Although caffeine is a major component of coffee, the content is highly variable—ranging between 30mg and 175mg in
a cup (150mL) of home-prepared coffee. Caffeine is the most widely consumed psychoactive drug worldwide and appears
to exert most of its biological effects through the antagonism of the adenosine receptor. Adenosine is an endogenous
inhibitory neuromodulator that prompts feelings of drowsiness, and thus caffeine induces generally stimulatory effects
in the central nervous system. In addition, the physiological effects of caffeine intake include acute elevation of blood
pressure, increasing metabolic rate, and diuresis.3 Based on the data reviewed, it can be concluded that moderate caffeine
intake (2–3 cups or 300mg/day) is not associated with
adverse effects, such as cardiovascular stimulatory effects and
behavioral changes, at least in healthy adults.4 However, caffeine
is not completely harmless. In fact, caffeine crosses