Quercetin is a flavonoid that is naturally found in fruits and vegetables. It can be found in red wine, onions, apples, and berries, and the richest sources are wine and onions. It is also commonly taken as a supplement. Beyond fruits and vegetables, it is also found in the plants of other herbal supplements such as Ginkgo biloba, elderberry, and St. John’s wort.[7]
What is quercetin?
Quercetin is a flavonoid that is naturally found in fruits and vegetables. It can be found in red wine, onions, apples, and berries, and the richest sources are wine and onions. It is also commonly taken as a supplement. Beyond fruits and vegetables, it is also found in the plants of other herbal supplements such as Ginkgo biloba, elderberry, and St. John’s wort.[7]
What are quercetin’s main benefits?
Some research suggests that quercetin may help improve systolic blood pressure and fasting blood glucose.[5] Some studies suggest that it may reduce inflammation by reducing C-reactive protein levels[3] and may reduce allergy symptoms,[6] but the research is still preliminary and not strong enough to draw any definitive conclusions about its benefits.
How does quercetin work?
Quercetin works in multiple ways. It can be an antioxidant, which can help neutralize free radicals in the body. It may also modulate a few biological pathways that may regulate cell death, inflammation, and cellular growth signals.[8] It’s important to note that while these mechanisms are intriguing, its effects in isolation may not always apply to humans.
What are other names for Quercetin?
Note that Quercetin is also known as:
- 3,3',4'5,7-Pentahydroxyflavone
Quercetin should not be confused with:
- Quercitrin
- Quinines (a class of medications)
- Quinolones (a class of medications)
- Quercitannic acid
- Quercitron
- Sophoretin
- Flavin meletin
- Quercetol
Dosage information
Formulation:
Quercetin comes as a liquid or in capsules, tablets, or softgels. Most supplements use the aglycone (free form) version, which is considered less bioavailable than the quercetin glucosides found in foods.[1]
Range of dosages studied:
30 mg to 3 grams
Effective Dosages:
Inflammation
Adults (≤45 years): 500 mg/day or higher for 6 to 10 weeks to reduce C-reactive protein levels.[2][3]
Special considerations: Appears to be most effective in adults younger than 45 years, but there’s less evidence of effectiveness in adults older than 45 years. It’s important to note that it does not appear to affect other inflammatory markers, like IL-6 and TNF-alpha.
Blood pressure
Adults (19–60 years): More than 500 mg/day for more than 8 weeks may reduce systolic and diastolic blood pressure.[4][5]
Special considerations: The reductions in diastolic blood pressure are less consistent. The studies showed heterogeneity, which suggests that the actual blood pressure effect may vary from person to person.
General cardiovascular health
Adults (19–60 years): 100 to 500 mg/day for 8 to 12 weeks may help improve total cholesterol and LDL-C. Higher doses of more than 500 mg/day may further enhance LDL-C reduction.[5][2]
Special considerations: The studies showed heterogeneity, which suggests that the actual effect on blood lipids may vary from person to person
Allergic rhinitis (seasonal allergies/hay fever)
Adults (19–60 years): 200 mg/day[6]
Special considerations: This dosage recommendation is based on only one study, so the certainty of this recommendation is low.
Other considerations:
Because there is a limited amount of research, it’s unclear whether quercetin’s bioavailability is affected by food. More research is needed to determine how food affects the absorption and metabolism of quercetin.
Frequently asked questions
What is quercetin?
What are quercetin’s main benefits?
Some research suggests that quercetin may help improve systolic blood pressure and fasting blood glucose.[5] Some studies suggest that it may reduce inflammation by reducing C-reactive protein levels[3] and may reduce allergy symptoms,[6] but the research is still preliminary and not strong enough to draw any definitive conclusions about its benefits.
Does quercetin help with allergies?
Some in vitro evidence has found that quercetin can stabilize mast cells (which release histamine during allergic reactions) and inhibit the inflammatory pathways associated with allergic diseases like allergic rhinitis.[8] However, human research is scarce.
There is one randomized controlled trial that found some benefit in improving symptoms of allergic rhinitis, but this has yet to be confirmed in other trials.[6]
Overall, quercetin might help with allergies, but more research is needed to determine how effective it truly is.
How does quercetin work?
Quercetin works in multiple ways. It can be an antioxidant, which can help neutralize free radicals in the body. It may also modulate a few biological pathways that may regulate cell death, inflammation, and cellular growth signals.[8] It’s important to note that while these mechanisms are intriguing, its effects in isolation may not always apply to humans.
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Research Breakdown
References
Examine Database References
- Oxidative Stress Biomarkers - Boots AW, Drent M, de Boer VC, Bast A, Haenen GRQuercetin reduces markers of oxidative stress and inflammation in sarcoidosisClin Nutr.(2011 Aug)
- Oxidative Stress Biomarkers - Randi L. Edwards, Tiffany Lyon, Sheldon E. Litwin, Alexander Rabovsky, J. David Symons, and Thunder JaliliQuercetin Reduces Blood Pressure in Hypertensive SubjectsAmerican Society for Nutrition.()
- Blood Pressure - Egert S, Rimbach G, Müller MJNo evidence for a thermic effect of the dietary flavonol quercetin: a pilot study in healthy normal-weight womenEur J Appl Physiol.(2011 May)
- Rating of Perceived Exertion - Cheuvront SN, Ely BR, Kenefick RW, Michniak-Kohn BB, Rood JC, Sawka MNNo effect of nutritional adenosine receptor antagonists on exercise performance in the heatAm J Physiol Regul Integr Comp Physiol.(2009 Feb)
- Exercise-induced Stress Response - Kuennen M, Gillum T, Dokladny K, Bedrick E, Schneider S, Moseley PThermotolerance and heat acclimation may share a common mechanism in humansAm J Physiol Regul Integr Comp Physiol.(2011 Aug)
- Anaerobic Capacity - Abbey EL, Rankin JWEffect of quercetin supplementation on repeated-sprint performance, xanthine oxidase activity, and inflammationInt J Sport Nutr Exerc Metab.(2011 Apr)
- High-density lipoprotein (HDL) - Talirevic E, Jelena SQuercetin in the treatment of dyslipidemiaMed Arh.(2012)
- Sleep Quality - Bigelman KA, Chapman DP, Freese EC, Trilk JL, Cureton KJEffects of 6 weeks of quercetin supplementation on energy, fatigue, and sleep in ROTC cadetsMil Med.(2011 May)
- Quality of Life - Mantadaki AE, Linardakis M, Vafeiadi M, Anastasiou F, Tsatsakis A, Symvoulakis EKThe Impact of Three-Month Quercetin Intake on Quality of Life and Anxiety in Patients With Type II Diabetes Mellitus: An Early Data Analysis From a Randomized Controlled Trial.Cureus.(2024 Apr)
- HbA1c - Mantadaki AE, Linardakis M, Tsakiri M, Baliou S, Fragkiadaki P, Vakonaki E, Tzatzarakis MN, Tsatsakis A, Symvoulakis EKBenefits of Quercetin on Glycated Hemoglobin, Blood Pressure, PiKo-6 Readings, Night-Time Sleep, Anxiety, and Quality of Life in Patients with Type 2 Diabetes Mellitus: A Randomized Controlled Trial.J Clin Med.(2024 Jun 15)
