ABSTRACT
Caffeine and its closely related purine alkaloids such as theophylline and theobromine are methylxanthines occurring in plants widely distributed geographically. The most popular caffeine-containing beverage is tea, prepared from the leaves of Thea sinensis (containing caffeine and small amounts of theophylline and thiobromine), a bush native to southern China and now extensively cultivated in other countries. More than half the population of the world consumes tea. The average citizen in China consumes some 2 to 3 cups of tea every day. Other examples are Cocoa and chocolate, from the seeds of Theobroma cacao, containing theobromine and caffeine. Coffee, the most important source of caffeine in the American diet, is extracted from the fruit of Coffea arabica and related species. Cola-flavored drinks usually contain considerable amounts of caffeine, in part because of their content of extracts of the nuts of Cola acuminata. Some statistic data shows that the consumption of caffeine in the Nordic countries and in Britain is close to 300 mg per day per inhabitant. The most important source of caffeine in China is tea. Caffeine consumption is of a similar magnitude in most countries. This means that caffeine is probably the most widely used of all psychoactive drugs. The only substance that can come anywhere close is ethanol.
