L-THEANINE
L-theanine is an amino acid found naturally in green tea and in smaller amounts in black tea. When you consume the whole tea leaves when you drink matcha, you get more L-theanine than with green tea that is strained. L-theanine also contributes to matcha's taste - the more L-theanine, the sweeter the matcha! In addition to green tea, L-theanine is also found in the brown sorrel mushroom.
L-theanine has a calming effect without making you feel tired and drowsy. It is the L-theanine that means that you do not get as fast a caffeine kick from matcha as you do when you drink coffee. We thus get the positive effect of caffeine but avoid both being speeded up or having a slump when the effect wears off.
According to some studies, L-theanine also has the ability to influence the release of serotonin and dopamine in the brain, which could be an explanation for why we can experience a sense of calm when we drink green tea. Some also experience better concentration and focus when they drink matcha instead of coffee, which could also be due to the L-theanine.