Guarana and physical performance: A myth or reality?

Guarana (Paullinia cupana) is a rainforest vine that was domesticated in the Amazon for its caffeine-rich fruits. Each fruit contains from one to three seeds which, properly dried, give rise to a brown paste with a bitter taste. The Food and Drug Administration generally recognizes guarana as safe, although there are no established dosages and it is unclear how much guarana is in each drink, because many companies do not list a milligram amount. The increasing number of energy drink with caffeine-related clearly shows that there seems to be a real risk for adverse health effects such as arrhythmias. However, under moderate use and without combining other stimulants or alcohol, the risk for such side effects seem negligible. Anyway, there is an overwhelming lack of evidence to substantiate claims that guarana contribute to the enhancement of physical or cognitive performance. Additional well-designed, randomized, placebo-controlled studies are needed in order to assess claims made for this product and further elucidate potential adverse effects.