Guarana (Paullinia cupana) is a creeping shrub native to the Amazon basin. It is prized for its bright red-orange berries, which possess numerous benefits. Guarana is commonly found in beverages, weight loss supplements, herbal tea and as extract, capsules or powder.

The most popular use for guarana is as an energy booster, since it's one of the few plants other than coffee that possesses caffeine. However, guarana contains twice as much caffeine as coffee as well as its own unique stimulant compounds. This has lead to its widespread usage in energy drinks and herbal energy pills, which appeal to people with a lot to do and not much time to do it in. Some research has also shown that guarana can enhance physical endurance, and some athletes use it regularly for this purpose.

Less well-known is guarana's benefit as an antioxidant supplement. It contains theobromine, a substance also found in cacao that may help improve mood. Another compound, theophylline, functions as a bronchodilator, fights inflammation, improves blood circulation and helps enhance cardiac efficiency. Furthermore, guarana contains catechin and epicatechin, two potent polyphenols that are commonly associated with green tea. There is also evidence suggesting that regular consumption of these polyphenols may help reduce the risk of many types of cancer.