Guarana

As with other plants producing caffeine, the high concentration of caffeine is a defensive toxin that repels pathogens from the berry and its seeds.

The guarana fruit's colour ranges from brown to red and contains black seeds which are partly covered by white arils. The colour contrast when the fruit has been split open has been likened to eyeballs; this has formed the basis of a myth.

The word guarana comes from the Portuguese guaraná, which has its origins in the Sateré-Maué word for the plant, warana.

Guarana plays an important role in Tupi and Guaraní Brazilian culture. According to a myth attributed to the Sateré-Maué tribe, guarana's domestication originated with a deity killing a beloved village child. In order to console the villagers, a more benevolent god plucked the left eye from the child and planted it in the forest, resulting in the wild variety of guarana. The god then plucked the right eye from the child and planted it in the village, giving rise to domesticated guarana.

The Guaranís would make a tea by shelling, washing and drying the seeds, followed by pounding them into a fine powder. The powder is kneaded into a dough and then shaped into cylinders. This product is known as guarana bread or Brazilia coke, which would be grated and then immersed into hot water along with sugar.

This plant was introduced to European Colonizers and Europe in the 17th century by Father Felip Betendorf. By 1958, guarana was commercialized.

The table to the right contains a partial listing of some of the chemicals found in guarana seeds, although other parts of the plant may contain them as well in varying quantities.

According to the Biological Magnetic Resonance Data Bank, guaranine is defined as only the caffeine chemical in guarana, it is identical to the caffeine chemical derived from other sources, for example coffee, tea, and maté. Guaranine, theine, and mateine are all synonyms for caffeine when the definitions of those words include none of the properties and chemicals of their host plants except the chemical caffeine. Natural sources of caffeine contain widely varying mixtures of xanthine alkaloids other than caffeine, including the cardiac stimulants theophylline and theobromine and other substances such as polyphenols which can form insoluble complexes with caffeine. The main polyphenols found in guarana are (+)-catechin and (-)-epicatechin.

Guarana is used in sweetened or carbonated soft drinks and energy shots, an ingredient of herbal tea or contained in capsules. Generally, South America obtains most of its caffeine from guarana.

Brazil, which is the third-largest consumer of soft drinks in the world, produces several soft drink brands from guarana extract. The Portuguese word "Guaraná" is widely used in Brazil as a synonym of "soda". Exceeding Brazilian sales of cola drinks, guarana-containing beverages may cause jitters associated with drinking coffee.

In Peru, Guaraná is a Peruvian brand of soft drink owned by Backus and Johnston and sold in Peru. Guaraná is a soft-drink containing guarana fruit and is sold in PET bottles of 500 ml. In 2007 the drink had 5% of the Peruvian soft drinks market, and was relaunched with a new bottle and label and a light version. A year later its sales had increased by 49%.

As guarana is rich in caffeine, it is of interest for its potential effects on cognition. In rats, guarana increased memory retention and physical endurance when compared with a placebo.

A 2007 human pilot study assessed acute behavioral effects to four doses (37.5 mg, 75 mg, 150 mg and 300 mg) of guarana extract. Memory, alertness and mood were increased by the two lower doses, confirming previous results of cognitive improvement following 75 mg guarana.

In the United States, guarana has the status of possibly being generally recognized as safe (GRAS).

Preliminary research has shown guarana may affect how quickly the body perceives itself to be full. One study showed an average 11.2 pound (5.1 kilogram) weight loss in a group taking a mixture of yerba mate, guarana, and damiana, compared to an average one pound loss in a placebo group after 45 days. 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.

Guarana extract reduced aggregation of rabbit platelets by up to 37 percent below control values and decreased platelet thromboxane formation from arachidonic acid by 78 percent below control values. It is not known if such platelet action has any effect on the risk of heart attack or ischemic stroke.

Other laboratory studies showed antioxidant and antibacterial effects, and also fat cell reduction in mice (when combined with conjugated linoleic acid) from chronic intake of guarana.

From anecdotal evidence of excessive consumption of energy drinks, guarana may contribute (alone or in combination with caffeine and taurine) to onset of seizures in some people.