Evidence Based
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5 Health Benefits of Guarana + Side Effects

Written by Carlos Tello, PhD (Molecular Biology) | Last updated:
Jonathan Ritter
Puya Yazdi
Medically reviewed by
Jonathan Ritter, PharmD, PhD (Pharmacology), Puya Yazdi, MD | Written by Carlos Tello, PhD (Molecular Biology) | Last updated:

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Guarana
Guarana (Paullinia cupana) is a plant that hails from the Amazon. Its many claimed benefits include stimulant, weight loss, and cognitive-enhancement effects. Because of the complexity of its constituents, it may work in many different ways. Read on to learn how guarana may benefit you, along with its potential side effects.

What Is Guarana?

Guarana (Paullinia cupana) is a species of climbing plant native to the Amazon regions and known for its stimulant and medicinal properties. It has been used for centuries by indigenous people of the Amazon for its diuretic properties, therapeutic effects against headaches, fever, and cramps, and aphrodisiac effects [1].

With a taste that is described as slightly bitter, astringent, and acidic, guarana powder dissolved in water is considered by indigenous peoples as an elixir that promotes long life [1].

The seeds of guarana contain approximately 4 times the amount of caffeine of a coffee bean. Other guarana components, such as saponins and tannins, provide extra stimulant effects [2, 3].

Guarana is still primarily produced in the Brazilian states of Amazonas and Bahia. Approximately 70% of the production is used by soft and energy drink industries, while the other 30% is made into guarana powder for direct consumption or dilution in water, or used as raw material for pharmaceutical and cosmetic industries [1].

Components

Guarana seeds contain high amounts of methylxanthines and tannins, as well as saponins, starches, polysaccharides, pigments, fats, and choline. Methylxanthines, including caffeine, theophylline, and theobromine, are found in the berries and seeds of the plant. Guarana also contains flavonoid and purine alkaloids [4, 5].

Other phenolic compounds found in guarana seeds include epicatechin, catechin, and ent-epicatechin [5].

Mechanisms

Guarana’s caffeine and catechins prevent the arteries from hardening (atherosclerosis) by reducing oxidative damage and lowering LDL, the “bad” cholesterol [6].

Caffeine and flavonoids (catechin or epicatechin), in the presence of potassium, act as mutagens and cause the death of harmful bacteria (E. coli, S. mutans, and Salmonella) by damaging their DNA [7].

Snapshot

Proponents

  • May improve cognitive performance
  • May boost energy and reduce fatigue
  • May help lose weight
  • May improve skin health and appearance
  • Associated with reduced risk of heart disease

Skeptics

  • Insufficient evidence for all potential benefits
  • Often investigated in combination with other herbs, vitamins, and minerals, making its effects difficult to estimate
  • High caffeine content, possibly causing its adverse effects

Health Benefits

Insufficient Evidence for:

1) Cognitive Performance

In a 6-day trial on 26 people, guarana improved secondary memory performance and increased alertness and mood. These changes could not be attributed to caffeine alone [3].

In another trial on 28 healthy volunteers, guarana improved performance in attention (although it reduced accuracy), sentence verification, and serial subtraction tasks. Its combination with ginseng also increased the speed of attention and memory tasks [8].

In 3 trials of 169 people, those who consumed multivitamins with guarana had an increased benefit of mood and cognitive performance and reduced mental fatigue compared to those who consumed the vitamins alone. Another multivitamin supplement with guarana improved decision making in a trial on 56 people [9, 10, 11, 12].

Consuming a similar multivitamin and multimineral complex with guarana before physical exercise reduced fatigue perception and improved memory after the exercise in a clinical trial on 40 active men. Similarly, a mouth rinsing with guarana, caffeine, and carbohydrates reduced fatigue perception and improved cognitive control and physical exercise performance in a clinical trial on 24 people [13, 14].

Guarana’s effect on mental health and performance may be attributable to a relatively high content of saponins and tannins that may work along with caffeine [3].

All in all, several studies suggest that guarana may improve cognitive performance. However, most of them were either too small or used guarana in combination with multivitamin and multimineral complexes, making guarana’s contribution difficult to estimate. Larger, more robust trials testing guarana alone are needed to confirm its effects on cognitive function.

