Research
L-Theanine
89 peer-reviewed studies curated from PubMed and Semantic Scholar.
Studies
Sorted by quality and recency
The effects of L-theanine consumption on sleep outcomes: A systematic review and meta-analysis.
This systematic review and meta-analysis evaluated the effects of L-theanine on sleep outcomes, including 19 articles with 897 participants. L-theanine significantly improved subjective sleep onset latency, daytime dysfunction, and overall sleep quality. The findings suggest potential use in managing sleep disturbances, though further studies on 'pure' L-theanine are needed.
Examining the effect of L-theanine on sleep: a systematic review of dietary supplementation trials.
Systematic review of 13 trials examining L-theanine supplementation (50-900 mg/day) on sleep-related outcomes. The review found that 200-450 mg/day of L-theanine supports healthy sleep in adults, improving sleep latency, maintenance, efficiency, and perceived sleep satisfaction.
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.
Systematic review and meta-analysis of RCTs assessing the effects of tea, theanine alone, or theanine plus caffeine on cognition, mood, and sleep in healthy participants. Theanine plus caffeine showed small-to-moderate improvements in cognition and mood outcomes compared to placebo. Theanine alone also showed benefits for choice reaction time.
The Effects of Green Tea Amino Acid L-Theanine Consumption on the Ability to Manage Stress and Anxiety Levels: a Systematic Review.
This systematic review evaluated the effect of pure L-theanine intake on stress responses and anxiety levels in human randomized controlled trials. The findings suggest that supplementation of 200-400 mg/day of L-theanine may assist in reducing stress and anxiety in people exposed to stressful conditions.
Impact of L-theanine and L-tyrosine on markers of stress and cognitive performance in response to a virtual reality based active shooter training drill.
RCT with 80 subjects examining the impact of L-theanine and L-tyrosine on stress markers and cognitive performance during a virtual reality active shooter drill and cognitive challenge. L-theanine and L-tyrosine did not impact stress markers, but L-tyrosine improved cognitive performance by reducing missed responses in the Stroop challenge.
Effect of a nutraceutical combination on sleep quality among people with impaired sleep: a randomised, placebo-controlled trial.
This randomized, placebo-controlled trial studied the effect of a nutraceutical combination containing L-theanine, lemon balm, valerian, and saffron extracts on sleep quality in adults with impaired sleep. The study found no significant improvement in objective or subjective sleep parameters in the active group compared to placebo.
L-Theanine adjunct to risperidone in the treatment of chronic schizophrenia inpatients: a randomized, double-blind, placebo-controlled clinical trial.
RCT of 80 chronic schizophrenia inpatients comparing risperidone plus L-theanine to risperidone plus placebo over 8 weeks. L-theanine group showed greater reductions in negative, general psychopathology, and total PANSS scores, indicating additional improvements in schizophrenia symptoms.
L-theanine combination therapy with fluvoxamine in moderate-to-severe obsessive-compulsive disorder: A placebo-controlled, double-blind, randomized trial.
RCT investigating the effects of L-theanine in combination with fluvoxamine on OCD symptoms. L-theanine showed significant improvement in obsession subscale scores and total Y-BOCS scores compared to placebo, suggesting it as an effective adjuvant therapy for moderate to severe OCD.
Effect of Combined Ingestion of L-Theanine and L-Arginine for Short-Term Psychological Stress in Young Adults: A Randomized Placebo-Controlled Study.
A randomized placebo-controlled trial with 120 healthy young adults evaluated the effects of combined ingestion of l-theanine and l-arginine on psychological stress. The theanine/arginine and theanine groups showed significant reductions in salivary alpha-amylase activity compared to placebo, indicating anti-stress effects. However, no significant difference was found between the theanine/arginine and theanine groups.
Effects of l-Theanine on Cognitive Function in Middle-Aged and Older Subjects: A Randomized Placebo-Controlled Study.
A double-blind, randomized, placebo-controlled study on Japanese men and women aged 50-69 years examined the effects of l-theanine on cognitive function. The study found that a single dose of l-theanine reduced reaction time in attention tasks and improved performance in working memory tasks, suggesting enhancements in attention, working memory, and executive functions.
Acute effects of tea constituents L-theanine, caffeine, and epigallocatechin gallate on cognitive function and mood: a systematic review and meta-analysis.
Systematic review and meta-analysis of 11 RCTs on acute effects of tea constituents L-theanine, caffeine, and epigallocatechin gallate on cognitive function and mood. Moderate effect sizes were found for combined caffeine and L-theanine on alertness and attentional switching accuracy within the first 2 hours postdose.
