GENEMEDICS APP

GENEMEDICS NUTRITION

HEALTH LIBRARY

L-theanine

L-theanine is an amino acid that is commonly present in green tea and in small amounts in Bay Bolete mushrooms. This compound is believed to be responsible for the “umami” flavor of green tea. Aside from its soothing taste, L-theanine promotes relaxation and helps the body fight stress by affecting the levels of brain chemicals or neurotransmitters such as dopamine (regulates mood, sleep and emotion) and the stress hormone cortisol. For people who don’t regularly consume tea products, L-theanine is also available in pill or tablet form at many health food stores.

Overall Health Benefits of L-theanine

  • Improves Cognitive Function [1-13]
  • Improves Mood [14-23]
  • Fights Stress [24-27]
  • Improves Sleep Quality and Fights Insomnia [28-34]
  • Boosts Immune Function [35-42]
  • Fights Cancer and Aids in Cancer Treatment [43-50]

How does L-theanine Work?

This amino acid impacts nerve impulses and aids in the release of brain neurotransmitters. A change in the process of nerve cell communication and balance of these brain chemicals is thought to positively affect overall mood and reduce stress levels.

Proven Health Benefits of L-theanine

Improves Cognitive Function

L-theanine is a nootropic or cognitive enhancer. Studies show that consumption of this compound can help improve various cognitive parameters:

  1. In young adults, supplementation with 97 mg of L-theanine improved focus attention during a demanding cognitive task. [1]
  2. In healthy male volunteers, L-theanine supplementation at dose of 200 mg improved cognitive and neurophysiological measures of selective attention. [2]
  3. In men and women with mild cognitive impairment, a combination of L-theanine and green tea extract improved memory in a test assessing recognition and increased the levels of brain theta waves, an indicator of cognitive alertness. [3]
  4. In healthy volunteers, L-theanine administration improved speed and accuracy of performance of the attention-switching task and reduced the rate of errors in the memory task. [4]
  5. In healthy, young participants, L-theanine administration at a dose of 500 mg improved mental alertness and increased alpha activity in the electroencephalogram, which is indicative of improved attention. [5]
  6. L-theanine administration at a dose of 250 mg led to faster reaction time and numeric working memory reaction time and improved sentence verification accuracy in healthy human subjects. [6]
  7. In healthy volunteers, L-theanine supplementation improved working memory and performance task. [7]
  8. In elderly persons with normal or slight cognitive dysfunction, ingestion of powdered green tea containing a high L-theanine concentration significantly reduced cognitive decline. [8]
  9. A study found that L-theanine may provide effective prophylaxis and treatment for Alzheimer’s disease by preventing programmed cell death (apoptosis) of brain cells. [9]
  10. In rats, ingestion of water containing 0.3% L-theanine for 3 weeks was associated with improved recognition memory. [10]
  11. In animal models, L-theanine improved learning and memory possibly through its neuroprotective effects. [11]
  12. In a mouse model of Alzheimer’s disease, L-theanine ameliorated memory impairment. [12]
  13. In rats, ingestion of L-theanine for 3 weeks ad libitum improved learning and memory. [13]

Improves Mood

Numerous high quality studies show that L-theanine plays a key role in mood support by positively affecting the production of neurotransmitters:

  1. In patients with major depressive disorder, L-theanine administration for 8 weeks improved depressive symptoms, anxiety, sleep disturbance and cognitive impairments. [14]
  2. In patients with schizophrenia, supplementation with 400 mg L-theanine along with regular medications for 8 weeks resulted in significant reductions in anxiety and general symptoms of psychopathology. [15]
  3. A dose of 250 mg per day of L-theanine also improved symptoms and sleep in schizophrenic patients. [16]
  4. Combination of L-theanine and the hormone pregnenolone improved negative symptoms in schizophrenic patients. [17]
  5. Administration of 200 mg of L-theanine was associated with increased brain alpha waves (stimulate creativity and reduce depression) and prolonged periods of relaxation. [18-19]
  6. L-theanine may also help improve mood by stimulating production of the relaxing neurotransmitter Gamma-Aminobutyric Acid (GABA). [20]
  7. In patients with generalized anxiety disorder, L-theanine treatment was associated with improved symptoms. [21]
  8. In animal models, L-theanine supplementation reduced symptoms of anxiety. [22]
  9. In a chronic unpredictable mild stress rat model, L-theanine ameliorated the depressive-like behaviors. [23]

Fights Stress

L-theanine does not only possess potent antidepressant and anti-anxiety properties, studies show that this powerful nootropic can also fight stress and its detrimental effects on the body:

