Relaxed but Alert Mental State Cognitive Support Non-GMO A Dietary Supplement Vegetarian/Vegan How it works: L-Theanine is an amino acid shown to be the constituent responsible for the calming properties of green tea. L-Theanine can cross the blood-brain barrier and enhances healthy alpha brain-wave activity, which is associated with a relaxed, but alert state. At the same time, L-Theanine helps to support the health of brain cells exposed to typical stimulation from excitatory neurotransmitters and promotes normal dopamine and GABA release. Clinical studies have shown that L-Theanine can support relaxation without drowsiness and promotes healthy cognitive function.