Guarana

Scientific Name(s): Paullinia cupana Kunth var. sorbilis (L.)
Common Name(s): Brazilian cocoa, Guarana, Guarana gum, Guarana paste, Zoom

Medically reviewed by Drugs.com. Last updated on Nov 30, 2022.

Clinical Overview

Use

Guarana has traditionally been used as a natural energizer and cognitive stimulant, as flavoring in beverages, and as a component in natural weight loss products; however, clinical data do not support use as a natural energizer or weight loss aid. Limited clinical trials have been conducted with guarana alone, with some evidence for use in chemotherapy-related fatigue.

Dosing

Doses ranging from 75 mg to 1,000 mg daily were administered in limited clinical trials.

Contraindications

Guarana is contraindicated in pregnancy and lactation.

Pregnancy/Lactation

Use is contraindicated. Low birthweight, birth defects, and premature birth have been documented with guarana use.

Interactions

Caffeine, a principal constituent of guarana, is unsafe as a food additive when combined with alcohol (ie, alcoholic beverages with added caffeine).

Adverse Reactions

Excessive nervousness, insomnia, and other health risks in patients sensitive to caffeine have been reported.

Toxicology

Research reveals little or no information regarding severe toxicity with the use of guarana. Because of its high tannin content, excessive use may lead to an increased risk of cancer of the oropharynx.

Scientific Family

• Sapindaceae (Soapberry)

Botany

P. cupana or Paullinia sorbilis are fast-growing, woody, perennial shrubs native to Brazil and other regions of the Amazon. The trees have large leaves and clusters of flowers that bear orange-yellow fruits containing up to 3 seeds each, similar in size to a coffee bean. Guarana is the dried paste made from the crushed seeds of P. cupana.Duke 2002, FDA 2010

History

Historically, guarana seeds were collected and dry roasted over fire; the kernels were then ground to a paste with cassava and molded into cylindrical sticks, which were then sun dried. Guarana has been traditionally used in South America and by Amazonian Indians to increase awareness and energy. In certain regions, the extract is believed to be an aphrodisiac and protectant against malaria and dysentery. In 19th century France, guarana became popular as an ingredient in beverages, due to its stimulant properties. In 1880, guarana was introduced as an official drug in the United States Pharmacopeia, where it remained listed until 1910. Natural diet aids containing daily doses of guarana (occasionally combined with glucomannan) have been advertised in the lay press. Guarana has also been used during periods of fasting to suppress appetite. Today, the most common forms of guarana include syrups, extracts, and distillates used for flavoring and as sources of caffeine by the soft drink industry. Indian tribes in Brazil use guarana for its stimulant properties in beverages such as tea or coffee; it is sometimes mixed with alcohol to make a more intoxicating beverage.Henman 1982, Higgins 2010, Lewis 1977, Schimpl 2013, Steinmetz 1965

Chemistry

In 1840, caffeine was identified as guarana's principal constituent, with levels ranging from 3% to greater than 5% by dry weight.Schimpl 2013 By comparison, coffee beans contain approximately 1% to 2% of caffeine and the content in dried tea leaves varies from 1% to 4%.Burke 2011 The related alkaloids theophylline and theobromine have also been identified in guarana. Guarana is high in tannins (primarily catechutannic acid and catechol), which are present in concentrations of 5% to 6% dry weight; these impart an astringent taste.Burke 2011

Trace amounts of a saponin known as timbonine, related to compounds reported in timbo fish poisons used by Amazonian Indians, have been reported.Henman 1982

Uses and Pharmacology

Limited clinical trials have been conducted using guarana alone.(Haskell 2013, Schimpl 2013)

Cognitive stimulant/CNS effects

Animal data

One study examined behavioral effects in rats and mice after acute and chronic guarana administration. Animals treated with guarana doses of 2,000 mg/kg showed no difference when compared with control groups in motor activity, tremor, or salivation parameters.(Mattei 1998) Another study showed an increase in physical capacity when mice were subjected to a stressful situation, such as forced swimming, after 3 to 6 months of guarana treatment.(Espinola 1997)

Clinical data

In a small study, 3 groups of healthy volunteers 20 to 35 years of age were given placebo, caffeine 25 mg, or 1,000 mg of guarana containing 2.1% caffeine (21 mg) daily. After 4 days, no reproducible improvement in cognition was noted in any group according to neuropsychological testing, assessment of sleep quality, and a State-Trait Anxiety Inventory.(Galduróz 1994) In another small study, the effects of long-term guarana administration on the cognition of healthy, elderly volunteers was assessed. Guarana did not result in statistically significant memory improvement.(Galduróz 1996)

