The caffeine that was discovered in tea roughly 180 years ago was originally called “tein”. Chemically, the caffeine in tea is identical to that in coffee. However, the caffeine in tea is not in free form like it is in coffee, but bound. In tea, the caffeine is bound to amino acids and tannins, which causes it to have a different effect.

The caffeine in tea provides continuous, mild stimulation that lasts longer than the stimulation provided by coffee. This is because the caffeine is bound to other substances in tea, as explained, but also because tea has a lower amount of caffeine per cup than coffee. A cup of coffee has between 30% and 60% more caffeine than a cup of tea