What is guarana?

Other Names: Paullinia cupana, Brazilian cocoa

Guarana (pronounced gwa-ra-NAH) is a creeping shrub native to Venezuela and northern Brazil in the Amazon rain forest. The fruit are small, bright-red, and contains black seeds.

Guarana seeds are rich in caffeine and contain up to 4-8% caffeine, more than coffee beans, which contain approximately 1–2.5% caffeine. The seeds are also rich in tannins and xanthine alkaloids theophylline and theobromine.

Why do people use guarana?
Guaraná is reputed to be a stimulant and increase mental alertness, fight fatigue, and increase stamina and physical endurance.

Guarana drinks and sodas are very popular in Brazil (where guarana is considered to be a health tonic), almost as popular as cola-based sodas. Sweet, carbonated guarana drinks include the popular brands Guaraná Antarctica, Guaraná Brahma, and Kuat (from Coca-Cola Company).

In North America, guarana has recently become a popular ingredient in energy drinks and teas.

Guarana is one of the richest sources of caffeine, containing up to three times the amount of caffeine as coffee. Unlike coffee, the amount of caffeine doesn't have to be listed on guarana drinks.

In addition to its stimulant properties, guarana is also a popular ingredient in herbal weight loss pills. Some evidence indicates that guarana may suppress appetite and increase fat-burning.

What research has been done on guarana?

An animal study examined the effect of 14 days of guarana supplementation on fat metabolism in sedentary and trained rats and found that the guarana's fat-burning effect is due to the caffeine content. Decaffeinated guarana extracts had no effect on lipid metabolism.

A Journal of Psychopharmacology study found that guarana improved memory, mood and alertness at low (37.5 mg, 75 mg) vs. higher (150 mg, 300 mg) doses. However, another study examined the long-term use of guarana, caffeine, or placebo on the cognition of 45 older individuals. There were no significant effects of guarana on cognition.

Safety
Guarana should not be used by people who are sensitive to caffeine or xanthines.

People with heart conditions, diabetes, high blood pressure, epilepsy, overactive thyroid, anxiety, insomnia, and kidney disease should only use guarana under the supervision of their doctor.

The safety of guarana in pregnant or nursing women has not been established. Since many doctors recommend limiting caffeine during pregnancy and nursing, guarana should be avoided because caffeine content differs from product to product and it isn't possible for consumers to accurately estimate how much caffeine they are consuming through guarana.

Guarana should not be taken with any products containing ephedra. Serious adverse effects have been reported with this combination. It may increase the risk of stroke, hemorrhage, myocardial infarction, and sudden death and has been associated with increases in heart rate, blood pressure, and potentially harmful changes in glucose and potassium levels.

A report published in the Journal of Herbal Pharmacotherapy described the case of a heart rhythm abnormality called premature ventricular contraction associated with two herbal supplements that both contained large doses of guarana.

Initial symptoms of guarana overdose include difficulty urinating, vomiting, and abdominal cramps and spasms. If you suspect a guarana overdose, seek medical attention immediately.

Common Forms
Guarana can be found in powder or pill form. It is an ingredient in energy drinks, sodas, and other beverages.

Drug interaction
Guarana has been found to decrease platelet aggregation and thromboxane synthesis, so it may increase the risk of bleeding when taken with aspirin, anticoagulants such as Warfarin (Coumadin®), and platelet inhibitors such as Ticlopidine (Ticlid®), Clopidogrel (Plavix®).

Guarana should not be combined with MAO-inhibitors, and may cause headaches.Sources

Baghkhani L and Jafari M. "Cardiovascular adverse reactions associated with Guarana: is there a causal effect?" Journal of Herbal Pharmacotherapy. 2.1 (2002):57-61.

Bydlowski SP et al. "A novel property of an aqueous guarana extract (Paullinia cupana): inhibition of platelet aggregation in vitro and in vivo." Brazilian Journal of Medical and Biological Research. 21.3 (1988):535-8.

Galduroz JC and Carlini EA. "The effects of long-term administration of guarana on the cognition of normal, elderly volunteers." Sao Paulo Medical Journal. 114.1 (1996):1073-8.

Lima WP et al. "Lipid metabolism in trained rats: effect of guarana (Paullinia cupana Mart.) supplementation." Clinical Nutrition. 24.6 (2005):1019-28.

Haskell CF et al. "A double-blind, placebo-controlled, multi-dose evaluation of the acute behavioural effects of guarana in humans." Journal of Psychopharmacology. 2006 Mar 13.

Nyska A et al. "Acute hemorrhagic myocardial necrosis and sudden death of rats exposed to a combination of ephedrine and caffeine." Toxicological Sciences. 83.2 (2005):388-96.