1,3,7-trimethylxanthine is a natural alkaloid found in the leaves, seeds and fruit of coffee, tea, cocoa, cola, guarana and mate plants and the drinks obtained from them. In coffee, it is found in higher concentrations in the Canephora species (Robusta, 1.8-3.5%) and lower concentrations in the Arabica species (0.7-1.5%).

It has a stimulating effect on the nervous system and, if consumed in high doses, can alter breathing and heartbeat.
It is also partly responsible for the bitterness in coffee extractions, meaning that Robusta coffees are normally more bitter due to the higher concentration of caffeine.