What is Green Matcha Tea and what are the health benefits? Matcha Tea is a special kind of green powdered tea that has been traditionally used in Japanese tea ceremonies for over 800 years. Matcha contains an amino acid called L-theanine. L-theanine is an amino acid that helps relax the brain, blood vessels and muscles. It can also help lower blood pressure and enhance a sense of wellbeing by stimulating brain waves associated with the feelings of happiness and relaxation.