To sleep or not to sleep: a systematic review of the literature of pharmacological treatments of insomnia in children and adolescents with attention-deficit/hyperactivity disorder.
Systematic review of pharmacological treatments for insomnia in children and adolescents with ADHD. L-theanine showed mixed results, with poor response in reducing sleep latency and increasing total sleep time, but an increase in sleep efficiency. Melatonin showed positive effects on sleep parameters.
High-dose L-theanine-caffeine combination improves neurobehavioural and neurophysiological measures of selective attention in acutely sleep-deprived young adults: a double-blind, placebo-controlled crossover study.
Double-blind, placebo-controlled crossover trial of 37 sleep-deprived young adults testing high-dose L-theanine-caffeine combination. The combination significantly improved selective attention, reaction time, and neurophysiological measures compared to placebo.
Effect of L-theanine on selective attention in a traffic-related reaction task in sleep-deprived young adults: a double-blind placebo-controlled, crossover study.
Double-blind, placebo-controlled, crossover study of 24 sleep-deprived young adults testing 200mg L-theanine on visual attention in a traffic-related task. L-theanine significantly reduced false alarms and improved target-distractor discriminability, suggesting enhanced selective attention.
Effect of Alpha-S1-Casein Tryptic Hydrolysate and L-Theanine on Poor Sleep Quality: A Double Blind, Randomized Placebo-Controlled Crossover Trial.
This double-blind, randomized, placebo-controlled crossover trial studied the effects of RLX2™ containing alpha-s1-casein tryptic hydrolysate and L-theanine on sleep quality in 39 working adults. The supplement improved PSQI total score, sleep latency, sleep duration, sleep habitual efficiency, and increased total and frontal alpha power significantly. The supplement prolonged total sleeping time by 45 minutes compared to placebo.
Use of Nutritional Supplements Based on L-Theanine and Vitamin B6 in Children with Tourette Syndrome, with Anxiety Disorders: A Pilot Study.
Open-label trial evaluating L-Theanine and Vitamin B6 supplementation in 34 children with Tourette syndrome or chronic tic disorder and anxiety symptoms. Supplementation was more effective than psychoeducation in reducing tics and anxiety symptoms, with significant differences in tic severity.
Dose-response effect of L-theanine on psychomotor speed, sustained attention, and inhibitory control: a double-blind, placebo-controlled, crossover study.
Double-blind, placebo-controlled, crossover study in 32 healthy young adults testing three doses of L-theanine (100, 200, and 400 mg) on attentional tasks. L-theanine significantly improved reaction times in simple visuomotor tasks, but not in more complex sustained attention or executive control tasks.
Effects of L-theanine-caffeine combination on sustained attention and inhibitory control among children with ADHD: a proof-of-concept neuroimaging RCT.
RCT examining the acute effects of L-theanine, caffeine, and their combination on sustained attention and inhibitory control in boys with ADHD. L-Theanine improved total cognition composite, while caffeine worsened inhibitory control. The combination improved cognition and showed trends of improvement in inhibitory control.
The effects of L-theanine (Suntheanine®) on objective sleep quality in boys with attention deficit hyperactivity disorder (ADHD): a randomized, double-blind, placebo-controlled clinical trial.
RCT investigating the efficacy and safety of L-theanine on sleep quality in 98 boys with ADHD. L-theanine improved sleep percentage and efficiency scores compared to placebo, with no significant adverse events reported.
A combination of green tea extract and l-theanine improves memory and attention in subjects with mild cognitive impairment: a double-blind placebo-controlled study.
This randomized, double-blind, placebo-controlled study investigated the effects of a combination of green tea extract and l-theanine (LGNC-07) on memory and attention in 91 subjects with mild cognitive impairment. LGNC-07 improved memory and selective attention, particularly in subjects with lower baseline cognitive scores, and increased brain theta waves, indicating cognitive alertness.
L-theanine relieves positive, activation, and anxiety symptoms in patients with schizophrenia and schizoaffective disorder: an 8-week, randomized, double-blind, placebo-controlled, 2-center study.
RCT of 60 patients with schizophrenia or schizoaffective disorder evaluating L-theanine augmentation of antipsychotic treatment over 8 weeks. L-theanine reduced anxiety and positive and general psychopathology scores compared to placebo, with modest to moderate effect sizes. L-theanine was safe and well-tolerated.
L-theanine and caffeine improve task switching but not intersensory attention or subjective alertness.
