Article / Updated 03-26-2016
Caffeine is a chemical compound in the leaves, seeds, and fruits of more than 63 plant species, but it most commonly comes from coffee and cocoa beans, cola nuts, and tea leaves. But coffee isn't the only source of caffeine — a can of cola contains 45 mg, green tea has 30 mg, an ounce of chocolate has 20 mg, and even Anacin comes in at 65 mg for two tablets.