L-theanine, unique amino acid of tea, and its metabolism, health effects, and safety

The effects of L-theanine consumption on sleep outcomes: A systematic review and meta-analysis

This systematic review ansd meta-analysis aimed to evaluate the effects of L-theanine, a non-proteinogenic amino acid found in tea, on sleep outcomes. Literature searches were conducted in five electronic databases (APA PsycINFO, CINAHL, Medline, Scopus, Web of Science), and one register (Cochrane Central Register of Controlled Trials) from inception until September 2024. Randomised controlled trials investigating the effects of L-theanine supplementation on sleep quality in humans of all ages and health status were included. Nineteen articles (N = 897 participants) were selected and 18 included in the meta-analysis. L-theanine was shown to significantly improve subjective sleep onset latency (SMD = 0.15, 95 % CI [0.01, 0.29], p = 0.04; n = 10 studies), subjective daytime dysfunction (SMD = 0.33, 95 % CI [0.16, 0.49], p < 0.001; n = 9 studies), and overall subjective sleep quality score (SMD = 0.43, 95 % CI [0.04, 0.83], p = 0.03; n = 12 studies). The findings indicate the potential use of L-theanine in the management of sleep disturbances; however, the lack of studies on "pure" L-theanine warrants further investigation. Future studies are needed to determine the adequate dose and duration of L-theanine supplementation for improving and maintaining sleep quality in healthy and clinical populations.

L-Theanine Mitigates Acute Alcoholic Intestinal Injury by Activating the HIF-1 Signaling Pathway to Regulate the TLR4/NF-κB/HIF-1α Axis in Mice

BACKGROUND/OBJECTIVES

Acute alcohol consumption can cause intestinal dysfunction, whereas L-theanine (LTA) has shown the potential to support intestinal health. We explored L-theanine's ability to protect against acute alcohol-induced injury.

METHODS

Male C57BL/6 mice were administered LTA for 28 d and then underwent acute alcohol intestinal injury modeling for 8 days.

RESULTS

The results revealed that LTA ameliorated alcohol-induced pathological damage in the duodenum and gut permeability, improved secretory immunoglobulin A (SIgA) content, and reduced oxidative stress, inflammatory markers, and serum lipopolysaccharide (LPS) content in mice. Furthermore, LTA restored the composition of the intestinal flora, increasing the abundance of Alloprevotella, Candidatus_Saccharimonas, Muribaculum, and Prevotellaceae_UCG-001. Additionally, LTA increased beneficial metabolites, such as oxyglutaric acid and L-ascorbic acid, in the HIF-1 pathway within the enrichment pathway. Further investigation into the HIF-1 signaling pathway identified up-regulation of claudin-1, HIF-1α, occludin, and ZO-1, and down-regulation of TLR4, PHD2, p65 NF-κB, TNF-α, and IFN-γ mRNA and protein levels.

CONCLUSIONS

These results suggest that LTA may enhance the intestinal barrier by activating the HIF-1 signaling pathway to regulate the TLR4/NF-κB/HIF-1α axis, thereby reducing acute alcoholic intestinal injury.

Natural Copper Ion Scavenger: Investigation of the Hepatoprotective Effects of Green Tea Extract in Toxic-Milk Mice with Wilson's Disease Model

Wilson's disease (WD) is an inherited disorder characterized by abnormal copper metabolism with complex pathological features. Currently, the mechanism of copper overload-induced hepatic injury is unclear. Green tea is a natural chelator, and its main ingredients, green tea polyphenol (GTP) and L-theanine (L-TA) are good at binding to heavy metals like iron and copper. There have been no reports on green tea extracts (GTE) for the treatment of Wilson's disease. This study investigated the hepatoprotective effect of GTE on WD model mice. Initially, we examined the impact of green tea extract on copper metabolism, excretion, and hepatoprotective effects in WD model toxic milk mice. Then, Ultra performance liquid chromatography (UPLC-DAD) was established to analyze GTP and L-TA in green tea extract. Further screening of eight active components and copper complex active components in green tea extract was carried out by ion analyzer. Finally, we verified the pharmacodynamic effects of these active ingredients at the animal level. The results showed that GTE improves liver function and attenuates liver injury in TX mice by promoting tissue copper excretion and inhibiting oxidative stress, which provides a theoretical basis for green tea's potential to improve the clinical symptoms of WD.

Genetic mapping of serum metabolome to chronic diseases among Han Chinese

Serum metabolites are potential regulators for chronic diseases. To explore the genetic regulation of metabolites and their roles in chronic diseases, we quantified 2,759 serum metabolites and performed genome-wide association studies (GWASs) among Han Chinese individuals. We identified 184 study-wide significant (p < 1.81 × 10-11) metabolite quantitative trait loci (metaboQTLs), 88.59% (163) of which were novel. Notably, we identified Asian-ancestry-specific metaboQTLs, including the SNP rs2296651 for taurocholic acid and taurochenodesoxycholic acid. Leveraging the GWAS for 37 clinical traits from East Asians, Mendelian randomization analyses identified 906 potential causal relationships between metabolites and clinical traits, including 27 for type 2 diabetes and 38 for coronary artery disease. Integrating genetic regulation of the transcriptome and proteome revealed putative regulators of several metabolites. In summary, we depict a landscape of the genetic architecture of the serum metabolome among Han Chinese and provide insights into the role of serum metabolites in chronic diseases.

l-theanine: From tea leaf to trending supplement - does the science match the hype for brain health and relaxation?

l-Theanine is a unique non-protein amino acid found abundantly in tea leaves. Interest in its potential use as a dietary supplement has surged recently, especially claims related to promoting relaxation and cognitive enhancement. This review surveys the chemistry, metabolism, and purported biological activities of l-theanine. It is well absorbed from the intestine and can cross the blood-brain barrier. Some studies suggest l-theanine may increase alpha waves in the brain associated with relaxation and selective attention, reduce stress and anxiety, and improve sleep quality, though findings are often inconsistent. Potential neuroprotective and anti-seizure effects have also been reported in animal models. When combined with caffeine, l-theanine may improve cognitive performance, alertness and focus. However, the evidence supporting many health claims remains limited, especially the lack of rigorous human clinical trials. While l-theanine exhibits a good safety profile based on toxicology studies, caution is warranted regarding the purported health benefits, until stronger scientific substantiation emerges. Overall, the mechanisms of action and therapeutic potential of l-theanine require further investigation, given the current interest and increasing popularity of this nutraceutical supplement marketed for brain health and relaxation. In the absence of well-designed and carefully controlled human clinical trials, we would urge caution in the use of l-theanine supplements at pharmacologic doses by the wider population, and believe that the science does not yet match the hype behind this trending supplement for brain health and relaxation.

Stress-Relieving Effects of Japanese Green Tea: Evaluation Using the Molar Ratio of Caffeine and Epigallocatechin Gallate to Theanine and Arginine as an Indicator

The major components of tea leaves and their infusions were analyzed for various types of green tea available in Japan in 2022. Almost all the green teas used were from the first crop, known for their high amino acid content. The amino acids theanine and arginine in green tea have been shown to reduce stress. On the other hand, epigallocatechin gallate (EGCG) and caffeine, the major components of green tea, counteract the effects of theanine and arginine. We have shown that the CE/TA ratio, which is the ratio of the molar sum of caffeine (C) and EGCG (E) to the molar sum of theanine (T) and arginine (A), can be used to evaluate the stress-relieving effects of each green tea. Green tea with a CE/TA ratio smaller than 3 can be expected to have a stress-reducing effect. The CE/TA ratios of the tea leaves and infusions of Gyokuro, Sencha, and Tamaryokucha were less than 3, indicating that these teas are expected to have stress-relieving effects. In addition, when the same tea leaves were infused repeatedly, it was found that most of the amino acids were eluted by the first and second cups; therefore, no stress-relieving effect could be expected after the third cup.

CsCIPK20 Improves Tea Plant Cold Tolerance by Modulating Ascorbic Acid Synthesis Through Attenuation of CsCSN5-CsVTC1 Interaction

Low temperature is a limiting environmental factor for tea plant growth and development. CBL-interacting protein kinases (CIPKs) are important components of the calcium pathway and involved in plant development and stress responses. Herein, we report the function and regulatory mechanisms of a low-temperature-inducible gene, CsCIPK20, in tea plants. The overexpression of CsCIPK20 in Arabidopsis and its transient knockdown in tea plants confirmed its positive role in cold resistance. Notably, the ascorbic acid (AsA) levels increased in the overexpression lines and decreased in the CsCIPK20 knockdown tea plants under freezing stress. Transcriptomic analysis revealed that genes involved in flavonoid metabolism, glutathione metabolism, and AsA biosynthesis were significantly regulated by CsCIPK20. Furthermore, we found that CsCSN5, a key component of the COP9 signalosome, interacted with CsCIPK20 to mediate CsCIPK20 degradation. CsCSN5 interacted with CsVTC1, a key enzyme in AsA biosynthesis, and mediated CsVTC1 degradation. Knockdown of CsVTC1 in tea plants enhanced sensitivity to low temperature. Moreover, we demonstrated that CsCIPK20 competed with CsVTC1 to bind to CsCSN5, which protected CsVTC1 from degradation mediated by CsCSN5 and contributed to AsA accumulation. Overall, our findings uncovered a mechanistic framework through which the CsCIPK20-CsCSN5-CsVTC1 module mediated AsA accumulation and low-temperature resistance in tea plants.