  1. In healthy participants, L-theanine administration reduced stress responses and cortisol levels. [24]
  2. In participants who underwent a series of stress test, L-theanine intake resulted in anti-stress effects as evidenced by reduced heart rate and salivary immunoglobulin A. [25-26]
  3. In healthy adults aged 18-40, L-theanine administration reduced subjective stress response. [27]

Improves Sleep Quality and Fights Insomnia

With its calming and anti-stress effects, L-theanine can benefit people suffering from sleeping difficulties. Studies show that administration of L-theanine has positive effects on sleep quality and quantity:

  1. In patients with attention deficit hyperactivity disorder (ADHD), L-theanine treatment was associated with higher sleep percentage and sleep efficiency scores. [28-29]
  2. In patients with schizophrenia, L-theanine treatment for 8 weeks improved sleep quality. [30]
  3. In patients with major depressive disorder, L-theanine administration improved scores on Pittsburgh Sleep Quality Index (PSQI). [31]
  4. In patients with generalized anxiety disorder, L-theanine treatment was associated with greater self-reported sleep satisfaction. [32]
  5. In animal models, L-theanine treatment was associated with improved NREM (non-rapid eye movement) sleep. [33]
  6. In rats, L-theanine reversed caffeine-induced sleep disturbances. [34]

Boosts Immune Function

L-theanine can also ward off a multitude of diseases. Studies show that L-theanine has immune-boosting properties:

  1. In well-trained men, L-theanine supplementation once daily for 2 weeks restored natural killer cell activity. [35]
  2. In long-distance runners, L-theanine supplementation for 7 days reduced the alteration of the immune state. [36]
  3. A study found that L-theanine can significantly decrease the incidence of upper respiratory tract infections. [37]
  4. In patients who had abdominal surgery, L-theanine treatment was associated with reduced intestinal inflammation. [38]
  5. L-theanine improves immunity by boosting the activity of T cells, which are immune cells that protect against infection and tumors. [39-40]
  6. One study found that regular consumption of L-theanine was associated with increased production of T cells. [41]
  7. In rats, L-theanine administration at a dose of 400 mg/kg improved immune function by altering the Th2/Th1 cytokine balance, increasing dopamine levels, and decreasing corticosterone levels. [42]

Fights Cancer and Aids in Cancer Treatment

According to studies, L-theanine also has potent anti-cancer properties that can help combat various types of malignant cells in the body:

  1. In patients undergoing chemotherapy, L-theanine reduced doxorubicin-induced adverse reactions. [43]
  2. In gastrointestinal cancer patients, oral administration of L-theanine reduced the side effects of chemotherapy. [44]
  3. In human liver cancer cell lines, L-theanine treatment greatly reduced cancer cell migration. [45]
  4. In human lung cancer and leukemia cell lines, L-theanine treatment suppressed metastasis by targeting signaling pathways involved in cancer cell growth. [46-47]
  5. In human liver and cervical cancer cell lines, L-theanine treatment induced programmed cell death. [48]
  6. A study found that L-theanine may help suppress cancer growth and reduce cancer prevalence through its antioxidant properties. [49]
  7. In mice with ovarian cancer, L-theanine enhanced the antitumor activities of chemotherapeutic drugs such as anthracyclines, cisplatin and irinotecan. [50]

References:

