L-theanine is a natural amino acid that improves mood, reduces stress, enhances thinking ability, and mitigates caffeine jitters.*

L-theanine is an amino acid in tea leaves that regulates the neurotransmitters GABA, dopamine, and serotonin. It improves mood, reduces stress, and enhances thinking ability. L-theanine also promotes brain alpha-wave function and produces a relaxed-alert state without causing drowsiness. And it mitigates the jittery effects of caffeine.*

  • Enhances speaking ability*
  • Reduces normal anxiety*
  • Improves cognition and mood*
  • Elevates sense of well-being*
  • Improves sleep patterns*


L-theanine is an amino acid in tea leaves. It has a long list of healthy benefits, from supporting liver function to maintaining optimal blood pressure.

L-theanine is also a powerful nootropic. It regulates the neurotransmitters GABA, dopamine, and serotonin, leading to improved mood, increased cognition, enhanced thinking ability, and improved sense of well-being, all without increasing drowsiness.

L-theanine also synergizes caffeine, enhancing caffeine's good qualities while mitigating its bad. That means it allows caffeine to give you heightened focus, awareness, and energy without all the nervousness or jitteriness.

  1. Park SK et al. 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. J Med Food. 2011 Apr;14(4):334-43. ABSTRACT: A combination of green tea extract and L-theanine (LGNC-07) has been reported to have beneficial effects on cognition in animal studies. In this randomized, double-blind, placebo-controlled study, the effect of LGNC-07 on memory and attention in subjects with mild cognitive impairment (MCI) was investigated. Ninety-one MCI subjects whose Mini Mental State Examination-K (MMSE-K) scores were between 21 and 26 and who were in either stage 2 or 3 on the Global Deterioration Scale were enrolled in this study. The treatment group (13 men, 32 women; 57.58 ± 9.45 years) took 1,680 mg of LGNC-07, and the placebo group (12 men, 34 women; 56.28 ± 9.92 years) received an equivalent amount of maltodextrin and lactose for 16 weeks. Neuropsychological tests (Rey-Kim memory test and Stroop color-word test) and electroencephalography were conducted to evaluate the effect of LGNC-07 on memory and attention. Further analyses were stratified by baseline severity to evaluate treatment response on the degree of impairment (MMSE-K 21-23 and 24-26). LGNC-07 led to improvements in memory by marginally increasing delayed recognition in the Rey-Kim memory test (P .0572). Stratified analyses showed that LGNC-07 improved memory and selective attention by significantly increasing the Rey-Kim memory quotient and word reading in the subjects with MMSE-K scores of 21-23 (LGNC-07, n = 11; placebo, n = 9). Electroencephalograms were recorded in 24 randomly selected subjects hourly for 3 hours in eye-open, eye-closed, and reading states after a single dose of LGNC-07 LGNC-07 (n = 12; placebo, n = 12). Brain theta waves, an indicator of cognitive alertness, were increased significantly in the temporal, frontal, parietal, and occipital areas after 3 hours in the eye-open and reading states. Therefore, this study suggests that LGNC-07 has potential as an intervention for cognitive improvement.
  2. Giesbrecht T et al. The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness. Nutr Neurosci. 2010 Dec;13(6):283-90. ABSTRACT: The non-proteinic amino acid L-theanine and caffeine, a methylxanthine derivative, are naturally occurring ingredients in tea. The present study investigated the effect of a combination of 97 mg L- theanine and 40 mg caffeine as compared to placebo treatment on cognitive performance, alertness, blood pressure, and heart rate in a sample of young adults (n = 44). Cognitive performance, self-reported mood, blood pressure, and heart rate were measured before L-theanine and caffeine administration (i.e. at baseline) and 20 min and 70 min thereafter. The combination of moderate levels of L-theanine and caffeine significantly improved accuracy during task switching and self-reported alertness (both P < 0.01) and reduced self-reported tiredness (P < 0.05). There were no significant effects on other cognitive tasks, such as visual search, choice reaction times, or mental rotation. The present results suggest that 97 mg of L-theanine in combination with 40 mg of caffeine helps to focus attention during a demanding cognitive task.
  3. Einšther SJ et al. L-theanine and caffeine improve task switching but not intersensory attention or subjective alertness. Appetite. 2010 Apr;54(2):406-9. ABSTRACT: Tea ingredients L-theanine and caffeine have repeatedly been shown to deliver unique cognitive benefits when consumed in combination. The current randomized, placebo-controlled, double-blind, cross-over study compared a combination of L-theanine (97 mg) and caffeine (40 mg) to a placebo on two attention tasks and a self-report questionnaire before, and 10 and 60 min after consumption. The combination of L-theanine and caffeine significantly improved attention on a switch task as compared to the placebo, while subjective alertness and intersensory attention were not improved significantly. The results support previous evidence that L-theanine and caffeine in combination can improve attention.
