What is Theanine?
This post was written with Consensus AI Academic Search Engine – please read our Disclaimer at the end of this article. Theanine, specifically L-theanine, is a unique amino acid predominantly found in tea leaves (Camellia sinensis) and certain mushrooms. It is known for its various health benefits, including neuroprotective, anti-stress, and immunomodulatory effects. This article explores the multifaceted roles of theanine, its mechanisms of action, and its potential therapeutic applications. Other names include: 2-Amino-4- (ethylcarbamoyl) Butyric Acid, 5-N-ethylglutamine, Gamma-ethylamino-L-glutamic acid, Gamma-glutamylethylamide, Gamma-N-ethylglutamine, L-gamma-glutamylethylamide, L-Theanine, L-Théanine, N-Éthyl-L-Glutamine, Teanina, Théanine.
Chemical Structure and Sources
Theanine, chemically known as γ-glutamylethylamide, is structurally similar to glutamate, a neurotransmitter involved in cognitive functions. It is primarily found in green tea leaves and is responsible for the umami flavor of tea9.
Health Benefits and Mechanisms of Theanine
Neuroprotective Effects
Theanine has been shown to have significant neuroprotective properties. It can cross the blood-brain barrier and exert cerebroprotective effects by antagonizing glutamate receptors and inhibiting the incorporation of extracellular glutamine into neurons. This action helps prevent neuronal cell death and cognitive dysfunction9. Additionally, theanine has been found to attenuate memory impairments in genetic aging models by modulating the JAK2/STAT3, M1 mAChR, and ERK signaling pathways7.
Anti-Stress and Anxiolytic Properties
Theanine is known to reduce psychological and physiological stress responses. It achieves this by blocking the binding of L-glutamic acid to glutamate receptors in the brain, thereby reducing heart rate and salivary immunoglobulin A (s-IgA) responses to acute stress tasks. This suggests that theanine can attenuate sympathetic nervous activation and promote relaxation3. Furthermore, theanine has been shown to relieve anxiety symptoms in patients with schizophrenia and schizoaffective disorder when used as an adjunct to antipsychotic treatment4.
Immunomodulatory Effects
Theanine also plays a role in enhancing immune function. It has been shown to reduce immunosuppression caused by strenuous exercise and prevent colds and influenza by improving immunity. Theanine achieves this by regulating γδT lymphocyte function, glutathione synthesis, and the secretion of cytokines and neurotransmitters8.
Anti-Inflammatory and Hepatoprotective Effects
Theanine exhibits anti-inflammatory and hepatoprotective effects, particularly in models of lipopolysaccharide (LPS)-induced inflammation and acute liver injury. It reduces liver damage and oxidative stress by decreasing the levels of inflammatory cytokines and inhibiting the NF-κB signaling pathway. Theanine also normalizes hypothalamic-pituitary-adrenal (HPA) axis hyperactivity, further contributing to its anti-inflammatory properties5.
Potential in Cancer Therapy
Theanine has shown promise in cancer therapy by inhibiting the proliferation, metastasis, and invasion of various cancer cell lines. It exerts its anticancer effects by targeting multiple signaling pathways, including EGFR, VEGFR, Met, Akt/mTOR, JAK2/STAT3, and ERK/NF-κB. Theanine also activates intrinsic apoptosis pathways and caspase-independent programmed cell death, suggesting its potential as an adjunct in cancer treatment1.
Metabolic Benefits
Theanine has been found to induce the browning of white adipose tissue (WAT) and enhance adaptive thermogenesis, which can help combat diet-induced obesity. It increases energy expenditure and improves glucose tolerance and insulin sensitivity, making it a potential therapeutic agent for metabolic disorders10.
Learn more with Consensus:
🧠Does theanine help improve memory in aging models?
💊Can theanine reduce liver damage caused by inflammation?
Adverse Effects of Theanine
General Safety and Toxicity
Studies have shown that theanine is generally safe with no consistent, statistically significant treatment-related adverse effects on behavior, morbidity, mortality, body weight, food consumption, clinical chemistry, hematology, or urinalysis in rats, even at high doses (up to 4000 mg/kg bw/day)2.
No consistent treatment-related adverse effects were observed in gross pathology, organ weights, or histopathology, suggesting a high no-observed-adverse-effect-level (NOAEL)2.
