Quercetin
Summary
In pooled trials, quercetin lowered blood pressure by about 2–3 mmHg, with significant effects mainly in trials using 500 mg/day or more. Blood lipids and glucose did not change overall. Endurance gains were statistically significant but trivial. Adverse effects were rare and mild in human studies; long-term safety above 1,000 mg/day is unknown.
Key facts
- Quercetin aglycone (most supplements), quercetin glucosides (isoquercetin), and enhanced-absorption formulations such as phytosomes[8][7]
- Quercetin-3-O-oligoglucosides were absorbed about 20 times better than the aglycone; lecithin phytosome and fenugreek-galactomannan formulations raised absorption 20- and 62-fold[7]
- Blood pressure ↓ (A); blood lipids and glucose: no overall change (no-effect); endurance performance and VO2max ↑, trivial (C)[1][2][3]
- Endurance trials averaged 960–1,000 mg/day; blood-pressure effects were significant in trials of 500 mg/day or more[4][3]
- Adverse effects were rarely reported and mild; no adequate data on more than 12 weeks at 1,000 mg/day or more[8]
- FDA had no questions about a GRAS notice for quercetin in foods and beverages at up to 500 mg per serving (closed November 22, 2010), noting some uses may require a color additive listing[11]
- 3 graded human outcomes on this page
- October 9, 2026
How it works
ProposedQuercetin is proposed to act through antioxidant and anti-inflammatory pathways, largely from experimental studies. Human meta-analyses of inflammation markers disagree: one found lower CRP, another found no overall effect on CRP, IL-6 or TNF-alpha.[9][10]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
At a glance: strongest evidence per outcome
| Outcome | Grade | Effect | Strongest evidence | Rows |
|---|---|---|---|---|
| Heart | Grade A | Worsened | Meta-analysis · n = 841 · 2022 | 1 row |
| Performance | Grade C | Improved | Meta-analysis · n = 288 · 2013 | 1 row |
| Metabolic | No effect | No effect | Meta-analysis · n = 896 · 2020 | 1 row |
Every graded row
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Systolic and diastolic blood pressure | Worsened | Grade A | Meta-analysis · n = 841 · 2022 Adults with normal, elevated or high blood pressure in 10 randomized controlled trials Form: Quercetin · Dose: Not stated in the abstract · Duration: Not stated in the abstract Quercetin lowered systolic blood pressure by 2.38 mmHg overall and by 1.82 mmHg in people with normal blood pressure, and lowered diastolic pressure by 3.14 mmHg in people with elevated or high blood pressure. | 35948195 (opens PubMed)Source [1] |
| Endurance performance and VO2max | Improved | Grade C | Meta-analysis · n = 288 · 2013 Trained and untrained people in 7 studies Form: Quercetin · Dose: Mean 960–1,000 mg/day · Duration: Mean 8–26 days Endurance performance improved 0.74% and VO2max 1.94% versus placebo; the gain was significant only in untrained people, and the authors judged the effects likely trivial. | 22805526 (opens PubMed)Source [3] |
| Blood lipids and glucose | No effect | No effect | Meta-analysis · n = 896 · 2020 Adults in 17 trials Form: Quercetin · Dose: Not stated in the abstract · Duration: Varied; subgroup of 8 weeks or more Neither lipid profiles nor glucose changed significantly overall, while blood pressure fell. In parallel-design trials lasting 8 weeks or more, HDL cholesterol and triglycerides changed significantly. | 31940027 (opens PubMed)Source [2] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Quercetin aglycone (quercetin dihydrate) | Varies[8] | Lowest absorption of the forms compared: about 20-fold lower than quercetin-3-O-oligoglucosides; dietary fat and fibre roughly doubled absorption.[7] | Adverse effects rarely reported and mild in human studies.[8] | Blood pressure, lipids, exercise performance |
| Quercetin glucosides (isoquercetin, enzymatically modified isoquercitrin) | Varies[7] | Quercetin-3-O-oligoglucosides were absorbed about 2 times better than quercetin-3-O-glucoside and 10 times better than rutin (quercetin-3-O-rutinoside).[7] | No form-specific tolerance data in our sources.[8] | Absorption studies |
| Enhanced-absorption formulations (lecithin phytosome, fenugreek galactomannan, cyclodextrin) | Varies[7] | Raised absorption versus aglycone: lecithin phytosome 20.1-fold, fenugreek-galactomannan/lecithin 62-fold, glucoside-cyclodextrin complex 10.8-fold.[7] | No form-specific tolerance data in our sources.[8] | Absorption studies |
Studied doses
Doses studied in human trials ranged from below 500 mg to about 1,000 mg of quercetin a day; blood-pressure effects appeared at 500 mg/day or more, and endurance trials averaged 960–1,000 mg/day for 8–26 days.[4][3][8]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Medicines
- Certain prescription drugsReviewShort-term human and animal studies found quercetin altered the bioavailability of certain drugs.[8]
Who should be careful
- Kidney problems
- Animal studies suggest quercetin could enhance kidney-toxic effects in an already damaged kidney; a safety review lists this as a possible risk group.[8]
- Hormone-sensitive conditions
- Animal studies raised the possibility that quercetin could promote tumor development, especially in estrogen-dependent cancer; a safety review lists this as a possible risk group.[8]
- High amounts long term
- No adequate safety data exist for more than 12 weeks at 1,000 mg/day or more.[8]
- Before you start
- Talk to your pharmacist or clinician before adding this supplement, especially if you take prescription medicines, are pregnant or breastfeeding, or have a chronic health condition.[8]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Articles about Quercetin
Plain-English answers to common questions, built on the evidence above.
