Guarana's journey from regional tonic to aphrodisiac and global energy drink.

Guaraná (Paullinia cupana H.B.K., Sapindaceae) is a rainforest vine that was domesticated in the Amazon for its caffeine-rich fruits. Guaraná has long been used as a tonic and to treat various disorders in Brazil and abroad and became a national soda in Brazil about a century ago. In the last two decades or so, guaraná has emerged as a key ingredient in various ?sports? and energy drinks as well as concoctions that allegedly boost one's libido. For some time, guaraná's high caffeine content was thought to be a detriment because of health concerns about excessive intake of caffeine-rich drinks. But it is precisely this quality, and the fact that it has a mysterious name and comes from an exotic land, that has propelled guaraná into a global beverage.