Randomized, placebo-controlled, double-blind, cross-over study comparing L-theanine (97 mg) and caffeine (40 mg) combination to placebo on attention tasks and subjective alertness. The combination significantly improved attention on a switch task but did not significantly improve subjective alertness or intersensory attention.
Co-administration of l-cystine and l-theanine enhances efficacy of influenza vaccination in elderly persons: nutritional status-dependent immunogenicity.
RCT in a nursing home with 65 elderly residents comparing l-cystine and l-theanine supplementation to placebo before influenza vaccination. While overall HI titers and seroconversion rates were not significantly different, the l-cystine and l-theanine group showed significantly greater seroconversion for influenza virus A (H1N1) among subjects with low serum total protein or hemoglobin.
L-theanine and caffeine in combination affect human cognition as evidenced by oscillatory alpha-band activity and attention task performance.
The study investigated the effects of L-theanine and caffeine, ingested separately or together, on visuospatial attentional deployment. The combined treatment increased hit rate and target discriminability compared to placebo, while caffeine alone increased discriminability but not hit rate. L-theanine alone showed no effects.
The effects of L-theanine, caffeine and their combination on cognition and mood.
Randomised, placebo-controlled, double-blind, balanced crossover study investigating the acute cognitive and mood effects of L-theanine (250 mg) and caffeine (150 mg), in isolation and in combination. L-Theanine increased 'headache' ratings and decreased correct serial seven subtractions. Caffeine improved reaction times and reduced 'mental fatigue'. The combination improved reaction times, accuracy, and mood ratings, suggesting a different pharmacological profile compared to caffeine alone.
Exploring the effect of L-theanine synergised with EGCG on starch digestibility in ultrasonic field from different perspectives.
The study explores the synergistic effect of L-theanine and EGCG on starch digestibility under ultrasound treatment. It finds that specific ratios of THE and EGCG promote starch aggregation and densification, reducing starch digestibility and inhibiting α-amylase activity through structural changes and interactions with the enzyme.
Unlocking the Facet‐Governed Zn Homoepitaxy Growth Induced by Dynamic l‐Theanine Evolution Process Realized Highly Reversible Zn Anodes
The paper investigates the role of l-theanine in the electrochemical behavior of zinc anodes for Zn-ion batteries. L-theanine molecules from a hydrogel matrix regulate the electrolyte environment, facilitating an in situ acid etching process that improves the lattice match between substrate and overgrowth crystals. This process enhances the cycling stability and Coulombic efficiency of Zn||Zn cells.
Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial.
This randomized, placebo-controlled, crossover, and double-blind trial examined the effects of four weeks of L-theanine administration on stress-related symptoms and cognitive functions in 30 healthy adults. L-theanine administration led to decreased scores in stress-related symptoms and improved cognitive functions, including verbal fluency and executive function.
The effect of L-theanine supplementation on the immune system of athletes exposed to strenuous physical exercise.
Double-blind RCT with 20 Polish Rowing Team members examining L-theanine supplementation's effect on immune response to strenuous exercise. L-theanine led to a significant post-exercise decrease in IL-10 concentration and altered immune cell ratios, suggesting a beneficial effect on Th1/Th2 balance.
L-theanine in the adjunctive treatment of generalized anxiety disorder: A double-blind, randomised, placebo-controlled trial.
A 10-week RCT involving 46 participants with GAD assessed the effects of adjunctive L-theanine (450-900 mg) versus placebo on anxiety, sleep quality, and cognition. L-theanine did not outperform placebo for anxiety reduction or insomnia severity, but participants reported greater sleep satisfaction. No significant cognitive effects were observed.
Caffeine and theanine exert opposite effects on attention under emotional arousal.
Double-blind, repeated-measures RCT with 36 participants evaluating the effects of caffeine and theanine on cognition under emotional arousal. Caffeine accentuated global processing of visual attention, while theanine accentuated local processing. The combination of caffeine and theanine did not differ from placebo in attentional processes.
Short-Term Impact of a Combined Nutraceutical on Cognitive Function, Perceived Stress and Depression in Young Elderly with Cognitive Impairment: A Pilot, Double-Blind, Randomized Clinical Trial.
Double-blind, cross-over RCT of 30 elderly subjects with cognitive impairment, testing a combination of nutraceuticals including Bacopa monnieri, L-theanine, Crocus sativus, copper, folate, and vitamins B and D. The treatment group showed significant improvements in cognitive function, perceived stress, and depression scores compared to placebo.
An intervention study on the effect of matcha tea, in drink and snack bar formats, on mood and cognitive performance.
