Coffee glossary
Caffeine
A natural stimulant (1,3,7-trimethylxanthine) found in coffee seeds; it works mainly by blocking adenosine receptors in the brain.
An average 240 ml (8 oz) cup of brewed coffee contains around 95 mg of caffeine, though the real number varies widely with the beans, the ratio and the method. For most healthy adults, up to 400 mg a day is not associated with harmful effects.