Guarana: benefits, dosage & side-effects

Guarana is a rainforest vine growing in the Amazon region in Brazil. Traditionally, Amazonian tribes brewed the seeds of the guarana plant to make an energy drink, and for hundreds of years, Brazilians have used it as an invigorating tonic.¹ Its secret ingredient? The seeds contain four times more caffeine than coffee, making guarana the most caffeine-rich plant in the world.² Guarana is available in tablets and capsules – either on its own or combined with other ingredients, often with ginseng. You can also find it in guarana drinks and smoothies.

Guarana seeds contain powerful antioxidants, including tannins, saponins and catechins,³ plus plant chemicals which stimulate the central nervous system, according to a 2010 study by the University of Florida.4 These include:

As a result of these stimulants, scientists think guarana may have the following effects: It can reduce feelings of tiredness Guarana has energising effects on the body, relieving fatigue and weakness, according to the European Medicines Agency.⁷ Indeed, a 2008 study by Northumbria University found that people who drank a cocktail of guarana, vitamins and minerals felt less tired after performing a series of mentally challenging tasks than those who drank a placebo.⁸

It may improve your concentration Guarana could also improve mental performance. In a 2007 study in Nutrients, guarana boosted memory and concentration, although researchers suggested more studies are needed.⁹ It was also found to improve long-term memory and increase alertness, according to a 2007 study in the Journal of Psychopharmacology.¹⁰

It may protect your heart Guarana can help limit the oxidation of harmful LDL cholesterol, according to a 2013 Brazilian study in Lipids in Health and Disease.¹¹ The oxidation of LDL cholesterol occurs when it is damaged by free radicals, which contributes to narrowing and hardening of the arteries – a condition that is linked to cardiovascular disease.¹² A 2008 report by the University of Cincinnati also found that guarana can improve blood flow and may even help prevent blood clots.¹³

There are no official guidelines on how much guarana is safe to consume, but 75mg has been shown to have a positive effect.¹⁴ Guarana shouldn’t be taken by:^15,16

Taken in excess, at doses of 250-300mg, guarana can produce similar symptoms to a high-caffeine intake including:17