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. 2025 Aug 13;13(8):e70811. doi: 10.1002/fsn3.70811

Pharmaceutical Activities of Theanine: A Phytochemical Nutrient

Xuelan Chong 1, Jian Hou 2, Hua‐Feng He 1,✉
PMCID: PMC12351064  PMID: 40822528

ABSTRACT

Theanine, first isolated from tea ( Camellia sinensis (L.) O. Kuntze), has been recognized for its multiple pharmaceutical functions. Typically, theanine is known for its protective effect on neural disorders. In this review, the neuroprotective effects of theanine were summarized in aspects of stress management, cognitive improvement, and reversal of neural injury. Meanwhile, the pharmaceutical functions of theanine in areas such as anti‐inflammatory effects, metabolic intervention, antineoplastic effect, etc., were explored and elucidated. Subsequently, functional expansion, applications for special medical purposes, and clarification of the pharmacological and metabolic mechanism of theanine were proposed as prospects for future research. All in all, identifying more desirable applications and furthering the functional advantages of theanine were the purposes. A systematic understanding of theanine's effect on neural health, as well as the development of theanine‐related products for mental health, would be desired.

Keywords: cognitive improvement, neuroprotection, stress management, theanine

The neuroprotective effects of theanine were summarized in aspect of stress management, cognitive improvement and reversal of neural injury. Pharmaceutical functions of theanine in areas such as anti‐inflammatory effects, metabolic intervention, antineoplastic effect, etc., were explored and elucidated. Functional expansion, applications for special medical purposes, and clarification for the pharmacological and metabolic mechanism of theanine were proposed as the prospect.

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1. Introduction

Theanine, which is abundant in Camellia sinensis (L.) O. Kuntze specifically, has been found in several plants (Muszynska et al. 2020). Owing to its prominent contribution and substantial presence (accounting for 1.0% to 2.5% of the dry weight), L ‐theanine stands as the primary factor responsible for the umami taste of tea (Zhang, Cao, Granato, et al. 2020; Rogers et al. 2007). Furthermore, it has become a consensus worldwide that drinking tea is beneficial for health (Muhammad et al. 2017). Apart from its spiritual and cultural connotations (Pan et al. 2022), the charm and prevalence of tea are attributed to its extensive health benefits, which are closely related to the antioxidant capacity of tea polyphenols (Bag et al. 2022; Jiang et al. 2022). In fact, there are amounts of physiologically active ingredients; theanine (Li, Liu, et al. 2022), caffeine, etc., make significant contributions (Rana et al. 2021; Payne et al. 2025).

Being structurally homologous to glutamyl peptides (Scheme 1), it is facilitated for theanine to bind to receptor subtypes such as N‐methyl‐D‐aspartate (NMDA), kainic acid, and amino‐3‐hydroxy‐5‐methyl‐4‐isoxazole propionic acid (Wang, Brennan, et al. 2022). Although it does not participate in protein formation, theanine plays a collaborative role in the development of lateral roots (Chen, Lin, et al. 2023). To the delight of many, theanine is demonstrated to be biosynthesized in the root, but the leaf is the destination for accumulation, making it convenient for humans to consume theanine (Luo and He 2025).

SCHEME 1.

SCHEME 1

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Chemical structure of theanine.

Pioneering literatures had pronounced multiple health benefits of theanine. Herein, documents closely related to the pharmaceutical functions of theanine disclosed in recent years were reviewed and presented in aspect of neuroprotective effect and pharmaceutical activities. Thereby, functional expansion, application in special medical purposes, and clarification of the pharmacological mechanism were proposed as the prospect for research on theanine.

2. Neuroprotective Effects of Theanine

With the accelerating pace of life, an increasing number of people are suffering from multifaceted stress. Neuropsychiatric disorders, e.g., sleep disorders, obsessive‐compulsive disorder (OCD), anxiety, depression, and psychotic symptoms, have emerged as significant threats. Coincidentally, aging as well as the chronic diseases it brings, e.g., cognitive disorders, are also a troublesome public health issue facing the world. Besides, complications after surgical operation as well as the side effects of drugs both could lead to pathological pain, even injury of organs. Pathologically, the abnormality of nerve cells is the root cause of these serious difficulties (Scheme 2). It has been demonstrated through amounts of documents that theanine could shield nerve cells from the pathological changes. Clinically, amelioration and improvement of theanine on sleep disorders, mood disorders, neuropathic pains, organ damage, and etc. were exhibited. The urgent need to develop lifestyle interventions for effectively managing mood disorders and ameliorating neurodegeneration has been highlighted as a critical issue. Compared to traditional drugs, nutrient combinations were generally considered healthier and more environmentally friendly in the treatment of mental disorders.

SCHEME 2.

SCHEME 2

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Participation of theanine in neuro‐related disorders.

2.1. Stress Management

Traditionally, intake of tea would be beneficial for staying awake. However, a new insight that the balance between pathological sleep and energy levels under stress was proposed (Ouyang et al. 2022). It is indicated that tea consumption would be beneficial in regulating sleep quality, distinguishing from nervous excitement. Antagonistically, theanine could reduce the excitotoxicity of caffeine that affects sleep quality (Dasdelen et al. 2022; Baba et al. 2023). A positive effect on duration and habitual efficiency of sleep was observed with the administration of theanine by working adults (Thiagarajah et al. 2022). Changes in electrochemical activity in the brain, i.e., decreased electrocorticogram frequency, increased amplitude, and enhanced delta wave powers, were detected with the administration of theanine, as well as the Mg‐theanine complex (Dasdelen et al. 2022). Increasing of acetylcholine and γ‐aminobutyric acid (GABA), while decreasing of serotonin in the brain were found when administration of theanine synergistically with Neumentix, indicating the improvements in sleep disorders (Zhang, Jia, et al. 2021).

By increasing frontal region α power, a feature indicating relaxation in the brain, theanine exhibited a rapid and significant effect on individuals experiencing stress (Evans et al. 2021). As documented, theanine could cause metabolic changes in the hippocampus, which were believed to exhibit antidepressant effect (Unno et al. 2021). Similar to herbal medicine, theanine had been utilized as a dietary natural nutrient to manage mood disorders (Wu et al. 2022; Sarris et al. 2022; Borgonetti et al. 2020). Modulating the expression of Npas4 (Neuronal PAS Domain Protein 4), alleviation of the stress induced by group rearing was exhibited with the administration of theanine to mice (Unno et al. 2023). According to Yuan and co‐workers, the beneficial effects of theanine may be mediated by the enhancement of intracortical facilitation, involving NMDA receptor‐mediated processes, as well as by the attenuation of intracortical inhibition exerted by GABA receptor in the human primary motor cortex (Yuan et al. 2021). In clinical practice, added as a complementary therapy, theanine was proved to be both effective and tolerable (Shamabadi et al. 2023). A combination of cystine and theanine had been used in perioperative nutritional therapy to mitigate surgical stress (Tsuchiya and Kurihara 2022; Okamoto et al. 2022). The combination of theanine and walnut peptides exhibited universal activities, including antianxiety effects, neuroprotective properties, and memory enhancement (Zhao et al. 2023). In terms of attenuating nicotine‐withdrawal symptoms, which were similar to those of OCD, theanine exhibited positive potential effects (Alkhlaif et al. 2023). Furthermore, theanine played a crucial role in restoring the levels of potential biomarkers involved in various metabolic pathways to normal (Zhu et al. 2023).

