Constituent from Green Tea


Mood Support*

Lower Blood Pressure*

Stress Relief*

Suntheanine® is a registered trademark of Taiyo International.

Where L-THEANINE is found

Native to:


L-Theanine is found from Green tea and is grown worldwide but mostly native to Asia. Stemming primarily from Japan & China with Japan making up almost 60% of the world's tea production.


Green Tea Caffeine:

L-theanine is a unique amino acid found in tea, especially green tea (Camellia sinensis). Green tea has long been heralded for its health benefits. One of them is the sense of calm it can bring, thanks in part to the amino acid, L-theanine.* Clinical research suggests that 50 mg – 200 mg Suntheanine stimulates activity in the brain known as alpha waves, which are associated with a relaxed but alert mental state. Suntheanine is the trade name for Taiyo’s patented pure form of L-theanine. Suntheanine is not an extract of green tea but rather is produced via a patented process that mimics the natural process in green tea leaves, resulting in a 100% pure L-isomer-theanine.



What does L-Theanine actually do?

Human clinical trials have shown Suntheanine to promote an alert state of relaxation without drowsiness, as indicated by an increase in Alpha brain waves, and a decrease in Beta brain waves.*

Improved Clarity:

Additional human clinical research suggests that Suntheanine may have application in improving the quality of sleep, diminishing normal symptoms of premenstrual syndrome (PMS), improving learning performance, heightening mental acuity, promoting concentration, reducing negative side effects of caffeine and supporting the immune system.*


Is Suntheanine made from green tea?

Suntheanine is not an extract of green tea but rather is produced via a patented process that mimics the natural process in green tea leaves, resulting in a 100% pure L-isomer-theanine.

What is the recommended use of Suntheanine?

The intended use for Suntheanine is as supplement to promote mental and physical relaxation without inducing drowsiness.*

What is the recommended dosage of Suntheanine?

Based on the results of clinical studies, it has been established that Suntheanine is effective in the range of 50 to 200 mg. It is suggested that subjects with higher levels of stress consume a minimum of 100 mg for best results. There is not a set schedule for taking Suntheanine and can be taken as desired.

How long does it take for the effects to be felt?

The effects of Suntheanine are generally felt within 30 minutes and have been shown to last up to 8 to 12 hours. Please note that if a person is already calm and relaxed, little to no effect will be noticed at any level of consumption.

What is the mechanism of Suntheanine?

Suntheanine directly stimulates the production of alpha brain waves, a state often achieved by meditation. It is one of deep relaxation and mental alertness.

Suntheanine is absorbed in the small intestine via a sodium-coupled active transport process and crosses the blood-brain barrier where it is absorbed into the brain in a dose-dependent manner. Suntheanine may compete for absorption in the intestinal tract and brain with amino acids found in the methionine group, including isoleucine, leucine and valine. Concentrations of other amino acids are unchanged by Suntheanine.

Suntheanine plays a role in the formation of the inhibitory neurotransmitter GABA and increases dopamine release through modulation of glycine and AMPA receptors. Suntheanine promotes a relaxation and excitatory inhibition effect without leading to drowsiness.*


Author: Williams, J.
Publication: Foods (Basel, Switzerland) 2020 Mar
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The effect of L-theanine incorporated in a functional food product (mango sorbet) on physiological responses in healthy males: a pilot randomized controlled trial

Abstract: Consumption of L-Theanine (L-THE) has been associated with a sensation of relaxation, as well as a reduction of stress. However, these physiological responses have yet to be elucidated in humans where L-THE is compared alongside food or as a functional ingredient within the food matrix. The aim of this study was to determine the physiological responses of a single intake of a potential functional food product (mango sorbet) containing L-THE (ms-L-THE; 200 mgw/w) in comparison to a flavour and colour-matched placebo (ms). Eighteen healthy male participants were recruited in this randomised, double-blind, placebo-controlled trial. The participants were required to consume ms-L-THE or placebo and their blood pressure (BP) (systolic and diastolic), heart rate (HR), and heart rate variability (HRV) were monitored continuously over 90 minutes. Eleven males (age 27.7 ± 10.8 years) completed the study. Changes in area under the curve for systolic and diastolic blood pressure and HRV over the 90 minute observation period indicated no differences between the three conditions (all p > 0.05) or within individual groups (all p > 0.05). The values for heart rate were also not different in the placebo group (p = 0.996) and treatment group (p = 0.066), while there was a difference seen at the baseline (p = 0.003). Based on the findings of this study, L-THE incorporated in a food matrix (mango sorbet) demonstrated no reduction in BP or HR and showed no significant parasympathetic interaction as determined by HRV high-frequency band and low-frequency/high-frequency ratio. Further studies should be focussed towards the comparison of pure L-THE and incorporation within the food matrix to warrant recommendations of L-THE alongside food consumption.

