L-Theanine From Green Tea

L-theanine from green tea readily crosses the blood-brain barrier, where it exerts a variety of neurophysiological and pharmacological effects helping depression, as a sleeping aid, and many more

L-theanine (N-ethyl-L-glutamine) is an amino acid found in green tea (Camellia sinensis). Some authors even mentioned black tea. L-theanine has been reported as a relaxing agent. Animal studies suggest that L-theanine increases brain serotonin, dopamine, and GABA levels. It has micromolar affinities for AMPA, Kainate, and NMDA receptors. In addition, neuroprotective effects in animal models have been shown, possibly through its antagonistic effects on group 1 metabotropic glutamate receptors. Finally, behavioral studies in animals suggest improvement in learning and memory. Overall, L-theanine exhibits neuropharmacology suggestive of a possible neuroprotective and cognitive enhancing agent and warrants further investigation in animals and humans (Pradeep J Nathan, 2006).

Importantly, L-theanine crosses the blood-brain barrier, where it exerts various neurophysiological and pharmacological effects. Its most well-documented effect has been its apparent anxiolytic and calming effect due to its up-regulation of inhibitory neurotransmitters and possible modulation of serotonin and dopamine in selected brain areas. It has also recently been shown to increase levels of the brain-derived neurotrophic factor. In addition, many studies demonstrate neuroprotective effects following cerebral infarct and injury. However, the exact molecular mechanisms remain fully elucidated. Theanine also elicits improvements in cognitive function, including learning and memory, in human and animal studies.

Furthermore, theanine administration elicits selective changes in alpha brain wave activity with concomitant increases in particular attention during the execution of mental tasks. Emerging studies also demonstrate a promising role for theanine in augmentation therapy for schizophrenia. At the same time, animal models of depression report positive improvements following theanine administration. Finally, several studies are beginning to examine a putative role in attention deficit hyperactivity disorder. Theoretical extrapolations for theanine’s therapeutic role in other psychiatric disorders such as anxiety disorders, panic disorder, obsessive-compulsive disorder, and bipolar disorder are beneficial, too (Anne L Lardner, 2014).

L-theanine is associated with numerous mental health benefits, including improvements in mood, cognition and a reduction of stress and anxiety-like symptoms (Jackson L Williams et al., 2020).

Hidese and colleagues, in their study, suggest that (8-week) L-theanine administration is safe. Furthermore, it has multiple positive effects on depressive symptoms, anxiety, sleep disturbance (insomnia), and cognitive impairments in patients with major depressive disorder (MDD) (Shinsuke Hidese et al., 2017).

Depression is a psychological disorder that affects 20 – 30% of the world’s population. Traditional Chinese medicine is gaining increasing attention due to its unique therapeutic effect in depression treatment. The article (Yan-Shuo Wang et al., 2019) “summarizes the work done on the natural products from TCM that have been reported to conceive antidepressant effects in the past two decades, which can be classified according to various mechanisms including increasing synaptic concentrations of monoamines, alleviating the hypothalamic-pituitary-adrenal (HPA) axis dysfunctions, lightening the impairment of neuroplasticity, fighting towards immune and inflammatory dysregulation.” According to this particular article (Yan-Shuo Wang et al., 2019), “the antidepressant active ingredients identified can be generally divided into saponins, flavonoids, alkaloids, polysaccharides, and others. Albiflorin, Baicalein, Berberine chloride, beta-Asarone, cannabidiol, Curcumin, Daidzein, Echinocystic acid (EA), Emodin, Ferulic acid, Gastrodin, Genistein, Ginsenoside Rb1, Ginsenoside Rg1, Ginsenoside Rg3, Hederagenin, Hesperidin, Honokiol, Hyperoside, Icariin, Isoliquiritin, Kaempferol, Liquiritin, L-theanine, Magnolol, Paeoniflorin, Piperine, Proanthocyanidin, Puerarin, Quercetin, Resveratrol (trans), Rosmarinic acid, Saikosaponin A, Senegenin, Tetrahydroxystilbene glucoside, and Vanillic acid are specified in this review. In addition, Chinese compound prescriptions and extracts that exert antidepressant effects are also introduced, which may serve as a source of inspiration for further development. In the present study, the antidepressant effect of certain TCMs is affirmative and encouraging. However, much work needs to be done to evaluate the exact therapeutic effects and mechanisms of those active ingredients, specifically, to establish a unified standard for diagnosing and evaluating curative effects (Yan-Shuo Wang et al., 2019).”

Sleep deprivation and insomnia are associated with an elevated risk of numerous diseases. It leads to inferior quality of life and negative socioeconomic consequences. Sleep inducers such as drugs and herbal remedies may lead to dependence and other side effects. L-theanine has anxiolytic effects via the induction of alpha brain waves without side effects associated with conventional sleep inducers (sleeping aids). Anxiolysis is required for the initiation of high-quality sleep. As per Theertham P. Rao et al., 2015, “L-theanine does not induce daytime drowsiness; it may be useful at any time of the day. Sleep deprivation-associated morbidity is an increasing public health concern posing a substantial socioeconomic burden. Chronic sleep disorders may seriously affect the quality of life. They may be etiological factors in many chronic diseases such as depression, obesity, diabetes, and cardiovascular diseases. Most sleep inducers are sedatives and are often associated with addiction and other side effects. L-Theanine promotes relaxation without drowsiness. Unlike conventional sleep inducers, L-theanine is not a sedative but promotes good sleep quality through anxiolysis.” This review suggests that L-theanine is a safe, natural sleep aid (Theertham P. Rao et al., 2015).

Respectfully,

Holistic Healthful

References

Pradeep J Nathan, Kristy Lu, M Gray, C Oliver, The neuropharmacology of L-theanine (N-ethyl-L-glutamine): a possible neuroprotective and cognitive enhancing agent. J Herb Pharmacother. 2006;6(2):21-30.

Anne L Lardner. Neurobiological effects of the green tea constituent theanine and its potential role in the treatment of psychiatric and neurodegenerative disorders. Nutr Neurosci. 2014 Jul;17(4):145-55.

Jackson L Williams, Julian M Everett, Nathan M D’Cunha, Domenico Sergi, Ekavi N Georgousopoulou, Richard J Keegan, Andrew J McKune, Duane D Mellor, Nicola Anstice, Nenad Naumovski. The Effects of Green Tea Amino Acid L-Theanine Consumption on the Ability to Manage Stress and Anxiety Levels: a Systematic Review. Plant Foods Hum Nutr. 2020 Mar;75(1):12-23.

Shinsuke Hidese, Miho Ota, Chisato Wakabayashi, Takamasa Noda, Hayato Ozawa, Tsutomu Okubo, Hiroshi Kunugi. Effects of chronic l-theanine administration in patients with major depressive disorder: an open-label study. Acta Neuropsychiatr. 2017 Apr;29(2):72-79.

Yan-Shuo Wang, Chun-Yan Shen, Jian-Guo Jiang. Antidepressant active ingredients from herbs and nutraceuticals used in TCM: pharmacological mechanisms and prospects for drug discovery. Pharmacol Res. 2019 Dec;150:104520.

Theertham P Rao, Motoko Ozeki, Lekh R Juneja. In Search of a Safe Natural Sleep Aid. J Am Coll Nutr. 2015;34(5):436-47.