2.2. Cognitive Improvement

A 1‐year observational study revealed that tea consumption was associated with a reduced risk of cognitive impairment among Chinese elderly individuals (Li, Yue, and Xiao 2022). In a survey of patients with mild cognitive impairments, tea consumption was shown to improve cognitive performance (Yin et al. 2023). The protective effect of theanine against isoflurane‐induced damage to neural stem cells indicated the potential to attenuate cognitive impairment (Chen, Lian, et al. 2020). Competitive inhibition of theanine on the cellular uptake of D ‐serine was observed, which related to the hypofunction of receptors in the brain and a deficit in cognitive functions (Lakatos et al. 2020). As to chronic neurodegenerative diseases, e.g., Parkinson's disease (PD) (Raj et al. 2022), and Alzheimer's disease (AD) (Zeng et al. 2021), theanine presented noteworthy value (Luo et al. 2023). Rotenone‐induced neurotoxicity exhibited similar pathophysiological features to PD and had been employed as an animal model for decades. Treatment with theanine had shown evidence of ameliorating the behavioral and neurochemical dysfunction induced by rotenone (Chen, Wang, Soung, Chen, et al. 2022). Potentially suppressing the nuclear factor kappa‐light‐chain‐enhancer of activated B cells (NF‐κB) induced by lipopolysaccharide (LPS), theanine was found to reverse the motor deficits of PD. (Kumar et al. 2023) Theanine also up‐regulated the expression of silent information regulator 1, a new potential therapeutic target for AD (Zhang and Tang 2023). Collaborating with epigallocatechin gallate (EGCG), theanine could promote the repair and regeneration of nerve cells, which in turn could be applied to slow down the progression of AD (Xie et al. 2022). To treat and alleviate AD, chemicals originating from both sea and terrestrial sources were combined to provide therapy (Wang, Kong, et al. 2022). As representatives, theanine and nobiletin were selected to be combined with Antarctic krill oil, which exhibited a synergistic effect in ameliorating memory and cognition deficiencies.

Apart from no adverse effects being reported, the linear dose‐dependent improvement in attention warranted therapeutic applications of theanine (Dassanayake et al. 2022). Taking theanine as a base, a supplement was applied to children with Tourette syndrome and anxiety disorders, and a reduction in the severity of tic symptoms and anxiety symptoms was experienced (Rizzo et al. 2022). For attention deficit hyperactivity disorder, a potential therapeutic option involving theanine and caffeine was proposed (Kahathuduwa et al. 2020). Both originating from natural plants, memory enhancement was found in mice when treated with fructooligosaccharide and theanine, implying the potential to be developed as dietary supplements to promote human memory and cognition (Li, Jiang, et al. 2024).

2.3. Reversal of Neural Injury

The powerful neuroprotective effect of theanine endows it with a promising application in coping with the neurological damage caused by the adverse events (AEs) of drug administration. Generally, AEs in chemotherapy for cancer patients, including various nociceptive pains, would affect the therapeutic effect and acceptance. Amelioration of these neuropathies and neurotoxicities had been evidenced with the supplementation of theanine (Yang et al. 2023; Ye et al. 2023). By blocking the signaling pathways of glycogen synthase kinase 3 and Akt in the prefrontal cortex, pretreatment with theanine would assist in preventing the Δ‐9‐tetrahydrocannabinol induced chronic neuropathological adaptations (De Felice et al. 2021). Treatment with theanine ameliorated the neuropathic pain induced by chronic constriction injury of the sciatic nerve (Chen, Wang, Soung, Tseng, et al. 2022). Promotion of recovery of behavioral motor functions post‐spinal cord injury indicated potential use of theanine in motor dysfunction induced by neurogenic injury (Yang et al. 2020).

Functional injuries of organs could be caused by the chronic accumulation of stress. Ingestion of theanine could suppress the chronic stress induced brain atrophy (Unno et al. 2020). Daily consumption of theanine was beneficial in suppressing chronic sympathetic hyperactivity, which would be protective of bladder function (Matsuoka et al. 2021). By down‐regulating the heme oxygenase‐1 expression, theanine inhibited the neuron damage and apoptosis in the hippocampus to alleviate the neurological damage induced by ischemia/reperfusion injury in stroke (Zhao et al. 2020). Dose‐dependently, theanine inhibited liver and kidney injury induced by sepsis, a dysregulated host response to infection (Malkoc et al. 2020). Under a high protein diet, theanine regulated the content of neurotransmitters, exerting the potential to protect the liver and brain (Xu et al. 2023). Alleviation of acute alcoholic liver injury was proclaimed by theanine by down‐regulating the tumor necrosis factor‐α/NF‐κB signaling pathway (Sun et al. 2021). Treatment with theanine could shield the mice from reactive oxygen species induced renal fibrosis and inflammation (Xia et al. 2024). Combining transcriptomics and metabolomics, Fang and co‐workers evidenced the enhancement of serum biochemical indicators and the reduction of inflammatory cytokine levels in serum and cardiac tissues with the supplement of theanine, leading to the reversal of cardiac injury induced by obesity (Fang, Shen, Wang, et al. 2024). In the field of cell therapy, healing effects on injured liver tissue were exhibited by mesenchymal stem cells pre‐treated with theanine (Lai et al. 2022). Moreover, theanine exhibited a protective effect against acute radiation injury on the small intestine and bone marrow and improved the survival rate (Mstsuu‐Matsuyama et al. 2020; Matsuu‐Matsuyama et al. 2023). A neutralizing effect was shown by theanine in response to high dose EGCG‐induced acute liver injury (Peng, Dai, et al. 2021; Zhu et al. 2024).

3. Pharmaceutical Activities of Theanine

3.1. Anti‐Inflammatory

When it turns to inflammatory damage, theanine also exhibits protective effects. Accordingly, theanine could ameliorate dextran sulfate sodium‐induced pathological damage, block the expression of proinflammatory cytokines, and restore the balance of intestinal barrier disruption, making it an alternative for addressing colonic mucosa injury (Wang et al. 2020). By inhibiting the TLR4/p38 mitogen‐activated protein kinase (MAPK)/NF‐κB signaling pathway, theanine attenuated intestinal mucosa inflammation and improved the expression of tight junction protein (Chen, Chen, et al. 2023; Li, Huang, et al. 2024). Overall, amelioration of intestinal barrier functions was authorized to theanine (Wang et al. 2024). Similarly, theanine displayed protective effects in inflammatory bowel disease by inhibiting the progression of inflammation in intestinal tissues (Chen, Xiao, et al. 2020). In prevention of osteoarthritis, theanine decreased inflammatory cytokines and protected against extracellular matrix degradation (Bai et al. 1988). As well, theanine down‐regulated the production of interleukin‐23 and chemokines, which drive the pathogenesis of psoriasis (Xu et al. 2021). In alleviating 5‐fluorouracil‐induced intestinal mucositis and diarrhea, theanine was also effective (Yoneda et al. 2021).

3.2. Metabolic Intervention

Regulating signaling pathways, theanine could participate in the metabolism of glucose, lipid, and protein (Lin et al. 2020). Oral administration of theanine could promote fat browning via up‐regulating the expression of thermogenic genes (He et al. 2021). Consequently, an improvement in thermogenesis was evidenced in the case of diet‐induced obesity. Intraperitoneal treatment with theanine could not only enhance adaptive thermogenesis but also increase energy expenditure, inducing the browning of inguinal white adipose tissue (Peng, Xiao, et al. 2021). Theanine prevented colonic damage and obesity induced by a high‐fat diet by suppressing the phosphorylation of important proteins in the NF‐κB/MAPK pathways and regulating the metabolism of short‐chain fatty acids (Fang, Shen, Ma, et al. 2024; Xu et al. 2020). Meanwhile, dysbiosis of gut microbiota would be mitigated. Based on these results, theanine's effect on intestinal mucosal immunity was demonstrated. Enhancement of the stabilization of intestinal and the metabolism of glutamine would be obtained with the presence of theanine (Liu, Gong, et al. 2020). A nutraceutical supplement with theanine as the fundamental component was proven effective in modulating the fecal microbiome, thereby regulating anxiety and stress‐triggered functional gastrointestinal disorders (Cannas et al. 2021). By acting on amino acid transporters, theanine influenced the absorption of amino acids in the intestine (Liu et al. 2023). Additionally, supplementation of theanine was also useful in the improvement of lipid metabolism. Theanine had been documented to inhibit the formation of advanced glycation end products (AGEs), thereby maintaining homeostasis in the body and ameliorating liver aging (Saleh et al. 2019; Zeng et al. 2020). Proliferation of Sertoli cells and consumption of glucose could be prompted with exposure to a pharmacological dose of theanine (50 μM), indicating its potential to enhance male reproduction (Dias et al. 2019). Cooperating with EGCG, theanine promoted glycogen metabolism while suppressing the effect of EGCG on fatty acid and protein synthesis via adenosine 5′‐monophosphate (AMP)‐activated protein kinase signals (Lin et al. 2021).