  4. Kim TI et al. L-Theanine, an amino acid in green tea, attenuates beta-amyloid-induced cognitive dysfunction and neurotoxicity: reduction in oxidative damage and inactivation of ERK/p38 kinase and NF-kappaB pathways. Free Radic Biol Med. 2009 Dec 1;47(11):1601-10. Epub 2009 Sep 16. ABSTRACT: Amyloid beta (Abeta)-induced neurotoxicity is a major pathological mechanism of Alzheimer disease (AD). In this study, we investigated the inhibitory effect of l-theanine, a component of green tea (Camellia sinensis), on Abeta(1-42)-induced neuronal cell death and memory impairment. Oral treatment of l-theanine (2 and 4 mg/kg) for 5 weeks in the drinking water of mice, followed by injection of Abeta(1-42) (2 microg/mouse, icv), significantly attenuated Abeta(1-42)-induced memory impairment. Furthermore, l-theanine reduced Abeta(1-42) levels and the accompanying Abeta(1-42)-induced neuronal cell death in the cortex and hippocampus of the brain. Moreover, l-theanine inhibited Abeta(1-42)-induced extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase as well as the activity of nuclear factor kappaB (NF-kappaB). l-Theanine also significantly reduced oxidative protein and lipid damage and the elevation of glutathione levels in the brain. These data suggest that the positive effects of l-theanine on memory may be mediated by suppression of ERK/p38 and NF-kappaB as well as the reduction of macromolecular oxidative damage. Thus, l-theanine may be useful in the prevention and treatment of AD.
  5. Gomez-Ramirez M et al. The effects of L-theanine on alpha-band oscillatory brain activity during a visuo-spatial attention task. Brain Topogr. 2009 Jun;22(1):44-51. ABSTRACT: Background/Objectives Ingestion of the non-proteinic amino acid L-theanine (gamma-glutamylethylamide) has been shown to influence oscillatory brain activity in the alpha band (8-14 Hz) in humans during resting electroencephalographic (EEG) recordings and also during cognitive task performance. We have previously shown that ingestion of a 250-mg dose of L-theanine significantly reduced tonic (background) alpha power during a demanding intersensory (auditory-visual) attentional cueing task. Further, cue-related phasic changes in alpha power, indexing the shorter-term anticipatory biasing of attention between modalities, were stronger on L-theanine compared to placebo. This form of cue-contingent phasic alpha activity is also known to index attentional biasing within visual space. Specifically, when a relevant location is pre-cued, anticipatory alpha power increases contralateral to the location to be ignored. Here we investigate whether the effects of L-theanine on tonic and phasic alpha activity, found previously during intersensory attentional deployment, occur also during a visuospatial task. Subjects/Methods 168-channel EEG data were recorded from thirteen neurologically normal individuals while engaged in a highly demanding visuo-spatial attention task. Participants underwent testing on two separate days, ingesting either a 250-mg colorless and tasteless solution of L-theanine mixed with water, or a water-based solution placebo on each day in counterbalanced order. We compared the alpha-band activity when subjects ingested L-Theanine vs. Placebo. Results We found a significant reduction in tonic alpha for the L-theanine treatment compared to placebo, which was accompanied by a shift in scalp topography, indicative of treatment-related changes in the neural generators of oscillatory alpha activity. However, L-theanine did not measurably affect cue-related anticipatory alpha effects. Conclusions This pattern of results implies that L- theanine plays a more general role in attentional processing, facilitating longer-lasting processes responsible for sustaining attention across the timeframe of a difficult task, rather than affecting specific moment-to-moment phasic deployment processes.
  6. Owen GN et al. The combined effects of L-theanine and caffeine on cognitive performance and mood. Nutr Neurosci. 2008 Aug;11(4):193-8. ABSTRACT: The aim of this study was to compare 50 mg caffeine, with and without 100 mg L-theanine, on cognition and mood in healthy volunteers. The effects of these treatments on word recognition, rapid visual information processing, critical flicker fusion threshold, attention switching and mood were compared to placebo in 27 participants. Performance was measured at baseline and again 60 min and 90 min after each treatment (separated by a 7-day washout). Caffeine improved subjective alertness at 60 min and accuracy on the attention-switching task at 90 min. The L- theanine and caffeine combination improved both speed and accuracy of performance of the attention-switching task at 60 min, and reduced susceptibility to distracting information in the memory task at both 60 min and 90 min. These results replicate previous evidence which suggests that L-theanine and caffeine in combination are beneficial for improving performance on cognitively demanding tasks.
  7. Nobre AC et al. L-theanine, a natural constituent in tea, and its effect on mental state. Asia Pac J Clin Nutr. 2008;17 Suppl 1: 167-8. ABSTRACT: Tea is the most widely consumed beverage in the world after water. Tea is known to be a rich source of flavonoid antioxidants. However tea also contains a unique amino acid, L-theanine that may modulate aspects of brain function in humans. Evidence from human electroencephalograph (EEG) studies show that it has a direct effect on the brain (Juneja et al. Trends in Food Science & Tech 1999;10;199-204). L-theanine significantly increases activity in the alpha frequency band which indicates that it relaxes the mind without inducing drowsiness. However, this effect has only been established at higher doses than that typically found in a cup of black tea (approximately 20mg). The aim of the current research was to establish this effect at more realistic dietary levels. EEG was measured in healthy, young participants at baseline and 45, 60, 75, 90 and 105 minutes after ingestion of 50mg L-theanine (n=16) or placebo (n=19). Participants were resting with their eyes closed during EEG recording. There was a greater increase in alpha activity across time in the L-theanine condition (relative to placebo (p+0.05). A second study replicated this effect in participants engaged in passive activity. These data indicate that L- theanine, at realistic dietary levels, has a significant effect on the general state of mental alertness or arousal. Furthermore, alpha activity is known to play an important role in critical aspects of attention, and further research is therefore focussed on understanding the effect of L-theanine on attentional processes.