Author: Hidese, S.
Publication: Nutrients 2019 Oct
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Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial

Abstract: This randomized, placebo-controlled, crossover, and double-blind trial aimed to examine the possible effects of four weeks L-theanine administration on stress-related symptoms and cognitive functions in healthy adults. Participants were 30 individuals (nine men and 21 women; age: 48.3 ± 11.9 years) who had no major psychiatric illness. L-theanine (200 mg/day) or placebo tablets were randomly and blindly assigned for four-week administration. For stress-related symptoms, Self-rating Depression Scale, State-Trait Anxiety Inventory-trait, and Pittsburgh Sleep Quality Index (PSQI) scores decreased after L-theanine administration (p = 0.019, 0.006, and 0.013, respectively). The PSQI subscale scores for sleep latency, sleep disturbance, and use of sleep medication reduced after L-theanine administration, compared to the placebo administration (all p < 0.05). For cognitive functions, verbal fluency and executive function scores improved after L-theanine administration (p = 0.001 and 0.031, respectively). Stratified analyses revealed that scores for verbal fluency (p = 0.002), especially letter fluency (p = 0.002), increased after L-theanine administration, compared to the placebo administration, in individuals who were sub-grouped into the lower half by the median split based on the mean pretreatment scores. Our findings suggest that L-theanine has the potential to promote mental health in the general population with stress-related ailments and cognitive impairments.

Author: DRAMARD, V.
Publication: Irish Veterinary Journal 2018 Oct
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Effect of L-theanine tablets in reducing stress-related emotional signs in cats: an open-label field study

Abstract: Background: L-theanine is an aminoacid found in tea leaves which has relaxing effects in humans and animals. It is a structural analogue of glutamate which can bind glutamate receptors. Although the relaxing action of L-theanine has been shown in humans, laboratory animals and dogs, it has never been published in cats. The goal of this open-label, multicentre and prospective trial was to determine whether an L-theanine based oral supplement (Anxitane®, Virbac, France) could attenuate manifestations of stress in cats under field conditions.

Case presentation: Thirty-three privately owned cats presenting signs associated with stress or fear (inappropriate urination/defecation, fear-induced aggressiveness, hypervigilance/tenseness or physical/functional manifestations of stress) for at least 1 month, were included in the study. They were given L-theanine (Anxitane®, 25 mg twice a day) for 30 days and 20 stress-related parameters were scored at Days 0, 15 and 30. The evolution of some parameters was also rated relative to Day 0. All median scores of the 20 parameters were significantly reduced at D30, and 30/33 cats (91%) had a reduced global score at the end of the study, including 21/33 with ≥50% score reduction. The median (IQR) global scores went from 18 (13-23) at D0 to 11 (8-13) at D15 and 5 (3-12) at D30 (p < 0.0001; Friedman test; significant reduction starting from D15). All the stress-related signs were significantly improved compared to D0, according to the owners, especially inappropriate elimination. Tablet palatability was judged good or very good in 94% of cases with spontaneous intake by cats when given by hand or in food. Tolerance was satisfactory as well, and no side effects were reported, so that most owners (27/33; 82%) were satisfied with the product.

Conclusions: Despite the lack of a placebo group, it can be concluded that L-theanine (Anxitane®) helped to improve the undesirable manifestations of stress in cats in as soon as 15 days, though better results could be seen after 30 days of administration. These encouraging results show that L-theanine can help manage stress-related behaviour, but additional trials with a placebo group should be run to confirm this effect.

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