Feasibility and Efficacy of a Novel Mindfulness App Used With Matcha Green Tea in Generally Healthy Adults: Randomized Controlled Trial

BACKGROUND

Mindfulness practices, such as breathing meditation (BM), reduce stress and enhance mood. One such practice is mindful eating, where a practitioner focuses on the five senses while eating or drinking. A novel set of prototypes has been developed, incorporating principles of mindful eating. These prototypes include matcha green tea and a mobile app that provides audio guidance for meditation during the preparation and consumption of the beverage (hereafter referred to as guided tea meditation [GTM]).

OBJECTIVE

This study assessed the feasibility and efficacy of GTM, evaluating meditation time, frequency, and prototype acceptability over 8 weeks, alongside changes in stress and mood. Additionally, other benefits of GTM were explored.

METHODS

A comparator group was established in which participants performed traditional BM without an app or audio guide (active control). This unblinded randomized controlled trial involved 100 healthy American volunteers (n=49 GTM, n=51 BM). During the 8-week study period, participants were encouraged to perform either GTM or BM for 10 minutes daily. The meditation activity was self-reported the following day. Only the GTM group assessed the prototype acceptability. The Perceived Stress Scale-10 was used to measure stress levels, while the Two-Dimensional Mood Scale was used to evaluate mood changes. Other meditation benefits were explored using a questionnaire. All questionnaires were presented and completed via an app. An intention-to-treat analysis was performed.

RESULTS

No significant between-group differences were found in total meditation time (P=.15) or frequency (P=.36). However, the weekly time and frequency of the GTM group remained above 50 minutes per week and 4 days per week, respectively. Over half of the GTM participants (≥28/49, ≥57%) accepted the prototype. The GTM group exhibited significant stress reductions at weeks 4 and 8 (both P<.001), similar to the BM group. Improvements in mood metrics were observed after a single GTM session on days 1 and 56, similar to the BM group. Moreover, increases in premeditation scores for relaxed and calm from day 1 to day 56 were significantly higher for the GTM group (P=.04 and .048, respectively). The majority of participants (≥25/49, ≥51%) assigned to GTM experienced positive changes in happiness, time management, quality of life, relationships, sleep, and work performance as they continued meditating. However, no significant between-group differences were found in these exploratory outcomes (P>.08).

CONCLUSIONS

We believe that GTM exhibits good feasibility. Meanwhile, GTM reduced stress, improved mood, and let the practitioners feel other benefits, similar to BM. Long-term practitioners of GTM may even feel more relaxed and calmer in the state of premeditation than those who practice BM.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05832645; https://clinicaltrials.gov/study/NCT05832645.

Functional Foods and Nutraceuticals for the Management of Cardiovascular Disease Risk in Postmenopausal Women

Cardiovascular disease (CVD) is a leading cause of death in women and risk of development is greatly increased following menopause. Menopause occurs over several years and is associated with hormonal changes, including a reduction in estradiol and an increase in follicle-stimulating hormone. This hormonal shift may result in an increased risk of developing abdominal adiposity, insulin resistance, dyslipidemia, vascular dysfunction, hypertension, type 2 diabetes mellitus (T2DM), metabolic dysfunction-associated fatty liver disease (MAFLD), and metabolic syndrome (MetS). Furthermore, with the onset of menopause, there is an increase in oxidative stress that is associated with impaired vascular function, inflammation, and thrombosis, further increasing the risk of CVD development. Despite the harmful consequences of the menopause transition being well known, women in premenopausal, perimenopausal, and postmenopausal stages are unlikely to be enrolled in research studies. Therefore, investigations on the prevention and treatment of cardiovascular and metabolic disease in middle-aged women are still relatively limited. Whilst lifestyle interventions are associated with reduced CVD risk in this population sample, the evidence still remains inconclusive. Therefore, it is important to explore the effectiveness of early intervention and potential therapeutic approaches to maintain cellular redox balance, preserve endothelium, and reduce inflammation. Glycine, N-acetylcysteine, and L-theanine are amino acids with potential antioxidant and anti-inflammatory activity and are identified as therapeutic interventions in the management of age-related and metabolic diseases. The benefits of the intake of these amino acids for improving factors associated with cardiovascular health are discussed in this review. Future studies using these amino acids are warranted to investigate their effect on maintaining the vascular health and cardiovascular outcomes of postmenopausal women.

CsSPX3-CsPHL7-CsGS1/CsTS1 module mediated Pi-regulated negatively theanine biosynthesis in tea (Camellia sinensis)

Phosphorus (P) is the macronutrients essential for the development and growth of plants, but how external inorganic phosphate (Pi) level and signaling affect tea plant growth and characteristic secondary metabolite biosynthesis are not understood. Theanine is major secondary metabolites, and its contents largely determine tea favor and nutrition qualities. Here, we found theanine contents in tea leaves and roots declined as Pi concentration increased in tea plants after Pi feeding. The transcriptome analysis of global gene expression in tea leaves under Pi feeding suggested a wide range of genes involved in Pi/N transport and responses were altered. Among them, CsSPX3 and CsPHL7 transcript levels in response to Pi feeding to tea plants, their expression patterns were generally opposite to these of major theanine biosynthesis genes, indicating possible regulatory correlations. Biochemical analyses showed that CsSPX3 interacted with CsPHL7, and CsPHL7 negatively regulated theanine biosynthesis genes CsGS1 and CsTS1. Meanwhile, VIGS and transient overexpression systems in tea plants verified the functions of CsSPX3 and CsPHL7 in mediating Pi-feeding-repressed theanine biosynthesis. This study offers fresh insights into the regulatory mechanism underlying Pi repression of theanine biosynthesis, and the CsSPX3-CsPHL7-CsGS1/CsTS1 module plays a role in high Pi inhibition of theanine production in tea leaves. It has an instructional significance for guiding the high-quality tea production in tea garden fertilization.

Biological potential and mechanisms of Tea's bioactive compounds: An Updated review

BACKGROUND

Tea (Camellia sinensis) has a rich history and is widely consumed across many countries, and is categorized into green tea, white tea, oolong tea, yellow tea, black tea, and dark tea based on the level of fermentation. Based on a review of previous literature, the commonly recognized bioactive substances in tea include tea polyphenols, amino acids, polysaccharides, alkaloids, terpenoids, macro minerals, trace elements, and vitamins, which have been known to have various potential health benefits, such as anticancer, antioxidant, anti-inflammatory, anti-diabetes, and anti-obesity properties, cardiovascular protection, immune regulation, and control of the intestinal microbiota. Most studies have only pointed out the characteristics of tea's bioactivities, so a comprehensive summary of the pharmacological characteristics and mechanisms of tea's bioactivities and their use risks are vital.

AIM OF REVIEW

This paper aims to summarize tea's bioactive substances of tea and their pharmacological characteristics and mechanisms, providing a scientific basis for the application of bioactive substances in tea and outlining future research directions for the study of bioactive substances in tea.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review summarizes the main biologically active substances, pharmacological effects, and mechanisms and discusses the potential risks. It may help researchers grasp more comprehensive progress in the study of tea bioactive substances to further promote the application of tea as a natural bioactive substance in the medical field.

Dynamic changes and correlation analysis of microorganisms and flavonoids/ amino acids during white tea storage

White tea stored for various times have different flavors. However, the mechanism of flavor conversion remains elusive. Flavonoids and amino acids are two typical flavor components in tea. Herein, the contents of 46 flavonoids and 40 amino acids were measured in white tea (Shoumei) stored for 1, 3, 5 and 7 years, respectively. L-tryptophan, L-ornithine and L-theanine contribute to the refreshing taste of Shoumei 1 and 3. Quercetin, rutin and hesperidin contribute to aging charm and grain aroma of Shoumei 5 and 7. 306 bacterial OTUs and 268 fungal OTUs core microbiota existed in all samples. Interestingly, white teas contained higher richness of fungi than bacteria. The correlation analysis showed that the cooperation with bacteria and fungi may result in the flavonoids and amino acids composition changes in white teas during storage. Overall, this study provides new insights into flavor conversion of white tea during storage.

Enhanced L-theanine production through semi-rational design of γ-glutamylmethylamide synthetase from Methylovorus mays

The thermal instability of γ-glutamylmethylamide synthetase (GMAS) from Methylovorus mays has imposed limitations on its industrial applications, affecting both stability and activity at reaction temperatures. In this study, disulfide bridges were introduced through a combination of directed evolution and rational design to enhance GMAS stability. Among the variants that we generated, M12 exhibited a 1.46-fold improvement in relative enzyme activity and a 6.23-fold increase in half-life at 40℃ compared to the wild-type GMAS. Employing variant M12 under optimal conditions, we achieved the production of 645.7 mM (112.49 g/L) L-theanine with a productivity of 29.3 mM/h, from 800 mM substrate in an ATP regeneration system. Our strategy significantly enhances the biosynthesis efficiency of L-theanine by preserving the structural stability of the enzyme during the catalysis process.