Frequently asked questions
Does quercetin lower blood pressure?
Meta-analyses of 7 to 17 trials found reductions of roughly 2–3 mmHg systolic, with significant effects mainly at 500 mg/day or more.[1][4][2]
Does quercetin lower cholesterol?
Overall, no. Two meta-analyses found no significant change in LDL or overall lipid profiles; some subgroups showed lower triglycerides.[2][5]
Does quercetin reduce inflammation?
The human data disagree. One meta-analysis of 7 trials found a small drop in CRP; another found no overall effect on CRP, IL-6 or TNF-alpha.[9][10]
Does quercetin help endurance?
Two meta-analyses found statistically significant but trivial-to-small improvements in endurance and VO2max (about 1–2%), mainly in untrained people.[3][6]
Which form is absorbed most easily?
In a 2025 review of 31 human studies, quercetin oligoglucosides and enhanced formulations such as lecithin phytosomes were absorbed many times better than plain quercetin aglycone. Adding dietary fat and fibre roughly doubled absorption.[7]
Is quercetin safe?
Adverse effects in human studies were rare and mild. Data on more than 12 weeks at 1,000 mg/day or more are lacking, and quercetin may change how some drugs are absorbed.[8]
Sources
- [1]The Effects of Quercetin Supplementation on Blood Pressure - Meta-Analysis.. Curr Probl Cardiol, 2022. meta-analysis
- [2]Effect of quercetin supplementation on plasma lipid profiles, blood pressure, and glucose levels: a systematic review and meta-analysis.. Nutr Rev, 2020. meta-analysis
- [3]Effects of quercetin supplementation on endurance performance and maximal oxygen consumption: a meta-analysis.. Int J Sport Nutr Exerc Metab, 2013. meta-analysis
- [4]Effects of Quercetin on Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.. J Am Heart Assoc, 2016. meta-analysis
- [5]Effects of quercetin supplementation on lipid profile: A systematic review and meta-analysis of randomized controlled trials.. Crit Rev Food Sci Nutr, 2017. meta-analysis
- [6]Quercetin and endurance exercise capacity: a systematic review and meta-analysis.. Med Sci Sports Exerc, 2011. meta-analysis
- [7]Improving quercetin bioavailability: A systematic review and meta-analysis of human intervention studies.. Food Chem, 2025. systematic-review
- [8]Safety Aspects of the Use of Quercetin as a Dietary Supplement.. Mol Nutr Food Res, 2018. review
- [9]Effects of supplementation with quercetin on plasma C-reactive protein concentrations: a systematic review and meta-analysis of randomized controlled trials.. Eur J Clin Nutr, 2017. meta-analysis
- [10]Impact of quercetin on systemic levels of inflammation: a meta-analysis of randomised controlled human trials.. Int J Food Sci Nutr, 2020. meta-analysis
- [11]GRN No. 341: Quercetin (FDA has no questions; some uses may require a color additive listing; closed Nov 22, 2010). U.S. Food and Drug Administration, 2010. database
What changed
- First draft. Every evidence-row PMID checked with NCBI E-utilities (esummary + efetch abstract) and re-read in an independent adversarial pass.