Graham HN. Green tea composition, consumption, and polyphenol chemistry. Prev Med 1992;21:334-50. View abstract.

Kakuda T, Yanase H, Utsunomiya K, et al. Protective effect of gamma-glutamylethylamide (theanine) on ischemic delayed neuronal death in gerbils. Neurosci Lett 2000;289:189-92. View abstract.

Kimura R, Murata T. Effect of theanine on norepinephrine and serotonin levels in rat brain. Chem Pharm Bull 1986;34:3053-57.

Yokogoshi H, Kobayashi M. Hypotensive effect of gamma-glutamylethylamide in spontaneously hypertensive rats. Life Sci 1998;62:1065-8. View abstract.

Sugiyama T, Sadzuka Y, Tanaka K, Sonobe T. Inhibition of glutamate transporter by theanine enhances the therapeutic efficacy of doxorubicin. Toxicol Lett 2000:121:89-96. View abstract.

Sadzuka Y, Sugiyama T, Sonobe T. Improvement of idarubicin induced antitumor activity and bone marrow suppression by theanine, a component of tea. Cancer Lett 2000;158:119-24. View abstract.

Sadzuka Y, Sugiyama T, Sonobe T. Efficacies of tea components on doxorubicin induced antitumor activity and reversal of multidrug resistance. Toxicol Lett 2000;114:155-62. View abstract.

Sugiyama T, Sadzuka Y. Combination of theanine with doxorobucin inhibits hepatic metastasis of M5076 ovarian sarcoma. Clin Cancer Res 1999;5:413-6. View abstract.

Kakuda T, Nozawa A, Unno T, et al. Inhibiting effects of theanine on caffeine stimulation evaluated by EEG in the rat. Biosci Biotechnol Biochem 2000;64:287-93. View abstract.

Yokozawa T, Oura H, Nakagawa H, et al. Effects of a component of green tea on the proliferation of vascular smooth muscle cells. Biosci Biotechnol Biochem 1995;59:2134-6. View abstract.

Yokozawa T, Dong E. Influence of green tea and its three major components upon low-density lipoprotein oxidation. Exp Toxicol Pathol 1997;49:329-35. View abstract.

Sadzuka Y, Sugiyama T, Miyagishima A, et al. The effects of theanine, as a novel biochemical modulator, on the antitumor activity of adriamycin. Cancer Lett 1996;105:203-9. View abstract.

Sugiyama T, Sadzuda Y. Enhancing effects of green tea components on the antitumor activity of adriamycin against M5076 ovarian sarcoma. Cancer Lett 1998;133:19-26. View abstract.

Yokogoshi H, Mochizuki M, Saitoh K. Theanine-induced reduction of brain serotonin concentration in rats. Biosci Biotechnol Biochem 1998;62:816-7. View abstract.

Zheng G, Sayama K, Okubo T, et al. Anti-obesity effects of three major components of green tea, catechins, caffeine and theanine, in mice. In Vivo 2004;18:55-62. View abstract.

Lu K, Gray MA, Oliver C, et al. The acute effects of L-theanine in comparison with alprazolam on anticipatory anxiety in humans. Hum Psychopharmacol 2004;19:457-65. View abstract.

Rogers, P. J., Smith, J. E., Heatherley, S. V., and Pleydell-Pearce, C. W. Time for tea: mood, blood pressure and cognitive performance effects of caffeine and theanine administered alone and together. Psychopharmacology (Berl) 2008;195(4):569-577. View abstract.

Haskell, C. F., Kennedy, D. O., Milne, A. L., Wesnes, K. A., and Scholey, A. B. The effects of L-theanine, caffeine and their combination on cognition and mood. Biol.Psychol. 2008;77(2):113-122. View abstract.

Giesbrecht, T., Rycroft, J. A., Rowson, M. J., and De Bruin, E. A. The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness. Nutr Neurosci. 2010;13(6):283-290. View abstract.

Sugiyama, T. and Sadzuka, Y. Theanine, a specific glutamate derivative in green tea, reduces the adverse reactions of doxorubicin by changing the glutathione level. Cancer Lett. 8-30-2004;212(2):177-184. View abstract.

