COMPOUNDS IN COFFEE THAT MAY AFFECT
HUMAN HEALTH
Caffeine
Caffeine (1,3,7-trimethylxanthine) is a purine alkaloid that occurs naturally in coffee beans (Figure 1).1 At intake levels associated with coffee consumption, caffeine appears to exert most of its biological effects through the antagonism of the A1 and A2 A subtypes of the adenosine receptor.6 Adenosine (Figure 1) is an endogenous neuromodulator with mostly inhibitory effects, and adenosine antagonism by caffeine results in effects that are generally stimulatory. Some physiological effects associated with caffeine administration include central nervous system stimulation, acute elevation of blood pressure, increased metabolic rate, and diuresis.7 Caffeine is rapidly and almost completely absorbed in the stomach and small intestine and distributed to all tissues, including the brain. Caffeine metabolism occurs primarily in the liver, where the activity of the cytochrome