SupplementsAntioxidantsHeartAnti-inflammatory
Quercetin is a flavonoid found in onions, apples and capers, sold for allergies, immunity and blood pressure. The evidence is modest but, in places, genuine.
Key takeaways
- A plant flavonoid with antioxidant and anti-inflammatory actions.
- Meta-analysis: lowers blood pressure, with a clearer effect at >500 mg/day.1
- Mild antihistamine/mast-cell effects (popular for allergies) and modest exercise-recovery signals.2
- Low bioavailability — often paired with vitamin C or bromelain; dose 500–1000 mg.
What it is
Quercetin is one of the most common dietary flavonoids. It stabilises mast cells (relevant to allergy) and modulates inflammatory and antioxidant pathways.
The evidence
A meta-analysis of randomised trials found quercetin significantly reduced systolic and diastolic blood pressure, especially above 500 mg/day.1 It also shows modest benefits for exercise-induced muscle damage and recovery,2 and is popular (with less hard evidence) for seasonal allergies.
Dose & how to use
500–1000 mg/day. Because absorption is poor, it’s often combined with vitamin C or bromelain, or taken as a phytosome.
Safety & who benefits
Generally safe short-term; may interact with some medications (it affects drug-metabolising enzymes). Of interest for blood pressure, allergies and active people.
References
Adult research summary for education, not a prescription. These are food supplements, not treatments for disease.
- Serban MC, et al. Effects of Quercetin on Blood Pressure: a systematic review and meta-analysis of RCTs. J Am Heart Assoc 2016. www.ahajournals.org
- Quercetin supplementation promotes recovery after exercise-induced muscle damage: a meta-analysis. 2023. pmc.ncbi.nlm.nih.gov
This article summarises nutrition science for education. It is not a substitute for individual medical advice; consult a professional before starting a supplement, in pregnancy, or alongside medication.