2) Boosting Energy and Reducing Fatigue

Guarana, along with taurine and sugar, is often included in high-energy drinks for its potential energy-boosting effects and high levels of caffeine, which may result in improved physical performance [5].

Guarana has been used as a stimulant for centuries by indigenous people of the Amazon. Consuming a multivitamin and multimineral complex with guarana before physical exercise reduced fatigue perception in a clinical trial on 40 active men. Similarly, a mouth rinsing with guarana, caffeine, and carbohydrates reduced fatigue perception and improved physical performance in a clinical trial on 24 people [13, 14].

Mice that ingested low (0.3 mg/mL) but not high (3.0 mg/L) of guarana had increased physical ability when subjected to forced swimming. Caffeine alone (0.1 mg/mL) was ineffective, suggesting that guarana’s benefits are not due solely to caffeine [15].

In 2 clinical trials on 83 people with different cancer types receiving chemotherapy, guarana extract improved fatigue while maintaining the quality of sleep and mood [16, 17].

However, the extract was ineffective in another trial of over 100 people on chemotherapy. The authors of the study proposed that the lack of effects observed was due to the unexpectedly high anti-fatigue activity of the placebo used [18].

Guarana may be ineffective for the fatigue and depression caused by radiotherapy, as seen in a clinical trial on 36 women treated for breast cancer [19].

Again, the evidence is insufficient to back the traditional use of guarana to boost energy. The trials evaluating physical performance were small and tested guarana in combination with other extracts, vitamins, and minerals. Those on fatigue caused by anticancer therapy were also small and had mixed results. More clinical trials are needed to shed some light on the anti-fatigue and energy-boosting effects of guarana.

3) Weight Loss

Guarana is classified as a metabolic stimulant, which means it may help burn more calories throughout the day because of its high caffeine content [5].

Overall, it may increase fat metabolism, enhance weight loss, and increase the amount of energy used for basic metabolic functions, such as breathing and digestion [20].

In an 8-week clinical trial on 67 people, an herbal supplement containing Ma Huang and guarana resulted in significantly reduced weight and hip circumference [21].

In another clinical trial on over 100 people, supplement 1 (with guarana, asparagus, green and black tea, mate, and kidney beans) combined with supplement 2 (with kidney bean pods, Garcinia cambogia, and chromium yeast) and taken for 12 weeks reduced body fat [22].

In 2 clinical trials on over 100 normal to slightly overweight people, a commercial herbal extract with guarana, yerba mate, and damiana delayed stomach emptying, which reduced hunger and calorie intake [23, 24].

A multi-ingredient fat-loss product with guarana, green tea, yerba mate, caffeine, saw palmetto, Fo-Ti, eleuthero root, cayenne pepper, and yohimbine improved fat burning from exercise, reduced the perception of fatigue, and increased satiety in a small trial on 12 people [25].

However, a commercial formula with guarana, green tea, and bitter orange had no effect on the metabolic rate in a small trial on 20 people [26].

In addition to burning fat, guarana may prevent the generation of fat altogether by decreasing the production of proteins that contribute to the fat generation and increasing the production of those that prevent it, as seen in a cell-based study [27].

Although several trials have been carried out, they all tested guarana as part of multi-herbal formulations. The evidence to support the use of guarana for weight loss is thus insufficient until more clinical trials using it alone are conducted.

4) Skin Health and Appearance

Guarana is often used in products for cellulitis, based on its high content of caffeine and alkaloids. Many anti-aging creams, cleansing lotions and soaps, shampoos, and conditioners also use guarana as an active ingredient [5].

In a clinical trial on 43 men, a topical formula with guarana, creatine, and glycerol applied for 6 weeks improved skin health. It increased collagen production and reduced cheek sagging, crow’s feet wrinkles, and under-eye wrinkles [28].

Seed extracts of guarana possess strong antimicrobial and antioxidant properties, possibly conferring additional benefits for their use as additives in cosmetics [5].

