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Guarana (Paullinia cupana)
A caffeine-rich Amazonian seed (Paullinia cupana) marketed for energy and mental performance. The energizing effect is genuine and caffeine-driven, but most cognition trials are small, use combination products, or show mostly null results — the clearest signal is for cancer-related fatigue. Evidence is emerging, not strong.
What the evidence says
Most Guarana studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from high-quality meta-analyses and randomised trials published 2006–2026 with a typical study size of 229 participants.
Based on 23 studies · 4 meta-analyses · 15 RCTs · 2,351 total participants
Confidence
High confidenceBy outcome
Energizing effects are real but caffeine-driven, and the only reproducible signal is one meta-analysis for cancer-related fatigue; controlled cognition trials are small, mostly null, or based on combination products.
23 rigorous studies
18 randomized trials · 5 meta-analyses · 5 systematic reviews
Our evidence rating for Guarana is accountable to this entire body of rigorous research indexed in PubMed — not a hand-picked subset.
PubMed · as of Jul 2026
2 trials ongoing or recruiting · 14 completed on ClinicalTrials.gov
Registered trials show research momentum for Guarana, not proof of effect — a registration is a plan, and posted results are sponsor-reported, not peer-reviewed. They are never counted toward the evidence rating above.
Browse these trials on ClinicalTrials.govClinicalTrials.gov · as of Sep 2026
Under EU law (Reg. 1924/2006), EFSA reviews whether a specific health claim for Guarana meets the evidence standard. These are independent regulatory decisions on claims — not studies, and never counted toward the evidence score above.
Not authorised by EFSA
“extract of guarana (Paullinia cupana) natural antioxidant, protect organism from oxidative damage, powerful antioxidants beneficial to human health”
“Not authorised” means the specific claim wording did not meet the EU’s evidence standard — often a matter of dossier or phrasing, not proof of no effect. EFSA judges marketing claims and is kept separate from our study-based evidence score.
Source: EU Register of nutrition and health claims (European Commission / EFSA) · register snapshot Feb 2013
Guarana is the seed of Paullinia cupana, an Amazonian climbing plant. By dry weight it is one of the most caffeine-dense plants known (often 2-4x coffee beans by weight), and it also contains theobromine, theophylline, tannins, and saponins.
Its energizing and alertness effects are real but largely explained by caffeine. The cognition story is weaker than marketing implies: a well-controlled acute crossover comparing 500 mg guarana (130 mg caffeine) to 100 mg caffeine and placebo found NO consistent benefit on cognitive performance or mood.
A widely-cited 'cognitive' benefit comes from a study of a multivitamin-mineral complex that happened to contain guarana, making it impossible to credit guarana specifically.
The most reproducible signal is for cancer-related fatigue: a 2024 meta-analysis of 5 studies (229 patients) found a significant reduction in fatigue (SMD -0.77), though with high heterogeneity and a call for larger RCTs.
Bottom line: a legitimate caffeine source with a niche fatigue signal, but no robust standalone cognitive enhancement.
Guarana seeds are exceptionally caffeine-rich; caffeine antagonizes adenosine receptors to increase alertness and reduce fatigue.
Theobromine, theophylline, and tannins may slow caffeine release, theoretically smoothing the stimulant curve.
How Guarana works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
Avoid or strictly limit — caffeine crosses the placenta and into breast milk.
Not recommended — caffeine-dense; ISSN energy-drink position stand advises caution.
Use caution or avoid due to high caffeine density.
Additive caffeine — guarana is very caffeine-dense, so stacking risks jitteriness, tachycardia, insomnia.
Caffeine with MAOIs may raise blood pressure.
Additive cardiovascular stimulation; use caution.
Tip: Use early in the day; lower dose
Tip: Reduce dose; avoid if caffeine-sensitive
Tip: Take with food
Guarana has an evidence score of 3/10 — emerging evidence based on 20 indexed studies, including 1 meta-analysis. A caffeine-rich Amazonian seed (Paullinia cupana) marketed for energy and mental performance. The energizing effect is genuine and caffeine-driven, but most cognition trials are small, use combination products, or show mostly null results — the clearest signal is for cancer-related fatigue. Evidence is emerging, not strong. Representative study: PMID 39536249.
The commonly studied dose of Guarana is 50-1000 mg guarana extract (trials use a wide range; 500 mg ≈ ~130 mg caffeine); cancer-fatigue trials often used ~50-75 mg/day standardized. Individual needs vary — start at the lower end of the range and adjust based on how you respond.
The best time to take Guarana is in the morning. It can be taken on an empty stomach. Caffeine content makes morning/early-afternoon use best to avoid sleep disruption.
Guarana is generally safe at recommended doses, with a few precautions worth noting. The most commonly reported side effects are insomnia / jitteriness, anxiety / palpitations, GI upset. Use caution if any of these apply to you: Caffeine sensitivity, arrhythmia, uncontrolled hypertension, anxiety disorders; Pregnancy/breastfeeding (caffeine).
Panax Ginseng
Likely helpsGinsenosides combat fatigue, sharpen cognitive function, and enhance stress resilience — distinct from American and Siberian ginseng.
Rhodiola Rosea
Probably helpsFast-acting adaptogen that combats mental fatigue and improves cognitive performance under stress — works within days, not weeks.
Ashwagandha
Likely helpsReduces cortisol and anxiety while improving sleep quality and physical recovery in stressed adults.
Beetroot
Likely helpsDietary nitrates convert to nitric oxide, enhancing oxygen delivery to muscles — a top-5 evidence-based ergogenic aid.
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Reviewed by Dr. Baher Al Hakim · Last reviewed June 2026 · evidence from 23 studies · how we score · editorial policy
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
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