Terashima, T., Takido, J., and Yokogoshi, H. Time-dependent changes of amino acids in the serum, liver, brain and urine of rats administered with theanine. Biosci.Biotechnol.Biochem. 1999;63(4):615-618. View abstract.

Sugiyama, T., Sadzuka, Y., Nagasawa, K., Ohnishi, N., Yokoyama, T., and Sonobe, T. Membrane transport and antitumor activity of pirarubicin, and comparison with those of doxorubicin. Jpn J Cancer Res 1999;90(7):775-780. View abstract.

Sadzuka, Y., Sugiyama, T., Suzuki, T., and Sonobe, T. Enhancement of the activity of doxorubicin by inhibition of glutamate transporter. Toxicol.Lett 9-15-2001;123(2-3):159-167. View abstract.

Kakuda, T. Neuroprotective effects of the green tea components theanine and catechins. Biol Pharm Bull 2002;25(12):1513-1518. View abstract.

Kakuda, T., Nozawa, A., Sugimoto, A., and 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):2683-2686. View abstract.

Kamath, A. B., Wang, L., Das, H., Li, L., Reinhold, V. N., and Bukowski, J. F. 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 U.S.A 5-13-2003;100(10):6009-6014. View abstract.

Sugiyama, T. and Sadzuka, Y. Theanine and glutamate transporter inhibitors enhance the antitumor efficacy of chemotherapeutic agents. Biochim.Biophys.Acta 12-5-2003;1653(2):47-59. View abstract.

Kimura, K., Ozeki, M., Juneja, L. R., and Ohira, H. L-Theanine reduces psychological and physiological stress responses. Biol Psychol. 2007;74(1):39-45. View abstract.

Egashira, N., Ishigami, N., Pu, F., Mishima, K., Iwasaki, K., Orito, K., Oishi, R., and Fujiwara, M. Theanine prevents memory impairment induced by repeated cerebral ischemia in rats. Phytother.Res 2008;22(1):65-68. View abstract.

Yang, Q. S., Xu, P. X., Li, Y. H., Jiang, S., Zhang, X., and Xue, M. [Effects of theanine and houpu extract in 7-day chick social separation-stress procedure]. Zhongguo Zhong.Yao Za Zhi. 2007;32(19):2040-2043. View abstract.

Yokogoshi, H., Kato, Y., Sagesaka, Y. M., Takihara-Matsuura, T., Kakuda, T., and Takeuchi, N. Reduction effect of theanine on blood pressure and brain 5-hydroxyindoles in spontaneously hypertensive rats. Biosci.Biotechnol.Biochem. 1995;59(4):615-618. View abstract.

Miyachi T, et al. Perioperative oral administration of cystine and theanine enhances recovery after distal gastrectomy: a prospective randomized trial. JPEN. 2013;37(3):384-391. View abstract.

Scheid L, et al. Kinetics of L-theanine uptake and metabolism in healthy participants are comparable after ingestion of L-theanin via capsules and green tea. J Nutr. 2012;142(12):2091-2096. View abstract.

Lyon MR, Kapoor MP, Juneja LR. The effects of L-theanine (Suntheanine®) on objective sleep quality in boys with attention deficit hyperactivity disorder (ADHD): a randomized, double-blind, placebo-controlled clinical trial. Altern Med Rev. 2011;16(4):348-354. View abstract.

Unno K, et al. Anti-stress effect of theanine on students during pharmacy practice: positive correlation among salivary a-amylase activity, trait anxiety and subjective stress. Pharmacol Biochem Behav. 2013;111:128-135. View abstract.

Yoto A, Motoki M, Murao S, Yokogoshi H. Effects of L-theanine or caffeine intake on changes in blood pressure under physical and psychological stresses. J Physiol Anthropol. 2012;31:28. View abstract.

Foxe JJ, et al. Assessing the effects of caffeine and theanine on the maintenance of vigilance during a sustained attention task. Neuropharmacology. 2012;62(7):2320-2327. View abstract.

Dodd FL, Kennedy DO, Riby LM, Haskell-Ramsay CF. A double-blind, placebo-controlled study evaluating the effects of caffeine and L-theanine both alone and in combination on cerebral blood flow, cognition and mood. Psychopharmacology. 2015;232(14):2563-2576. View abstract.