A single clinical trial cannot attest to the effectiveness of topical guarana to improve skin health and appearance. Its preliminary results should be replicated in more trials on larger populations.

5) Preventing Heart Disease

In an observational study on over 600 elderly people, the regular intake of guarana was associated with a reduced incidence of high blood pressure, obesity, and metabolic syndrome. In women, it was also associated with lower cholesterol (total and LDL cholesterol) levels [20].

In another study on 42 healthy elderly patients, regular guarana intake was associated with reduced LDL oxidation, suggesting it may help prevent artery clogging (atherosclerosis) [29].

However, both studies dealt with associations only, which means that a cause-and-effect relationship hasn’t been established. Just because guarana intake has been linked with a reduced incidence of heart disease doesn’t mean that it helps prevent this condition. Other environmental and genetic factors may have contributed to the effects observed.

Animal and Cell Research (Lack of Evidence)

No clinical evidence supports the use of guarana for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies should not be interpreted as supportive of any health benefit.

Antioxidant

The extract of guarana seeds has free radical-scavenging effects, possibly due to the high concentration of tannins in the seeds [5].

Guarana protected against cadmium-induced free radical damage by reducing morphological changes in Leydig cells (critical to the male reproductive system) and inflammatory responses in rats exposed to this metal. This promoted sperm and testosterone production [5, 30].

Antibacterial

Guarana extract killed E. coli in test tubes. Although E. coli bacteria are a normal component of the gut microbiota, certain strains can grow rapidly in inflammatory environments and produce alpha-hemolysin, a toxin that may cause inflammation, bleeding, and “leaky gut” [7, 31].

Guarana extract also killed Streptococcus mutans, a bacterium associated with cavities, caries, and gingivitis [32, 33, 34].

Guarana induced harmful mutations in Salmonella typhimurium, a microbe that causes food poisoning with typhoid-like symptoms [7].

Note, however, that these are very preliminary results that haven’t been replicated in humans and even in animals. Further clinical research is needed to determine if guarana may be of any use in treating or preventing infections caused by these microorganisms.

Cancer

Below, we will discuss some preliminary research on guarana’s potential anticancer effects. It’s still in the animal and cell stage and further clinical studies have yet to determine if its extract may be useful in cancer therapies.

Do not under any circumstances attempt to replace conventional cancer therapies with guarana or any other supplements. If you want to use it as a supportive measure, talk to your doctor to avoid any unexpected interactions.

Guarana contains several compounds with potential anti-cancer effects (catechin, epicatechin, ent-epicatechin, and procyanidins B1, B2, B3, B4, A2, and C1) [35].

In mice, guarana inhibited, delayed, or reversed the development, growth, and spreading of tumors, as well as increasing cancer cell death [35, 36].

Guarana delayed the growth and reduced the survival of colon and breast cancer cells [37, 38].

Limitations and Caveats

There are very few human trials available. Additionally, guarana was often used in combination with other herbal extracts or multivitamin and multimineral complexes. More clinical research testing guarana alone is needed to confirm their preliminary results.

Little is known about the other constituents of guarana because its effects are often attributed solely to caffeine. It is difficult to assess to what degree these constituents contribute to the full effects of guarana.

Herbal extracts have complex dose-effect relationships on behavior and physiology, and it is possible that artificially higher doses of caffeine are masking the effects of the other active ingredients. In an untampered formula, guarana’s constituents may act more synergistically [3].

Although guarana has been marketed as an aphrodisiac by soda manufacturers to help launch guarana drinks in industrial nations, no clinical research on this effect has been conducted. Unless combined with other active ingredients, its effects as an aphrodisiac are probably negligible [39].

Side Effects

Keep in mind that the safety profile of guarana is relatively unknown, given the lack of well-designed clinical studies. The list of side effects below is not a definite one and you should consult your doctor about other potential side effects based on your health condition and possible drug or supplement interactions.

Most cited negative effects of guarana are a direct result of the use of energy drinks with guarana extract. Consumers experienced negative symptoms similar to caffeine overdose or those associated with sugar and high fructose corn syrup [40, 41].

Although not widely or specifically studied, guarana should be expected to exhibit the same range of adverse effects as those associated with caffeine [42].

