What L-theanine Actually Is and How It Relates to Matcha and Gyokuro

Have you heard of it before? L-Theanine is a unique amino acid found especially in high quality green tea and very few other sources. While L-Theanine is known for increasing the taste of umami, a sweet full-bodied flavor, L-Theanine is also known for its benefits as a relaxant. It generates alpha-waves in the brain. Alpha waves are emitted when the brain is in a relaxed state. Scientists are also examining L-Theanine’s ability to improve the brain’s memory capability.

Are their ways of increasing or decreasing the L-theanine in the tea plant? Well, L-theanine can only stay in the leaf while it is in the shade or in sunlight for shorter periods. L-theanine will turn to tannin under full sunlight. The shading process that is used for Tencha and Gyokuro reduces photosynthesis resulting in increased l-theanine. Higher quality Tencha and Gyokuro are grown with a longer shading process, thus higher grade tea tends to contain more L-Theanine.

Den-chan observing the kabuse or special nets used to shade the tea leaves.

L-Theanine has other benefits as demonstrated in an experiment using L-theanine at a company in the United States. The volunteers were 87 females between the ages of 35 and 60 with symptoms of a menopausal disorder. Among the ladies in the group who took an extraction of L-theanine, there were emotional and physical improvements with reductions in swelling and headaches. L-theanine also suppresses the stimulant function of caffeine and this is why high quality green tea helps to make you relax even though the tea contains caffeine.

A bowl of tencha leaves. These shaded leaves contain high amounts of L-theanine and are used to make matcha.

The new buds and leaves of higher quality sencha are picked early once they are flushed and spend less time under sunshine compared with middle or lower grade senchas. Bancha contains very little or no l-theanine because it is grown under sunshine for longer than sencha. The stem of the tea plant is considered to contain more L-theanine than the leaf part, because the stems are not as affected by photosynthesis. Therefore Green Kukicha may contain more L-theanine than Sencha and Karigane (Gyokuro Kukicha) may contain more L-theanine than Gyokuro depending on the grade of Kukicha. Karigane in particular offers perhaps one of the highest amounts of L-theanine per gram out of all the teas we offer because karigane, as mentioned above, is made entire of gyokuro stems, gyokuro already being a shaded green tea.

We hope this information helps you and please let us know if you have any questions by emailing us Follow our instagram and tiktok for more tea related content and subscribe to our newsletter by entering your email address in the designated area at the bottom of any page on our website.

Source: The Science of Tea (Cha no Kagaku), Keiichiro Muramatsu (ed.).