Green tea contains L-theanine, an amino acid that has a calming effect and can increase concentration at the same time. In ...

For example, in 1820, the German chemist Runge, discovered the caffein of coffee, and a few years after, Oudry, the French chemist, discovered the thein of tea—both crystalline bitter substances ...

Tea and coffee are both good sources of caffeine and antioxidants. Coffee contains twice as much caffeine as tea, and can give you a more immediate energy boost. Tea contains L-theanine ...