3.3. Antineoplastic Effect

In vitro, ex vivo, and in vivo studies ascertained the participation of theanine in the treatment of various cancers (Shojaei‐Zarghani, Rafraf, and Yari‐Khoroushahi 2021). The intake of theanine would be associated with the amelioration of cancer cachexia, which was evidenced by the prevention of weight loss, internal fat loss, lower limb muscle loss, and an increase in serum interleukin‐6 levels (Kudamatsu et al. 2023). By inhibiting the extracellular signal‐regulated protein kinase/NF‐κB signaling pathway, theanine suppressed the transcription of matrix metalloproteinase 9 and snail. As a result, theanine may be considered a promising candidate for antimetastatic therapy of prostate cancer (Fan et al. 2021). By enhancing the expression of brain and muscle arnt‐like protein 1, a clock gene in melanoma cells, the viability of melanoma cells was reduced by theanine, along with the promoted apoptosis of melanoma cells and inhibition of migration (Zhang et al. 2022). In the case of dimethylhydrazine‐induced cancerous and precancerous lesions, the chemo‐preventive effect was displayed by theanine, which would be more pronounced when combined with theobromine (Shojaei‐Zarghani, Khosroushahi, and Rafraf 2021). Employing theanine as an adjuvant, liposomes were prepared with optimal sizes to sustain the release of doxorubicin and reduce adverse reactions in chemotherapy for malignant tumors (Zhao et al. 2019). A phase II trial indicated oral administration of cystine and theanine could reduce the incidence of AEs in chemotherapy, e.g., diarrhea, peripheral neuropathy (Hamaguchi et al. 2020; Kobayashi et al. 2020; Kawashiri et al. 2020).

3.4. Other Pharmaceutical Activities and Applications of Theanine

Additionally, as shown in Table 1, theanine has been found to exhibit various pharmaceutical activities beneficial to health (Maloh et al. 2022), including the prevention of cardiovascular diseases (CVDs) and immunomodulation. On the other hand, applications of theanine in the food industry and feed additives were documented. Even in fields such as contaminant degradation, bacterial infection control, nerve tissue engineering, and athletic performance enhancement, theanine plays a pivotal role.

TABLE 1.

Other pharmaceutical activities and applications of theanine.

Function Key finding References
Prevention of CVDs Theanine regulated scavenger receptor A at the translational level, inhibited the abnormal proliferation and migration of vascular smooth muscle cells (Lei et al. 2021; Bi et al. 2020)
Immunomodulation Theanine participated in adjusting immune function (Chen, Kang, et al. 2023; Kikuchi et al. 2022; Ribeiro et al. 2020)
Feed additive Dietary supplementation with theanine was helpful to improve meat quality and to neutralize oxidative stress, heat stress in poultry, cattle, Chinese mitten crabs ( Eriocheir sinensis ) (Dai et al. 2023; Muhammad et al. 2020; Alagawany et al. 2020; Zhang, Wang, Zhao, et al. 2020; Zhang, Wang, Chen, et al. 2020; Uyanga et al. 2022; Wang, Tang, et al. 2022; Wang et al. 2021; Yang et al. 2022, 2024; Muhammad, Xu, Zhang, et al. 2018; Muhammad, Xu, Faiz‐ul, et al. 2018)
Food industry Addition of theanine was beneficial for storage of bacteria, development of resistant starch and ginkgo seed protein (Kwon et al. 2025; Liu, Chen, et al. 2020; Hao et al. 2024; Zhang, Ge, et al. 2024)
Nerve tissue engineering Theanine endowed graphene oxide the ability to withstand injury to the central nervous system (Qi et al. 2020)
Bacterial infection control A copper cluster equipped with theanine peptide exhibit outstanding antibacterial effects (Zhang, Zhang, et al. 2021)
Degradation of contaminants Theanine participated in the formation of iron‐based nanoparticles as sweeper to remove As(V). Reactive carbonyl species (Wu et al. 2021; Zhong et al. 2023; Zhang, Yang, et al. 2024)
Athletic nutrition Theanine enhanced shooting accuracy, cognitive function, and skeletal muscle fiber type transition in athletes (Yilmaz et al. 2023; Chen, Zhang, Xue, Liang, et al. 2022; López‐Martínez et al. 2022)
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4. Prospect for Future Research on Theanine

4.1. Functional Expansion of Theanine

Based on pioneer work, pharmaceutical functions of theanine had been demonstrated. However, as research advances and emerging health threats evolve, the multifaceted functions of theanine await systematic exploration. In addition to its intrinsic activities, the synergistic enhancement of theanine's efficacy when combined with other phytochemicals, particularly those coexisting in tea (Xia et al. 2022; Liu et al. 2022; Jia et al. 2022), warrants further investigation.

4.2. Applications of Theanine for Special Medical Purposes

Its potent neurorestorative properties endow theanine with boundless prospects for therapeutic development in neuroscience. Furthermore, no AEs and dosage limitations guarantee the dietary supplement of theanine. Listed among approved additives by the International Society of Sports Nutrition (Jagim et al. 2023), theanine demonstrates potential for development as a nutritional ergogenic aid for athletic performance enhancement.

4.3. Clarification for the Pharmacological and Metabolic Mechanism of Theanine

Although the neuropharmacological effects of theanine have been well‐characterized, particularly in neuroprotection and cognitive enhancement, its underlying molecular mechanisms and direct therapeutic targets require further investigation. Meanwhile, the in vivo metabolic dynamics of theanine, encompassing rapid intestinal absorption, extensive tissue distribution, enzymatic biotransformation pathways, and efficient renal excretion, remain to be elucidated.

Besides, the low content of metabolites, coupled with poor genetic stability and high costs, was all a disadvantage of endogenous theanine synthetase, hampering its use for industrial theanine production. Enzymatic recombination could be an alternative to address the low catalytic efficiency and specificity of natural enzymes.

5. Conclusion

Theanine has been shown to have various pharmaceutical functions, typically in neuroprotection including stress management, cognitive improvement, and reversal of nerval injury. Furthermore, pharmaceutical activities such as anti‐inflammatory, metabolic intervention, and antineoplastic effect, etc., were summarized. Moreover, future research on theanine is proposed to focus on functional expansion, applications for special medical purposes, and clarification for the pharmacological and metabolic mechanism of theanine. Additionally, microbial and enzyme engineering techniques would be proposed for large‐scale preparation of theanine. It is hoped that the advantages of theanine in the field of bioengineering and the pharmaceutical industry would continue to drive research efforts in this area. In the face of multiple threats to human health, theanine has the potential to contribute greener and more healthful solutions in the future.

Author Contributions

Xuelan Chong: data curation (equal), investigation (supporting), writing – original draft (lead). Jian Hou: writing – review and editing (equal). Hua‐Feng He: conceptualization (lead), data curation (equal), supervision (lead), writing – review and editing (lead).

Conflicts of Interest

The authors declare no conflicts of interest.

Chong, X. , Hou J., and He H.‐F.. 2025. “Pharmaceutical Activities of Theanine: A Phytochemical Nutrient.” Food Science & Nutrition 13, no. 8: e70811. 10.1002/fsn3.70811.

Funding: This study was supported by the National Natural Science Foundation of China [grant numbers 32102443].

Data Availability Statement

The authors have nothing to report.

