Methylxanthines
are a group of compounds found in more than fifty types of plants. Caffeine
is a
methylxanthine. It is also a drug, classified pharmacologically as a
mild stimulant. It stimulates the central nervous system. Is that what
you think about when you grab for a sip of diet soda or a swing of coffee?
Our Stone Age ancestors probably didn't think about such things, either.
But caffeine use has been documented as far back as the Stone Age.
Caffeine is present is coffee, tea, cola, and chocolate. Many people
get used to the "up" - the stimulant effect - they think they
feel after drinking beverages that contain caffeine. Others know that
if they partake of a caffeine-containing beveragve in the evening, they
might have trouble sleeping or, in fact, be up all night.
But what is realy happening inside the body to cause such effects? In
addition to stimulating the central nervous system, caffeine can increase
heartbeat and metabolic rate. It can also step up the production of
stomach acid and dilate blood vessels.
Although many caffeine users are unaware of exactly what the drug is
doing inside their body, most believe its effects wear off fairly quickly.
However, according to a recent scientific status summary from the Institute
of Food Technologists' Expert Panel on Food Safety and Nutrition, the
half-life of caffeine can last several days. A half-life is the time
it takes the body to eliminate only half of a substance that has been
introduced into it. The report goes on to say that factors such as smoking,
age, sex, and hormonal conditions can all come into play in determining
how long it takes for the effects of caffeine to dissipate.