Randomized, placebo-controlled, single-blind study with 23 participants assessing the effects of matcha tea and a matcha-containing product on mood and cognitive performance. Matcha tea showed significant improvements in basic attention abilities and psychomotor speed, but no significant changes in mood. The drink format outperformed the bar format in cognitive performance measures.
l-Theanine and caffeine improve target-specific attention to visual stimuli by decreasing mind wandering: a human functional magnetic resonance imaging study.
This study used fMRI to investigate the effects of l-theanine and caffeine on attention to visual stimuli in a randomized 4-way crossover design with 9 healthy adult men. l-Theanine and its combination with caffeine improved target-specific attention by decreasing mind wandering and neural resource allocation to distractors.
Anti-Stress, Behavioural and Magnetoencephalography Effects of an L-Theanine-Based Nutrient Drink: A Randomised, Double-Blind, Placebo-Controlled, Crossover Trial.
This double-blind, placebo-controlled, crossover trial studied the effects of an L-theanine-based nutrient drink on stress and mood in 34 healthy adults. The L-theanine drink significantly reduced subjective stress response and salivary cortisol levels after a cognitive stressor, with no changes in cognitive performance. Resting state alpha oscillatory activity increased in those with higher trait anxiety.
Acute effects of theanine, caffeine and theanine-caffeine combination on attention.
Placebo-controlled, five-way crossover trial in 20 healthy male volunteers comparing the effects of l-theanine, caffeine, their combination, black tea, and placebo on cognitive and neurophysiological measures of attention. Theanine and caffeine improved recognition visual reaction time and elicited larger N2-P300 ERP amplitudes, with theanine-caffeine combination showing additive effects.
Effect of L-theanine on glutamatergic function in patients with schizophrenia.
RCT of L-theanine (250 mg/day) added to antipsychotic treatment in 17 schizophrenia patients for 8 weeks. Significant improvements were observed in PANSS positive scale and sleep quality. MRS findings suggest L-theanine stabilizes glutamatergic concentration in the brain.
Effect of L-theanine on sensorimotor gating in healthy human subjects.
RCT examining the effect of l-theanine on sensorimotor gating in 14 healthy adults. Administration of 200mg and 400mg of l-theanine significantly increased prepulse inhibition (PPI) compared to baseline, suggesting increased sensorimotor gating at these doses.
Effects of L-theanine or caffeine intake on changes in blood pressure under physical and psychological stresses.
RCT with 14 participants comparing the effects of L-theanine, caffeine, and placebo on blood pressure and mood under stress. L-theanine significantly inhibited blood-pressure increases and reduced Tension-Anxiety scores, while caffeine had a smaller effect.
Kinetics of L-theanine uptake and metabolism in healthy participants are comparable after ingestion of L-theanine via capsules and green tea.
Randomized crossover study investigating the kinetics of L-theanine uptake and metabolism in 12 healthy participants after ingestion via capsules and green tea. L-theanine increased in plasma, erythrocytes, and urine with comparable results after both treatments, and was rapidly absorbed and hydrolyzed to ethylamine and glutamic acid.
Serum levels of brain-derived neurotrophic factor and cortisol to sulfate of dehydroepiandrosterone molar ratio associated with clinical response to L-theanine as augmentation of antipsychotic therapy in schizophrenia and schizoaffective disorder patients.
Double-blind, randomized, placebo-controlled trial of L-theanine (400 mg/d) as augmentation to antipsychotic therapy in 40 schizophrenia and schizoaffective disorder patients over 8 weeks. L-theanine improved positive, activation, and anxiety symptoms, with serum BDNF levels and cortisol-to-DHEAS*100 molar ratio significantly associated with clinical benefits.
The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness.
RCT investigating the effect of 97 mg L-theanine and 40 mg caffeine on cognitive performance and alertness in 44 young adults. The combination significantly improved accuracy during task switching and self-reported alertness, and reduced self-reported tiredness.
The combined effects of L-theanine and caffeine on cognitive performance and mood.
RCT comparing 50 mg caffeine, with and without 100 mg L-theanine, on cognition and mood in 27 healthy volunteers. The combination improved speed and accuracy on attention-switching tasks and reduced susceptibility to distractions, while caffeine alone improved alertness and accuracy on attention-switching tasks.
L-Theanine reduces psychological and physiological stress responses.
RCT with 12 participants examining the effects of L-Theanine on stress responses using a mental arithmetic task. L-Theanine intake reduced heart rate and salivary immunoglobulin A responses to stress, suggesting anti-stress effects via inhibition of cortical neuron excitation.
