Like tea, coffee, and chocolate, Guarana contains alkaloids in the caffeine family, such as theobromine and theophylline.

Caffeine is known to reduce pain, treat headaches, and fight fatigue. In addition, it may, under certain circumstances, increase stamina and physical endurance, improve mental alertness, and modestly aid weight loss. 

As a stimulant, Guarana acts on the central nervous system to prevent fatigue and break down lactic acid from muscle stress.

Guarana is reputed to discourage blood clots, stimulate the urinary system, and promote production of digestive juices. It is said to be a high energy source that slows the pulse, decreases the appetite, fights fatigue, and acts as an excellent mood elevator.  Guarana has been used to treat diarrhea, decrease fatigue, reduce hunger, and to help arthritis. It has also been used as a nervine tonic for hangovers, neuralgia and menstrual headaches, leucorrhea, diarrhea, and fevers.

Guarana drinks and sodas are very popular in Brazil where Guarana is considered to be a health tonic.  It is almost as popular as cola-based sodas.

RESEARCH STUDIES

Antibacterial and antioxidant activities of ethanol extract from Paullinia cupana Mart
J Ethnopharmacol. 2005 Oct 31

COGNITION
Chemically equivalent to caffeine, Guarana is of interest for its potential effects on cognition.

In a study conducted in 1997, Guarana increased memory retention and physical endurance in rats when compared with a placebo.

Pharmacological activity of Guarana (Paullinia cupana Mart.) in laboratory animals
J Ethnopharmacol. 1997 Feb.

In a double-blind, counterbalanced, placebo-controlled 2004 study, the cognitive and mood effects of separate single doses Guarana, ginseng and their combination were assessed.  All three treatments resulted in improved task performance.   Interestingly, the study indicated that the effects were unlikely to be a result of Guarana’s caffeine content.

Improved cognitive performance in human volunteers following administration of Guarana (Paullinia cupana) extract: comparison and interaction with Panax ginseng
Pharmacol Biochem Behav. 2004 Nov

A 2007 human pilot study looked at “dose-related” behavioral effects of Guarana extract. According to their findings, “Guaraná improved secondary memory performance and increased alert and content mood ratings. The two lower doses produced more positive cognitive effects than the higher doses.”  Which also suggests that the result are not attributable to the caffeine.

A double-blind, placebo-controlled, multi-dose evaluation of the acute behavioral effects of guaraná in humans
J Psychopharmacol. 2007 Jan

WEIGHT LOSS
In addition to its stimulant properties, Guarana is also a popular ingredient in herbal weight loss pills. Preliminary research indicates that Guarana may suppress appetite and increase fat-burning.

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.

Lipid metabolism in trained rats: effect of Guarana (Paullinia cupana Mart.) supplementation
Clinical Nutrition, 2005

One study on overweight patients showed an average 11.2 pound weight loss in a group taking a mixture of yerba mate, Guarana, and damiana, compared to an average 1 pound loss in a placebo group after 45 days.

Weight loss and delayed gastric emptying following a South American herbal preparation in overweight patients
Hum Nutr Diet. 2001 Jun

Although inconclusive about specific effects due only to Guarana, this study differs from another showing no effect on body weight of a formula containing Guarana.

Metabolic and physiological effects of ingesting extracts of bitter orange, green tea and Guarana at rest and during treadmill walking in overweight males
Int J Obes (Lond). 2006 May

CONCLUSIONS
The results from these preliminary studies are promising, but far from conclusive. However, with it's rising popularity, Guarana is sure to be a focus of intense research and product development for years to come.

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