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Japanese Green Tea's Scientific Effects on Reducing Stress

Stress is a common factor in everyday life. While manageable levels of stress can lead to higher concentration, too much stress can lead to symptoms and mental disorders.

Continued stress can trigger depression, anxiety, and other diseases.

Let's see how Japanese Green Tea helps prevent these diseases.

This article was last modified December 11th, 2022. by Yuki

Stress in Singapore

According to MOH, 1 out of 16 Singaporeans will have exhibited depression symptoms once in their life. [4] Depression is the most common mental disorder in Singapore.

Continued exposure to stress is a significant cause of depression, and it is essential to control the amount of stress on yourself.

Theanine in Japanese Green Tea has Strong Effects in Reducing stress.

Theanine is a type of amino acid found in the tea leaf.

Roughly 1-2% of the leaves weight is Theanine. It is the most prominent amino acid in Japanese green tea and accounts for the Umami taste.

Japanese green tea is considered a higher quality when there is more umami. Therefore the Theanine content directly impacts the quality of Japanese tea.

Theanine can be absorbed in the intestines and reach the brain through the bloodstream. It has shown strong stress reduction effects in humans through clinical research. [1]

It is reported that Theanine can reduce stress, promote relaxation, improve sleep, improve memory, reduce the stimulation effect of caffeine, and reduce depression and other mental diseases. [3]

It is also reported that Theanine can improve depression symptoms as well. In an experiment where patients were given 250 mg of Theanine for eight weeks, they showed significant improvements in depression symptoms.

The report concluded that Theanine is "safe and has multiple beneficial effects on depressive symptoms, anxiety, sleep disturbance and cognitive impairments in patients with MMD (Major Depressive Disorder)." [5]

Additional Research on the Effects of Theanine

Several studies in Japan have observed that the frequency of green tea consumption corresponds with lower levels of depression symptoms. [6]

Groups who drink more than 4 cups a week show a lower probability of depression symptoms.

As not all of these studies indicate the type of green tea consumed. Therefore, the quantity of green tea is more important than the exact type or grade.

However, some studies show that the amount of Theanine in green tea is also a crucial component of the effect.

In a study that compared different types of Matcha and their effects on stress, researchers observed that high-grade Matcha was required to show positive results. [2]

Theanine Increases in Higher-grade Japanese Green Tea

Theanine increases in higher-grade Japanese green tea. This is because high-grade green tea is grown to enhance umami and reduce the astringency in the tea.

This means they maximize the Theanine in the tea during the cultivation process.

For example, ceremonial grade matcha is an excellent way of taking Theanine. If preparing Matcha is tedious, high-grade loose-leaf tea such as Gyokuro and high-end Sencha is also effective.

Author Yuki


Yuki is the Editor-in-Chief AND Community Manager at Tealife. He bleeds Japanese Tea and loves being a part of the Japanese Tea journey of others. Writes, does events, conducts tasting sessions, drinks, drinks and drinks tea! Easily accessible - hit him up on whatsapp (+65) 85882980.


[1] Kimura K, Ozeki M, Juneja LR, Ohira H. L-Theanine reduces psychological and physiological stress responses. Biol Psychol. 2007 Jan;74(1):39-45. doi: 10.1016/j.biopsycho.2006.06.006. Epub 2006 Aug 22. PMID: 16930802.

[2] Unno K, Furushima D, Hamamoto S, Iguchi K, Yamada H, Morita A, Horie H, Nakamura Y. Stress-Reducing Function of Matcha Green Tea in Animal Experiments and Clinical Trials. Nutrients. 2018 Oct 10;10(10):1468. doi: 10.3390/nu10101468. PMID: 30308973; PMCID: PMC6213777.

[3] Unno K. 抗ストレス作用. 茶の健康効果20選


[5] Hidese S, Ota M, Wakabayashi C, Noda T, Ozawa H, Okubo T, Kunugi H. Effects of chronic l-theanine administration in patients with major depressive disorder: an open-label study. Acta Neuropsychiatr. 2017 Apr;29(2):72-79. doi: 10.1017/neu.2016.33. Epub 2016 Jul 11. PMID: 27396868.

[6] 功⼑ 浩. うつ病に緑茶は貢献. 茶の健康20選