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.[reference|url=https://pubmed.ncbi.nlm.nih.gov/38258783|title=Therapeutic Potential and Clinical Effectiveness of Quercetin: A Dietary Supplement.|published=2024|authors=Devi V, Deswal G, Dass R, Chopra B, Kriplani P, Grewal AS, Guarve K, Dhingra AK|journal=Recent Adv Food Nutr Agric|]
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.[reference|url=https://pubmed.ncbi.nlm.nih.gov/38258783|title=Therapeutic Potential and Clinical Effectiveness of Quercetin: A Dietary Supplement.|published=2024|authors=Devi V, Deswal G, Dass R, Chopra B, Kriplani P, Grewal AS, Guarve K, Dhingra AK|journal=Recent Adv Food Nutr Agric|]
What are quercetin’s main benefits?
Some research suggests that quercetin may help improve systolic blood pressure and fasting blood glucose.[reference|url=https://doi.org/10.1016/j.jff.2024.106175|title=The effect of quercetin supplementation on the components of metabolic syndrome in adults: A systematic review and dose–response meta-analysis of randomized controlled trials|authors=Noshadi, I. et al|journal=Journal of Functional Foods|published=2024-05-01] Some studies suggest that it may reduce inflammation by reducing C-reactive protein levels[reference|url=https://pubmed.ncbi.nlm.nih.gov/28537580|title=Effects of supplementation with quercetin on plasma C-reactive protein concentrations: a systematic review and meta-analysis of randomized controlled trials.|published=2017 Sep|authors=Mohammadi-Sartang M, Mazloom Z, Sherafatmanesh S, Ghorbani M, Firoozi D|journal=Eur J Clin Nutr|] and may reduce allergy symptoms,[reference|url=https://pubmed.ncbi.nlm.nih.gov/35776034|title=Effects of repeated oral intake of a quercetin-containing supplement on allergic reaction: a randomized, placebo-controlled, double-blind parallel-group study|published=2022 Jun|authors=S Yamada, M Shirai, Y Inaba, T Takara|journal=Eur Rev Med Pharmacol Sci|] 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.[reference|url=https://pubmed.ncbi.nlm.nih.gov/26999194|title=Quercetin, Inflammation and Immunity.|published=2016-Mar-15|authors=Li Y, Yao J, Han C, Yang J, Chaudhry MT, Wang S, Liu H, Yin Y|journal=Nutrients|][reference|url=https://pubmed.ncbi.nlm.nih.gov/26999194|title=Quercetin, Inflammation and Immunity.|published=2016-Mar-15|authors=Li Y, Yao J, Han C, Yang J, Chaudhry MT, Wang S, Liu H, Yin Y|journal=Nutrients|] 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.[reference|url=https://doi.org/10.1016/j.jff.2024.106175|title=The effect of quercetin supplementation on the components of metabolic syndrome in adults: A systematic review and dose–response meta-analysis of randomized controlled trials|authors=Noshadi, I. et al|journal=Journal of Functional Foods|published=2024-05-01] Some studies suggest that it may reduce inflammation by reducing C-reactive protein levels[reference|url=https://pubmed.ncbi.nlm.nih.gov/28537580|title=Effects of supplementation with quercetin on plasma C-reactive protein concentrations: a systematic review and meta-analysis of randomized controlled trials.|published=2017 Sep|authors=Mohammadi-Sartang M, Mazloom Z, Sherafatmanesh S, Ghorbani M, Firoozi D|journal=Eur J Clin Nutr|] and may reduce allergy symptoms,[reference|url=https://pubmed.ncbi.nlm.nih.gov/35776034|title=Effects of repeated oral intake of a quercetin-containing supplement on allergic reaction: a randomized, placebo-controlled, double-blind parallel-group study|published=2022 Jun|authors=S Yamada, M Shirai, Y Inaba, T Takara|journal=Eur Rev Med Pharmacol Sci|] 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.[reference|url=https://pubmed.ncbi.nlm.nih.gov/26999194|title=Quercetin, Inflammation and Immunity.|published=2016-Mar-15|authors=Li Y, Yao J, Han C, Yang J, Chaudhry MT, Wang S, Liu H, Yin Y|journal=Nutrients|] 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.[reference|url=https://pubmed.ncbi.nlm.nih.gov/35776034|title=Effects of repeated oral intake of a quercetin-containing supplement on allergic reaction: a randomized, placebo-controlled, double-blind parallel-group study|published=2022 Jun|authors=S Yamada, M Shirai, Y Inaba, T Takara|journal=Eur Rev Med Pharmacol Sci|]
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.[reference|url=https://pubmed.ncbi.nlm.nih.gov/26999194|title=Quercetin, Inflammation and Immunity.|published=2016-Mar-15|authors=Li Y, Yao J, Han C, Yang J, Chaudhry MT, Wang S, Liu H, Yin Y|journal=Nutrients|][reference|url=https://pubmed.ncbi.nlm.nih.gov/26999194|title=Quercetin, Inflammation and Immunity.|published=2016-Mar-15|authors=Li Y, Yao J, Han C, Yang J, Chaudhry MT, Wang S, Liu H, Yin Y|journal=Nutrients|] It’s important to note that while these mechanisms are intriguing, its effects in isolation may not always apply to humans.
