The Health Benefits of Guarana

Guarana (Paullinia cupana) is a plant native to northern Brazil and other regions of the Amazon. Said to fight fatigue, boost mental alertness, and promote weight loss, guarana is often found in popular sodas and energy drinks, such as Red Bull and Monster. A seed paste, syrup, or extract is made from the guarana plant and then added to these drinks. In Brazil, guarana drinks are considered "health tonics" and are almost as popular as traditional cola-based sodas. Guarana is also sold in supplement form.

The fruit contains caffeine-rich seeds that have up to three times the amount of caffeine as coffee beans. The seeds are also rich in tannins and the stimulants theophylline and theobromine.

Health Benefits

Many people who consume beverages containing guarana are devotees, and they may not concern themselves with research that proves how the drinks make them feel. Nevertheless, it's worth digging into what is proven (and not).

Decreased Fatigue

A 2011 study of breast cancer patients undergoing systemic chemotherapy and a 2018 study of patients with chronic kidney disease found that patients taking guarana experienced significantly reduced fatigue compared with those taking a placebo.

The study of breast cancer patients used a 50 milligram (mg) dose twice daily, and the study in patients with chronic kidney disease examined the effects of doses as high as 200 mg and 400 mg, indicating anti-fatigue effects at low and high doses.

Additionally, antioxidant effects of guarana extracts have been observed in pre-clinical trials, according to a review published in 2018. According to one study, oxidative stress shows promise as a potential biomarker for chronic fatigue syndrome.

Improved Cognition

A randomized, double-blind crossover study assessed cognitive performance with a go/no-go task in 56 participants after they had ingested either a multi-vitamin/mineral preparation supplemented with 300 mg guarana, a caffeine supplement, or a placebo supplement. It was found that responses were faster on the go/no-go task, without a change in accuracy, between 30 and 90 minutes after ingesting the guarana.

A significant decrease in heart rate variability was observed during the first hour after taking the caffeine, yet remained stable after taking guarana, suggesting guarana may be able to improve decision-making performance without destabilizing autonomic nervous system regulation during the first hour as much as caffeine does.

Another double-blind, placebo-controlled study of guarana use throughout the day found that guarana improved secondary memory performance, mood, and alertness at low (37.5 mg, 75 mg) and higher (150 mg, 300 mg) doses, with the lower doses being more effective.

While this data is promising for acute uses, a study examining the use of guarana, caffeine, and placebo on the cognition of 45 older individuals found no significant lasting effects of guarana on cognition long-term.

Weight Loss

Guarana supplement manufacturers sometimes claim that guarana is helpful for promoting weight loss, but there is not a lot of clinical research to support this.

It is possible that proponents are relying on data from a 2001 study—a randomized, double-blind, placebo-controlled trial that examined the effects of 240 mg/day of guarana (as a caffeine source) combined with 72 mg/day of ma huang (ephedra), which contains ephedrine alkaloids. Over the eight weeks of treatment, this combination led to a significantly greater loss of weight and fat as well as larger reductions in hip circumference and serum triglyceride levels, as compared with placebo.

It's important to note that these effects cannot be attributed to the guarana alone, and eight of the 35 study participants receiving the guarana-ma huang combination quit the study early as a result of unwanted side effects—insomnia and headache being among the most frequently reported.

An animal study from 2005 examined the effect of 14 days of guarana supplementation on fat metabolism in sedentary and trained rats and found a fat-burning effect attributable to the caffeine content, but more research is needed.

Possible Side Effects

Guarana contains a large amount of caffeine, and the precise amount may not be properly documented on the label. Side effects can include those common to many stimulants:

• Stomach irritation
• Increased heart rate
• Increased blood pressure
• Nervousness/agitation

Industrial processing methods for guarana seeds may increase the presence of polycyclic aromatic hydrocarbons, a group of chemical carcinogens that have also been associated with pulmonary, gastrointestinal, and dermatologic side effects.

Precautions and Contraindications

Guarana products differ in the amount of caffeine they contain. If you are sensitive to caffeine or xanthines or have heart problems, high blood pressure, an overactive thyroid, an anxiety disorder, insomnia, or epilepsy, you should talk with your healthcare provider before taking guarana.

Since many doctors recommend limiting caffeine during pregnancy and breastfeeding, and it isn't possible for consumers to accurately determine how much caffeine they are consuming when using these products, it is best for pregnant and nursing women to avoid them.

Known Interactions

Patients that could be harmed from the stimulating properties of guarana were excluded from at least one clinical trial, as were those taking antidepressants, anxiolytics, or sleeping pills, with which the effects of guarana might interfere.

Combining guarana with other stimulants like yerba mate, diet aids, or performance-enhancing supplements may lead to palpitations, arrhythmias, high blood pressure, seizures, and other adverse effects.

Combining guarana with ma huang 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. 

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 Coumadin (warfarin), and platelet inhibitors such as Ticlid (ticlopidine) and Plavix (clopidogrel).

Guarana should also not be taken with alcohol or monoamine oxidase inhibitors (MAOIs), as combining these with caffeine may cause encephalopathy, neuromuscular irritability, hypotension, or sinus tachycardia, though this has not been well studied in patients taking guarana specifically.

Dosage and Preparation

Typically, guarana supplements are made by preparing an extract from the seeds or grinding the seeds into a powder.

A dose of 70 mg guarana powder is on the lower end for available supplements, but is all you really need to get the benefits, which (for some uses) may actually lessen at higher doses.

What to Look For

The popular energy drinks Full Throttle, Monster, Red Bull, and Rockstar all contain guarana, but are marketed as conventional beverages, not as dietary supplements, and are not the healthiest or most sustainable ways to get the benefits.

The highest degree of quality control for guarana supplements can be found in those made by the Sateré-Mawé people, who continue to harvest the plant through traditional methods. The Sateré-Mawé formulation is called warana and can be identified by a packaging label indicating certification by the International Analog Forestry Network. Note, however, that fewer than two tons of warana are put up for sale per year, and the Sateré-Mawé are not the source of most guarana supplements on the market.

Other Questions

What does guarana mean?

Guarana plays an important role in the mythology of the Sateré-Mawé people of Brazil, for whom the word guaraná translates to "the beginning of all knowledge." The seeds are a foundation of the Sateré-Mawé economy.

Is there a best time of day to drink a guarana supplement?

One manufacturer recommends taking guarana 15 minutes prior to a planned activity in order to receive maximum benefits to focus. There is no absolutely "right" or "wrong" time of day to drink guarana, though you may find it harder to sleep if you drink it within six hours of bedtime.

Are most guarana supplements sustainably harvested and fair trade?

Unfortunately, no. The rising popularity of guarana worldwide and the competitive pressure of commercial growers from abroad has led to the decline of guarana and traditional methods of cultivation.

In 2006, the Consortium of Sateré-Mawé Producers, part of the General Council of the Sateré-Mawé Tribe, their largest body of political representation, began a project to obtain protected status for the guarana plant, called the Presidia, designed to preserve traditional methods of cultivation, harvesting, and consumption. Today, the Slow Food Foundation for Biodiversity recognizes the guarana plant as endangered and the industry as a threat to Mawé biocultural survival.