Guaraná plays an important role in Tupi and Guarani culture. According to a myth attributed to the Sateré-Maué tribe, guaraná's domestication originated with a deity killing a beloved village child. 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 guaraná. The god then plucked the right eye from the child and planted it in the village, giving rise to domesticated guarana.
Natural sources of caffeine contain widely varying mixtures of xanthine alkaloids other than caffeine, including the cardiac stimulants theophylline, theobromine and other substances such as polyphenols, which can form insoluble complexes with caffeine. The main natural phenols found in guarana are (+)-catechin and (-)-epicatechin.
The tannins in guarana may relieve diarrhea by preventing water loss. Meanwhile, the caffeine in guarana may relieve constipation by stimulating contractions in your intestines and colon that push contents toward the rectum.
In the same study, scientists performed test-tube experiments to discover if guarana could protect eye cells against compounds that create oxidative stress. Guarana significantly reduced the amount of DNA damage and eye cell death, compared to a placebo (45).
Test-tube studies have found that guarana may combat oxidative stress, which is linked to age-related eye disorders. However, this area of research is limited, so more human-based studies are needed before providing recommendations.
Researchers once believed that the active ingredient of guarana was a chemical specific to the plant -- guaranine. But they later discovered that it was just caffeine. Guarana has among the highest concentrations of caffeine in any plant. It may contain up to 3.6% to 5.8% caffeine by weight. Coffee only has up to 2%.
Coffee and other caffeinated beverages seem to increase alertness when consumed throughout the day. Caffeine can improve mental performance and alertness in sleep-deprived people, and guarana would logically have the same effect.
Guarana is the dried paste made from the crushed seeds of P. cupana or P. sorbilis, a woody perennial shrub native to Brazil and other regions of the Amazon. It bears orange-yellow fruits that contain up to 3 seeds each. The seeds are collected and dry-roasted over fire. The kernels are ground to a paste with cassava and molded into cylindrical sticks, which are then sun-dried. Today, the most common forms of guarana include syrups, extracts, and distillates used as flavorings and a source of caffeine by the soft drink industry. Guarana also is used as an ingredient in herbal weight loss preparations usually in combination with ephedra.
Guarana has played an important role in the Amazonian Indians' society. It often is taken during periods of fasting to improve tolerance of dietary restrictions. In certain regions, the extract is believed to be an aphrodisiac and to protect from malaria and dysentery. In 1840, caffeine was identified as guarana's principal constituent. In the 19th century, guarana became popular as a stimulating drink in France. In 1880 it was introduced as an official drug in the US Pharmacopeia, where it remained listed until 1910. Guarana is used by Brazilian Indians in a stimulating beverage used like tea or coffee. It sometimes is mixed with alcohol to prepare a more intoxicating beverage. The stems, leaves, and roots of guarana are used as a fish-killing drug in Central and South America.
Natural diet aids, which rely on daily doses of guarana, have been advertised in the lay press. Guarana occasionally is combined with glucomannan in natural weight loss tablets. The advertisements indicate that the ingredients in guarana have the same chemical makeup as caffeine and cocaine, but can be used for weight reduction without any of the side effects of these drugs. This is not entirely correct. Guarana does not contain cocaine, and may have serious side effects for some people.
The appetite suppressant effect is related to the caffeine content. The energy that guarana tablets are reported to give also is due to caffeine. This stimulating effect is so widely recognized that 1 guarana product was marketed as \"Zoom.\" Numerous investigational studies have shown the ability of the sympathetic stimulant ephedrine, when coupled with caffeine, to have a synergistic effect on increasing metabolic rates with subsequent increased energy expenditure (thermogenesis), and to have fat reducing (lipolytic) effects. These effects have resulted in a statistically significant weight loss in animal and human trials when combined with diet.
Extension in longevity in people living in Maués, an Amazon region in Brazil, hasbeen associated to Amazonian diet, including habitual intake of guarana (4). Furthermore, an epidemiological studyassociated guarana ingestion with low prevalence of chronic age-related diseases inthe Amazonian population (5). Recently, astudy also demonstrated anti-aging potential of guarana seed extract inCaenorhabditis elegans (6). However, the mechanisms underlying the guarana effects on aging werenot identified.
