Westerners' favourite beverages are herbal stimulants in the form of caffeinated drinks, including coffee, tea and cola.
Caffeine is an alkaloid that is a potent nervous system stimulant. It was first isolated from coffee, a shrubby tree native to Ethiopia (Coffea arabica), Saudi Arabia (C. robusta) and elsewhere, in 1821. Americans drink an average of 28 gallons of coffee annually, or approximately 10 fl.oz per day. They also spend more money on cola than on breakfast cereal or any other grocery item, according to the US Department of Labor. Caffeine from other sources, including a number of over-the-counter pain medications, boosts the average caffeine consumption in the USA to between 175 and 225mg per day.
Nor is caffeine the only potentially stimulating chemical in coffee and other caffeinated beverages. Tea is derived from the dried leaves and stems of an evergreen plant (Camellia sinensis) native to Asia. In Britain and many of its former colonies, where the drinking of tea is a national pastime, addictions to tea are not uncommon. Americans drink more iced tea (an estimated 95 million glasses a day) than hot tea. Most green tea is drunk in China and Japan, though green tea is beginning to become more common in Europe and North America as its potential health benefits are recognized.
A 5 fl.oz cup of tea contains less caffeine (an average of 50 to 75mg) than coffee (which contains anywhere from 75 to 150mg) but slightly more than a cola (which has 35 to 55mg per 12fl.oz). Note that actual caffeine content may vary considerably depending upon such factors as quality and amount of herb used, brewing time and brewing method.
Cola-flavoured soft drinks are something of a misnomer. Though some colas in their early formulations contained extracts from the kola nut, today most colas contain little of the bitter herb. The kola nut is a seed kernel from a tree (Cola nitida, C. vera, C. acuminata and other species) that is native to tropical Africa and is cultivated also in the Caribbean, South America and Indonesia. The plant is in the same family as the cacao tree and, like cacao, contains the stimulants caffeine (about 1 to 3 percent by weight) and theobromine. Theobromine is a chemical relative of caffeine that has similar (though less potent) effects on the body. People in some parts of the world chew the kola nut for its stimulant effect.
Most of the caffeine in colas is either synthetically derived caffeine or caffeine from coffee. Cola drinks also typically are extremely high in sugar, with some containing the equivalent of 10 teaspoons per 12fl.oz.
Another common source of caffeine in the Western diet is chocolate. Derived from seeds (called cacao or cocoa beans) of the tropical cacao tree (Theobroma cacao), chocolate is a bitter-tasting herb that is almost always combined with large amounts of fat and sugar to make it palatable. It contains a small amount of caffeine but a relatively large amount of theobromine. Americans each consume an average of nine pounds of chocolate per year.
Caffeine is undeniably an effective central nervous system stimulant. It stimulates the brain, increases the secretion of adrenaline (epinephrine) and boosts heart rate. Although relatively safe, long-term use in excess of 250 to 300mg daily may cause numerous health problems. Caffeine has been known to raise blood cholesterol levels, deplete B vitamins, irritate the stomach and bladder, exhaust the adrenals and possibly lead to breast and prostate problems.
In high doses caffeine can cause heart palpitations, headaches, anxiety, panic disorders and insomnia. In industrial societies, its use frequently results in dependence. Andrew Weil, MD, an authority on psychoactive substances, says, 'I estimate that 80 percent of coffee users are addicted to it. The addiction is physical, with a prominent withdrawal reaction when use is suddenly discontinued.'
Withdrawal symptoms such as headaches and irritability usually start within twenty-four to thirty six hours of one's last caffeine dose.