubo, Takanao Hashimoto, Shigekazu Kurihara, Tetsuro Shibakusa, Takashi KayaharaOral administration of the amino acids cystine and theanine attenuates the adverse events of S-1 adjuvant chemotherapy in gastrointestinal cancer patientsInt J Clin Oncol.(2016 Dec)
77.^Adasa Kardashev, Yael Ratner, Michael S RitsnerAdd-On Pregnenolone with L-Theanine to Antipsychotic Therapy Relieves Negative and Anxiety Symptoms of Schizophrenia: An 8-Week, Randomized, Double-Blind, Placebo-Controlled TrialClin Schizophr Relat Psychoses.(Spring 2018)
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79.^Shigeo Kawada, Kando Kobayashi, Masaru Ohtani, Chiho FukusakiCystine and theanine supplementation restores high-intensity resistance exercise-induced attenuation of natural killer cell activity in well-trained menJ Strength Cond Res.(2010 Mar)
80.^Shigeki Murakami, Shigekazu Kurihara, C Alan Titchenal, Masaru OhtaniSuppression of exercise-induced neutrophilia and lymphopenia in athletes by cystine/theanine intake: a randomized, double-blind, placebo-controlled trialJ Int Soc Sports Nutr.(2010 Jun 4)
81.^T Giesbrecht, J A Rycroft, M J Rowson, E A De BruinThe combination of L-theanine and caffeine improves cognitive performance and increases subjective alertnessNutr Neurosci.(2010 Dec)
82.^David J White, Suzanne de Klerk, William Woods, Shakuntla Gondalia, Chris Noonan, Andrew B ScholeyAnti-Stress, Behavioural and Magnetoencephalography Effects of an L-Theanine-Based Nutrient Drink: A Randomised, Double-Blind, Placebo-Controlled, Crossover TrialNutrients.(2016 Jan 19)
83.^Park SK, Jung IC, Lee WK, Lee YS, Park HK, Go HJ, Kim K, Lim NK, Hong JT, Ly SY, Rho SSA combination of green tea extract and l-theanine improves memory and attention in subjects with mild cognitive impairment: a double-blind placebo-controlled studyJ Med Food.(2011 Apr)
84.^Tomohiro Miyachi, Takashi Tsuchiya, Atsushi Oyama, Takahiro Tsuchiya, Naomi Abe, Atsuko Sato, Yasumasa Chiba, Shigekazu Kurihara, Tetsuro Shibakusa, Takashi MikamiPerioperative oral administration of cystine and theanine enhances recovery after distal gastrectomy: a prospective randomized trialJPEN J Parenter Enteral Nutr.(May-Jun 2013)
85.^A F Cicero, M Bove, A Colletti, M Rizzo, F Fogacci, M Giovannini, C BorghiShort-Term Impact of a Combined Nutraceutical on Cognitive Function, Perceived Stress and Depression in Young Elderly with Cognitive Impairment: A Pilot, Double-Blind, Randomized Clinical TrialJ Prev Alzheimers Dis.(2017)
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