L-theanine is a non-protein forming, water-soluble amino acid commonly used to treat anxiety and high blood pressure. Found naturally in green tea leaves, specifically Camellia sinensis, it has nootropic qualities and is clinically proven to increase alpha brain waves, delivering a calm focused state. While drinking a cup of green tea delivers soothing and energizing benefits, it will not provide you with the same amount of L-Theanine as in supplementation, approximately 20mg.