Caffeine is a bitter, white crystalline xanthine alkaloid that is a psychoactive stimulant drug. Caffeine was discovered by a German chemist, Friedrich Ferdinand Runge, in 1819. He coined the term “kaffein”, a chemical compound in coffee, which in English became caffeine. Caffeine is also part of the chemical mixtures and insoluble complexes guaranine found in guarana, mateine found in mate, and theine found in tea; all of which contain additional alkaloids such as the cardiac stimulants theophylline and theobromine, and often other chemicals such as polyphenols which can form insoluble complexes with caffeine.
Caffeine is found in varying quantities in the beans, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants. It is most commonly consumed by humans in infusions extracted from the cherries of the coffee plant and the leaves of the tea bush, as well as from various foods and drinks containing products derived from the kola nut. Other sources include yerba mate, guarana berries, and the Yaupon Holly.
The chemical compound is derived from plants. Caffeine most often consumed in beverages, such as coffee, tea, soft drinks and energy drinks. It may also be found in powder or pill form.
Caffeine is widely used to improve alertness and elevate moods. Certain pain relievers contain caffeine, as the compound has been shown to increase drug effectiveness and help the body absorb the pain relieving drug more quickly.
In humans, caffeine is a central nervous system (CNS) stimulant, having the effect of temporarily warding off drowsiness and restoring alertness. Beverages containing caffeine, such as coffee, tea, soft drinks, and energy drinks enjoy great popularity. Caffeine is the world’s most widely consumed psychoactive substance, but unlike many other psychoactive substances it is legal and unregulated in nearly all jurisdictions. In North America, 90% of adults consume caffeine daily. The U.S. Food and Drug Administration lists caffeine as a “Multiple Purpose Generally Recognized as Safe Food Substance”.
Caffeine has diuretic properties, at least when administered in sufficient doses to subjects who do not have a tolerance for it. Regular users, however, develop a strong tolerance to this effect, and studies have generally failed to support the common notion that ordinary consumption of caffeinated beverages contributes significantly to dehydration.
Caffeine is a diuretic, meaning it increases the need to urinate. It also temporarily increases alertness and, when taken near bed-time, may disrupt sleep patterns. When taken in large doses, caffeine can cause nervousness, jitteriness and tension.
Caffeine intake during pregnancy is linked to an increased risk of miscarriage.
Caffeine is addictive. Tolerance and dependence may develop after prolonged caffeine use. This reduces the chemical compound’s perceived stimulant effects. To temporarily overcome the body’s tolerance to the substance, caffeine must be consumed in increasingly larger doses. When caffeine consumption is halted, it can lead to a “crash”, including irritability, anxiety, loss of concentration and other withdrawal symptoms.
An acute overdose of caffeine can cause caffeine intoxication. This condition is similar to overdose from other stimulants. In extreme cases, psychosis and death may occur.