Hepatoprotective effects and mechanisms of l-theanine and epigallocatechin gallate combined intervention in alcoholic fatty liver rats

BACKGROUND

Chronic excessive alcohol consumption can lead to alcoholic fatty liver, posing substantial health risks. l-Theanine (LTA) and epigallocatechin gallate (EGCG) in tea exert antioxidant and hepatoprotective effects. However, the combined effects of LTA and EGCG on rats with alcoholic fatty liver, and the underlying mechanisms of such effects, remain unclear. In this study, Sprague Dawley (SD) rats were fed with alcohol for 6 weeks to induce alcoholic fatty liver. Subsequently, for another 6 weeks, the rats were administered LTA (200 mg kg-1 day-1), EGCG (200 mg kg-1 day-1), or a combination of LTA with EGCG (40 mg kg-1 day-1 l-Thea +160 mg kg-1 day-1 EGCG), respectively.

RESULTS

The combined use of LTA and EGCG for alcoholic fatty liver disease had more significant effects than their individual administration. This combination reduced the activity of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) as well as the levels of hepatic triglyceride (TG), malondialdehyde (MDA), and reactive oxygen species (ROS) in the rats. The combined intervention also increased hepatic superoxide dismutase (SOD) and glutathione peroxidase activity. Reductions in hepatic fat accumulation and inflammatory responses were observed. The mechanism underlying these effects primarily involved the inhibition of fatty acid synthesis and the alleviation of lipid peroxidation through the downregulation of the mRNA and protein expression of TNF-α, SREBP1c, and CYP2E1 and the upregulation of the mRNA and protein expression of ADH1, ALDH2, Lipin-1, PPARαPPARα, AMPK, and PGC-1α, thereby promoting the oxidative decomposition of fatty acids and reducing the synthesis of cholesterol and glucose.

CONCLUSION

l-Theanine and EGCG appear to be able to alleviate alcoholic fatty liver by modulating lipid metabolism and ameliorating oxidative stress, indicating their potential as natural active ingredients in anti-alcoholic fatty liver food products. © 2024 Society of Chemical Industry.

L-Theanine Ameliorates Obesity-Related Complications Induced by High-Fat Diet in Mice: Insights from Transcriptomics and Metabolomics

Obesity is a major public health concern globally. Plant-based ingredients have been proposed as alternative treatments for obesity. L-Theanine (THE), a unique nutraceutical component of tea, is known for its neuroprotective and cognitive benefits. However, there are few reports on THE's effects and mechanisms in improving obesity and its complications. In this study, the alleviating effects and potential mechanisms of THE on obesity-related complications (ORCs) induced by a high-fat diet(HFD) in mice were explored by performing biochemical, hepatic transcriptomics, and plasma metabolomics analyses. The results indicated THE (900 mg/kg of body weight) was effective in mitigating ORCs by decreasing body weight gain and fat deposition, improving glycolipid metabolism disorders, inflammation dysregulation, and alleviating fatty liver formation due to long-term HFD. The hepatic transcriptomics data suggested that THE intervention suppresses the lipid metabolism and inflammation pathways in HFD-fed mice, thereby inhibiting hepatic steatosis and inflammation. Moreover, plasma metabolomics analysis revealed that THE exhibited positive effects on the homeostasis of plasma metabolite balance, such as phosphatidylcholine (PC(14:0/18:1)), phosphatidylethanolamine (Lyso-PE(14:0)), phosphatidic acid (PA(16:0e/18:0)), stigmasterol, and deoxycholic acid glycine conjugate. These metabolites were strongly correlated with ORC-related indicators. Our results indicated that THE, as a functional food additive, possesses potential for ORC alleviation. However, the exact molecular mechanism of how THE alleviates ORCs needs to be investigated in the future.

Survey of U.S. Residents and Their Usage of Electronic Cigarettes with Drugs Other Than Nicotine

Electronic cigarettes (e-cigs), originally intended to be used as cigarette substitutes, have evolved into discreet devices for consuming drugs other than nicotine (DOTNs). Presented are the results of an exploratory survey in which information regarding demographics, e-cig device type, DOTN use, frequency and context of use was collected. The average reported age of respondents was 27.4 years of age (SD = 12.0), and respondents predominantly identified as male (73%). Vape pens (disposable or refillable) were the most reported device across all DOTN classes. Cannabinoids were the most reported class of DOTN used, for both lifetime and past 30-day use. Other DOTNs reported included herbal supplements, amphetamines, caffeine, kratom, vitamins, opiates, DMT, fentanyl, and ketamine. Combinations of DOTNs used in e-cigs and trends in poly-substance use were reported. The most commonly reported context was vaping alone, followed by with friends, at home, and at social events; less commonly reported contexts included when driving, at work, and at school. Results from this study are useful for developing future national surveys to consider a comprehensive substance use-focused strategy that includes vaping, building awareness of DOTN e-cig use, and highlighting public safety issues in driving impairment, crime scene investigations, and death investigations.

Efficient vegetation indices for phenotyping of abiotic stress tolerance in tea plant (Camellia sinensis (L.) Kuntze)

Early non-destructive detection of stress effect is crucial for efficient breeding strategies and germplasm characterization. Recently developed hyperspectral technologies allow to perform fast real-time phenotyping through reflectance-based vegetation indices. However, efficiency of these vegetation indices has to be validated for each crop in different environment. The aim of this study was to reveal efficient vegetation indices for phenotyping of abiotic stress (cold, freezing and nitrogen deficiency) response in tea plant. Among 31 studied VIs, few indices were efficient to distinguish tolerant and susceptible tea plants under abiotic stress: ZMI (Zarco-Tejada & Miller Index), VREI1,2,3 (Vogelmann Red Edge Indices), RENDVI (Red Edge Normalized Difference Vegetation Index), CTR1 and CTR2 (Carter Indices). Most of these indices are calculated based on reflectance in near-infrared area at 705-760 nm, indicating this range as promising for tea germplasm characterization under abiotic stresses. Tolerant tea plants showed the following values under freezing: ZMI ≥1.90, VREI1 ≥ 1.40, RENDVI ≥0.38, Ctr1 ≤ 1.74. The leaf N-content was positively correlated (Pearson's) with the following indices ZMI, VREI1, RENDVI, while negatively correlated with CTR, and VREI2,3. These results will be useful for tea germplasm management, genomics and breeding research aimed at abiotic stress tolerance of tea plant.

Herbal and Natural Supplements for Improving Sleep: A Literature Review

OBJECTIVE

Herbal and natural supplements have gained popularity as alternative treatments to insomnia and sleep disorders due to their perceived safety and potential effectiveness. This literature review summarizes the current evidence on the efficacy, safety, and mechanisms of action of commonly used supplements for sleep, including valerian, hops, kava, German chamomile, cherry, tryptophan, theanine, melatonin, magnesium, and zinc.

METHODS

We conducted literature review of clinical research on herbal and supplements for sleep reported to date. We summarized key findings and reviewed outcomes related to clinical efficacy and side effects.

RESULTS

Findings suggest that certain supplements, particularly valerian, hops, and melatonin, could be effective in improving sleep quality and reducing insomnia symptoms through modulation of neurotransmitter systems and regulation of sleep-wake cycles. However, the strength of the evidence varies with unestablished optimal dosages, formulations, and treatment durations. Although generally considered safe, these supplements are not without risks, such as rare but serious adverse effects associated with kava and potential interactions with prescription medications. The quality and purity of supplements also vary widely due to a lack of strict regulations.

CONCLUSION

Healthcare providers should remain informed about the latest research and work closely with patients to develop personalized treatment plans. Herbal and natural supplements may offer promising alternatives or adjunct treatments for insomnia and sleep disorders, but their use should be guided by the best available evidence and individual patient requirements. Larger, well-designed clinical trials are needed to establish the efficacy and safety of these supplements for clinical decision-making.

Research Progress on the Regulating Factors of Muscle Fiber Heterogeneity in Livestock: A Review

The type of muscle fiber plays a crucial role in the growth, development, and dynamic plasticity of animals' skeletal muscle. Additionally, it is a primary determinant of the quality of both fresh and processed meat. Therefore, understanding the regulatory factors that contribute to muscle fibers' heterogeneity is of paramount importance. Recent advances in sequencing and omics technologies have enabled comprehensive cross-verification of research on the factors affecting the types of muscle fiber across multiple levels, including the genome, transcriptome, proteome, and metabolome. These advancements have facilitated deeper exploration into the related biological questions. This review focused on the impact of individual characteristics, feeding patterns, and genetic regulation on the proportion and interconversion of different muscle fibers. The findings indicated that individual characteristics and feeding patterns significantly influence the type of muscle fiber, which can effectively enhance the type and distribution of muscle fibers in livestock. Furthermore, non-coding RNA, genes and signaling pathways between complicated regulatory mechanisms and interactions have a certain degree of impact on muscle fibers' heterogeneity. This, in turn, changes muscle fiber profile in living animals through genetic selection or environmental factors, and has the potential to modulate the quality of fresh meat. Collectively, we briefly reviewed the structure of skeletal muscle tissue and then attempted to review the inevitable connection between the quality of fresh meat and the type of muscle fiber, with particular attention to potential events involved in regulating muscle fibers' heterogeneity.

