WHAT IS GUARANA AND DOES IT REALLY WORK?
Guarana is a plant named for the Guarani tribe in the Amazon, who used the seeds to brew a drink. Today, guarana seeds are still used as medicine.
Guarana is used for weight loss, to enhance athletic performance, as a stimulant, and to reduce mental and physical fatigue. It is a frequent addition to energy and weight loss products.
Some people also use guarana to treat low blood pressure and chronic fatigue syndrome (CFS), and to prevent malaria and dysentery. It is also used to enhance sexual desire, to increase urine flow, and as an astringent.
Other uses include treatment of ongoing diarrhea, fever, heart problems, headache, joint pain, backache, and heat stress.
In food manufacturing, guarana has been used as a flavoring ingredient in beverages and candy.
How does it work?
Guarana contains caffeine. Caffeine works by stimulating the central nervous system (CNS), heart, and muscles. Guarana also contains theophylline and theobromine, which are chemicals similar to caffeine.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Guarana is classified as a metabolic stimulant, which means it may help burn more calories throughout the day because of its high caffeine content.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Seed extracts of guarana possess strong antimicrobial and antioxidant properties, possibly conferring additional benefits for their use as additives in cosmetics.
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.
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.
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).
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.