Oxidative stress appears to be a major factor limiting lifespan in both C.elegans and humans and is associated to many age-related diseases(20,21), which directs attention toward antioxidant compounds with effectsin vivo. To further investigate whether GEE could extendlifespan through an antioxidant activity, its effect on mev-1 wormswas evaluated. This strain is characterized by superoxide overproduction and has ashorter lifespan compared to wild-type strain (22). Consistent with previously described antioxidant effects of guaranaextract (6), GEE treatment significantlyextended mean and maximum lifespan of mev-1 worms.
Methylxanthines, as caffeine, are the main components of guarana and it is well knownthat these compounds can act through adenosine receptors in mammals (29). Caffeine has been associated withbeneficial effects, including aging-related effects (30,31) and improvement ofcognitive impairment phenotypes by antagonizing the adenosine receptorsA1 and A2A in rodents (32). Thus, we tested if the GEE-induced extension of lifespan might alsodepend upon ADOR-1, an adenosine receptor homolog (33). Our results indicated that ador-1(ox489) wormsfailed to show extended lifespan, demonstrating, for the first time, a possible roleof the purinergic system in lifespan extension. Accordingly, purinergic signalingmay be profitably studied in the future as a potential target for longevitymodulation.
The planarian locomotor velocity (pLmV) test was adapted to assess the stimulant properties of guarana [42, 43]. We began by testing a gauntlet of concentrations including 0.001, 0.003, 0.01, 0.03, 0.1, 0.3, 1.0, 3.0 and 10 mM and observing planarian motility after a two-minute incubation period in guarana seed extract (Fig 1A). From the tested concentrations, the most effective stimulation occurred above 0.003 mM, with significant stimulation occurring at 0.01 mM (p = 0.02), 0.1 mM (p = 0.008) and 1.0 mM (p = 0.006). 10 mM guarana seed extract proved inhibitory to planarian motility (Fig 1A) and caused the worms to coil repeatedly during the test. To determine if a longer exposure to guarana would provide an added stimulation, or allow the lower concentrations an opportunity to have an effect, we observed planarian motility after one hour in 0.001, 0.003, 0.01, 0.03 and 0.1 mM guarana seed extract (Fig 1B). As with the two-minute exposure, after one hour there was no significant stimulation of planarian motility at 0.001 and 0.003 mM. We still observed significantly increased activity at 0.01 mM (p = 0.009), but the effect was lost at 0.1 mM.
Shown are selected pLmV data relative to water-only controls for Dugesia tigrina exposed to varying concentrations of guarana extract. Planarians were habituated in their respective conditions for either 2 minutes (a) or 1 hour (b) before their pLmV activity was monitored. Planarian motility was monitored after the worms were placed in a Petri dish containing the appropriate concentration of guarana seed extract following the tested habituation period. The Petri dishes were placed over graph paper and the number of grid-lines crossed was monitored for three minutes. The white bar represents the normalized control pLmV, while the black bars indicate relative to control test pLmV values. Error bars indicate the standard deviation, while a * indicates a p-value of less than 0.05 relative to the water-only control.
Due to the fact that our results indicated that guarana does provide for significantly greater stimulation of planarian motility, we went on to test the effect of purified caffeine on pLmV. Since other investigators determined that caffeine does not provide a significant stimulation of planarian motility we aimed to use the system to assess whether guarana provides an added stimulus over caffeine alone [47, 50]. It was necessary, however, to determine if our system and choice of planarian species offered a comparable backdrop to these published reports. Again, we began by testing the planarian motility using a range of caffeine concentrations (0.001, 0.003, 0.01, 0.03, 0.1, 0.3, 1.0, 3.0 and 10 mM) after a two-minute period of exposure (Fig 2A). Although planarian motility was slightly elevated at concentrations between 0.003 mM and 3.0 mM, we did not observe any significant increase in overall planarian activity compared to the water only controls. However, because the calculated p-value for the pLmV using 0.001 mM caffeine was 0.05, suggesting a borderline significance, we tested if even lower concentrations of caffeine would produce a significant peak of activity. To this end, we examined the effect of both 0.0001 and 0.0003 mM caffeine, but still did not obser