The acute effects of L-theanine in comparison with alprazolam on anticipatory anxiety in humans.
This study compared the acute effects of L-theanine and alprazolam on anticipatory anxiety in 16 healthy volunteers using a double-blind placebo-controlled design. L-theanine showed some relaxing effects during the baseline condition, but neither L-theanine nor alprazolam demonstrated significant anxiolytic effects during experimentally induced anxiety.
L-theanine ameliorates traumatic-brain-injury-induced hippocampal neuronal death in rats.
The study investigates the neuroprotective potential of l-theanine against hippocampal damage in a TBI rat model. L-theanine treatment significantly mitigated zinc accumulation, neuronal death, and cognitive impairments associated with TBI, likely due to inhibition of AMPA receptor activity and reduction in neuroinflammation.
Spectral analysis and computational simulation to investigate the synergistic mechanism of L-theanine and epigallocatechin gallate in inhibiting α-glucosidase activity.
The study investigates the synergistic mechanism of L-theanine and epigallocatechin gallate in inhibiting α-glucosidase activity using spectral analysis and computational simulation. The combination of 1.6 mM L-theanine and 0.11 mM EGCG significantly enhanced α-glucosidase inhibition, with findings suggesting non-covalent interactions with key enzyme residues.
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
Animal study investigating L-theanine's protective effects against acute alcohol-induced intestinal injury in mice. L-theanine ameliorated pathological damage, improved gut permeability, and reduced oxidative stress and inflammatory markers. It also restored intestinal flora composition and activated the HIF-1 signaling pathway.
L‐Theanine Ameliorates Doxorubicin‐Induced Ovarian Toxicity by Reducing Endoplasmic Reticulum Stress
The study investigated the effects of L-theanine on ovarian endoplasmic reticulum stress in doxorubicin-induced rats. L-theanine was found to reverse doxorubicin-induced stress by lowering oxidative stress, inflammation, and apoptosis, with the 400 mg/kg dose showing more significant effects.
L-Theanine prevents ulcerative colitis by regulating the CD4+ T cell immune response through the gut microbiota and its metabolites.
The study investigates the preventive effects of L-theanine on ulcerative colitis (UC) by regulating gut microbiota and immune responses. L-theanine optimized gut microbiota and its metabolites, improving colonic structure and immune factors, and decreasing inflammatory factors, demonstrating its preventive effect on UC.
L-Theanine Extends the Lifespan of Caenorhabditis elegans by Reducing the End Products of Advanced Glycosylation
The study investigated the effects of L-theanine on the lifespan of Caenorhabditis elegans, finding that it significantly reduces the accumulation of advanced glycation end products (AGEs) and extends lifespan under normal and high-glucose-induced stress conditions. L-theanine modulates the DAF-2/DAF-16 insulin-like signaling pathway, suggesting its potential as an anti-aging intervention.
In vitro ATP regeneration via immobilized anaerobic glycolytic enzymes: System construction and application in l-theanine production.
The study constructed an ATP regeneration system using immobilized anaerobic glycolytic enzymes to synthesize L-theanine through an in vitro pathway. The system demonstrated increased L-theanine yield from 1.7 g/L to 9.6 g/L after optimization, highlighting the potential for enzymatic production of high-value compounds.
L-Theanine Mitigates Chronic Alcoholic Intestinal Injury by Regulating Intestinal Alcohol and Linoleic-Arachidonic Acid Metabolism in Rats
Animal study investigating the effects of L-theanine on chronic alcoholic intestinal injury in rats. L-theanine alleviated duodenal pathology, reduced intestinal oxidative stress and inflammatory response, and improved gut microbiota composition. It also altered metabolic profiles related to ethanol and linoleic-arachidonic acid metabolism.
Anti-Melanogenic Effects of L-Theanine on B16F10 Cells and Zebrafish
The study evaluated the anti-melanogenic effects of L-theanine on B16F10 murine melanoma cells and zebrafish. L-theanine reduced intracellular tyrosinase activity and melanin content, and modulated signaling pathways related to melanogenesis. The findings suggest L-theanine's potential as a skin-whitening compound.
Integrated proteomics and metabolomics to clarify the essential beneficial mechanisms of L-theanine in alleviating ISO-induced cardiac damage in mice.
The study explored the mechanisms by which L-theanine alleviates isoproterenol-induced cardiac damage in mice using proteomic and metabolomic data. L-theanine improved cardiac performance, reduced inflammation, and decreased apoptosis in cardiac tissue, suggesting its potential as a dietary supplement for managing cardiac damage.
