Guarana seed is used as an energy stimulant; it contains twice the caffeine of a comparable sized coffee bean although in a form different from the caffeine in coffee. It has been used in South America for hundreds of years and is especially abundant around Brazil. It is used by native tribes to sustain them on long journeys. The plant is a vine that produces bunches of berries with a large seed in each berry. It is the seed that is used. It is a stimulant, use it carefully to overcome exhaustion or long work hours.