References

  1. Alagawany, M. E. , Abd Ei‐Hack M., Saeed M., et al. 2020. “Nutritional Applications and Beneficial Health Applications of Green Tea and L ‐Theanine in Some Animal Species: A Review.” Journal of Animal Physiology and Animal Nutrition 104: 245–256. [DOI] [PubMed] [Google Scholar]
  2. Alkhlaif, Y. , El‐Halawany M., Toma W., et al. 2023. “ L ‐Theanine Attenuates Nicotine Reward and Withdrawal Signs in Mice.” Neuroscience Letters 807: 137279. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Baba, Y. , Takihara T., and Okamura N.. 2023. “Theanine Maintains Sleep Quality in Healthy Young Women by Suppressing the Increase in Caffeine‐Induced Wakefulness After Sleep Onset.” Food & Function 14: 7109–7116. [DOI] [PubMed] [Google Scholar]
  4. Bag, S. , Mondal A., Majumder A., and Banik A.. 2022. “Tea and Its Phytochemicals: Hidden Health Benefits & Modulation of Signaling Cascade by Phytochemicals.” Food Chemistry 371: 131098. [DOI] [PubMed] [Google Scholar]
  5. Bai, H. , Zhang Z., Li Y., et al. 1988. “ L ‐Theanine Reduced the Development of Knee Osteoarthritis in Rats via Its Anti‐Inflammation and Anti‐Matrix Degradation Actions: In Vivo and In Vitro Study.” Nutrients 2020: 12. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Bi, A. , Hang Q., Huang Y., et al. 2020. “ L ‐Theanine Attenuates Neointimal Hyperplasia via Suppression of Vascular Smooth Muscle Cell Phenotypic Modulation.” Journal of Nutritional Biochemistry 82: 108398. [DOI] [PubMed] [Google Scholar]
  7. Borgonetti, V. , Governa P., Biagi M., and Galeotti N.. 2020. “Novel Therapeutic Approach for the Management of Mood Disorders: In Vivo and In Vitro Effect of a Combination of L ‐Theanine, Melissa officinalis L. and Magnolia officinalis Rehder & E.H. Wilson.” Nutrients 12, no. 6: 1803. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Cannas, S. , Tonini B., Belà B., et al. 2021. “Effect of a Novel Nutraceutical Supplement (Relaxigen Pet Dog) on the Fecal Microbiome and Stress‐Related Behaviors in Dogs: A Pilot Study.” Journal of Veterinary Behavior 42: 37–47. [Google Scholar]
  9. Chen, C.‐N. , Wang M.‐H., Soung H.‐S., et al. 2022. “L‐Theanine Ameliorated Rotenone‐Induced Parkinsonism‐Like Symptoms in Rats.” Neurotoxicity Research 40: 241–258. [DOI] [PubMed] [Google Scholar]
  10. Chen, L. , Xiao W.‐J., Yan Q.‐X., et al. 2020. “Protective Effects of L ‐Theanine on Rats With Dextran Sulfate Sodium‐Induced Inflammatory Bowel Disease.” Archives of Pharmacal Research 43: 821–862. [DOI] [PubMed] [Google Scholar]
  11. Chen, S. , Kang J., Zhu H., et al. 2023. “ L ‐Theanine and Immunity: A Review.” Molecules 28: 3846. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Chen, S.‐M. , Wang M.‐H., Soung H.‐S., et al. 2022. “Neuroprotective Effect of L ‐Theanine in a Rat Model of Chronic Constriction Injury of Sciatic Nerve‐Induced Neuropathic Pain.” Journal of the Formosan Medical Association 121: 802–814. [DOI] [PubMed] [Google Scholar]
  13. Chen, T. , Lin S., Chen Z., et al. 2023. “Theanine, a Tea‐Plant‐Specific Non‐Proteinogenic Amino Acid, Is Involved in the Regulation of Lateral Root Development in Response to Nitrogen Status.” Horticulture Research 10: uhac267. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Chen, X. , Chen L., Jia G., Zhao H., Liu G., and Huang Z.. 2023. “ L ‐Theanine Improves Intestinal Barrier Functions by Increasing Tight Junction Protein Expression and Attenuating Inflammatory Reaction in Weaned Piglets.” Journal of Functional Foods 100: 105400. [Google Scholar]
  15. Chen, X. , Zhang M., Xue Y., et al. 2022. “Effect of Dietary L ‐Theanine Supplementation on Skeletal Muscle Fiber Type Transformation In Vivo .” Journal of Nutritional Biochemistry 99: 108859. [DOI] [PubMed] [Google Scholar]
  16. Chen, Y. , Lian F., Lu Q., et al. 2020. “ L ‐Theanine Attenuates Isoflurane‐Induced Injury in Neural Stem Cells and Cognitive Impairment in Neonatal Mice.” Biological & Pharmaceutical Bulletin 43: 938–945. [DOI] [PubMed] [Google Scholar]
  17. Dai, H. , Chen X., He J., et al. 2023. “Dietary L ‐Theanine Supplementation Improves Antioxidant Capacity and Lipid Metabolism in Finishing Pigs.” Journal of Functional Foods 110: 105831. [Google Scholar]
  18. Dasdelen, M. F. , Er S., Kaplan B., et al. 2022. “A Novel Theanine Complex, Mg‐ L ‐Theanine Improves Sleep Quality via Regulating Brain Electrochemical Activity.” Frontiers in Nutrition 9: 874254. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Dassanayake, T. L. , Kahathuduwa C. N., and Weerasinghe V. S.. 2022. “ L ‐Theanine Improves Neurophysiological Measures of Attention in a Dose‐Dependent Manner: A Double‐Blind, Placebo‐Controlled, Crossover Study.” Nutritional Neuroscience 25, no. 4: 698–708. [DOI] [PubMed] [Google Scholar]
  20. De Felice, M. , Renard J., Hudson R., et al. 2021. “ L ‐Theanine Prevents Long‐Term Affective and Cognitive Side Effects of Adolescent ∆‐9‐Tetrahydrocannabinol Exposure and Blocks Associated Molecular and Neuronal Abnormalities in the Mesocorticolimbic Circuitry.” Journal of Neuroscience 41, no. 4: 739–750. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Dias, T. R. , Bernardino R. L., Alves M. G., et al. 2019. “ L ‐Theanine Promotes Cultured Human Sertoli Cells Proliferation and Modulates Glucose Metabolism.” European Journal of Nutrition 58: 2961–2970. [DOI] [PubMed] [Google Scholar]
  22. Evans, M. , McDonald A. C., Xiong L., Crowley D. C., and Guthrie N.. 2021. “A Randomized, Triple‐Blind, Placebo‐Controlled, Crossover Study to Investigate the Efficacy of a Single Dose of AlphaWave L ‐Theanine on Stress in a Healthy Adult Population.” Neurology and Therapy 10: 1061–1078. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Fan, X. , Zhou J., Bi X., et al. 2021. “ L ‐Theanine Suppresses the Metastasis of Prostate Cancer by Downregulating MMP9 and Snail.” Journal of Nutritional Biochemistry 89: 108556. [DOI] [PubMed] [Google Scholar]
  24. Fang, C. , Shen Y., Ma Z., et al. 2024. “ L ‐Theanine Prevents Colonic Damage via NF‐κB/MAPK Signaling Pathways Induced by a High‐Fat Diet in Rats.” Molecular Nutrition & Food Research 68, no. 8: 2300797. [DOI] [PubMed] [Google Scholar]
  25. Fang, C. , Shen Y., Wang F., et al. 2024. “Combined Transcriptomics and Metabolomics to Elucidate the Underlying Beneficial Mechanisms of L ‐Theanine in Mitigating Obesity‐Induced Cardiac Injury in Rats.” Journal of Functional Foods 113: 106037. [Google Scholar]
  26. Hamaguchi, R. , Tsuchiya T., Miyata G., et al. 2020. “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).” Supportive Care in Cancer 28: 3649–3657. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Hao, Z. , Hu A., Cheng J., et al. 2024. “Mechanism of Interaction Between L ‐Theanine and Maize Starch in Ultrasonic Field Based on DFT Calculations: Rheological Properties, Multi‐Scale Structure and In Vitro Digestibility.” International Journal of Biological Macromolecules 261: 129869. [DOI] [PubMed] [Google Scholar]