Improvement of both human and animal memory by synergy between fructooligosaccharide and L-theanine function establishing a safe and effective food supplement

Aging is classically associated with a decline of cognitive abilities, especially in relation to memory. While the development of potential treatments for neurodegenerative diseases has been in sharp focus, mild cognitive impairment (MCI), a form of age-related memory loss, in the absence of severe functional impairment, a condition experienced by many healthy adults, has received relatively little attention. Advances in this space would make significant contributions to the goal of healthy aging and may also help promote cognitive performance across the wider population. The individual action of either fructooligosaccharide (FOS) or L-theanine, both natural plant-derived molecules, has been tentatively linked with improvements in cognition, but our understanding remains far from complete. We therefore determined the effect of different dose combinations of FOS and L-theanine (termed MT-01/GBL-Memory1) in mice against FOS and L-theanine monotherapy. FOS and L-theanine were found to synergistically enhance murine memory in our animal tests at a dose of 100 mg/kg (coefficient of drug interaction (CDI) < 1). In a subsequent human trial, we demonstrated that MT-01 improved the memory of healthy adults after 1 month of consumption. Our results suggest that a combination of FOS and L-theanine synergistically enhances murine memory within a specific dose range. We show that this plant natural product regimen also improves human memory in a population of healthy adults. MT-01 therefore represents a novel, safe, and effective dietary supplement to promote human memory and cognition.

Protective effects of L-theanine and dihydromyricetin on reproductive function in male mice under heat stress

Heat stress can impair the male reproductive function. L-Theanine and dihydromyricetin have biological activities against heat stress; however, their effects on reproductive function in heat-stressed males are unclear. In this study, male mice were given L-theanine, dihydromyricetin, or a combination of both for 28 days, followed by 2 h of heat stress daily for 7 days. All interventions alleviated heat stress-induced testicular damage, improving the testicular organ index, sperm density, acrosome integrity, sperm deformity rate, and hormone levels. Treatment increased the antioxidant enzyme activity and decreased the markers of oxidative and inflammatory stress in the testes. A combination dose of 200 + 200 mg kg-1 d-1 showed the best protective effect. The potential mechanism involves the regulation of HSP27 and HSP70, which regulate the levels of reproductive hormones through the StAR/Cyp11a1/Hsd3b1/Cyp17a1/Hsd17b3 pathway, alleviate inflammation and oxidative stress through the P38/NF-κB/Nrf2/HO-1 pathway, and regulate the Bcl-2/Fas/Caspase3 apoptotic pathway. Overall, L-theanine and dihydromyricetin may play a protective role against heat stress-induced reproductive dysfunction, suggesting their potential use in heat stress-resistant foods.

Pruned tea biomass plays a significant role in functional food production: A review on characterization and comprehensive utilization of abandon-plucked fresh tea leaves

Tea is the second largest nonalcoholic beverage in the world due to its characteristic flavor and well-known functional properties in vitro and in vivo. Global tea production reaches 6.397 million tons in 2022 and continues to rise. Fresh tea leaves are mainly harvested in spring, whereas thousands of tons are discarded in summer and autumn. Herein, pruned tea biomass refers to abandon-plucked leaves being pruned in the non-plucking period, especially in summer and autumn. At present, no relevant concluding remarks have been made on this undervalued biomass. This review summarizes the seasonal differences of intrinsic metabolites and pays special attention to the most critical bioactive and flavor compounds, including polyphenols, theanine, and caffeine. Additionally, meaningful and profound methods to transform abandon-plucked fresh tea leaves into high-value products are reviewed. In summer and autumn, tea plants accumulate much more phenols than in spring, especially epigallocatechin gallate (galloyl catechin), anthocyanins (catechin derivatives), and proanthocyanidins (polymerized catechins). Vigorous carbon metabolism induced by high light intensity and temperature in summer and autumn also accumulates carbohydrates, such as soluble sugars and cellulose. The characteristics of abandon-plucked tea leaves make them not ideal raw materials for tea, but suitable for novel tea products like beverages and food ingredients using traditional or hybrid technologies such as enzymatic transformation, microbial fermentation, formula screening, and extraction, with the abundant polyphenols in summer and autumn tea serving as prominent flavor and bioactive contributors.

A universal plasma metabolites-derived signature predicts cardiovascular disease risk in MAFLD

BACKGROUND

Metabolic associated fatty liver disease (MAFLD) is a novel concept proposed in 2020, which is more practical for identifying patients with fatty liver disease with high risk of disease progression. Fatty liver is a driver for extrahepatic complications, particularly cardiovascular diseases (CVD). Although the risk of CVD in MAFLD could be predicted by carotid ultrasound test, a very early stage prediction method before the formation of pathological damage is still lacking.

METHODS

Stool microbiomes and plasma metabolites were compared across 196 well-characterized participants encompassing normal controls, simple MAFLD patients, MAFLD patients with carotid artery pathological changes, and MAFLD patients with diagnosed coronary artery disease (CAD). 16S rDNA sequencing data and untargeted metabolomic profiles were interrogatively analyzed using differential abundance analysis and random forest (RF) machine learning algorithm to identify discriminatory gut microbiomes and metabolomic.

RESULTS

Characteristic microbial changes in MAFLD patients with CVD risk were represented by the increase of Clostridia and Firmicutes-to-Bacteroidetes ratios. Faecalibacterium was negatively correlated with mean-intima-media thickness (IMT), TC, and TG. Megamonas, Bacteroides, Parabacteroides, and Escherichia were positively correlated with the exacerbation of pathological indexes. MAFLD patients with CVD risk were characterized by the decrease of lithocholic acid taurine conjugate, and the increase of ethylvanillin propylene glycol acetal, both of which had close relationship with Ruminococcus and Gemmiger. Biotin l-sulfoxide had positive correlation with mean-IMT, TG, and weight. The general auxin pesticide beta-naphthoxyacetic acid and the food additive glucosyl steviol were both positively correlated with the increase of mean-IMT. The model combining the metabolite signatures with 9 clinical parameters accurately distinguished MAFLD with CVD risk in the proband and validation cohort. It was found that citral was the most important discriminative metabolite marker, which was validated by both in vitro and in vivo experiments.

CONCLUSIONS

Simple MAFLD patients and MAFLD patients with CVD risk had divergent gut microbes and plasma metabolites. The predictive model based on metabolites and 9 clinical parameters could effectively discriminate MAFLD patients with CVD risk at a very early stage.

CsMOF1-guided regulation of drought-induced theanine biosynthesis in Camellia sinensis

The distinctive flavor and numerous health benefits of tea are attributed to the presence of theanine, a special amino acid found in tea plants. Nitrogen metabolite is greatly impacted by drought; however, the molecular mechanism underlying the synthesis of theanine in drought-stricken tea plants is still not clear. Through the drought transcriptome data of tea plants, we have identified a gene CsMOF1 that appears to play a role in theanine biosynthesis under drought stress, presenting a significantly negative correlation with both theanine content and the expression of CsGS1. Further found that CsMOF1 is a transcription factor containing a MYB binding domain, localized in the nucleus. Upon silencing CsMOF1, there was a prominent increase in the level of the theanine and glutamine, as well as the expression of CsGS1, while glutamic acid content decreased significantly. Conversely, overexpression of CsMOF1 yielded opposite effects. Dual luciferase reporter assay and electromobility shift assays demonstrated that CsMOF1 binds to the promoter of CsGS1, thereby inhibiting its activity. These results indicate that CsMOF1 plays a crucial role in theanine biosynthesis in tea plants under drought stress, acting as a transcriptional repressor related to theanine biosynthesis. This study provides new insights into the tissue-specific regulation of theanine biosynthesis and aids with the cultivation of new varieties of tea plants.

Coffee, tea, and cocoa in obesity prevention: Mechanisms of action and future prospects

Obesity, a major public health problem, causes numerous complications that threaten human health and increase the socioeconomic burden. The pathophysiology of obesity is primarily attributed to lipid metabolism disorders. Conventional anti-obesity medications have a high abuse potential and frequently deliver insufficient efficacy and have negative side-effects. Hence, functional foods are regarded as effective alternatives to address obesity. Coffee, tea, and cocoa, three widely consumed beverages, have long been considered to have the potential to prevent obesity, and several studies have focused on their intrinsic molecular mechanisms in past few years. Therefore, in this review, we discuss the mechanisms by which the bioactive ingredients in these three beverages counteract obesity from the aspects of adipogenesis, lipolysis, and energy expenditure (thermogenesis). The future prospects and challenges for coffee, tea, and cocoa as functional products for the treatment of obesity are also discussed, which can be pursued for future drug development and prevention strategies against obesity.

The protective effect of L-theanine on the intestinal barrier in heat-stressed organisms

Heat stress caused by heatwaves, extreme temperatures, and other weather can damage the intestinal barrier of organisms. L-Theanine (LTA) attenuates heat stress-induced oxidative stress, inflammatory responses, and impaired immune function, but its protective effect on the intestinal barrier of heat-stressed organisms is unclear. In this study, low (100 mg kg-1 d-1), medium (200 mg kg-1 d-1), and high (400 mg kg-1 d-1) dosages of LTA were used in the gavage of C57BL/6J male mice that were experimented on for 50 d. These mice were subjected to heat stress for 2 h d-1 at 40 ± 1 °C and 60 ± 5% RH in the last 7 d. LTA attenuated the heat stress-induced decreases in body mass and feed intake, and the destruction of intestinal villi and crypt depth; reduced the serum levels of FITC-dextran and D-LA, as well as the DAO activity; and upregulated the colonic tissues of Occludin, Claudin-1, and ZO-1 mRNA and occludin protein expression. The number of goblet cells in the colon tissue of heat-stressed organisms increased in the presence of LTA, and the expression levels of Muc2, Muc4 mRNA, and Muc2 protein were upregulated. LTA increased the abundance of Bifidobacterium and Turicibacter, and decreased the abundance of Enterorhabdus and Desulfovibrio in the intestinal tract of heat-stressed organisms and restored gut microbiota homeostasis. LTA promoted the secretion of IL-4, IL-10, and sIgA and inhibited the secretion of TNF-α and IFN-γ in the colon of heat-stressed organisms. The expressions of Hsf1, Hsp70, Hsph1, TLR4, P38 MAPK, p-P65 NF-κB, MLCK mRNA, and proteins were downregulated by LTA in the colon of heat-stressed organisms. These results suggest that LTA protects the intestinal barrier in heat-stressed organisms by modulating multiple molecular pathways. Therefore, this study provides evidence on how tea-containing LTA treatments could be used to prevent and relieve intestinal problems related to heat stress.