Potential for Genetic Predisposition
An increased incidence of renal tubular cell adenomas was observed in high-dose female rats, but this was attributed more to genetic predisposition rather than direct organ toxicity from theanine2.
Hepatotoxicity Concerns
Cases of hepatotoxicity associated with the consumption of green tea extract, which contains theanine, have been reported, indicating a potential risk for liver damage in some individuals9.
Interaction with Other Compounds
Theanine has been shown to attenuate adverse reactions of certain chemotherapy drugs, such as doxorubicin and S-1, by modulating oxidative stress and glutathione levels, suggesting it may have protective effects rather than causing additional adverse effects in these contexts1 6 7.
Psychotropic Effects
Theanine has been found to reduce psychological and physiological stress responses, which may be beneficial, but the long-term effects and potential for dependency or other psychotropic side effects require further investigation9 10.
Learn more with Consensus:
🌟What are the adverse effects of theanine?
℞Has theanine been associated with reducing adverse reactions to chemotherapy drugs?
How has Theanine Improved Patient Outcomes?
Reduction in Anxiety and Psychopathology in Schizophrenia and Schizoaffective Disorder
L-theanine supplementation reduced anxiety and positive symptoms in patients with schizophrenia and schizoaffective disorder, showing significant improvements in general psychopathology scores1.
Improvement in Depressive Symptoms and Cognitive Function in Major Depressive Disorder (MDD)
Chronic L-theanine supplementation lowered depression scores, reduced anxiety, improved sleep quality, and enhanced cognitive functions such as executive function and verbal memory in patients with MDD2.
Enhanced Recovery and Reduced Inflammation Post-Surgery
Perioperative administration of cystine and theanine (CT) reduced inflammation markers and improved early rehabilitation and recovery in patients undergoing esophagectomy and distal gastrectomy3 4.
Improvement in Stress-Related Symptoms and Cognitive Functions in Healthy Adults
L-theanine administration decreased stress-related symptoms, improved sleep quality, and enhanced cognitive functions such as verbal fluency and executive function in healthy adults5.
Neuroprotective Effects in Cerebral Ischemia-Reperfusion Injury
Theanine demonstrated neuroprotective effects by reducing neuron damage, oxidative stress, and inflammation in a rat model of cerebral ischemia-reperfusion injury6.
Improvement in Attention and Cognitive Performance in ADHD
L-theanine, alone or in combination with caffeine, improved sustained attention, impulse control, and overall cognitive performance in children with ADHD7 8.
Potential Anticancer Effects
Theanine showed moderate effects in inhibiting cancer cell proliferation, metastasis, and invasion, and promoted apoptosis in various cancer cell lines9.
Maintenance of Sleep Quality
Theanine mitigated the negative effects of caffeine on sleep quality, reducing wakefulness after sleep onset in healthy young women10.
Learn more with Consensus:
💆🏻How has theanine improved patient outcomes?
👩🏻Can L-theanine improve sleep quality in healthy adults?
Common Complaints Associated with Theanine Use
General Safety and Tolerability
L-theanine is generally considered safe and well-tolerated, with no significant side effects reported in various studies1 2 4.
Potential Hepatotoxicity
There have been reports of hepatotoxicity associated with the consumption of green tea extract, suggesting a need for caution, especially at higher doses or with prolonged use2.
Lack of Significant Side Effects
In studies involving both healthy adults and patients with schizophrenia or schizoaffective disorder, L-theanine did not significantly affect general functioning, side effects, or quality of life measures, indicating minimal adverse effects1 4.
Learn more with Consensus:
☢️Has L-theanine been associated with liver toxicity in certain cases?
🤯Does L-theanine affect the quality of life in patients with schizophrenia?
Disclaimer
The content presented in this blog is generated by Consensus, an AI-powered academic search engine, and is based on publicly available scientific literature. While every effort is made to provide accurate, up-to-date, and well-researched information, the content is intended for informational and educational purposes only. It does not constitute medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional before making any decisions regarding medical conditions, treatments, or medications. The AI system’s analysis may not cover all perspectives, emerging research, or individual cases, and it is not a substitute for professional expertise. Neither the blog publisher nor the developers of the AI-powered search engine are responsible for any actions taken based on the information provided in this content. Use of this information is at your own risk. Citations to the original scientific studies are included for reference, but these studies should be reviewed in full and interpreted with the guidance of a healthcare or research professional.
If you are experiencing a medical emergency, please seek immediate attention from a healthcare provider.