In the Amazon Basin of South America a bushy shrub called quarana, which sometimes manifests as a climbing plant of the maple family, produces clusters of berries containing black seeds. These black seeds are especially rich in caffeine, sometimes reported as high as 3.5 to 7.0 % on a dry weight basis. In comparison, coffee beans are generally 1% to 2.5% caffeine. The purpose for such a high concentration, as far as the plant is concerned, is as a defensive toxin that repels insects. Since the dried seeds can be ground up for readily accessible caffeine, such guarana powder is often the commercial form. This powder can be combined with hot water to give a beverage, or it can be incorporated as a powder into bread or cookie forms. More recently guarana has been combined as a component in herbal medications sold as tablets or in capsules. Soft drinks containing dissolved guarana are also available. In any of these forms guarana provides a ready source of caffeine.
Native people in Brazil often just chewed the seeds which have the appearance of a pair of small eyeballs. Because of that appearance, a legend about the plant and its seed is widespread in Brazil. According to the legend an angry deity of darkness, jealous of a beautiful young boy, transformed himself into a serpent and killed the child. As a recompense to the grieving parents and villagers, the head god told the bereaved mother to plant the boy‚Äö√Ñ√¥s eyes in the ground. From this planting came the guarana bush growing wild and later cultivated. The fruit of this bush, when opened, reveals what resembles two human eyes, two dark spots each on a white background, peering out. A missionary named Betendorf who visited the Amazon regions in 1669 was among the first Europeans to document the use of guarana as a stimulant and performance enhancer. Explorers Humboldt and Bonpland collected plant specimens in the Orinoco area in 1810. A hundred years later a chemical analysis of guarana confirmed the presence of caffeine.
As guarana has become commercialized, the plant is cultivated in Brazil. The product powder and drinks derived from guarana are widely used in Europe and in the United States. Many of these products of both kinds have especially high concentrations of caffeine, making them especially strong for the users. Since the per dose amount of caffeine can be adjusted by the formulator of a drink or an encapsulated powder mix, it is inaccurate to say that guarana is more or less potent than other caffeine sources. The actual caffeine content of the finished product governs the physiological response.