L-Theanine alleviates heat stress through modulation of gut microbiota and immunity

BACKGROUND

Heat stress (HS) damages the intestines, disrupting gut microbiota and immune balance. l-Theanine (LTA), found in tea, alleviates oxidative stress and cell apoptosis under HS; however, its effects on gut microbiota and immunity under HS remain unclear. To investigate this, we administered LTA doses of 100, 200, and 400 mg·kg-1 ·d-1 to C57BL/6J mice. On day 44, the model group and LTA intervention group were subjected to continuous 7-day HS treatment for 2 h per day.

RESULTS

The results demonstrated that LTA intervention improved food intake, body weight, and intestinal epithelium, and reduced the water intake of heat-stressed mice. It increased the abundance of Turicibacter, Faecalibaculum, Bifidobacterium, and norank_f_Muribaculaceae, while reducing that of Lachnoclostridium and Desulfovibrio. LTA intervention also increased the concentrations of amino acid and lipid metabolites, regulated macrophage differentiation stimulated by gut microbiota and metabolites, reduced the antigen presentation by macrophages to the specific immune system, promoted B-cell differentiation and sIgA secretion, inhibited pro-inflammatory factors, and enhanced intestinal defense. Mechanistically, LTA downregulated heat shock protein 70 expression and the TLR4/NF-κB/p38 MAPK signaling pathway, restoring gut microbiota and immune balance.

CONCLUSION

We suggest that LTA can alleviate HS by modulating gut microbiota, metabolites, and immunity, indicating its potential as a natural active ingredient for anti-HS food products. © 2023 Society of Chemical Industry.

l-Theanine delays d-galactose-induced senescence by regulating the cell cycle and inhibiting apoptosis in rat intestinal cells

BACKGROUND

Intestinal senescence is associated with several aging-related diseases. l-Theanine (LTA) has demonstrated strong potential as an antioxidant and antisenescence agent. This study investigated the regulatory effect of LTA on cellular senescence using an in vitro model of d-galactose (D-Gal)-induced senescence in the rat epithelial cell line, intestinal epithelioid cell-6 (IEC-6).

RESULTS

Treatment of IEC-6 cells with 40 mg/mL D-Gal for 48 h resulted in the successful development of the senescent cell model. Compared with D-Gal alone, both LTA preventive and delayed intervention increased cell viability and the ratio of JC-1 monomers to aggregates, increased the antioxidant capacity, and decreased the advanced glycation end product (AGE) levels and the overall number of senescent cells. Preventive and delayed intervention with 1000 μM LTA alleviated the D-Gal-induced cell cycle arrest by regulating p38, p53, CDK4, and CDK6 expression at the mRNA and protein levels, and further induced CycD1 proteins. Moreover, LTA preventive intervention reduced apoptosis to a greater degree than delayed intervention by upregulating the expression of the receptors of AGEs, Bax, Bcl-2, and NF-κB at the mRNA and protein levels.

CONCLUSION

Our findings indicate that LTA intervention could attenuate senescence in IEC-6 cells by regulating the cell cycle and inhibiting apoptosis. © 2023 Society of Chemical Industry.

Development of a SERS aptasensor for the determination of L-theanine using a noble metal nanoparticle-magnetic nanospheres composite

An ultrasensitive surface-enhanced Raman spectroscopy (SERS) aptamer sensor (aptasensor) using a noble metal nanoparticle-magnetic nanospheres composite was developed for L-theanine detection. It makes use of Fe3O4@Au MNPs and Au@Ag NPs embedded with the Raman reporter 4-mercaptobenzoic acid (4MBA). Au@4MBA@Ag NPs modified by aptamer and Fe3O4@Au MNPs modified by cDNA created the aptasensor with the strongest Raman signal of 4MBA through the specific binding of the aptamer. With the preferred binding of L-theanine aptamer to L-theanine, Au@4MBA@Ag NPs were released from Fe3O4@Au MNPs, causing a linear decrease in SERS intensity to achieve the SERS detection of the L-theanine. The SERS peak of 4MBA at 1078 cm-1 was used for quantitative determination. SERS intensity showed a good log-linear relationship within the range 10-10 to 10-6 M of L-theanine. The aptasensor has a high selectivity for L-theanine compared with other twelve tested analytes. Hence, this aptasensor is a promising analytical tool for L-theanine detection. The developed method was applied to the analysis of real samples, demonstrating excellent performance. The comparison with the standard liquid chromatography mass spectrometry method showed an error within 20%.

Effect of tea intake on genetic predisposition to gout and uric acid: a Mendelian randomization study

Objective

The effect of tea on gout and uric acid is still controversial. This study aims to analyze the effect of tea intake on genetic predisposition to gout, idiopathic gout, gout due to impairment of renal function as well as uric acid by Mendelian randomization (MR).

Methods

Forty independent single nucleotide polymorphisms (SNPs) associated with tea intake were selected from UK Biobank. SNPs for uric acid were obtained from BioBank Japan, SNPs for gout were obtained from UK Biobank, and SNPs for gout due to impairment of renal function and idiopathic gout were derived from FinnGen. The causal relationship of exposure-outcome was tested using inverse variance weighted, MR-Egger and weighted median. MR-Egger intercept was employed to assess horizontal pleiotropy, Cochran's Q test was used to assess heterogeneity, and leave-one-out sensitivity analysis was utilized to analyze the stability of the results.

Results

The results of MR analysis showed that tea intake was negatively associated with gout due to impairment of renal function (OR 0.997, 95% CI 0.994 to 0.999, P = 0.017), whereas there was no causal association with gout, idiopathic gout, and uric acid (P > 0.05), for which sensitivity analysis suggested that these results were robust.

Conclusions

There was a genetic predisposition effect of increased tea intake on the reduced risk of gout due to impairment of renal function, whereas there was no such effect on gout, idiopathic gout, and uric acid. Tea intake may become an important option in the dietary treatment of gout due to impairment of renal function.

L-Theanine adjunct to risperidone in the treatment of chronic schizophrenia inpatients: a randomized, double-blind, placebo-controlled clinical trial

RATIONALE

Inadequate responses to current schizophrenia treatments have accelerated research into novel therapeutic approaches.

OBJECTIVES

This study investigated the efficacy and tolerability of adjunctive L-theanine, an ingredient with neuroimmunomodulatory and neuroprotective properties, for chronic schizophrenia.

METHODS

Eighty chronic schizophrenia inpatients were equally assigned to receive risperidone (6 mg/day) plus either L-theanine (400 mg/day) or matched placebo in this 8-week, randomized, parallel-group, double-blind, placebo-controlled trial. The participants were assessed using the Positive and Negative Syndrome Scale (PANSS) by recording the results of subscales at baseline and weeks 4 and 8 to measure treatment efficacy. Additionally, the participants were assessed for the Hamilton Depression Rating Scale (HDRS) and adverse events, including the Extrapyramidal Symptom Rating Scale (ESRS).

RESULTS

Sixty patients, 30 in each group, were included in the analyses. All baseline demographic and clinical characteristics were comparable between the groups (p-values > 0.05). The reduction rates from baseline to endpoint in negative, general psychopathology, and total scores of PANSS were greater in the L-theanine group (p-values = 0.03, 0.01, and 0.04, respectively). Regarding general psychopathology scores, the reduction in the L-theanine group was also greater until week 4 (p-value < 0.01). The time × treatment interaction effect was significant on negative (p-value = 0.03), general psychopathology (p-value < 0.01), and total (p-value = 0.04) scores of PANSS, indicating additional improvements in the L-theanine group. The HDRS and side effects were comparable between the groups (p-values > 0.05).

CONCLUSIONS

L-Theanine adjunct to risperidone safely and tolerably outperformed adjunctive placebo for schizophrenia, and promising evidence indicated its effects on primary negative symptoms, which need to be scrutinized in further studies.

TRIAL REGISTRATION

The study protocol was registered and published prospectively in the Iranian Registry of Clinical Trials ( http://www.irct.ir ; registration number: IRCT20090117001556N133) on 2020-12-12.

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

PURPOSE

Previous studies have investigated the effect of single or combined caffeine (CAF) and L-theanine (THE) intake on attention performance. However, its effect on shooting performance and cognitive performance in a sport is unknown. The aim of this study was to investigate the hypothesis "Does single or combined CAF and THE supplementation have an effect on shooting and cognitive performance in elite curling athletes?." It is predicted that over the next decade, studies based on nutritional ergogenic supplements in the developing sport of curling will continue to increase, leading to a significant increase in studies examining the effects of CAF and THE supplementation, alone or in combination, on throwing and cognitive performance in elite curling athletes.

