An herbal supplement containing an extract from guarana (Paullinia cupana), a climbing plant of the Sapindaceae family which is native to the Amazon basin, with stimulant, antioxidant and potential chemoprotective activities. Guarana supplement contains various phytochemicals, including caffeine, theobromine, theophylline, tannins, saponins, catechins, epicatechins, proanthocyanidols and other compounds in minor concentrations. Caffeine is a central nervous system stimulant and may reduce chemotherapy-related fatigue. Tannins and other polyphenols may have chemopreventive activity. Intake of the guarana supplement may prevent cancer-related anorexia. In addition, animal studies have demonstrated that the ingestion of guarana resulted in decreased proliferation and increased apoptosis of tumor cells.