The major pharmacologically active ingredient in coffee is the central nervous system stimulant caffeine, 1, 3, 7-trimethylxanthine. Caffeine occurs naturally in some 60 plant species, of which cocoa-beans, tea and coffee are the most well known. Following consumption, caffeine is absorbed into the blood and body tissues, and has a half-life of approximately fours hours, although this can vary and is known to be shorter in smokers and longer in pregnant women, The amount of caffeine consumed throughcoffee varies and is dependent, for example, on how strong the coffee is brewed, on the type of coffee be it Robusta or Arabica, and of course on how much is consumed.
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