METHODS

In this double-blind, randomized controlled crossover study, twenty-two elite national curling athletes (age 20.20 ± 1.61 and sports age 6.20 ± 0.51 years, height 174.10 ± 7.21 cm, BMI 21.80 ± 3.47 kg/m2) were randomly assigned to CAF (6 mg/kg single dose CAF), THE (6 mg/kg single dose THE), CAF*THE (6 mg/kg CAF and 6 mg/kg THE combined) and PLA (400 mg maltodextrin) groups at each of four sessions. 60 minutes after taking the supplement, the athletes were first given the Stroop test and then asked to shoot.

RESULTS

Our main findings have shown that the performance of athletes in guard (F=3.452, P < .001, ηp2 = .842), draw (F=1.647, P < .001, ηp2 = .485), and take-out (F=3.121, P < .001, ηp2 = .743) shot styles significantly improved when comparing the combined intake of CAF and THE to the PLA. Regarding cognitive performance evaluation through the Stroop test, during the NR task (F=4.743, P = .001, ηp2 = .653), the combined intake of CAF and THE significantly improved reaction times compared to the intake of single CAF, THE, or PLA. The best reaction times during the CR and ICR (respectively; F=2.742, P = .004, ηp2 = .328; F = 1.632, P < .001, ηp2 = .625) tasks were achieved with the combined CAF and THE intake, showing a significant improvement compared to PLA. During the NER (F=2.961, P < .001, ηp2 = .741), task, the combined intake of CAF and THE significantly improved error rates compared to the intake of CAF, THE, or PLA single. The best accuracy rates during the CER and ICER (respectively; F=4.127, P < .001, ηp2 = .396; F=3.899, P < .001, ηp2 = .710) tasks were achieved with the combined CAF and THE intake, leading to a significant reduction in error rates compared to PLA. Based on these findings, it has been demonstrated in this study that the best shooting scores and cognitive performance were achieved, particularly with the combined intake of CAF and THE.

CONCLUSIONS

Based on these findings, it has been demonstrated in this study that the best shooting scores and cognitive performance were achieved, particularly with the combined intake of CAF and THE. The combined use of these supplements has been found to be more effective on shooting and cognitive performance than their single use.

External application of brassinolide enhances cold resistance of tea plants (Camellia sinensis L.) by integrating calcium signals

MAIN CONCLUSION

Exogenous brassinolide can activate the expression of key genes in the calcium signalling pathway to enhance cold resistance of tea plants. Brassinolide is an endogenous sterol phytohormone containing multiple hydroxyl groups that has the important function of improving plant cold resistance and alleviating freeze damage. To explore the molecular mechanism of how brassinolide improves the cold resistance of tea plants, "Qiancha 1" was used as the material, and the method of spraying brassinolide on the leaves was adopted to explore its effects on the tea plants under 4 °C low-temperature treatment. The results showed that brassinolide can significantly increase the protective enzyme activity of tea plants under cold stress and reduce cold damage. At the transcriptome level, brassinolide significantly enhanced the expression of key genes involved in calcium signal transduction, Calmodulin (CaM), Calcium-dependent protein kinase (CDPK), calcineurin B-like protein (CBL) and calmodulin-binding transcriptional activators (CAMTA), which then activated the downstream key genes transcriptional regulator CBF1 (CBF1) and transcription factor ICE1 (ICE1) during cold induction. Quantitative real-time PCR (qRT‒PCR) results showed that the expression of these genes was significantly induced after treatment with brassinolide, especially CaM and CBF1. When calcium signalling was inhibited, the upregulated expression of CBF1 and ICE1 disappeared, and when CAMTA was knocked down, the expression of other genes under cold stress was also significantly reduced. The above results indicate that brassinolide combined with the calcium signalling pathway can improve the cold resistance of tea plants. This study provides a new theoretical basis for the study of the cold resistance mechanism of brassinolide.

The R2R3-MYB transcription factor CsMYB42 regulates theanine biosynthesis in albino tea leaves

Theanine is a unique secondary metabolite in tea plants and contributes to the umami taste and health benefits of tea. However, theanine biosynthesis in tea plants is not fully understood, and its mechanism of transcriptional regulation remains poorly reported. Theanine content was significantly correlated with the expression of theanine biosynthesis-related gene CsGS1c and transcription factor CsMYB42 in different leaf positions and picking times, but there was no significant correlation in different tissues of albino tea plant 'Anjibaicha'. This suggests that CsMYB42 may regulate CsGS1c to synthesize theanine in albino tea leaves, and the regulation is tissue specific. CsMYB42 is a nuclear-localized R2R3-MYB transcription factor gene with transcriptional activation activity. Yeast one-hybrid assay and electrophoretic mobility shift assay confirmed the direct binding of CsMYB42 to the promoter of CsGS1c. Luciferase assay showed that CsMYB42 activates the CsGS1c expression. Furthermore, the inhibition of CsMYB42 using an antisense oligonucleotide in tea leaves decreased CsGS1c expression and theanine content. These results indicate that CsMYB42 plays a crucial role in activating the expression of CsGS1c and may be involved in the biosynthesis of theanine in albino tea leaves. This study provides fresh insights into the tissue-specific regulation of theanine biosynthesis, which laid a foundation for breeding high-theanine tea plants.

Long-Term Consumption of Green Tea Can Reduce the Degree of Depression in Postmenopausal Women by Increasing Estradiol

Postmenopausal women face a higher risk of depression due to a combination of social and physiological factors. As a beverage rich in a variety of bioactive substances, green tea has significant effects on metabolism, inflammation and endocrine, and may reduce the risk of depression, but few studies have looked at the effects of green tea on postmenopausal women. Therefore, we designed this study to investigate the effects of long-term green tea consumption on inflammation, endocrine and depression levels in postmenopausal women. We investigated a tea-producing village and eventually included 386 postmenopausal women, both in the tea drinking and control groups. The results showed that there were significant differences in the degree of insomnia, degree of depression, BMI, SII and estradiol between the two groups. And, green tea consumption may reduce the risk of depression through the mediating pathway of sleep, SII and estradiol. In summary, long-term green tea consumption can reduce the risk of depression in postmenopausal women by reducing inflammation and increasing estradiol. This kind of living habit deserves further promotion.

Possible Mechanisms of Dark Tea in Cancer Prevention and Management: A Comprehensive Review

Tea is one of the most popular drinks in the world. Dark tea is a kind of post-fermented tea with unique sensory characteristics that is produced by the special fermentation of microorganisms. It contains many bioactive substances, such as tea polyphenols, theabrownin, tea polysaccharides, etc., which have been reported to be beneficial to human health. This paper reviewed the latest research on dark tea's potential in preventing and managing cancer, and the mechanisms mainly involved anti-oxidation, anti-inflammation, inhibiting cancer cell proliferation, inducing cancer cell apoptosis, inhibiting tumor metastasis, and regulating intestinal flora. The purpose of this review is to accumulate evidence on the anti-cancer effects of dark tea, the corresponding mechanisms and limitations of dark tea for cancer prevention and management, the future prospects, and demanding questions about dark tea's possible contributions as an anti-cancer adjuvant.

L-theanine combination therapy with fluvoxamine in moderate-to-severe obsessive-compulsive disorder: A placebo-controlled, double-blind, randomized trial

AIM

The main aim of this study was to investigate the additional effects of L-theanine, an amino acid in tea and an analog of glutamate with neuroprotective and anti-depressant properties, on obsessive-compulsive disorder (OCD) symptoms in combination with fluvoxamine.

METHODS

Patients from either sex aged between 18 and 60 years diagnosed with OCD, based on the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), who had a Yale-Brown Obsessive Compulsive Scale (Y-BOCS) score of more than 21 were enrolled in a double-blinded, parallel-group, placebo-controlled, clinical trial of 10 weeks to receive either L-theanine (100 mg twice daily) and fluvoxamine (100 mg daily initially followed by 200 mg daily after week 5) or placebo and fluvoxamine. The primary outcome of interest in this study was the Y-BOCS total score decrease from baseline.

RESULTS

From a total of 95 evaluated patients, 50 completed our study; 30 were randomly assigned to each group. Multivariate analysis (ANOVA) showed a significant effect of time× $$ \times $$ treatment for L-theanine in obsession subscale (F = 5.51, P = 0.008) of the Y-BOCS score but not in the total and compulsion scores. Our results showed significantly more improvement in obsession subscale scores in L-theanine compared to placebo group (P = 0.007, Cohen's d = 0.82). Also, total Y-BOCS scores were lower in L-theanine compared to placebo group at week 5 (P = 0.039, Cohen's d = 0.60) and 10 (P = 0.008, Cohen's d = 0.80). However, there was no significant between-group differences in compulsion subscale scores. Complete response was also more frequent in the L-theanine group (P = 0.0001).

CONCLUSION

Findings in this study suggest L-theanine as a relatively safe and effective adjuvant therapy for moderate to severe OCD.