Camfield DA, Stough C, Farrimond J, Scholey AB. Actue effects of tea constituents L-theanine, caffeine, and epigallocatechin gallate on cognitive function and mood: a systematic review and meta-analysis. Nutr Rev. 2014;72(8):507-522. View abstract.

Sakato Y. The chemical constituents of tea: III. A new amide theanine. Nippon Nogei Kagakukaishi 1949;23:262-267.

Williams J, Kellett J, Roach PD, et al. L-theanine as a functional food additive: its role in disease prevention and health promotion. Beverages 2016;2(2):13.

Hidese S, Ota M, Wakabayashi C, et al. Effects of chronic l-theanine administration in patients with major depressive disorder: an open-label study. Acta Neuropsychiatr 2017;29(2):72-9. View abstract.

Kawada S, Kobayashi K, Ohtani M, Fukusaki C. Cystine and theanine supplementation restores high-intensity resistance exercise-induced attenuation of natural killer cell activity in well-trained men. J Strength Cond Res 2010;24(3):846-51. View abstract.

Murakami S, Kurihara S, Koikawa N, et al. Effects of oral supplementation with cystine and theanine on the immune function of athletes in endurance exercise: randomized, double-blind, placebo-controlled trial. Biosci Biotechnol Biochem 2009;73(4):817-21. View abstract.

Tsuchiya T, Honda H, Oikawa M, et al. Oral administration of the amino acids cystine and theanine attenuates the adverse events of S-1 adjuvant chemotherapy in gastrointestinal cancer patients. Int J Clin Oncol 2016;21(6):1085-90. View abstract.

Owen GN, Parnell H, De Bruin EA, Rycroft JA. The combined effects of L-theanine and caffeine on cognitive performance and mood. Nutr Neurosci 2008;11(4):193-8. View abstract.

Einöther SJ, Martens VE, Rycroft JA, De Bruin EA. L-theanine and caffeine improve task switching but not intersensory attention or subjective alertness. Appetite 2010;54(2):406-9. View abstract.

Kahathuduwa CN, Dassanayake TL, Amarakoon AMT, Weerasinghe VS. effects of theanine, caffeine and theanine-caffeine combination on attention. Nutr Neurosci 2017;20(6):369-77. View abstract.

Kelly SP, Gomez-Ramirez M, Montesi JL, Foxe JJ. L-theanine and caffeine in combination affect human cognition as evidenced by oscillatory alpha-band activity and attention task performance. J Nutr 2008;138(8):1572S-1577S. View abstract.

Park SK, Jung IC, Lee WK, et al. 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. J Med Food 2011;14(4):334-43. View abstract.

Ritsner MS, Miodownik C, Ratner Y, et al. 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 2011;72(1):34-42. View abstract.

Miodownik C, Maayan R, Ratner Y, et al. Serum levels of brain-derived neurotrophic factor and cortisol to sulfate of dehydroepiandrosterone molar ratio associated with clinical response to L-theanine as augmentation of antipsychotic therapy in schizophrenia and schizoaffective disorder patients. Clin Neuropharmacol 2011;34(4):155-60. View abstract.

Kardashev A, Ratner Y, Ritsner MS.Add-on pregnenolone with L-theanine to antipsychotic therapy relieves negative and anxiety symptoms of schizophrenia: an 8-week, randomized, double-blind, placebo-controlled trial. Clin Schizophr Relat Psychoses. 2018;12(1):31-41. doi: 10.3371/CSRP.KARA.070415. View abstract.

Hamaguchi R, Tsuchiya T, Miyata G, et al. Efficacy 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. 2019. View abstract.

Hidese S, Ogawa S, Ota M, et al. Effects of L-theanine administration on stress-related symptoms and cognitive functions in healthy adults: A randomized controlled trial. Nutrients. 2019;11(10). pii: E2362. View abstract.

Lin L, Zeng L, Liu A, et al. L-theanine regulates glucose, lipid, and protein metabolism via insulin and AMP-activated protein kinase signaling pathways. Food Funct. 2020;11(2):1798-1809. View abstract.

Kahathuduwa CN, Wakefield S, West BD, et al. Effects of L-theanine-caffeine combination on sustained attention and inhibitory control among children with ADHD: a proof-of-concept neuroimaging RCT. Sci Rep 2020;10(1):13072. View abstract.

