The major sources of caffeine are tea and coffee, although cacao trees, kola nuts, and 60 other plants all contain differing amounts of caffeine.1,2 Shen Nong (meaning “Divine Farmer” in Chinese) was credited with the discovery of tea.

Shen Nong was the emperor when agriculture started in China around 2737 b.c. He invented the plow, taught his people husbandry, and discovered the curative value of plants. On one of his trips to visit his constituency, his servant boiled water for him using the branches of a tea tree to make the fire. Some of the tea leaves fell into the wok, and the emperor found the water refreshing and exhilarating. From then on, he always asked for those particular tea leaves to make his drinks.

One of Shen Nong’s most important contributions was pioneering Chinese herbal medicine. Legend has it that he tasted 100 plants to gauge their medicinal utility. Unavoidably, he ingested poisonous leaves on many occasions. Whenever he did, he would chew tea leaves to expel the poison, and he went on to live more than 100 years. From then on, tea drinking became an integral part of Chinese culture. It was revered almost as a panacea, a cure for headache, indigestion, kidney trouble, and ulcers. It was also viewed as a guard against the noxious gases of the body and lethargy. The art of tea drinking reached its pinnacle in the Tang Dynasty (618 a.d. to 907 a.d.) when Lu Yu, a well-known poet, wrote Chб Jing (The Classics of Tea) at the request of a group of tea merchants. Chб Jing detailed every aspect of tea growing, harvesting, manufacturing, brewing, and drinking. Because the Tang Dynasty boasted the most civilized and richest culture in the world, scholars and merchants from other countries flocked to China to learn agriculture, military, trade, and language. Tea culture rapidly spread through Asia and the Middle East. By the 1600s, tea was being imported to the West in general and England in particular. Nowadays, it is hard to imagine British culture without tea. Most interestingly, tea helped initiate the American Revolution, when King George III imposed upon the 13 colonies exorbitant tariffs on tea and other goods through the 1765 Stamp Act. The revolution began with the Boston Tea Party, when colonists threw tea overboard in protest. The rest is history. In a way, tea was partially responsible for the birth of the United States of America.

According to legend, coffee was discovered by a goatherd. A long, long time ago, Kaldi, a young Ethiopian goatherd, noticed that some of his goats became exceedingly energetic after having chewed the red berries of a hillside shrub. Interest piqued, Kaldi picked some berries and chewed some himself. Soon enough he found his sleepiness and weariness gone and felt refreshed, even exhilarated. The monks in a nearby monastery learned of Kaldi’s experience and began to boil the red berries in their drinks so that they could keep awake during long hours of praying. Word started to spread about the magic berries, and coffee became a favorite drink in Africa and the Middle East. In the 1600s and 1700s, coffee drinking was adopted in Europe and has become popular ever since. In 1820, German chemist Friedlieb Ferdinand Runge isolated an alkaloid from the coffee bean, which he dubbed “caffeine,” indicating something found in coffee. Caffeine is capable of eliciting many central nervous system effects. Mechanisti- cally, caffeine’s major physiological effect is the result of inhibiting the adenosine receptor in the brain. Without caffeine, adenosine acts as a neuromodulator that slows down the movements of neurotransmitters by binding tightly to their receptors, thus inducing sleep. Caffeine competes with adenosine for binding to the receptors of other neurotransmitters and keeps us awake. Despite its universal use, caffeine is rarely overdosed, simply because people become too anxious after consuming too much caffeine. Like all chemicals, caffeine is toxic at high doses. It takes 10 grams of caffeine, which is the equivalent of about that in 100 cups of coffee consumed one after another without interruption, to kill a person. Consumption of too much caffeine has been linked to a higher rate of kidney, bladder, and pancreatic cancer, fibrocystic breast disease, and osteoporosis, although the direct linkage is hard to pin down. Cheap female viagra Both France and Denmark have banned high caffeine-content drinks such as Red Bull, citing health concerns about the elevated caffeine level.