  28. He, J. , Chen J., He Q., et al. 2021. “Oral L ‐Theanine Administration Promotes Fat Browning and Prevents Obesity in Mice Fed High‐Fat Diet Associated With the Modulation of Gut Microbiota.” Journal of Functional Foods 81: 104476. [Google Scholar]
  29. Jagim, A. R. , Harty P. S., Tinsley G. M., et al. 2023. “International Society of Sports Nutrition Position Stand: Energy Drinks and Energy Shots.” Journal of the International Society of Sports Nutrition 20, no. 1: 2171314. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Jia, L. , Wang F., Zhang K., et al. 2022. “ L ‐Theanine Inhibits (−)‐Epigallocatechin‐3‐Gallate Oxidation via Chelating Copper.” Journal of Agricultural and Food Chemistry 70: 7751–7761. [DOI] [PubMed] [Google Scholar]
  31. Jiang, Y. , Huang Y., Wu Y., and Wang L.. 2022. “Drinking Tea Improves the Convergent Creativity Performance.” Food Quality and Preference 95: 104360. [Google Scholar]
  32. Kahathuduwa, C. N. , Wakefield S., West B. D., et al. 2020. “Effects of L ‐Theanine–Caffeine Combination on Sustained Attention and Inhibitory Control Among Children With ADHD: A Proof‐Of‐Concept Neuroimaging RCT.” Scientific Reports 10: 13072. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Kawashiri, T. , Kobayashi D., Egashira N., Tsuchiya T., and Shimazoe T.. 2020. “Oral Administration of Cystine and Theanine Ameliorates Oxaliplatin‐Induced Chronic Peripheral Neuropathy in Rodents.” Scientific Reports 10: 12665. [DOI] [PMC free article] [PubMed] [Google Scholar]
  34. Kikuchi, H. , Harata K., Akiyoshi S., Sagara T., Madhyastha H., and Kuribayashi F.. 2022. “Potential Role of Green Tea Amino Acid L ‐Theanine in the Activation of Innate Immune Response by Enhancing Expression of Cytochrome b558 Responsible for the Reactive Oxygen Species‐Generating Ability of Leukocytes.” Microbiology and Immunology 66: 342–349. [DOI] [PubMed] [Google Scholar]
  35. Kobayashi, M. , Sato R., Komura T., et al. 2020. “Protective Effect of the Oral Administration of Cystine and Theanine on Oxaliplatin‐Induced Peripheral Neuropathy: A Pilot Randomized Trial.” International Journal of Clinical Oncology 25: 1814–1821. [DOI] [PMC free article] [PubMed] [Google Scholar]
  36. Kudamatsu, H. , Kawashiri T., Mine K., et al. 2023. “Ameliorating Effects of Cystine and Theanine in a Cancer Cachexia Mouse Model.” Journal of Pharmacological Sciences 152: 163–166. [DOI] [PubMed] [Google Scholar]
  37. Kumar, S. , Awasthi A., Raj K., and Singh S.. 2023. “L‐Theanine Attenuates LPS‐Induced Motor Deficit in Experimental Rat Model of Parkinson's Disease: Emphasis on Mitochondrial Activity, Neuroinflammation, and Neurotransmitters.” Psychopharmacology 240: 1493–1508. [DOI] [PubMed] [Google Scholar]
  38. Kwon, H.‐J. , Nguyen T. H., Kim J.‐S., and Kang C. H.. 2025. “The Protective Effect of L ‐Theanine Addition to a Cryoprotectant on the Storage Viability of Lactic Acid Bacteria.” International Microbiology 28: 45–52. [DOI] [PubMed] [Google Scholar]
  39. Lai, Y.‐J. , Sung Y.‐T., Lai Y.‐A., Chen L. N., Chen T. S., and Chien C. T.. 2022. “ L ‐Theanine‐Treated Adipose‐Derived Mesenchymal Stem Cells Alleviate the Cytotoxicity Induced by N‐Nitrosodiethylamine in Liver.” Tissue Engineering and Regenerative Medicine 19, no. 6: 1207–1221. [DOI] [PMC free article] [PubMed] [Google Scholar]
  40. Lakatos, P. P. , Vincze I., Nyariki N., Bagaméry F., Tábi T., and Szökő É.. 2020. “The Effect of L ‐Theanine and S ‐Ketamine on D ‐Serine Cellular Uptake.” BBA‐Proteins Proteom 1868: 140473. [DOI] [PubMed] [Google Scholar]
  41. Lei, J. , Ye J., She R., et al. 2021. “ L ‐Theanine Inhibits Foam Cell Formation via Promoting the Scavenger Receptor A Degradation.” European Journal of Pharmacology 904: 174181. [DOI] [PubMed] [Google Scholar]
  42. Li, M.‐Y. , Liu H.‐Y., Wu D.‐T., et al. 2022. “ L ‐Theanine: A Unique Functional Amino Acid in Tea ( Camellia sinensis L.) With Multiple Health Benefits and Food Applications.” Frontiers in Nutrition 9: 853846. [DOI] [PMC free article] [PubMed] [Google Scholar]
  43. Li, W. , Yue L., and Xiao S.. 2022. “Prospective Associations of Tea Consumption With Risk of Cognitive Decline in the Elderly: A 1‐Year Follow‐Up Study in China.” Frontiers in Nutrition 9: 752833. [DOI] [PMC free article] [PubMed] [Google Scholar]
  44. Li, Y. , Jiang Y., Zhang Z., et al. 2024. “Improvement of Both Human and Animal Memory by Synergy Between Fructooligosaccharide and L ‐Theanine Function Establishing a Safe and Effective Food Supplement.” Food Science & Nutrition 00: 1–15. [DOI] [PMC free article] [PubMed] [Google Scholar]
  45. Li, Z. , Huang Z., Jia G., Zhao H., Liu G., and Chen X.. 2024. “ L ‐Theanine Attenuates H2O2‐Induced Inflammation and Apoptosis in IPEC‐J2 Cells via Inhibiting p38 MAPK Signaling Pathway.” Food and Chemical Toxicology 186: 114561. [DOI] [PubMed] [Google Scholar]
  46. Lin, L. , Zeng L., Liu A., et al. 2020. “ L ‐Theanine Regulates Glucose, Lipid, and Protein Metabolism via Insulin and AMP‐Activated Protein Kinase Signaling Pathways.” Food & Function 11: 1798–1809. [DOI] [PubMed] [Google Scholar]
  47. Lin, L. , Zeng L., Liu A., et al. 2021. “Role of Epigallocatechin Gallate in Glucose, Lipid, and Protein Metabolism and L ‐Theanine in the Metabolism‐Regulatory Effects of Epigallocatechin Gallate.” Nutrients 13: 4120. [DOI] [PMC free article] [PubMed] [Google Scholar]
  48. Liu, A. , Gong Z., Lin L., et al. 2020. “Effects of L ‐Theanine on Glutamine Metabolism in Enterotoxigenic Escherichia coli (E44813)‐Stressed and Non‐Stressed Rats.” Journal of Functional Foods 64: 103670. [Google Scholar]
  49. Liu, B. , Chen Z., Zhang Y., et al. 2022. “Epigallocatechin‐3‐Gallate + L ‐Theanine/β‐Cyclodextrin Inclusion Complexes Enhance Epigallocatechin‐3‐Gallate Bioavailability and Its Lipid‐Lowering and Weight Loss Effects.” Journal of Functional Foods 90: 104998. [Google Scholar]
  50. Liu, K. , Peng Y., Lin L., Gong Z., Xiao W., and Li Y.. 2023. “ L ‐Theanine Regulates the Abundance of Amino Acid Transporters in Mice Duodenum and Jejunum via the mTOR Signaling Pathway.” Nutrients 15: 142. [DOI] [PMC free article] [PubMed] [Google Scholar]
  51. Liu, Z. , Chen J., Zheng B., Lu Q., and Chen L.. 2020. “Effects of Matcha and Its Active Components on the Structure and Rheological Properties of Gluten.” LWT ‐ Food Science and Technology 124: 109197. [Google Scholar]
  52. López‐Martínez, M. I. , Miguel M., and Garcés‐Rimón M.. 2022. “Protein and Sport: Alternative Sources and Strategies for Bioactive and Sustainable Sports Nutrition.” Frontiers in Nutrition 9: 926043. [DOI] [PMC free article] [PubMed] [Google Scholar]
