Caffeine Coffee Espresso

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. Caffeine is a type of drug called a stimulant, meaning it increases chemicals in your brain called neurotransmitters. Feb 21, 2025up 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. 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. Jun 3, 2020caffeine is a natural stimulant consumed throughout the world. This article reviews caffeine and its health effects, both good and bad.

Jan 8, 2026learn about caffeine's effects on the human body. Caffeine has a stimulating effect on the central nervous system, heart, blood vessels, and kidneys. 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. Nov 3, 2025caffeine is a stimulant and the most commonly used drug in the world. May 8, 2025four out of every five adults consume caffeine daily.

Your caffeine intake depends on the caffeine-containing products you prefer. Mar 19, 2025caffeine revs up your nervous system, impacts your heart and irritates your gut.