Over the Counter Supplements for Memory: A Review of Available Evidence

In 2021, the Global Brain Health Supplement Industry Market size was valued at US$7.6 billion. It is predicted to increase to US$15.59 billion by 2030. Memory and its enhancement are a segment of the market that comprised the highest global revenue share in 2021. In the USA alone, dietary supplement sales reached US$18 billion in 2018. The US Food and Drug Administration (FDA) does not have the authority to approve dietary supplements' safety, effectiveness, or labeling before products go on the market. The FDA often does not even review supplements before they go to market. Supplement manufacturers are thus responsible for ensuring their products are safe and that their claims are truthful. An extensive review of current supplements on the market was performed by surveying memory products for sale at local and national pharmacies and grocery stores. A list of 103 supplements was compiled and the ingredients in these memory supplements were reviewed. The 18 most common ingredients in these supplements were identified. Each of the supplements included at least one of the 18 most common ingredients. Scientific data relative to these ingredients and their effect on memory was searched using PubMed and Cochrane library databases. Currently, there is no compelling evidence for use of apoaequorin, coenzyme Q10, coffee extracts, L-theanine, omega-3 fatty acids, vitamin B6, vitamin B9, or vitamin B12 supplementation for memory. On the other hand, there is some current evidence for memory benefit from supplementation with ashwagandha, choline, curcumin, ginger, Lion's Mane, polyphenols, phosphatidylserine, and turmeric. There are current studies with mixed results regarding the benefit of carnitine, gingko biloba, Huperzine A, vitamin D, and vitamin E supplementation for memory. Dietary supplements geared toward improving cognition are a billion-dollar industry that continues to grow despite lacking a solid scientific foundation for their marketing claims. More rigorous studies are needed relative to the long-term use of these supplements in homogenous populations with standardized measurements of cognition. Health care providers need to be aware of any and all supplements their older adult patients may be consuming and be educated about their side effects and interactions with prescription medications. Lastly, the FDA needs to take an active position relative to monitoring marketed supplements regarding safety, purity and claims of efficacy.

Green Tea Catechins as Therapeutic Antioxidants for Glaucoma Treatment

Glaucoma is the leading cause of irreversible blindness and visual impairment, affecting more than 80 million individuals worldwide. Oxidative stress and inflammation-induced neurodegenerative insults to retinal ganglion cells are the main pathogenesis of glaucoma. Retinal ganglion cells, the retinal neurons transmitting the visual signals to the visual cortex in the brain, have very limited regeneration or recovery capacity after damages. Apart from intraocular pressure-lowering treatments, there is still no clinically effective treatment to rescue the degeneration of retinal ganglion cells in glaucoma. Dietary antioxidants are easily accessible and can be applied as supplements assisting in the clinical treatments. Catechins, a chemical family of flavonoids, are the phenolic compounds found in many plants, especially in green tea. The anti-oxidative and anti-inflammatory properties of green tea catechins in vitro and in vivo have been well proven. They could be a potential treatment ameliorating retinal ganglion cell degeneration in glaucoma. In this review, the chemistry, pharmacokinetics, and therapeutic properties of green tea catechins were summarized. Research updates on the biological effects of green tea catechins in cellular and animal experimental glaucoma models were reviewed. In addition, clinical potentials of green tea catechins for glaucoma treatment were also highlighted.

Establishment of an efficient transformation system and its application in regulatory mechanism analysis of biological macromolecules in tea plants

Tea (Camellia sinensis), one of the most important beverage crops originated from China and is now cultivated worldwide, provides numerous secondary metabolites that account for its health benefits and rich flavor. However, the lack of an efficient and reliable genetic transformation system has seriously hindered the gene function investigation and precise breeding of C. sinensis. In this study, we established a highly efficient, labor-saving, and cost-effective Agrobacterium rhizogenes-mediated hairy roots genetic transformation system for C. sinensis, which can be used for gene overexpression and genome editing. The established transformation system was simple to operate, bypassing tissue culture and antibiotic screening, and only took two months to complete. We used this system to conduct function analysis of transcription factor CsMYB73 and found that CsMYB73 negatively regulates L-theanine synthesis in tea plant. Additionally, callus formation was successfully induced using transgenic roots, and the transgenic callus exhibited normal chlorophyll production, enabling the study of the corresponding biological functions. Furthermore, this genetic transformation system was effective for multiple C. sinensis varieties and other woody plant species. By overcoming technical obstacles such as low efficiency, long experimental periods, and high costs, this genetic transformation will be a valuable tool for routine gene investigation and precise breeding in tea plants.

Quantitative fusion omics reveals that refrigeration drives methionine degradation through perturbing 5-methyltetrahydropteroyltriglutamate-homocysteine activity

Postharvest senescence and quality deterioration of fresh tea leaves occurred due to the limitation of processing capacity. Refrigerated storage prolongs the shelf life of fresh tea. In this study, quantitative fusion omics delineated the translational landscape of metabolites and proteins in time-series (0-12 days) refrigerated tea by UHPLC-Q-Orbitrap HRMS. Accurate quantification results showed the content of amino acids, especially l-theanine, decreased with the lengthening of the storage duration (15.57 mg g^-1 to 7.65 mg g^-1) driven by theanine synthetase. Downregulation of enzyme 5-methyltetrahydropteroyltriglutamate-homocysteine methyltransferase expression led to methionine degradation (6.29 µg g^-1 to 1.78 µg g^-1). Refrigerated storage inhibited serine carboxypeptidase-like acyltransferases activity (59.49 % reduction in 12 days) and induced the polymerization of epicatechin and epigallocatechin and generation of procyanidin dimer and δ-type dehydrodicatechin, causing the manifestation of color deterioration. A predictive model incorporating zero-order reaction and Arrhenius equation was constructed to forecast the storage time of green tea.

Protective Effect of l-Theanine on Cyclophosphamide-Induced Testicular Toxicity in Mice

l-Theanine is the most abundant free amino acid present in tea. Several tea components have been studied for their impact on male fertility, but little is known about the effects of l-theanine. Cyclophosphamide (CP) is an antineoplastic and immunosuppressive agent that reduces fertility in males. In the present study, we evaluated the effect of l-theanine on CP-induced testicular toxicity in male mice. A single dosage of 50 mg/kg saline or CP was administered intraperitoneally over the course of 5 days. Mice were administered l-theanine (80 mg/kg) or saline by gavage for 30 days. Animals were euthanized 24 h after the last l-theanine administration, and the testes were removed for histopathological and transmission electron microscopy analysis. Histological evaluation and transmission electron microscopy showed that administration of l-theanine alleviated CP-induced damage to the testicles, including spermatogonial cells, epithelial cells, seminiferous tubules, and basement membrane. An integrated proteomics and metabolomics investigation of testes revealed that l-theanine therapy substantially affected the quantity of 719 proteins (395 upregulated and 324 downregulated) and 196 metabolites (75 upregulated and 111 downregulated). The top three enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways for these proteins and metabolites were purine metabolism, choline metabolism in cancer, and arachidonic acid metabolism. This is the first study to reveal the protective effect of l-theanine on CP-induced testicular toxicity. l-Theanine could be a potential natural active substance for resistance to the testis toxicity induced by CP.

Long-term cold, freezing and drought: overlapping and specific regulatory mechanisms and signal transduction in tea plant (Camellia sinensis (L.) Kuntze)

Introduction

Low temperatures and drought are two main environmental constraints reducing the yield and geographical distribution of horticultural crops worldwide. Understanding the genetic crosstalk between stress responses has potential importance for crop improvement.

Methods

In this study, Illumina RNA-seq and Pac-Bio genome resequencing were used to annotate genes and analyze transcriptome dynamics in tea plants under long-term cold, freezing, and drought.

Results

The highest number of differentially expressed genes (DEGs) was identified under long-term cold (7,896) and freezing (7,915), with 3,532 and 3,780 upregulated genes, respectively. The lowest number of DEGs was observed under 3-day drought (47) and 9-day drought (220), with five and 112 genes upregulated, respectively. The recovery after the cold had 6.5 times greater DEG numbers as compared to the drought recovery. Only 17.9% of cold-induced genes were upregulated by drought. In total, 1,492 transcription factor genes related to 57 families were identified. However, only 20 transcription factor genes were commonly upregulated by cold, freezing, and drought. Among the 232 common upregulated DEGs, most were related to signal transduction, cell wall remodeling, and lipid metabolism. Co-expression analysis and network reconstruction showed 19 genes with the highest co-expression connectivity: seven genes are related to cell wall remodeling (GATL7, UXS4, PRP-F1, 4CL, UEL-1, UDP-Arap, and TBL32), four genes are related to calcium-signaling (PXL1, Strap, CRT, and CIPK6), three genes are related to photo-perception (GIL1, CHUP1, and DnaJ11), two genes are related to hormone signaling (TTL3 and GID1C-like), two genes are involved in ROS signaling (ERO1 and CXE11), and one gene is related to the phenylpropanoid pathway (GALT6).

Discussion

Based on our results, several important overlapping mechanisms of long-term stress responses include cell wall remodeling through lignin biosynthesis, o-acetylation of polysaccharides, pectin biosynthesis and branching, and xyloglucan and arabinogalactan biosynthesis. This study provides new insight into long-term stress responses in woody crops, and a set of new target candidate genes were identified for molecular breeding aimed at tolerance to abiotic stresses.

The effect of coffee and black tea consumption on sleep bruxism intensity based on polysomnographic examination

Background

Sleep bruxism (SB) is a common behavior that can result in various clinical consequences on human health. Risk factors for SB include among others emotional stress, anxiety, tobacco smoking, and excessive alcohol consumption. Coffee and black tea are among the most commonly consumed beverages worldwide. This study explores the influence of coffee and black tea consumption on bruxism intensity, as observed in polysomnographic examination.

Methods

Polysomnographic examination with simultaneous camera recording was conducted in 106 adult subjects. The results were evaluated according to guidelines set out by the American Academy of Sleep Medicine (AASM). The study group was divided according to habitual stimulant usage, as declared by the participants in a self-reported questionnaire. Four groups were identified: coffee drinkers versus non-drinkers and black tea drinkers versus non-drinkers.