  53. Luo, M. , Gan R.‐Y., Li B.‐Y., et al. 2023. “Effects and Mechanisms of Tea on Parkinson's Disease, Alzheimer's Disease and Depression.” Food Review International 39, no. 1: 278–306. [Google Scholar]
  54. Luo, Q. , and He H.‐F.. 2025. “Accumulation of Theanine in Tea Plant ( Camellia sinensis (L.) O. Kuntze): Biosynthesis, Transportation and Strategy for Improvement.” Plant Science 352: 112406. [DOI] [PubMed] [Google Scholar]
  55. Malkoc, M. , Patan H., Yaman S. O., et al. 2020. “ L ‐Theanine Alleviates Liver and Kidney Dysfunction in Septic Rats Induced by Cecal Ligation and Puncture.” Life Sciences 249: 117502. [DOI] [PubMed] [Google Scholar]
  56. Maloh, J. , Chakkalakal M., Sulaiman F., Burney W., Chambers C., and Sivamani R.. 2022. “Combining Topical and Oral Botanicals for Skin Redness, Pigmentation, Sleep, and Mood: A Randomized Controlled Study.” Journal of Clinical Medicine 11: 6690. [DOI] [PMC free article] [PubMed] [Google Scholar]
  57. Matsuoka, K. , Akaihata H., Hata J., et al. 2021. “ L ‐Theanine Protects Bladder Function by Suppressing Chronic Sympathetic Hyperactivity in Spontaneously Hypertensive Rat.” Metabolites 11: 778. [DOI] [PMC free article] [PubMed] [Google Scholar]
  58. Matsuu‐Matsuyama, M. , Shichijo K., Tsuchiya T., and Nakashima M.. 2023. “The Effects of Cystine and Theanine Mixture on the Chronic Survival Rate and Tumor Incidence of Rats After Total Body X‐Ray Irradiation.” Journal of Radiation Research 64, no. 4: 738–742. [DOI] [PMC free article] [PubMed] [Google Scholar]
  59. Mstsuu‐Matsuyama, M. , Shichijo K., Tsuchiya T., et al. 2020. “Protective Effects of a Cystine and Theanine Mixture Against Acute Radiation Injury in Rats.” Environmental Toxicology and Pharmacology 78: 103395. [DOI] [PubMed] [Google Scholar]
  60. Muhammad, S. , Muhammad N., Muhammad A., et al. 2017. “Green Tea ( Camellia sinensis ) and L ‐Theanine: Medicinal Values and Beneficial Applications in Humans ‐ A Comprehensive Review.” Biomedicine & Pharmacotherapy 95: 1260–1275. [DOI] [PubMed] [Google Scholar]
  61. Muhammad, S. , Muhammad S. K., Asghar A. K., et al. 2020. “ L ‐Theanine: An Astounding Sui Generis Amino Acid in Poultry Nutrition.” Poultry Science 99, no. 11: 5625–5636. [DOI] [PMC free article] [PubMed] [Google Scholar]
  62. Muhammad, S. , Xu Y., Faiz‐ul H., et al. 2018. “Influence of Graded Levels of L ‐Theanine Dietary Supplementation on Growth Performance, Carcass Traits, Meat Quality, Organs Histomorphometry, Blood Chemistry and Immune Response of Broiler Chickens.” International Journal of Molecular Sciences 19, no. 2: 462. [DOI] [PMC free article] [PubMed] [Google Scholar]
  63. Muhammad, S. , Xu Y., Zhang T., et al. 2018. “16S Ribosomal RNA Sequencing Reveals a Modulation of Intestinal Microbiome and Immune Response by Dietary L ‐Theanine Supplementation in Broiler Chickens.” Poultry Science 98, no. 2: 842–854. [DOI] [PMC free article] [PubMed] [Google Scholar]
  64. Muszynska, B. , Kata K., Lazur J., et al. 2020. “Imleria Badia Culinary‐Medicinal Mushroom With Interesting Biological Properties.” Food Bioscience 37: 100663. [Google Scholar]
  65. Okamoto, H. , Taniyama Y., Sakurai T., et al. 2022. “Perioperative Administration of Cystine and Theanine Suppresses Inflammation and Facilitates Early Rehabilitation and Recovery After Esophagectomy: A Randomized, Double‐Blind, Controlled Clinical Trial.” Nutrients 14: 2319. [DOI] [PMC free article] [PubMed] [Google Scholar]
  66. Ouyang, J. , Peng Y., and Gong Y.. 2022. “New Perspectives on Sleep Regulation by Tea: Harmonizing Pathological Sleep and Energy Balance Under Stress.” Food 11: 3930. [DOI] [PMC free article] [PubMed] [Google Scholar]
  67. Pan, S.‐Y. , Nie Q., Tai H.‐C., et al. 2022. “Tea and Tea Drinking: China's Outstanding Contributions to the Mankind.” Chinese Medicine 17: 27. [DOI] [PMC free article] [PubMed] [Google Scholar]
  68. Payne, E. R. , Aceves‐Martins M., Dubost J., Greyling A., and de Roos B.. 2025. “Effects of Tea ( Camellia sinensis ) or Its Bioactive Compounds L ‐Theanine or L ‐Theanine Plus Caffeine on Cognition, Sleep, and Mood in Healthy Participants: A Systematic Review and Meta‐Analysis of Randomized Controlled Trials.” Nutrition Reviews 2: nuaf054. [DOI] [PMC free article] [PubMed] [Google Scholar]
  69. Peng, W.‐Q. , Xiao G., Li B.‐Y., Guo Y. Y., Guo L., and Tang Q. Q.. 2021. “ L ‐Theanine Activates the Browning of White Adipose Tissue Through the AMPK/a‐Ketoglutarate/Prdm16 Axis and Ameliorates Diet‐Induced Obesity in Mice.” Diabetes 70: 1458–1472. [DOI] [PubMed] [Google Scholar]
  70. Peng, Y. , Dai S., Lu Y., et al. 2021. “Theanine Improves High‐Dose Epigallocatechin‐3‐Gallate‐Induced Lifespan Reduction in Caenorhabditis elegans .” Food 10: 1404. [DOI] [PMC free article] [PubMed] [Google Scholar]
  71. Qi, Z. , Chen X., Guo W., Fu C., and Pan S.. 2020. “Theanine‐Modified Graphene Oxide Composite Films for Neural Stem Cells Proliferation and Differentiation.” Journal of Nanomaterials 2020: 3068173. [Google Scholar]
  72. Raj, K. , Gupta G. D., and Singh S.. 2022. “ L ‐Theanine Ameliorates Motor Deficit, Mitochondrial Dysfunction, and Neurodegeneration Against Chronic Tramadol Induced Rats Model of Parkinson's Disease.” Drug and Chemical Toxicology 45, no. 5: 2097–2108. [DOI] [PubMed] [Google Scholar]
  73. Rana, A. , Rana S., and Kumar S.. 2021. “Phytotherapy With Active Tea Constituents: A Review.” Environmental Chemistry Letters 19: 2031–2041. [Google Scholar]
  74. Ribeiro, M. , Lopes S., Picascia S., Gianfrani C., and Nunes F. M.. 2020. “Reinventing the Nutraceutical Value of Gluten: The Case of L ‐Theanine‐Gluten as a Potential Alternative to the Gluten Exclusion Diet in Celiac Disease.” Food Chemistry 324: 126840. [DOI] [PubMed] [Google Scholar]
  75. Rizzo, R. , Prato A., Scerbo M., Saia F., Barone R., and Curatolo P.. 2022. “Use of Nutritional Supplements Based on L ‐Theanine and Vitamin B6 in Children With Tourette Syndrome, With Anxiety Disorders: A Pilot Study.” Nutrients 14: 852. [DOI] [PMC free article] [PubMed] [Google Scholar]
  76. Rogers, P. J. , Smith J. E., Heatherley S. V., and Pleydell‐Pearce C. W.. 2007. “Time for Tea: Mood, Blood Pressure and Cognitive Performance Effects of Caffeine and Theanine Administered Alone and Together.” Psychopharmacology 195, no. 4: 569–577. [DOI] [PubMed] [Google Scholar]
  77. Saleh, D. O. , Mansour D. F., Hashad I. M., and Bakeer R. M.. 2019. “Effects of Sulforaphane on D ‐Galactose‐Induced Liver Aging in Rats: Role of Keap‐1/Nrf‐2 Pathway.” European Journal of Pharmacology 855: 40–49. [DOI] [PubMed] [Google Scholar]
