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

This is the metadata section. Skip to content viewer section. Coffee and tea are both drunk in most countries, but typically one predominates. Coffee is the preferred drink in Europe and the Americas, ...

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 ...