As a natural phytochemical found in Japanese green tea, L-Theanine is a non-essential amino acid that is present in the brain. A close relative of Glutamate, studies indicate that L-Theanine interacts with the neurotransmitter, GABA (gammaminobutyrate). GABA, known for its importance in nervous system functioning, works with the mood centers of the brain. Studies in Japan show that L-Theanine helps support the bodys ability to deal with PMS and occasional, everyday anxiety.