Results

The bruxism episode index (BEI) was increased in coffee-drinkers as opposed to non-drinkers (4.59 ± 3.44 vs. 2.87 ± 1.50, p = 0.011). Sleep fragmentation, measured according to the arousal index, was comparable in coffee drinkers and non-drinkers. Electrolyte and lipid levels were similar in coffee drinkers and non-drinkers. Habitual black tea intake did not affect sleep architecture or bruxism intensity.

Conclusions

The study showed that habitual coffee consumption is a risk factor for the increased intensity of sleep bruxism. Neither coffee nor tea consumption is related to sleep fragmentation in habitual drinkers. Coffee and tea intake does not affect electrolyte and lipid concentrations. Caution should therefore be recommended in drinking coffee in people with sleep bruxism.

l-theanine adjunct to sertraline for major depressive disorder: A randomized, double-blind, placebo-controlled clinical trial

BACKGROUND

Unsatisfactory responses to major depressive disorder (MDD) therapeutics available necessitated up-to-date treatment approaches. This study sought to investigate the efficacy and tolerability of adjunctive l-theanine, a tea constituent with neuropsychotropic effects, for MDD.

METHODS

Sixty MDD (DSM-5) patients were equally assigned to receive sertraline (100 mg/d) plus either l-theanine (200 mg/d) or matched placebo in a six-week randomized, parallel-group, double-blind, placebo-controlled study. The participants were assessed using the Hamilton depression rating scale (HDRS) at baseline and weeks 2, 4, and 6. Changes in scores, early improvement, response and remission rates, and adverse events were compared between the groups.

RESULTS

Twenty-five participants in each group, a total of 50 patients, completed the study. All baseline characteristics were similar between the groups. The general linear model repeated-measures analysis demonstrated a significant time-treatment interaction effect for HDRS during the trial (p-value = 0.014), indicating more remarkable symptom improvement in the l-theanine group. A greater reduction in HDRS scores was observed in the l-theanine group from baseline to weeks 2, 4, and 6 (p-values = 0.02, 0.03, and 0.01, respectively). All patients responded to sertraline plus l-theanine until week 6. l-theanine was superior to placebo regarding response to treatment and remission rates at week 6 (p-values = 0.05 and 0.02, respectively). The frequency of side effects was comparable between the groups.

LIMITATIONS

The small sample size and short study period were limitations.

CONCLUSIONS

l-theanine adjunct to sertraline outperforms placebo in treating MDD in a safe manner. Further long-term, large-scale studies are recommended to confirm this evidence.

Biochemical Characterization of γ-Glutamyl Transpeptidase from Bacillus altitudinis IHB B1644 and Its Application in the Synthesis of l-Theanine

An extracellular γ-glutamyl transpeptidase (GGT) produced from Bacillus altitudinis IHB B1644 was purified to homogeneity employing ion-exchange chromatography. GGT comprised two subunits of 40 and 22 kDa determined by SDS-PAGE. The maximum enzyme activity was optimal at pH 9 and 37 °C. The purified enzyme was stable from pH 5-10 and <50 °C. Steady-state kinetic studies revealed a K_m value of 0.538 mM against γ-GpNA. For substrate specificity, GGT showed highest affinity for l-methionine. The inhibitors' effect demonstrated that serine or threonine and tryptophan residues are essential for enzyme activity. l-Theanine production was optimized by employing a one-variable-at-a-time approach with 60-65% conversion rate. The final reaction consisted of 20 mM l-glutamine, 200 mM ethylamine hydrochloride, and 10 U mL^-1 enzyme concentration at 37 °C in Tris-Cl (50 mM, pH 9) for 5 h. l-Theanine was purified using a Dowex 50W X 8 hydrogen form resin and confirmed by HPLC and ¹H NMR spectroscopies.

Special tea products featuring functional components: Health benefits and processing strategies

The functional components in tea confer various potential health benefits to humans. To date, several special tea products featuring functional components (STPFCs) have been successfully developed, such as O-methylated catechin-rich tea, γ-aminobutyric acid-rich tea, low-caffeine tea, and selenium-rich tea products. STPFCs have some unique and enhanced health benefits when compared with conventional tea products, which can meet the specific needs and preferences of different groups and have huge market potential. The processing strategies to improve the health benefits of tea products by regulating the functional component content have been an active area of research in food science. The fresh leaves of some specific tea varieties rich in functional components are used as raw materials, and special processing technologies are employed to prepare STPFCs. Huge progress has been achieved in the research and development of these STPFCs. However, the current status of these STPFCs has not yet been systematically reviewed. Here, studies on STPFCs have been comprehensively reviewed with a focus on their potential health benefits and processing strategies. Additionally, other chemical components with the potential to be developed into special teas and the application of tea functional components in the food industry have been discussed. Finally, suggestions on the promises and challenges for the future study of these STPFCs have been provided. This paper might shed light on the current status of the research and development of these STPFCs. Future studies on STPFCs should focus on screening specific tea varieties, identifying new functional components, evaluating health-promoting effects, improving flavor quality, and elucidating the interactions between functional components.

Antarctic Krill Oil Exhibited Synergistic Effects with Nobiletin and Theanine on Regulating Ligand-Specific Receptor-Mediated Transcytosis in Blood-Brain Barrier by Inhibiting Alkaline Phosphatase in SAMP8 Mice

Blood-brain barrier (BBB) impairment is related to the development of Alzheimer's disease (AD), which is dependent not only on tight junction but also on transcytosis of brain endothelial cells (BECs) in the BBB. Aging induces the decrease of ligand-specific receptor-mediated transcytosis (RMT) and the increase of non-specific caveolar transcytosis in BECs, which lead to the entry into parenchyma of neurotoxic proteins and the smaller therapeutic index in central nervous system drug delivery, further provoking neurodegenerative disease. A previous study suggests that sea-derived Antarctic krill oil (AKO) exhibits synergistic effects with land-derived nobiletin (NOB) and theanine (THE) on ameliorating memory and cognitive deficiency in SAMP8 mice. However, it is still unclear whether BBB change is involved. Hence, the effects of AKO combined with NOB and THE on aging-induced BBB impairment, including tight junction between BECs, ligand-specific RMT, and non-specific caveolar transcytosis in BECs, are investigated. The results suggest that AKO exhibits synergistic effects with NOB and THE on regulating ligand-specific RMT in BBB by inhibiting alkaline phosphatase (ALPL). The study provides a potential strategy candidate or targeted dietary patterns to prevent and treat AD by improving the BBB function.

Nutritional Composition and Antioxidant Activity of Gonostegia hirta: An Underexploited, Potentially Edible, Wild Plant

Wild, edible plants have received increasing attention as an important complement to cultivate vegetables, as they represent an easily accessible source of nutrients, mineral elements, and antioxidants. In this study, the tender stems and leaves of Gonostegia hirta, an edible species for which only scarce data are available in the literature, are thoroughly evaluated for their nutritional profile, chemical characterization, and antioxidant activity. Being considered as an underexploited, potentially edible plant, the nutritional composition of Gonostegia hirta was identified, and several beneficial compounds were highlighted: sugars, potassium, calcium, organic acids, fatty acids, phenolics, and flavonoids. A total of 418 compounds were identified by metabolomic analysis, including phenolic acids, flavonoids, amino acids, lipids, organic acids, terpenoids, alkaloids, nucleotides, tannins, lignans, and coumarin. The plant sample was found to have good antioxidant capacities, presented by DPPH, FRAP, ABTS⁺, hydroxyl radical scavenging capacity, and its resistance to the superoxide anion radical test. In general, Gonostegia hirta has a good nutritional and phytochemical composition. The health benefits of Gonostegia hirta as a vegetable and herbal medicine is important for both a modern diet and use in medication.

Proteomic Analysis Reveals the Association between the Pathways of Glutathione and α-Linolenic Acid Metabolism and Lanthanum Accumulation in Tea Plants

Lanthanum can affect the growth and development of the tea plant. Tieguanyin (TGY) and Shuixian (SX) cultivars of Camellia sinensis were selected to explore the mechanism underlying the accumulation of lanthanum (tea plants' most accumulated rare earth element) through proteomics. Roots and fresh leaves of TGY and SX with low- and high-accumulation potential for lanthanum, respectively, were studied; 845 differentially expressed proteins (DEPs) were identified. Gene ontology analysis showed that DEPs were involved in redox processes and related to molecular functions. Kyoto Encyclopedia of Genes and Genomes metabolic pathway analysis showed that DEPs were associated with glutathione (GSH) and α-linolenic acid metabolism, plant pathogen interaction, and oxidative phosphorylation. Thirty-seven proteins in the GSH metabolism pathway showed significant differences, wherein 18 GSH S-transferases showed differential expression patterns in the root system. Compared with the control, expression ratios of GST (TEA004130.1) and GST (TEA032216.1) in TGY leaves were 6.84 and 4.06, respectively, after lanthanum treatment; these were significantly higher than those in SX leaves. The LOX2.1 (TEA011765.1) and LOX2.1 (TEA011776.1) expression ratios in the α-linolenic acid metabolic pathway were 2.44 and 6.43, respectively, in TGY roots, which were significantly higher than those in SX roots. The synthesis of specific substances induces lanthanum-associated defense responses in TGY, which is of great significance for plant yield stability.