Guarana is a woody, evergreen perennial vine native to the Amazon basin of Uruguay and northern Brazil. Reaching up to 10 meters in length, guarana has large palmate leaves, which are distinctly ribbed and have scalloped or serrated edges. The plant flowers in clusters of short-stalked, yellow to white blossoms, which eventually produce orange-red, grape-sized fruit. The fruit is divided into three sections, each containing one dark purple to black seed. The seed is roasted and ground into a paste, which is rolled into cylindrical pieces and dried. The resulting sticks are used to make a stimulant drink.
Native tribes of the Amazon rain forest used crushed guarana seeds as a stimulant beverage.
Guarana contains a high concentration of caffeine (about three times as much as found in coffee). It also contains high levels of tannins and various saponins.
Modern use of guarana centers on its high caffeine content, which has made it popular for promoting mental and physical endurance. Natives of Brazil and Uruguay use guarana sticks to make a hot beverage much like coffee. Guarana seeds are also used as an ingredient in carbonated soft drinks. Some studies suggest that guarana may promote cardiovascular health by inhibiting the oxidation of LDL (the "bad' cholesterol) and by reducing the tendency of blood platelets to clump together.
Guarana is consumed liberally as a stimulant drink, and animal studies indicate that it has very low toxicity. Due to its high caffeine content, caution is advised for persons with sensitive cardiovascular systems, renal diseases, hyperthyroidism, or psychological disorders such as panic/anxiety attacks. As with other caffeine-containing beverages, excessive consumption should also be avoided by pregnant women or nursing mothers.