Theanine is an amino acid found in green tea that produces calming effects in the brain by increasing levels of serotonin and dopamine, and blocking the binding of L-glutamic acid to glutamate receptors. Life Extension Foundation members can enjoy the benefits of this unique ingredient in a 100 mg supplement—L-Theanine. A “feel good” supplement, theanine causes no adverse reactions. In fact, in Japan, theanine is added to soft drinks and chewing gum for the purpose of inducing relaxation.
The calming, mood-enhancing effect is achieved by helping to increase alpha-brain waves, electrical brain activity commonly present when you are very relaxed, literally putting you in a better mood.

Just as meditation, massage, or aromatherapy quiets the mind and body, so too theanine plays a role in inducing the same calm and feeling of well-being—without drowsiness. It is a non-toxic, highly desirable mood modulator.