Wikipedia:Today's featured article/September 16, 2006



Caffeine is a xanthine alkaloid compound that acts as a stimulant in humans. It is found in the leaves and beans of the coffee plant, in tea, yerba mate, guarana berries, and in small quantities in cocoa, the kola nut and the Yaupon Holly. Overall, caffeine is found in the beans, leaves, and fruit of over 60 plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding upon them. Its name is derived from the Italian caffè plus the alkaloid suffix -ine. Caffeine is a central nervous system stimulant, having the effect of warding off drowsiness and restoring alertness. Beverages containing caffeine, such as coffee, tea, soft drinks and energy drinks, enjoy popularity great enough to make caffeine the world's most widely consumed psychoactive substance. In North America, 90% of adults consume caffeine daily. Many natural sources of caffeine also contain widely varying mixtures of other xanthine alkaloids, including the cardiac stimulants theophylline and theobromine and other substances such as tannins. When a given caffeine mixture appears to have different effects, depending on its source, it is due primarily to varying concentrations of other stimulants and absorption rates of the mixture. (more...)

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