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What Is L-Theanine?

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March 18, 2020

You may have heard that drinking tea is good for your health—but what is it exactly that makes tea so healthy? Tea is rich in antioxidants, but it also contains a unique amino acid called L-theanine, which plays a significant role in tea’s wellness benefits.

L-theanine has been studied for its effects on human brain functioning, mood, sleep, and emotional response. The human body does not produce L-theanine, making tea one of the best natural sources of this beneficial compound.

What is L-theanine?

L-theanine is an amino acid that is found in certain fungal and plant species—most notably the tea plant Camellia sinensis. All teas produced from the leaves from this plant (including black, green, oolong, and white tea) contain varying levels of L-theanine. Interestingly, this amino acid is also thought to be the source of umami flavor in green tea and certain broths.

The compound was first identified by Japanese scientists in Kyoto in 1949. The U.S. Food and Drug Administration considers L-theanine to be generally recognized as safe (GRAS) and allows it to be sold as a dietary supplement.

What are the health benefits of L-theanine?

Researchers studying L-theanine have made some interesting and highly promising discoveries. Possible health benefits include reduced stress, improved mood, better sleep, and enhanced cognitive function.* 

At realistic dietary doses, L-theanine elevates serotonin, dopamine, and GABA levels in the brain.* These neurotransmitters may regulate mood, emotions, concentration, sleep, and appetite. Increasing their levels may boost mental focus, encourage relaxation without drowsiness, and improve sleep quality.*

L-theanine has also been shown to trigger the release of alpha-waves, which enhance feelings of creativity and gentle alertness.* Daydreaming or becoming lost in the moment while pursuing a creative hobby is  associated with an increased alpha activity.

How much L-theanine is in tea?

Green tea—specifically shade-grown matcha green tea—has been shown to contain a  high concentration of L-theanine. 

On average, a typical cup of brewed green tea contains around 6.56 milligrams of L-theanine, while a typical cup of brewed black tea contains roughly 5.13 milligrams. Oolong teas and white teas tend to fall somewhere in the middle of the scale. 

When you find yourself needing a boost to get through the day, consider steeping a cup of your favorite tea. Take a quiet moment to sit and sip, and savor the feeling of peace and gentle alertness that washes over you. At The Republic of Tea, we call this TeaMind.

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.