L-theanine alleviates ulcerative colitis by repairing the intestinal barrier through regulating the gut microbiota and associated short-chain fatty acids.
The study investigated the effects of L-theanine on ulcerative colitis (UC) in mice, focusing on gut barrier repair through gut microbiota and short-chain fatty acids (SCFAs). L-theanine regulated gut microbiota structure, increased SCFA contents, and promoted gut barrier repair, suggesting its potential as a dietary supplement for UC treatment.
L-theanine alleviates muscle oxidative damage by improving mitochondrial function, maintaining calcium homeostasis and inhibiting ferroptosis.
The study investigates the protective effects of L-theanine against oxidative stress-induced muscle damage. L-theanine pretreatment reversed pathological alterations caused by diquat exposure, enhancing antioxidant capacity, improving mitochondrial function, maintaining calcium homeostasis, and inhibiting ferroptosis.
Soil nutrient deficiency decreases the postharvest quality-related metabolite contents of tea (Camellia sinensis (L.) Kuntze) leaves.
The study analyzed tea plants cultivated in unfertilized soil for 11 years, finding that soil nutrient deficiency decreased l-theanine content to 11.4% of control levels, affecting tea taste quality. It also decreased the abundance of aroma compounds, influencing tea color, taste, and aroma.
Protective Effect of l-Theanine against DSS-Induced Colitis by Regulating the Lipid Metabolism and Reducing Inflammation via the NF-κB Signaling Pathway.
The study investigated the protective effects of l-theanine on DSS-induced colitis in a mice model. L-theanine pretreatment prevented intestinal damage, reduced inflammation markers, and protected the intestinal epithelial barrier, mainly via the NF-κB signaling pathway and lipid metabolism regulation.
l-Theanine Ameliorates d-Galactose-Induced Brain Damage in Rats via Inhibiting AGE Formation and Regulating Sirtuin1 and BDNF Signaling Pathways
The study investigates the effects of l-theanine on d-galactose-induced brain damage in rats, focusing on Alzheimer's disease markers. l-Theanine reduced AGEs and Aβ1-42 levels, inhibited inflammatory factors, and upregulated antioxidant proteins, suggesting potential preventive effects against Alzheimer's disease through regulation of SIRT1 and BDNF proteins.
l-Theanine Activates the Browning of White Adipose Tissue Through the AMPK/α-Ketoglutarate/Prdm16 Axis and Ameliorates Diet-Induced Obesity in Mice
The study investigates the effects of l-theanine on the browning of white adipose tissue and its potential to combat diet-induced obesity in mice. l-Theanine treatment enhanced adaptive thermogenesis, increased energy expenditure, and improved glucose tolerance and insulin sensitivity in high-fat diet-fed mice.
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.
This study investigated the effects of L-theanine supplementation on DSS-induced colitis in C57BL/6J male mice. L-theanine significantly decreased the disease activity index, ameliorated inflammation-associated pathological damage, and inhibited proinflammatory cytokines expression. It also protected against intestinal barrier disruption and altered microbial community composition.
l-Theanine regulates glucose, lipid, and protein metabolism via insulin and AMP-activated protein kinase signaling pathways.
The study investigates the effects of l-theanine on glucose, lipid, and protein metabolism in male Sprague-Dawley rats. l-Theanine increased hepatic and muscle glycogen, serum total protein, and albumin, lowered LDL-C levels, and modulated various metabolic pathways via insulin and AMPK signaling.
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
The study investigated the effects of L-theanine on IL-1β-stimulated chondrocytes and in an injury-induced osteoarthritis rat model. L-theanine decreased the expression of pro-inflammatory mediators and inhibited matrix metalloproteinases, reducing OA lesions and OARSI scores, suggesting its potential as a therapeutic strategy for OA prevention.
Characterization of L-theanine hydrolase in vitro and subcellular distribution of its specific product ethylamine in tea (Camellia sinensis).
The study characterizes L-theanine hydrolase and its role in L-theanine metabolism in tea (Camellia sinensis). It identifies the gene CsPDX2.1, which catalyzes L-theanine hydrolysis into ethylamine and L-glutamate, and examines the subcellular distribution of ethylamine in tea leaves.
L-Theanine affects intestinal mucosal immunity by regulating short-chain fatty acid metabolism under dietary fiber feeding.
