Caffeine As can be seen above, caffeine consists of two carbon/nitrogen rings with oxygen and methyl groups as substituents. The fused rings are similar to those in adenine only the substituents differ. Caffeine is found in coffee, tea, and many soft drinks. There is also some amount of caffeine in chocolate, as well as a closely related stimulant, theobromine. The caffeine in sodas is generally produced from the cola berries, and is either a by-product of the cola flavoring or is added for flavor and stimulant effect. There are four ways in which caffeine stimulates the nervous system. Of these, one is of primary improtance. Ano