Williams J, McKune AJ, Georgousopoulou EN, et al. The effect of L-theanine incorporated in a functional food product (mango sorbet) on physiological responses in healthy males: a pilot randomised controlled trial. Foods 2020;9(3):371. View abstract.

Sarris J, Byrne GJ, Cribb L, et al. L-theanine in the adjunctive treatment of generalized anxiety disorder: a double-blind, randomized, placebo-controlled trial. J Psych Res 2019;110:31-7. View abstract.

Baba Y, Inagaki S, Nakagawa S, Kaneko T, Kobayashi M, Takihara T. Effects of l-Theanine on Cognitive Function in Middle-Aged and Older Subjects: A Randomized Placebo-Controlled Study. J Med Food 2021;24(4):333-341. View abstract.

Evans M, McDonald AC, Xiong L, Crowley DC, Guthrie N. A Randomized, Triple-Blind, Placebo-Controlled, Crossover Study to Investigate the Efficacy of a Single Dose of AlphaWave(R) L-Theanine on Stress in a Healthy Adult Population. Neurol Ther 2021;10(2):1061-1078. View abstract.

Rizzo R, Prato A, Scerbo M, Saia F, Barone R, Curatolo P. Use of Nutritional Supplements Based on L-Theanine and Vitamin B6 in Children with Tourette Syndrome, with Anxiety Disorders: A Pilot Study. Nutrients 2022;14(4):852. View abstract.

Thiagarajah K, Chee HP, Sit NW. Effect of Alpha-S1-Casein Tryptic Hydrolysate and L-Theanine on Poor Sleep Quality: A Double Blind, Randomized Placebo-Controlled Crossover Trial. Nutrients 2022;14(3):652. View abstract.

Noah L, Morel V, Bertin C, et al. Effect of a Combination of Magnesium, B Vitamins, Rhodiola, and Green Tea (L-Theanine) on Chronically Stressed Healthy Individuals-A Randomized, Placebo-Controlled Study. Nutrients. 2022 Apr 29;14(9):1863. View abstract.

Küçükibrahimoglu E, Saygin MZ, Caliskan M, Kaplan OK, Unsal C, Gören MZ. The change in plasma GABA, glutamine and glutamate levels in fluoxetine- or S-citalopram-treated female patients with major depression. Eur J Clin Pharmacol. 2009 Jun;65(6):571-7. doi: 10.1007/s00228-009-0650-7. View abstract.

Brennan BP, Admon R, Perriello C, et al. Acute change in anterior cingulate cortex GABA, but not glutamine/glutamate, mediates antidepressant response to citalopram. Psychiatry Res Neuroimaging. 2017 Nov 30;269:9-16. View abstract.

Furushima D, Sugiyama I, Nomura Y, Unno K, Yamada H. Effect of Combined Ingestion of L-Theanine and L-Arginine for Short-Term Psychological Stress in Young Adults: A Randomized Placebo-Controlled Study. J Nutr Sci Vitaminol (Tokyo) 2022;68(6):540-546. View abstract.

Langan-Evans C, Hearris MA, Gallagher C, et al. Nutritional Modulation of Sleep Latency, Duration, and Efficiency: A Randomized, Repeated-Measures, Double-Blind Deception Study. Med Sci Sports Exerc 2023;55(2):289-300. View abstract.

Dassanayake TL, Wijesundara D, Kahathuduwa CN, Weerasinghe VS. Dose-response effect of L-theanine on psychomotor speed, sustained attention, and inhibitory control: a double-blind, placebo-controlled, crossover study. Nutr Neurosci 2022. View abstract.

Maloh J, Chakkalakal M, Sulaiman F, Burney W, Chambers CJ, Sivamani RK. Combining Topical and Oral Botanicals for Skin Redness, Pigmentation, Sleep, and Mood: A Randomized Controlled Study. J Clin Med 2022;11(22):6690. View abstract.

Okamoto H, Taniyama Y, Sakurai T, et al. Perioperative Administration of Cystine and Theanine Suppresses Inflammation and Facilitates Early Rehabilitation and Recovery after Esophagectomy: A Randomized, Double-Blind, Controlled Clinical Trial. Nutrients 2022;14(11):2319. View abstract.