A 28-day feeding experiment in Sprague-Dawley rats investigated the effects of l-Theanine on intestinal mucosal immunity and SCFA metabolism under dietary fiber feeding. L-Theanine increased the proportion of certain gut bacteria, SCFA contents, and immunoglobulin levels, while affecting gene expression related to metabolism.
Effect of l-theanine on the growth performance, immune function, and jejunum morphology and antioxidant status of ducks.
The study investigated the effects of l-theanine as a feed additive on growth performance, immune function, and jejunum morphology in ducks. Supplementation with l-theanine improved body weight, feed intake, and immune parameters, and enhanced antioxidant status and jejunum morphology. Optimal supplementation level was found to be 600 to 900 mg/kg.
Seasonal Theanine Accumulation and Related Gene Expression in the Roots and Leaf Buds of Tea Plants (Camellia Sinensis L.)
The study measured theanine contents in the roots and leaf buds of 13 tea cultivars at four time points from winter to spring. It found significant seasonal accumulation patterns and examined the expression of theanine biosynthesis and amino acid transporter genes, providing insight into the regulation of theanine biosynthesis and transport in tea plants.
16S ribosomal RNA sequencing reveals a modulation of intestinal microbiome and immune response by dietary L-theanine supplementation in broiler chickens
The study investigated the effects of dietary L-theanine supplementation on the intestinal microbiome and immune response in broiler chickens. L-theanine increased Lactobacillus populations in the ileum and jejunum and decreased mRNA expression of TLRs and cytokines, indicating a positive influence on gut health and immune response.
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
The study evaluated the effect of different dietary levels of l-theanine on growth performance, meat quality, immune response, and blood metabolites in 400 broiler chickens. The intermediate level of l-theanine (200 mg/kg diet) improved body weight gain, feed conversion ratio, and antioxidant status, while reducing serum cholesterol and cytokine levels. Higher levels (300 mg/kg diet) may have negative effects.
L-Theanine Content and Related Gene Expression: Novel Insights into Theanine Biosynthesis and Hydrolysis among Different Tea Plant (Camellia sinensis L.) Tissues and Cultivars
The study explores L-theanine content and gene expression related to theanine biosynthesis and hydrolysis in different tissues and cultivars of the tea plant Camellia sinensis. It identifies correlations between theanine content and the expression profiles of genes involved in theanine metabolism across various tissues and cultivars.
Therapeutic Role of l-Theanine in Mitigating Cognitive Dysfunction and Neuropathology in Scopolamine-Treated Mice.
The study investigated the effects of l-theanine (LTA) on cognitive dysfunction and neuropathology in scopolamine-treated mice, a model for Alzheimer's disease. LTA improved learning and memory performance, enhanced autophagy, promoted neuronal survival, and reduced oxidative stress, showing effects similar to donepezil treatment.
l-theanine: From tea leaf to trending supplement – does the science match the hype for brain health and relaxation?
This narrative review surveys the chemistry, metabolism, and purported biological activities of l-theanine, a non-protein amino acid found in tea leaves. It discusses its potential effects on relaxation, cognitive enhancement, stress reduction, and sleep improvement, though findings are inconsistent and lack rigorous human clinical trials. The review highlights the need for further investigation into l-theanine's mechanisms and therapeutic potential.
The function and application potential of L-theanine: From biotechnological production, biosynthesis, bioactivity to food industry.
This review discusses the biosynthesis, biotechnological production, and bioactivity of L-theanine, highlighting its roles in neuroprotection, anti-obesity effects, and immunomodulation. It also explores its applications in cognitive-enhancing beverages and as a plant-based preservative and umami enhancer.
L-Theanine and Immunity: A Review
This review discusses the immunomodulatory effects of L-theanine, highlighting its role in reducing immunosuppression from strenuous exercise and preventing colds and influenza. It also covers L-theanine's impact on inflammation, nerve damage, the intestinal tract, and tumors through various mechanisms.
L-Theanine: A Unique Functional Amino Acid in Tea (Camellia sinensis L.) With Multiple Health Benefits and Food Applications
This review summarizes the health benefits and molecular mechanisms of L-theanine, a bioactive compound in tea, including its antioxidant, anti-inflammatory, neuroprotective, anticancer, metabolic regulatory, cardiovascular protective, liver and kidney protective, immune regulatory, and anti-obesity effects. It also discusses the influencing factors of L-theanine content in teas and its applications in functional foods.
From Tea Leaves to Factories: A Review of Research Progress in l-Theanine Biosynthesis and Production.
This review summarizes research progress in l-theanine biosynthesis and production, focusing on its synthesis metabolism in tea plants and production methods such as plant extraction, chemical synthesis, and enzymatic transformation. It discusses challenges and future research directions for large-scale l-theanine production.