  78. Sarris, J. , Byrne G. J., Oliver G., et al. 2022. “Treatment of Refractory Obsessive–Compulsive Disorder With Nutraceuticals (TRON): A 20‐Week, Open Label Pilot Study.” CNS Spectrums 27, no. 5: 588–597. [DOI] [PubMed] [Google Scholar]
  79. Shamabadi, A. , Fattollahzadeh‐Noor S., Fallahpour B., A. Basti F., Khodaei Ardakani M. R., and Akhondzadeh S.. 2023. “ L ‐Theanine Adjunct to Risperidone in the Treatment of Chronic Schizophrenia Inpatients: A Randomized, Double‐Blind, Placebo‐Controlled Clinical Trial.” Psychopharmacology 240: 2631–2640. [DOI] [PubMed] [Google Scholar]
  80. Shojaei‐Zarghani, S. , Khosroushahi A. Y., and Rafraf M.. 2021. “Oncopreventive Effects of Theanine and Theobromine on Dimethylhydrazine‐Induced Colon Cancer Model.” Biomedicine & Pharmacotherapy 134: 111140. [DOI] [PubMed] [Google Scholar]
  81. Shojaei‐Zarghani, S. , Rafraf M., and Yari‐Khoroushahi A.. 2021. “Theanine and Cancer: A Systematic Review of the Literature.” Phytotherapy Research 35: 4782–4794. [DOI] [PubMed] [Google Scholar]
  82. Sun, L. , Wen S., Li Q., et al. 2021. “ L ‐Theanine Relieves Acute Alcoholic Liver Injury by Regulating the TNF‐α/NF‐κB Signaling Pathway in C57BL/6J Mice.” Journal of Functional Foods 86: 104699. [Google Scholar]
  83. Thiagarajah, K. , Chee H. P., and Sit N. W.. 2022. “Effect of Alpha‐S1‐Casein Tryptic Hydrolysate and L ‐Theanine on Poor Sleep Quality: A Double Blind.” Randomized Placebo‐Controlled Crossover Trial, Nutrients 14: 652. [DOI] [PMC free article] [PubMed] [Google Scholar]
  84. Tsuchiya, T. , and Kurihara S.. 2022. “Cystine and Theanine as Stress‐Reducing Amino Acids‐Perioperative Use for Early Recovery After Surgical Stress.” Nutrients 14: 129. [DOI] [PMC free article] [PubMed] [Google Scholar]
  85. Unno, K. , Muguruma Y., Inoue K., et al. 2021. “Theanine, Antistress Amino Acid in Tea Leaves, Causes Hippocampal Metabolic Changes and Antidepressant Effects in Stress‐Loaded Mice.” International Journal of Molecular Sciences 22: 193. [DOI] [PMC free article] [PubMed] [Google Scholar]
  86. Unno, K. , Sumiyoshi A., Konishi T., et al. 2020. “Theanine, the Main Amino Acid in Tea, Prevents Stress‐Induced Brain Atrophy by Modifying Early Stress Responses.” Nutrients 12: 174. [DOI] [PMC free article] [PubMed] [Google Scholar]
  87. Unno, K. , Taguchi K., Konishi T., Ozeki M., and Nakamura Y.. 2023. “Theanine, a Tea‐Leaf‐Specific Amino Acid, Alleviates Stress Through Modulation of Npas4 Expression in Group‐Housed Older Mice.” International Journal of Molecular Sciences 24: 3983. [DOI] [PMC free article] [PubMed] [Google Scholar]
  88. Uyanga, V. A. , Oke E. O., Amevor F. K., et al. 2022. “Functional Roles of Taurine, L ‐Theanine, Lcitrulline, and Betaine During Heat Stress in Poultry.” Journal of Animal Science and Biotechnology 13: 23. [DOI] [PMC free article] [PubMed] [Google Scholar]
  89. Wang, B. , Liu S., Lin L., Xu W., Gong Z., and Xiao W.. 2024. “The Protective Effect of L ‐Theanine on the Intestinal Barrier in Heat‐Stressed Organisms.” Food & Function 15, no. 6: 3036–3049. [DOI] [PubMed] [Google Scholar]
  90. Wang, C.‐C. , Kong J.‐Y., Li X.‐Y., et al. 2022. “Antarctic Krill Oil Exhibited Synergistic Effects With Nobiletin and Theanine in Ameliorating Memory and Cognitive Deficiency in SAMP8 Mice: Applying the Perspective of the Sea–Land Combination to Retard Brain Aging.” Frontiers in Aging Neuroscience 14: 964077. [DOI] [PMC free article] [PubMed] [Google Scholar]
  91. Wang, D. , Cai M., Wang T., et al. 2020. “Ameliorative Effects of L ‐Theanine on Dextran Sulfate Sodium Induced Colitis in C57BL/6J Mice Are Associated With the Inhibition of Inflammatory Responses and Attenuation of Intestinal Barrier Disruption.” Food Research International 137: 109409. [DOI] [PubMed] [Google Scholar]
  92. Wang, L. , Brennan M., Li S., Zhao H., Lange K. W., and Brennan C.. 2022. “How Does the Tea L ‐Theanine Buffer Stress and Anxiety.” Food Science and Human Wellness 11: 467–475. [Google Scholar]
  93. Wang, Z. , Tang Y., Long L., and Zhang H.. 2022. “Effects of Dietary L ‐Theanine on Growth Performance, Antioxidation, Meat Quality, and Intestinal Microflora in White Feather Broilers With Acute Oxidative Stress.” Frontiers in Veterinary Science 9: 889485. [DOI] [PMC free article] [PubMed] [Google Scholar]
  94. Wang, Z. , Zhang L., Li Z., et al. 2021. “Alterations of Endotoxin Distribution Across Different Biofluids and Relevant Inflammatory Responses by Supplementing L ‐Theanine in Dairy Cows During Heat Stress.” Animal Nutrition 7: 1253–1257. [DOI] [PMC free article] [PubMed] [Google Scholar]
  95. Wu, S.‐X. , Li J., Zhou D.‐D., et al. 2022. “Possible Effects and Mechanisms of Dietary Natural Products and Nutrients on Depression and Anxiety: A Narrative Review.” Antioxidants 11: 2132. [DOI] [PMC free article] [PubMed] [Google Scholar]
  96. Wu, Z. , Su X., Lin Z., Khan N. I., Owens G., and Chen Z.. 2021. “Removal of as(V) by Iron‐Based Nanoparticles Synthesized via the Complexation of Biomolecules in Green Tea Extracts and an Iron Salt, Science.” Total Environment 764: 142883. [DOI] [PubMed] [Google Scholar]
  97. Xia, Y. , Ni W., Wang X., Wang Y., and Huang X.. 2022. “Intermolecular Hydrogen Bonds Between Catechin and Theanine in Tea: Slow Release of the Antioxidant Capacity by a Synergetic Effect.” RSC Advances 12: 21135–21144. [DOI] [PMC free article] [PubMed] [Google Scholar]
  98. Xia, Z. , Wei Z., Li X., et al. 2024. “C/EBPα Aggravates Renal Fibrosis in CKD Through the NOX4‐ROS‐Apoptosis Pathway in Tubular Epithelial Cells.” Biochimica et Biophysica Acta 1870, no. 3: 167039. [DOI] [PubMed] [Google Scholar]
  99. Xie, X. , Wan J., Zheng X., et al. 2022. “Synergistic Effects of Epigallocatechin Gallate and L ‐Theanine in Nerve Repair and Regeneration by Anti‐Amyloid Damage, Promoting Metabolism, and Nourishing Nerve Cells.” Frontiers in Nutrition 9: 951415. [DOI] [PMC free article] [PubMed] [Google Scholar]
  100. Xu, W. , Lin L., Liu A., et al. 2020. “ L ‐Theanine Affects Intestinal Mucosal Immunity by Regulating Short‐Chain Fatty Acid Metabolism Under Dietary Fiber Feeding.” Food & Function 11, no. 9: 8369–8379. [DOI] [PubMed] [Google Scholar]
  101. Xu, W. , Song Y., Xiao W., et al. 2023. “Regulatory Effects and Mechanisms of L ‐Theanine on Neurotransmitters via Liver–Brain Axis Under a High Protein Diet.” Molecular Neurobiology 61, no. 1: 1–16. [DOI] [PubMed] [Google Scholar]
  102. Xu, Y. , Zhu J., Hu J., et al. 2021. “ L ‐Theanine Alleviates IMQ‐Induced Psoriasis Like Skin Inflammation by Downregulating the Production of IL‐23 and Chemokines.” Frontiers in Pharmacology 12: 719842. [DOI] [PMC free article] [PubMed] [Google Scholar]
