Caffeine Occurrence

Caffeine is found in many plant species, where it acts as a natural pesticide, with high caffeine levels being reported in seedlings that are still developing foliages, but are lacking mechanical protection; caffeine paralyzes and kills certain insects feeding upon the plant. High caffeine levels have also been found in the surrounding soil of coffee bean seedlings. Therefore, it is understood that caffeine has a natural function as both a natural pesticide and an inhibitor of seed germination of other nearby coffee seedlings, thus giving it a better chance of survival.

Common sources of caffeine are coffee, tea, and to a lesser extent cocoa bean. Less commonly used sources of caffeine include the yerba maté and guarana plants, which are sometimes used in the preparation of teas and energy drinks. Two of caffeine's alternative names, ''mateine'' and ''guaranine'', are derived from the names of these plants. Some yerba mate enthusiasts assert that mateine is a stereoisomer of caffeine, which would make it a different substance altogether.

One of the world's primary sources of caffeine is the coffee "bean" (which is the seed of the coffee plant), from which coffee is brewed. Caffeine content in coffee varies widely depending on the type of coffee bean and the method of preparation used; even beans within a given bush can show variations in concentration. In general, one serving of coffee ranges from 40 milligrams, for a single shot (30 milliliters) of ''arabica''-variety espresso, to about 100 milligrams for a cup (120 milliliters) of drip coffee. In general, dark-roast coffee has less caffeine than lighter roasts because the roasting process reduces the bean's caffeine content. ''Arabica'' coffee normally contains less caffeine than the ''robusta'' variety. Teas like the pale Japanese green tea gyokuro, for example, contain far more caffeine than much darker teas like lapsang souchong, which has very little.

Caffeine is also a common ingredient of soft drinks such as cola, originally prepared from kola nuts. Soft drinks typically contain about 10 to 50 milligrams of caffeine per serving. By contrast, energy drinks such as Red Bull can start at 80 milligrams of caffeine per serving. The caffeine in these drinks either originates from the ingredients used or is an additive derived from the product of decaffeination or from chemical synthesis. Guarana, a prime ingredient of energy drinks, contains large amounts of caffeine with small amounts of theobromine and theophylline in a naturally occurring slow-release excipient.

Chocolate derived from cocoa bean contains a small amount of caffeine. The weak stimulant effect of chocolate may be due to a combination of theobromine and theophylline as well as caffeine. A typical 28-gram serving of a milk chocolate bar has about as much caffeine as a cup of ''decaffeinated'' coffee.

In recent years, various manufacturers have begun putting caffeine into shower products such as shampoo and soap, claiming that caffeine can be absorbed through the skin. However, the effectiveness of such products has not been proven, and they are likely to have little stimulatory effect on the central nervous system because caffeine is not readily absorbed through the skin.

Various manufacturers market caffeine tablets, claiming that using caffeine of pharmaceutical quality improves mental alertness. These effects have been borne out by research that shows that caffeine use (whether in tablet form or not) results in decreased fatigue and increased attentiveness. These tablets are commonly used by students studying for their exams and by people who work or drive for long hours.

Caffeine is also used pharmacologically to treat apnoea in premature newborns and as such is one of the 10 drugs most commonly given in neonatal intensive care, though questions are now raised based on experimental animal research whether it might have subtle harmful side-effects. Early peoples found that chewing the seeds, bark, or leaves of certain plants had the effects of easing fatigue, stimulating awareness, and elevating one's mood. Only much later was it found that the effect of caffeine was increased by steeping such plants in hot water. Many cultures have legends that attribute the discovery of such plants to people living many thousands of years ago.

According to one popular Chinese legend, the Emperor of China Shennong, reputed to have reigned in about 3000 BC, accidentally discovered that when some leaves fell into boiling water, a fragrant and restorative drink resulted. Shennong is also mentioned in Lu Yu's ''Cha Jing'', a famous early work on the subject of tea.

The history of coffee has been recorded as far back as the ninth century. During that time, coffee beans were available only in their native habitat, Ethiopia. A popular legend traces its discovery to a goatherder named Kaldi, who apparently observed goats that became elated and sleepless at night after grazing on coffee shrubs and, upon trying the berries that the goats had been eating, experienced the same vitality. The earliest literary mention of coffee may be a reference to Bunchum in the works of the 9th-century Persian physician al-Razi. In 1587, Malaye Jaziri compiled a work tracing the history and legal controversies of coffee, entitled "Undat al safwa fi hill al-qahwa". In this work, Jaziri recorded that one Sheikh, Jamal-al-Din al-Dhabhani, mufti of Aden, was the first to adopt the use of coffee in 1454, and that in the 15th century the Sufis of Yemen routinely used coffee to stay awake during prayers.

Towards the close of the 16th century, the use of coffee was recorded by a European resident in Egypt, and about this time it came into general use in the Near East. The appreciation of coffee as a beverage in Europe, where it was first known as "Arabian wine," dates from the 17th century. A legend states that, after the Ottoman Turks retreated from the walls of Vienna after losing a battle for the city, many sacks of coffee beans were found among their baggage. Europeans did not know what to do with all the coffee beans, being unfamiliar with them. So Franz George Kolschitzky, a Pole who had actually worked for the Turks, offered to take them. He subsequently taught the Viennese how to make coffee, and the first coffee house in the Western world was opened in Vienna, thus starting a long tradition of coffee appreciation. In Britain, the first coffee houses were opened in London in 1652, at St Michael's Alley, Cornhill. They soon became popular throughout Western Europe, and played a significant role in social relations in the 17th and 18th centuries.

The kola nut, like the coffee berry and tea leaf, appears to have ancient origins. It is chewed in many West African cultures, individually or in a social setting, to restore vitality and ease hunger pangs. In 1911, kola became the focus of one of the earliest documented health scares when the US government seized 40 barrels and 20 kegs of Coca-Cola syrup in Chattanooga, Tennessee, alleging that the caffeine in its drink was "injurious to health". On March 13, 1911, the government initiated ''United States v. Forty Barrels and Twenty Kegs of Coca-Cola'', hoping to force Coca-Cola to remove caffeine from its formula by making claims, such as that the excessive use of Coca-Cola at one girls' school led to "wild nocturnal freaks, violations of college rules and female proprieties, and even immoralities." Although the judge ruled in favor of Coca-Cola, two bills were introduced to the U.S. House of Representatives in 1912 to amend the Pure Food and Drug Act, adding caffeine to the list of "habit-forming" and "deleterious" substances, which must be listed on a product's label.

The earliest evidence of cocoa bean use comes from residue found in an ancient Mayan pot dated to 600 BC. In the New World, chocolate was consumed in a bitter and spicy drink called ''xocoatl'', often seasoned with vanilla, chile pepper, and achiote. Xocoatl was believed to fight fatigue, a belief that is probably attributable to the theobromine and caffeine content. Chocolate was an important luxury good throughout pre-Columbian Mesoamerica, and cocoa beans were often used as currency.

Xocoatl was introduced to Europe by the Spaniards and became a popular beverage by 1700. They also introduced the cacao tree into the West Indies and the Philippines. It was used in alchemical processes, where it was known as Black Bean.

The leaves and stems of the Yaupon Holly (''Ilex vomitoria'') were used by Native Americans to brew a tea called Asi or the "black drink". Archaeologists have found evidence of this use stretch back far into antiquity, possibly dating to Late Archaic times.

Further Reading

• What is Caffeine?
• Caffeine Pharmacology
• What is Decaffeination?

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