L-theanine: an astounding sui generis amino acid in poultry nutrition
Narrative review discussing the potential benefits of L-theanine, a nonprotein amino acid found in green tea, in poultry nutrition. The review highlights its antioxidant, immune-boosting, and anti-stress properties, and calls for more research on its use in poultry.
L-theanine attenuates transport stress-induced impairment of meat quality of broilers through improving muscle antioxidant status.
The study investigated the effect of dietary L-theanine supplementation on growth performance, immune organ indexes, and meat quality in transported broilers. L-theanine improved feed conversion ratio, final body weight, and muscle antioxidant status, while reducing transport-induced stress effects on immune organ indexes and meat quality.
Effect of L-theanine on growth performance, intestinal development and health, and peptide and amino acid transporters expression of broilers.
The study investigated the effect of L-theanine on growth performance, intestinal development, and health in broilers. L-theanine improved body weight, average daily gain, and intestinal health markers, suggesting its potential as a feed additive for broilers.
Synaptic modification by L‐theanine, a natural constituent in green tea, rescues the impairment of hippocampal long‐term potentiation and memory in AD mice
The study investigates the role of L-theanine in hippocampal synaptic transmission and memory improvement in transgenic AD mice. L-theanine facilitated synaptic transmission, improved memory, and rescued hippocampal LTP impairment in AD mice, likely through the dopamine D1/5 receptor-PKA pathway.
L‐theanine ameliorate depressive‐like behavior in a chronic unpredictable mild stress rat model via modulating the monoamine levels in limbic–cortical–striatal–pallidal–thalamic‐circuit related brain regions
The study investigates the effects of L-theanine on monoamine levels in a rat model of depression. L-theanine ameliorated depressive-like behaviors and increased levels of serotonin, norepinephrine, and dopamine in specific brain regions, suggesting antidepressant-like effects.
Protective Effect and Mechanism of Theanine on Lipopolysaccharide-Induced Inflammation and Acute Liver Injury in Mice.
The study evaluated the anti-inflammatory and hepatoprotective effects of theanine in a lipopolysaccharide-induced inflammation mouse model. Theanine treatment significantly increased survival rates, reduced liver damage and oxidative stress, and decreased inflammatory markers. Theanine's mechanism involved normalization of HPA axis hyperactivity and inactivation of the NF-κB signaling pathway.
L-Theanine Administration Modulates the Absorption of Dietary Nutrients and Expression of Transporters and Receptors in the Intestinal Mucosa of Rats
The study investigated the effects of L-theanine on intestinal nutrient absorption in rats. L-theanine administration modulated the expression of transporters and receptors in the intestinal mucosa, inhibiting glucose uptake and stimulating amino acid absorption.
L-Theanine Improves Immunity by Altering TH2/TH1 Cytokine Balance, Brain Neurotransmitters, and Expression of Phospholipase C in Rat Hearts
Animal study investigating the effects of L-theanine on immune function in rats. L-theanine administration improved immune function by increasing splenic weight, altering Th2/Th1 cytokine balance, decreasing corticosterone levels, elevating dopamine and 5-hydroxytryptamine in the brain, and regulating mRNA expression of PLC isomers in the heart.
Effects of chronic l-theanine administration in patients with major depressive disorder: an open-label study.
Open-label study of 20 patients with major depressive disorder receiving 250 mg/day l-theanine for 8 weeks. Results showed reductions in depression and anxiety scores, improved sleep quality, and enhanced cognitive functions.
Enhancement of antigen-specific immunoglobulin G production in mice by co-administration of L-cystine and L-theanine.
Animal study investigating the effects of oral administration of L-cystine and L-theanine on GSH levels and immune responses. Co-administration significantly increased liver GSH levels and enhanced serum antigen-specific IgG levels, suggesting improved immune function.
The beneficial health effects of green tea amino acid l‐theanine in animal models: Promises and prospects for human trials
Narrative review of l-theanine, an amino acid from green tea, highlighting its antioxidant-like properties and therapeutic effects in animal models. The review discusses potential benefits for brain and gastrointestinal function, cancer drug efficacy, antihypertensive effects, and immune function, and suggests further research for human trials.
l-Theanine as a Functional Food Additive: Its Role in Disease Prevention and Health Promotion
This review article outlines the synthesis, extraction, and purification methods of theanine and examines its potential health benefits, including improvements in cognitive and immune function, cancer prevention, and reduced cardiovascular risk.