  103. Yang, C.‐C. , Chang K.‐C., Wang M.‐H., et al. 2020. “ L ‐Theanine Improves Functional Recovery After Traumatic Spinal Cord Injury in Rats.” Journal of the Formosan Medical Association 119: 1405–1414. [DOI] [PubMed] [Google Scholar]
  104. Yang, C.‐C. , Wang M.‐H., Soung H.‐S., et al. 2023. “Through Its Powerful Antioxidative Properties, L ‐Theanine Ameliorates Vincristine‐Induced Neuropathy in Rats.” Antioxidants 12: 803. [DOI] [PMC free article] [PubMed] [Google Scholar]
  105. Yang, L. , Zhang L., Zhang P., et al. 2022. “Alterations in Nutrient Digestibility and Performance of Heat‐Stressed Dairy Cows by Dietary L ‐Theanine Supplementation.” Animal Nutrition 11: 350–358. [DOI] [PMC free article] [PubMed] [Google Scholar]
  106. Yang, M. , Pan T., Li T., Duan G., Jiang H., and Ling J.. 2024. “The Effects of Dietary L ‐Theanine on the Growth Performance, Non‐Specific Immunity, Antioxidant Status, and Intestinal Microflora of Female Chinese Mitten Crabs ( Eriocheir sinensis ).” Aquaculture Reports 34: 101923. [Google Scholar]
  107. Ye, Y. , Fang C., Li L., et al. 2023. “Protective Effect of L ‐Theanine on Cyclophosphamide‐Induced Testicular Toxicity in Mice.” Journal of Agricultural and Food Chemistry 71: 8050–8060. [DOI] [PubMed] [Google Scholar]
  108. Yilmaz, U. , Buzdagli Y., Lütfü P. M., et al. 2023. “Effect of Single or Combined Caffeine and L ‐Theanine Supplementation on Shooting and Cognitive Performance in Elite Curling Athletes: A Double‐Blind, Placebo‐Controlled Study.” Journal of the International Society of Sports Nutrition 20, no. 1: 2267536. [DOI] [PMC free article] [PubMed] [Google Scholar]
  109. Yin, S. , Xiao J., Xiong J., et al. 2023. “Associations of Tea Consumption With Cognitive Function and Mental Health Among Older Adults in China.” Current Psychology 42: 29257–29267. [Google Scholar]
  110. Yoneda, J. , Nishikawa S., and Kurihara S.. 2021. “Oral Administration of Cystine and Theanine Attenuates 5‐Fluorouracil‐Induced Intestinal Mucositis and Diarrhea by Suppressing Both Glutathione Level Decrease and ROS Production in the Small Intestine of Mucositis Mouse Model.” BMC Cancer 21: 1343. [DOI] [PMC free article] [PubMed] [Google Scholar]
  111. Yuan, S. , Brown J. C., Gold M., Tirrell E., Jones R. N., and Carpenter L. L.. 2021. “Effects of Single‐Dose L ‐Theanine on Motor Cortex Excitability.” Clinical Neurophysiology 132: 2062–2064. [DOI] [PMC free article] [PubMed] [Google Scholar]
  112. Zeng, L. , Lin L., Chen L., Xiao W., and Gong Z.. 2021. “ L ‐Theanine Ameliorates D ‐Galactose‐Induced Brain Damage in Rats via Inhibiting AGE Formation and Regulating Sirtuin1 and BDNF Signaling Pathways.” Oxidative Medicine and Cellular Longevity 2021: 8850112. [DOI] [PMC free article] [PubMed] [Google Scholar]
  113. Zeng, L. , Lin L., Peng Y., et al. 2020. “ L ‐Theanine Attenuates Liver Aging by Inhibiting Advanced Glycation End Products in D ‐Galactose‐Induced Rats and Reversing an Imbalance of Oxidative Stress and Inflammation.” Experimental Gerontology 131: 110823. [DOI] [PubMed] [Google Scholar]
  114. Zhang, C. , Wang C., Chen K., Zhao X., and Geng Z.. 2020. “Effect of L ‐Theanine on Growth Performance, Intestinal Development and Health, and Peptide and Amino Acid Transporters Expression of Broilers.” Journal of the Science of Food and Agriculture 100, no. 4: 1718–1725. [DOI] [PubMed] [Google Scholar]
  115. Zhang, C. , Wang C., Zhao X., Chen K., and Geng Z.. 2020. “Effect of L ‐Theanine on Meat Quality, Muscle Amino Acid Profiles, and Antioxidant Status of Broilers.” Animal Science Journal 91: e13351. [DOI] [PubMed] [Google Scholar]
  116. Zhang, L. , Cao Q.‐Q., Granato D., Xu Y.‐Q., and Ho C.‐T.. 2020. “Association Between Chemistry and Taste of Tea: A Review.” Trends in Food Science & Technology 101: 139–149. [Google Scholar]
  117. Zhang, L. , Ge H., Zhao J., Liu C., and Wang Y.. 2024. “ L ‐Theanine Improves the Gelation of Ginkgo Seed Proteins at Different pH Levels.” Gels 10: 131. [DOI] [PMC free article] [PubMed] [Google Scholar]
  118. Zhang, M. , and Tang Z.. 2023. “Therapeutic Potential of Natural Molecules Against Alzheimer's Disease via SIRT1 Modulation.” Biomedicine & Pharmacotherapy 161: 114474. [DOI] [PubMed] [Google Scholar]
  119. Zhang, R. , Zheng S., Guo Z., et al. 2022. “ L ‐Theanine Inhibits Melanoma Cell Growth and Migration via Regulating Expression of the Clock Gene BMAL1.” European Journal of Nutrition 61: 763–777. [DOI] [PubMed] [Google Scholar]
  120. Zhang, X. , Zhang Z., Shu Q., et al. 2021. “Copper Clusters: An Effective Antibacterial for Eradicating Multidrug‐Resistant Bacterial Infection In Vitro and In Vivo .” Advanced Functional Materials 31: 2008720. [Google Scholar]
  121. Zhang, Y. , Jia X., Chen X., et al. 2021. “ L ‐Theanine and Neumentix Mixture Improves Sleep Quality and Modulates Brain Neurotransmitter Levels in Mice.” Annals of Palliative Medicine 10, no. 4: 4572–4581. [DOI] [PubMed] [Google Scholar]
  122. Zhang, Y. , Yang C., Lu Y., et al. 2024. “Theanine Capture of Reactive Carbonyl Species in Humans After Consuming Theanine Capsules or Green Tea.” Journal of Agricultural and Food Chemistry 72: 13240–13249. [DOI] [PubMed] [Google Scholar]
  123. Zhao, B. , Jia X., Feng H., et al. 2023. “Nutrient Combinations Exhibit Universal Antianxiety, Antioxidant, Neuro‐Protecting, and Memory‐Improving Activities.” Frontiers in Nutrition 9: 996692. [DOI] [PMC free article] [PubMed] [Google Scholar]
  124. Zhao, J. , Zhao X., Tian J., et al. 2020. “Theanine Attenuates Hippocampus Damage of Rat Cerebral Ischemiareperfusion Injury by Inhibiting HO‐1 Expression and Activating ERK1/2 Pathway.” Life Sciences 241: 117160. [DOI] [PubMed] [Google Scholar]
  125. Zhao, S. , Cao W., Xing S., et al. 2019. “Enhancing Effects of Theanine Liposomes as Chemotherapeutic Agents for Tumor Therapy.” ACS Biomaterials Science & Engineering 5: 3373–3379. [DOI] [PubMed] [Google Scholar]
  126. Zhong, Y. , Lu Y., and Lv L.. 2023. “Theanine in Tea: An Effective Scavenger of Single or Multiple Reactive Carbonyl Species at the Same Time.” Journal of Agricultural and Food Chemistry 71, no. 45: 17153–17162. [DOI] [PubMed] [Google Scholar]
  127. Zhu, K. , Zeng H., Yue L., Huang J., Ouyang J., and Liu Z.. 2024. “The Protective Effects of L ‐Theanine Against Epigallocatechin Gallate‐Induced Acute Liver Injury in Mice.” Food 13: 1121. [DOI] [PMC free article] [PubMed] [Google Scholar]
  128. Zhu, Y. , Wang F., Han J., et al. 2023. “Untargeted and Targeted Mass Spectrometry Reveal the Effects of Theanine on the Central and Peripheral Metabolomics of Chronic Unpredictable Mild Stress‐Induced Depression in Juvenile Rats.” Journal of Pharmaceutical Analysis 13: 73–87. [DOI] [PMC free article] [PubMed] [Google Scholar]

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