Quick summary

Guarana (Paullinia cupana) is a plant known for its caffeine content and other bioactive compounds. It has been studied primarily for its effects on cognitive performance, fatigue (including cancer-related fatigue), and physical performance. Clinical research shows small or mixed effects on cognitive response time and some evidence for benefit in cancer-related fatigue, but the overall quality of evidence is low. Guarana is commonly used in energy drinks and dietary supplements, with most safety concerns related to its caffeine content.

What is it

Guarana is a climbing plant native to the Amazon basin, particularly in Brazil. It contains seeds rich in caffeine, as well as other compounds thought to have stimulant and antioxidant effects. The extract from guarana seeds is a popular ingredient in energy beverages and nutritional supplements aiming to boost energy and mental alertness.

Traditional uses

Traditionally, indigenous peoples in the Amazon have used guarana seeds for their stimulating effects, to reduce fatigue, improve endurance, and support mental focus. It has been incorporated in traditional remedies to combat tiredness and to promote vitality.

Active compounds

  • Caffeine: the primary active stimulant compound.
  • Theobromine and theophylline: other methylxanthines with mild stimulant properties.
  • Tannins and saponins: plant compounds contributing to antioxidant activity.
  • Flavonoids and catechins: antioxidants possibly supporting health effects.

Potential benefits with evidence levels

  • Improvement in response time in cognitive tasks (Low): Meta-analyses of acute guarana ingestion indicate a small effect on improving response time during cognitive tasks without affecting accuracy. The effects may be primarily due to caffeine and require further studies to confirm independent benefits.
  • Potential reduction in cancer-related fatigue (Very Low): Some randomized controlled trials suggest guarana might reduce cancer-related fatigue, but the evidence is limited by variability in study design and small sample sizes.
  • Possible enhancement in perceptual-motor cognitive domain (Very Low): Preliminary network meta-analysis data suggest guarana may improve perceptual-motor skills in healthy older adults, though evidence remains limited.
  • Support for sustained energy and cognitive activation (Insufficient): Guarana is used as part of multi-ingredient energy drinks that may support cognitive and physical performance, but the specific contribution of guarana has not been clearly established.

Side effects

  • Potential cardiovascular effects including increased heart rate and blood pressure, mostly related to caffeine content.
  • Possible neurological effects with excessive intake, such as nervousness or insomnia.
  • Adverse events have been reported with energy drink consumption that includes guarana and caffeine.
  • No serious adverse reactions have been specifically attributed to guarana alone in clinical trials.

Drug interactions

  • Guarana may interact with drugs metabolized by cytochrome P450 enzymes, similar to caffeine.
  • Direct evidence on guarana-specific interactions is limited; caution is advised when used with stimulants or medications affected by caffeine.

Who should avoid it

  • Individuals sensitive to caffeine or other stimulants.
  • Children and adolescents, especially when consuming energy drinks containing guarana.
  • Pregnant and breastfeeding women, due to caffeine-related risks.
  • People with cardiovascular conditions should exercise caution and consult healthcare providers before use.

Evidence limitations

  • Many clinical trials on guarana have small sample sizes, high or unclear risk of bias, and heterogeneous interventions.
  • Lack of well-powered, standardized, multicenter randomized controlled trials isolating guarana’s effects from caffeine.
  • Difficulty distinguishing effects of guarana from caffeine’s known stimulatory actions.
  • Insufficient data on long-term safety, optimal dosing, and standardized extract preparations.
  • Limited information on drug interactions and adverse effects specific to guarana alone.
  • Mixed and inconclusive evidence regarding efficacy for cancer-related fatigue and cognitive enhancement.

References

Last reviewed

April 2024

Informational disclaimer: This page is for educational purposes only and does not provide medical advice. Always consult your healthcare provider before using herbal products, especially if you have pre-existing conditions, take medications, are pregnant, or breastfeeding.