Caffeine is a naturally occurring compound found in the leaves, seeds, or fruits of more than 60 plants, including coffee (Coffea arabica) beans, cacao (Theobroma cacao) beans, kola (Cola acuminata) nuts, guarana (Paullinia cupana) berries, and tea (Camellia sinensis) leaves. Caffeine is consumed regularly in the United States and throughout the world. It is found in many beverages, including coffee, chocolate, some energy drinks, and tea. More than seven kilograms of caffeine per person are consumed in the United States per year.

Caffeine was first discovered in 1819 by the German chemist Friedlieb Ferdinand Runge. He coined the term Kaffein, a chemical compound in coffee, which became caffeine in English.

Humans have consumed caffeine since the Stone Age. It was during this time that people discovered that chewing the seeds, bark, and leaves of certain plants reduced fatigue, increased awareness, and improved mood. The first known pot of tea dates back to 2737 BC, when the Chinese emperor Shen Nung boiled drinking water when the leaves of a nearby bush fell into the pot. Coffee was first noted in Africa around AD 575, when beans were used as money and eaten as food. Arabians of the 11th Century were known to have coffee beverages. In 1519, Spanish conquerors were treated to a chocolate drink by the Aztec emperor Montezuma. The world’s first caffeinated soft drinks were created in the 1880s.

In people, caffeine may be useful to stimulate the heart and increase urine flow. Caffeine has been shown to affect mood, endurance, the brain, and blood vessels, as well as activity in both the stomach and colon. Caffeine has also been marketed as a weight loss tool and is often included in various weight loss supplements.