  8. Bryan J et al. Psychological effects of dietary components of tea: caffeine and L-theanine. Nutr Rev. 2008 Feb;66(2):82-90. ABSTRACT: This review summarizes the literature on the association between two dietary components of tea, caffeine and L-theanine, and the psychological outcomes of consumption; it also identifies areas for future research. The studies reviewed suggest that caffeinated tea, when ingested at regular intervals, may maintain alertness, focused attention, and accuracy and may modulate the more acute effects of higher doses of caffeine. These findings concur with the neurochemical effects of L-theanine on the brain. L- theanine may interact with caffeine to enhance performance in terms of attention switching and the ability to ignore distraction; this is likely to be reflective of higher-level cognitive activity and may be sensitive to the detrimental effects of overstimulation. Further research should investigate the interactive effects of caffeine, L-theanine, and task complexity, utilize a range of ecologically valid psychological outcomes, and assess the neuroprotective effects of L-theanine using epidemiological or longer-term intervention studies among individuals at risk of neurodegenerative disease.
  9. Haskell CF et al. The effects of L-theanine, caffeine and their combination on cognition and mood. Biol Psychol. 2008 Feb;77(2):113-22. ABSTRACT: L-Theanine is an amino acid found naturally in tea. Despite the common consumption of L-theanine, predominantly in combination with caffeine in the form of tea, only one study to date has examined the cognitive effects of this substance alone, and none have examined its effects when combined with caffeine. The present randomised, placebo-controlled, double-blind, balanced crossover study investigated the acute cognitive and mood effects of L-theanine (250 mg), and caffeine (150 mg), in isolation and in combination. Salivary caffeine levels were co-monitored. L-Theanine increased 'headache' ratings and decreased correct serial seven subtractions. Caffeine led to faster digit vigilance reaction time, improved Rapid Visual Information Processing (RVIP) accuracy and attenuated increases in self-reported 'mental fatigue'. In addition to improving RVIP accuracy and 'mental fatigue' ratings, the combination also led to faster simple reaction time, faster numeric working memory reaction time and improved sentence verification accuracy. 'Headache' and 'tired' ratings were reduced and 'alert' ratings increased. There was also a significant positive caffeine x L- theanine interaction on delayed word recognition reaction time. These results suggest that beverages containing L-theanine and caffeine may have a different pharmacological profile to those containing caffeine alone.
  10. Nathan PJ et al. The neuropharmacology of L-theanine(N-ethyl-L-glutamine): a possible neuroprotective and cognitive enhancing agent. J Herb Pharmacother. 2006;6(2):21-30. ABSTRACT: L-theanine (N-ethyl-L-glutamine) or theanine is a major amino acid uniquely found in green tea. L-theanine has been historically reported as a relaxing agent, prompting scientific research on its pharmacology. Animal neurochemistry studies suggest that L- theanine increases brain serotonin, dopamine, GABA levels and has micromolar affinities for AMPA, Kainate and NMDA receptors. In addition has been shown to exert neuroprotective effects in animal models possibly through its antagonistic effects on group 1 metabotrophic glutamate receptors. Behavioural studies in animals suggest improvement in learning and memory. Overall, L-theanine displays a neuropharmacology suggestive of a possible neuroprotective and cognitive enhancing agent and warrants further investigation in animals and humans.
  11. Kimura K et al. L-Theanine reduces psychological and physiological stress responses. Biol Psychol. 2007 Jan;74(1):39-45. ABSTRACT: L-theanine is an amino acid contained in green tea leaves which is known to block the binding of L-glutamic acid to glutamate receptors in the brain. Because the characteristics of L-Theanine suggest that it may influence psychological and physiological states under stress, the present study examined these possible effects in a laboratory setting using a mental arithmetic task as an acute stressor. Twelve participants underwent four separate trials: one in which they took L-Theanine at the start of an experimental procedure, one in which they took L-Theanine midway, and two control trials in which they either took a placebo or nothing. The experimental sessions were performed by double-blind, and the order of them was counterbalanced. The results showed that L-Theanine intake resulted in a reduction in the heart rate (HR) and salivary immunoglobulin A (s-IgA) responses to an acute stress task relative to the placebo control condition. Moreover, analyses of heart rate variability indicated that the reductions in HR and s-IgA were likely attributable to an attenuation of sympathetic nervous activation. Thus, it was suggested that the oral intake of L- Theanine could cause anti-stress effects via the inhibition of cortical neuron excitation.

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