  1. Giesbrecht T, Rycroft JA, Rowson MJ, De bruin EA. The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness. Nutr Neurosci. 2010;13(6):283-90.
  2. Kahathuduwa CN, Dassanayake TL, Amarakoon AMT, Weerasinghe VS. Acute effects of theanine, caffeine and theanine-caffeine combination on attention. Nutr Neurosci. 2017;20(6):369-377.
  3. 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.
  4. 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.
  5. Nobre AC, Rao A, Owen GN. L-theanine, a natural constituent in tea, and its effect on mental state. Asia Pac J Clin Nutr. 2008;17 Suppl 1:167-8.
  6. Haskell CF, Kennedy DO, Milne AL, Wesnes KA, Scholey AB. The effects of L-theanine, caffeine and their combination on cognition and mood. Biol Psychol. 2008;77(2):113-22.
  7. Schmidt A, Hammann F, Wölnerhanssen B, et al. Green tea extract enhances parieto-frontal connectivity during working memory processing. Psychopharmacology (Berl). 2014;231(19):3879–3888. doi:10.1007/s00213-014-3526-1
  8. Kakuda T. Neuroprotective effects of theanine and its preventive effects on cognitive dysfunction. Pharmacol Res. 2011;64(2):162-8.
  9. Di X, Yan J, Zhao Y, et al. L-theanine protects the APP (Swedish mutation) transgenic SH-SY5Y cell against glutamate-induced excitotoxicity via inhibition of the NMDA receptor pathway. Neuroscience. 2010;168(3):778-86.
  10. Tamano H, Fukura K, Suzuki M, Sakamoto K, Yokogoshi H, Takeda A. Advantageous effect of theanine intake on cognition. Nutr Neurosci. 2014;17(6):279-83.
  11. Nathan PJ, Lu K, Gray M, Oliver C. The neuropharmacology of L-theanine(N-ethyl-L-glutamine): a possible neuroprotective and cognitive enhancing agent. J Herb Pharmacother. 2006;6(2):21-30.
  12. Zhu G, Yang S, Xie Z, Wan X. Synaptic modification by L-theanine, a natural constituent in green tea, rescues the impairment of hippocampal long-term potentiation and memory in AD mice. Neuropharmacology. 2018;138:331-340.
  13. Yamada T, Terashima T, Honma H, et al. Effects of theanine, a unique amino acid in tea leaves, on memory in a rat behavioral test. Biosci Biotechnol Biochem. 2008;72(5):1356-9.
  14. 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):72-79.
  15. 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.
  16. Ota M, Wakabayashi C, Sato N, et al. Effect of L-theanine on glutamatergic function in patients with schizophrenia. Acta Neuropsychiatr. 2015;27(5):291-6.
  17. 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. 2015.
  1. Available from https://www.researchgate.net/publication/244889510_200_mg_of_Zen_L-Theanine_Boosts_Alpha_Waves_Promotes_Alert_Relaxation.
  2. Dietz C, Dekker M. Effect of Green Tea Phytochemicals on Mood and Cognition. Curr Pharm Des. 2017;23(19):2876-2905.
  3. Nathan PJ, Lu K, Gray M, et al. The neuropharmacology of L-theanine(N-ethyl-L-glutamine): a possible neuroprotective and cognitive enhancing agent. J Herb Pharmacother. 2006;6(2):21-30.
  4. Sarris J, Byrne GJ, Cribb L, et al. L-theanine in the adjunctive treatment of generalized anxiety disorder: A double-blind, randomised, placebo-controlled trial. J Psychiatr Res. 2019;110:31-37.
  5. Wise LE, Premaratne ID, Gamage TF, et al. l-theanine attenuates abstinence signs in morphine-dependent rhesus monkeys and elicits anxiolytic-like activity in mice. Pharmacol Biochem Behav. 2012;103(2):245-52.
  6. Shen M, Yang Y, Wu Y, et al. L-theanine ameliorate depressive-like behavior in a chronic unpredictable mild stress rat model via modulating the monoamine levels in limbic-cortical-striatal-pallidal-thalamic-circuit related brain regions. Phytother Res. 2019;33(2):412-421.
  7. White, D.J.; de Klerk, S.; Woods, W.; Gondalia, S.; Noonan, C.; Scholey, A.B. Anti-stress, behavioural and magnetoencephalography effects of an l-theanine-based nutrient drink: A randomised, double-blind, placebo-controlled, crossover trial. Nutrients 2016, 8, 53.
  8. Kimura K, Ozeki M, Juneja LR, Ohira H. L-Theanine reduces psychological and physiological stress responses. Biol Psychol. 2007;74(1):39-45.
  9. Unno K, Tanida N, Ishii N, et al. Anti-stress effect of theanine on students during pharmacy practice: positive correlation among salivary α-amylase activity, trait anxiety and subjective stress. Pharmacol Biochem Behav. 2013;111:128-35.
  10. White DJ, De klerk S, Woods W, Gondalia S, Noonan C, Scholey AB. Anti-Stress, Behavioural and Magnetoencephalography Effects of an L-Theanine-Based Nutrient Drink: A Randomised, Double-Blind, Placebo-Controlled, Crossover Trial. Nutrients. 2016;8(1).
  11. Barrett JR, Tracy DK, Giaroli G. To sleep or not to sleep: a systematic review of the literature of pharmacological treatments of insomnia in children and adolescents with attention-deficit/hyperactivity disorder. J Child Adolesc Psychopharmacol. 2013;23(10):640–647. doi:10.1089/cap.2013.0059.