In an Italian randomized, single-blind, crossover trial of 27 healthy volunteers, guarana 350 mg (2.5% caffeine) 3 times daily for 5 days did not produce any effects on psychological well-being, anxiety, or mood compared with placebo. However, a subpopulation of female participants reported an increase in self-acceptance scores.(Silvestrini 2013)

A group of researchers in Brazil evaluated the effect of guarana on chemotherapy-related fatigue, and reported favorable outcomes for guarana 37.5 mg to 75 mg orally twice daily.(da Costa 2009, de Oliveira 2011, del Giglio 2013, Palma 2016) In 2018, the American Society of Clinical Oncology (ASCO) endorsed the Society for Integrative Oncology's (SIO) evidence-based guideline for the use of integrative therapies after breast cancer treatment, stating that guarana should not be recommended for improving fatigue during treatment (grade D).(Greenlee 2017, Lyman 2018)

Other uses

Some researchers suggest that the revitalizing effects of guarana result partly from its antioxidant action.(Mattei 1998)

Guarana's potential appetite suppressant and energy-inducing effects are likely related to its caffeine content. Numerous investigational studies have shown the sympathetic stimulant ephedrine, when combined with caffeine, demonstrates a synergistic effect on increasing metabolic rates, with subsequent increased energy expenditure (thermogenesis), as well as lipolytic actions.(Breum 1994) These effects resulted in statistically significant weight loss when guarana was combined with diet in short-term animal and clinical trials. However, a review reports a lack of unequivocal benefits of guarana over water or sports drinks.(Higgins 2010)

A study in rats with diet-induced hypercholesterolemia demonstrated reductions from baseline levels in total cholesterol and low-density lipoprotein cholesterol with guarana doses of 12.5, 25, or 50 mg/day for 4 weeks.(Ruchel 2016)

The effects of a guarana extract (12.24 mg/g of caffeine) on 7 chemotherapeutic drugs used in the treatment of breast cancer were tested in vitro in a breast cancer cell line. Cell proliferation decreased about 20% to 25% with the extract alone, but guarana extract plus cyclophosphamide resulted in an 80% decrease in cancer cell population compared to the control group after 72 hours. Guarana added to the other 6 agents resulted in decreases in cell proliferation of 40% to 50%.(Hertz 2015)

Dosing

Doses ranging from 75 mg to 1,000 mg daily have been used in limited clinical trials evaluating stimulant effects.Haskell 2013

A group of researchers in Brazil evaluated the effect of guarana on chemotherapy-related fatigue and reported favorable outcomes with doses of 37.5 mg to 75 mg orally twice daily.da Costa 2009, de Oliveira 2011, del Giglio 2013, Palma 2016

Pregnancy / Lactation

Use is contraindicated. Low birthweight, birth defects, and premature birth have been documented with guarana use.Ernst 2002

Interactions

The Food and Drug Administration (FDA) has ruled that caffeine is unsafe as a food additive when combined with alcohol (ie, alcoholic beverages with added caffeine).FDA 2010, Marczinski 2014 In vitro, guarana extract inhibited aggregation of platelets, possibly due to inhibition of platelet thromboxane synthesis.Bydlowski 1991

Based on the caffeine content of guarana, interactions with clozapine, lithium, anxiolytic agents, pseudoephedrine, and antihypertensive agents are theoretically possible.Woods 2012

Adverse Reactions

Individuals sensitive to caffeine, including those taking herbal weight loss preparations, should use guarana with caution. Guarana use has led to excessive nervousness and insomnia.

Toxicology

Case reports of dysrhythmias and seizures related to overconsumption of energy drinks exist in the literature;Higgins 2010, Iyadurai 2007, Seifert 2013 however, most cases of toxicity in adults appear to be mild and clinically benign. Accidental overdose in children may be more serious.Lüde 2016, Seifert 2013 Pure caffeine/guaranine is potentially fatal at a dose of 10 g.Burke 2011

Because of its high tannin content, excessive use of guarana may lead to an increased risk of cancer of the oropharynx.Brinker 1998

Index Terms

• Paullinia sorbilis

References

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