L-Theanine

Theanine is an amino acid commonly found in tea . Theanine can cross the blood-brain barrier. As it can enter the brain, theanine has psychoactive properties. Theanine has been shown to reduce mental and physical stress, and may produce feelings of relaxation and improve cognition and mood when taken in combination with caffeine.

Theanine is speculated to produce these effects by increasing the level of gamma-aminobutyric acid (GABA) production. Theanine increases brain serotonin, dopamine, GABA levels and has micromolar affinities for AMPA, Kainate and NMDA receptors.

L-theanine may help the body's immune response to infection by boosting the disease-fighting capacity of gamma delta T cells.