  12. 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):348-54.
  13. Ota M, Wakabayashi C, Sato N, et al. Effect of L-theanine on glutamatergic function in patients with schizophrenia. Acta Neuropsychiatr. 2015;27(5):291-6.
  14. 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):72-79.
  15. https://www.ncbi.nlm.nih.gov/pubmed/30580081Sarris J, Byrne GJ, Cribb L, et al. L-theanine in the adjunctive treatment of generalized anxiety disorder: A double-blind, randomised, placebo-controlled trial. J Psychiatr Res. 2019;110:31-37.
  16. Kim S, Jo K, Hong KB, Han SH, Suh HJ. GABA and l-theanine mixture decreases sleep latency and improves NREM sleep. Pharm Biol. 2019;57(1):65–73. doi:10.1080/13880209.2018.1557698.
  17. Jang HS, Jung JY, Jang IS, et al. L-theanine partially counteracts caffeine-induced sleep disturbances in rats. Pharmacol Biochem Behav. 2012;101(2):217-21.
  18. 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.
  19. Murakami S, Kurihara S, Titchenal CA, Ohtani M. Suppression of exercise-induced neutrophilia and lymphopenia in athletes by cystine/theanine intake: a randomized, double-blind, placebo-controlled trial. J Int Soc Sports Nutr. 2010;7(1):23.
  20. Available from https://www.mdpi.com/2306-5710/2/2/13/htm.
  21. Miyachi T, Tsuchiya T, Oyama A, et al. Perioperative oral administration of cystine and theanine enhances recovery after distal gastrectomy: a prospective randomized trial. JPEN J Parenter Enteral Nutr. 2013;37(3):384-91.
  22. Kamath AB, Wang L, Das H, Li L, Reinhold VN, Bukowski JF. 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. 2003;100(10):6009–6014. doi:10.1073/pnas.1035603100.
  23. Bukowski JF, Percival SS. L-theanine intervention enhances human gammadeltaT lymphocyte function. Nutr Rev. 2008;66(2):96-102.
  24. Kamath AB, Wang L, Das H, Li L, Reinhold VN, Bukowski JF. 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. 2003;100(10):6009–6014. doi:10.1073/pnas.1035603100.
  25. Li C, Tong H, Yan Q, et al. L-Theanine Improves Immunity by Altering TH2/TH1 Cytokine Balance, Brain Neurotransmitters, and Expression of Phospholipase C in Rat Hearts. Med Sci Monit. 2016;22:662–669. Published 2016 Feb 28. doi:10.12659/MSM.897077.
  26. Sugiyama T, Sadzuka Y. Theanine, a specific glutamate derivative in green tea, reduces the adverse reactions of doxorubicin by changing the glutathione level. Cancer Lett. 2004;212(2):177-84.
  27. 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):1085–1090. doi:10.1007/s10147-016-0996-7.
  28. Zhang G, Li Z, Wan X, et al. Repression of Human Hepatocellular Carcinoma Growth by Regulating Met/EGFR/VEGFR-Akt/NF-κB Pathways with Theanine and Its Derivative, (R)-2-(6,8-Dibromo-2-oxo-2H-chromene-3-carboxamido)-5-(ethylamino)-5-oxopentanoic Ethyl Ester (DTBrC). J Agric Food Chem. 2016;64(37):7002-13.
  29. Zhang G, Ye X, Ji D, et al. Inhibition of lung tumor growth by targeting EGFR/VEGFR-Akt/NF-κB pathways with novel theanine derivatives. Oncotarget. 2014;5(18):8528–8543. doi:10.18632/oncotarget.2336.
  30. Liu Q, Duan H, Luan J, Yagasaki K, Zhang G. Effects of theanine on growth of human lung cancer and leukemia cells as well as migration and invasion of human lung cancer cells. Cytotechnology. 2009;59(3):211–217. doi:10.1007/s10616-009-9223-y.
  31. Available from https://www.spandidos-publications.com/mmr/18/5/4535.
  32. Available from http://cebp.aacrjournals.org/content/15/12_Supplement/A157.
  33. Sugiyama T, Sadzuka Y. Theanine and glutamate transporter inhibitors enhance the antitumor efficacy of chemotherapeutic agents. Biochim Biophys Acta. 2003;1653(2):47-59.

Sucess Stories

men testimonial before after

At the age of 60, I look and feel better than I ever have in my entire life! Switching my health program and hormone replacement therapy regimen over to Genemedics was one of the best decisions I’ve ever made in my life! Genemedics and Dr George have significantly improved my quality of life and also dramatically improved my overall health. I hav...
Nick Cassavetes ,60 yrs old Movie Director (“The Notebook”, “John Q”, “Alpha Dog”), Actor and Writer

Call 800-277-4041 for a Free Consultation

What to expect during your consultation:
  • Usually takes 15-30 minutes
  • Completely confidential
  • No obligation to purchase anything
  • We will discuss your symptoms along with your health and fitness goals
  • Free post-consult access for any additional questions you may have
Contact Us Page
Sending

Genemedics® Health Institute is a global premier institute dedicated to revolutionizing health and medicine through healthy lifestyle education, guidance and accountability in harmony with functional medicine. Our physician-supervised health programs are personally customized to help you reach your health and fitness goals while looking and feeling better than ever.