The most common sources of caffeine for human consumption are the tea leaves of the Camellia sinensis plant and the coffee bean, the seed of the Coffea plant. Some people drink beverages …

Dec 2, 2025 · Caffeine, nitrogenous organic compound of the alkaloid group, substances that have marked physiological effects. Caffeine occurs in tea, coffee, guarana, maté, kola nuts, and cacao. …

Caffeine is a natural chemical with stimulant effects. It is found in coffee, tea, cola, cocoa, guarana, yerba mate, and over 60 other products. Caffeine works by stimulating the central...

Mar 21, 2025 · What is caffeine? Caffeine is a type of drug called a stimulant, meaning it increases chemicals in your brain called neurotransmitters.

Feb 21, 2025 · Up to 400 milligrams (mg) of caffeine a day seems safe for most adults. That's about the amount of caffeine in four cups of brewed coffee, 10 cans of cola or two "energy shot" drinks. Keep …

Jun 3, 2020 · Caffeine is a natural stimulant consumed throughout the world. This article reviews caffeine and its health effects, both good and bad.

Although we tend to associate caffeine most often with coffee or tea, the research below focuses mainly on the health effects of caffeine itself. Visit our features on coffee, tea, and energy drinks for more …

Nov 3, 2025 · Caffeine is a stimulant and the most commonly used drug in the world. Benefits can include increased alertness, energy, and concentration. However, it can also lead to insomnia and …

Nov 19, 2025 · Caffeine is a central nervous system stimulant that can improve sports performance and aspects of cognitive function. Caffeine or caffeine-containing beverages are often taken to help …

Apr 1, 2025 · Caffeine is a substance that is found in certain plants. It can also be man-made and added to foods. It is a central nervous system stimulant and a diuretic (substance that helps rid your body of …