In one case, a 44-year-old man with no significant health problems had symptoms of caffeine toxicity after ingesting guarana extract. He experienced nausea, vomiting, anxiety, and heart palpitations [43, 44].

Human brain cells had increased cell death in the presence of a combination of caffeine, taurine, and guarana [41].

Tannins in guarana may cause inflammation [45].

In a study involving 27 people, no subjects reported any adverse effect on mood or anxiety after taking guarana extract 360 mg 3x/day for 5 days [46].

The extract of guarana seeds showed low toxicity, evidenced by an unchanged average lifespan, in mice subjected to long-term ingestion [15, 5].

Drug Interactions

Supplement/Herb/Nutrient-drug interactions can be dangerous and, in rare cases, even life-threatening. Always consult your doctor before supplementing and let them know about all drugs and supplements you are using or considering.

Amiodarone, a drug used to treat irregular heartbeat, was given to a group of rats along with guarana extract. The rats taking guarana had decreased blood levels of amiodarone, indicating a reduced bioavailability of the drug [47].

Supplement Interactions

Ginseng

Extracts of Panax ginseng, which are often sold in combination with guarana, contain similar potentially active components. In a clinical trial on 28 healthy people, a combination of guarana and ginseng significantly improved their performance in numerical tasks. However, there is no evidence of synergism between the 2 supplements [8].

YDG

YDG is an herbal supplement composed of yerba mate, guarana, and damiana. In a group of 58 normal-to-slightly-overweight women, YDG consumption decreased food intake [24].

Catuama

Catuama is a preparation consisting of guarana, ginger, Muira puama (potency wood), and Trichilia catigua. It showed a potent relaxing effect on blood vessels in different animal species. Catuama reverted heartbeat irregularities in isolated rabbit hearts. However, scientists believe that guarana doesn’t contribute to this effect [48].

Caffeine

Because guarana contains a naturally high concentration of caffeine, it grants many of the same effects obtained with this compound alone [3].

Supplementation

Sources

Commercially available products containing guarana come in many forms. Confections (such as chocolate products), fruit juice-based drinks, “energy drinks”, dietary supplements, and weight-loss products are a few examples. The main commercial use of guarana in Brazil is to make a carbonated soft drink [5].

Guarana Extract

In guarana extract, the caffeine concentration can be 2x-3x that found in the seed. Traditionally, guarana extract is prepared in Brazil using hot water or hydro-alcoholic solutions as a solvent. One of the uses of concentrate extracts is to produce guarana-based energy tonics. Guarana extract is commercially available as a pill or powder [1].

Guarana Soda

Guarana sodas in the form of energy drinks mostly contain caffeine, taurine, L-carnitine, carbohydrates, glucuronolactone, vitamins, and occasional herbal supplements such as ginseng. Additives such as yerba mate, cocoa, and kola nut may increase the caffeine content of such sodas [49].

User Reviews

The opinions expressed in this section are solely those of guarana users, who may or may not have medical or scientific training. Their reviews do not represent the opinions of SelfHacked. SelfHacked does not endorse any specific product, service, or treatment.

Do not consider user experiences as medical advice. Never delay or disregard seeking professional medical advice from your doctor or other qualified healthcare providers because of something you have read on SelfHacked. We understand that reading individual, real-life experiences can be a helpful resource, but it is never a substitute for professional medical advice, diagnosis, or treatment from a qualified healthcare provider.

Consumers of guarana extracts reported experiencing increased physical capacity and vigor, which helped them get through the day or strenuous activity without a crash. They also reported improved mood and contentment.

About the Author

Carlos Tello

Carlos Tello

PhD (Molecular Biology)
Carlos received his PhD and MS from the Universidad de Sevilla.
Carlos spent 9 years in the laboratory investigating mineral transport in plants. He then started working as a freelancer, mainly in science writing, editing, and consulting. Carlos is passionate about learning the mechanisms behind biological processes and communicating science to both academic and non-academic audiences. He strongly believes that scientific literacy is crucial to maintain a healthy lifestyle and avoid falling for scams.

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