Tea contains L-theanine, a unique amino acid that promotes calm alertness.

L-theanine, or gamma-glutamylethylamide, is a non-protein amino acid primarily found in the Camellia sinensis plant. It was first isolated from green tea by Japanese scientists at the Kyoto Prefectural Tea Experiment Station in 1949. This compound is unique because it can cross the blood-brain barrier within 30 to 40 minutes of ingestion.Once in the brain, L-theanine increases the activity of inhibitory neurotransmitters like GABA, which has anti-anxiety effects. It also increases dopamine and the production of alpha brain waves, which are associated with a state of 'wakeful relaxation.' This is the same brain state achieved during deep meditation or creative flow.Research published in the journal 'Biological Psychology' in 2007 demonstrated that L-theanine reduces heart rate and immune responses to physical and mental stress. When paired with caffeine, it creates a synergistic effect that improves cognitive performance and attention. A 2008 study in 'Asia Pacific Journal of Clinical Nutrition' confirmed that the alpha wave increase is significant enough to counteract the overstimulating effects of caffeine.While a standard cup of black tea contains about 20 to 30 milligrams of L-theanine, high-quality matcha can contain significantly more. This chemical profile explains why tea drinkers report a more sustained level of energy compared to the rapid spike and crash of coffee. The combination essentially provides the brain with the fuel to focus while preventing the nervous system from becoming over-aroused.