How can quercetin help me? What the research says

Quercetin, found in many plant-based foods and available as a supplement, is linked to better body terrainthe internal conditions of your body, including nutritional status, fitness, blood sugar balance, hormone balance, inflammation and more, and especially lower inflammation.

How can quercetin help me? What the research says

We summarize the clinical evidence for each medical benefit here. We begin with our assessment of the strength of evidence within each category, followed by a brief summary of individual studies or reviews of several studies. In assessing the strength of evidence, we consider the study design, number of participants, and the size of the treatment effect (how much outcomes changed with treatment).

Our assessments of evidence for each medical benefit fall into one of these categories:

Strong evidence: consistent, significant effects in several large (or at least one very large) well designed clinical studies or at least two meta-analysesa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of clinical studies of moderate or better quality (or one large meta-analysis) finding similar results
Good evidence: significant effects in one large or several mid-sized and well-designed clinical studies ( randomized controlled trialsa study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects with an appropriate placebo or other strong comparison control or observational studies that control for confounds)
Modest evidence: significant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies), or several small studies aggregated into a meta-analysis
Preliminary evidence: significant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect
Weak evidence: one or more case studies, supported by animal evidence OR small treatment effects of limited clinical significance OR studies with no controls OR weak trends of effects
Insufficient evidence: preclinical evidence only OR clinical studies with such poor or unclear methodology that no conclusion can be drawn OR conflicting findings across clinical studies with no preponderance of evidence in one direction; conflicting evidence occurs when studies find conflicting effects (positive effect vs no effect or negative effect) with the same treatment and the same general study population (same cancer type, for example)

How We Rate Therapies

Learn more about how we research and rate therapies and practices.

Improving treatment outcomes

Is quercetin linked to improved survival? Is it linked to less cancer growth or metastasis? Does it enhance the anticancer action of other treatments or therapies? We present the evidence.

Leukemia or lymphoma

Weak evidenceone or more case studies, supported by animal evidence OR small treatment effects of limited clinical significance OR studies with no controls OR weak trends of effects (this is the CancerChoices definition; other researchers and studies may define this differently) of stabilized lymphocyte counts among people with chronic lymphocytic leukemia or small lymphocytic lymphoma treated with quercetin

Optimizing your body terrain

Does quercetin promote an environment within your body that is less supportive of cancer development, growth, or spread? We present the evidence.

Optimizing Your Body Terrain

Research has only begun studying the connections between body terrain factors and cancer outcomes, and the oncology community is not yet sure how to interpret all the findings. If any of these terrain factors could be an issue for you, we recommend that you ask your doctor if you need any diagnostic tests to detect terrain imbalances or any adjustments to your lifestyle or medications.

We also recommend that you share with your doctor the information here about how quercetin might affect these terrain factors if you have any imbalances.

Body weight

No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on measures of body weight among overweight or obese people treated with quercetin in a combined analysis of studies

Bleeding and coagulation imbalance

Weak evidenceone or more case studies, supported by animal evidence OR small treatment effects of limited clinical significance OR studies with no controls OR weak trends of effects (this is the CancerChoices definition; other researchers and studies may define this differently) of less blood clotting among people with advanced cancer at high risk for blood clots treated with isoquercetin

High blood sugar and insulin resistance

Modest evidencesignificant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observational studies), or several small studies aggregated into a meta-analysis (this is the CancerChoices definition; other researchers and studies may define this differently) of lower fasting plasma glucose, although no evidence of an effect on HbA1c levels or a marker of insulin resistance, among people with metabolic syndrome and related disorders treated with quercetin

Insufficient evidencepreclinical evidence only OR clinical studies with such poor or unclear methodology that no conclusion can be drawn OR conflicting findings across clinical studies with no preponderance of evidence in one direction; conflicting evidence occurs when studies find conflicting effects (positive effect vs no effect or negative effect) with the same treatment and the same general study population (same cancer type, for example) (this is the CancerChoices definition; other researchers and studies may define this differently) of a lower marker of insulin resistance and no evidence of an effect on fasting blood glucose or insulin among women with polycystic ovary syndrome treated with quercetin

Hormone imbalance

Preliminary evidencesignificant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect (this is the CancerChoices definition; other researchers and studies may define this differently) of lower levels of and luteinizing hormone (LH) and higher levels of adiponectin among women with polycystic ovary syndrome treated with quercetin

Inflammation

Good evidencesignificant effects in one large or several mid-sized and well-designed clinical studies (randomized controlled trials (RCTs) with an appropriate placebo or other strong comparison control or observational studies that control for confounds) (this is the CancerChoices definition; other researchers and studies may define this differently) of some lower markers of inflammation among people with various noncancer health conditions (not limited to cancer) treated with quercetin

Oxidative stress

Preliminary evidence of lower markers of oxidative stressan imbalance between free radicals and antioxidants in your body in which antioxidant levels are lower than normal; this imbalance can cause harmful oxidation reactions in your body chemistry among people treated with quercetin (not specific to cancer)

Quercetin in combination with other therapies

Quercetin and (-)-epicatechin: weak evidence of lower fasting plasma glucose and fewer nuclei abnormalities in buccal epithelial cells among adults at risk of metabolic syndrome eating bread enriched with (-)-epicatechin and quercetin

Managing side effects and promoting wellness

Is quercetin linked to fewer or less severe side effects or symptoms? Is it linked to less toxicity from cancer treatment? Does it support your quality of life or promote general well-being? We present the evidence.

Oral symptoms

No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on oral mucositisinflammation and ulceration of the mucous membranes lining the digestive tract, usually as an adverse effect of chemotherapy and radiotherapy treatment for cancer during high-dose chemotherapy for blood malignancies among people with treated with quercetin

Quercetin in combination with other therapies

Curcumin, quercetin, hyaluronic acid, and chondroitin sulfate: preliminary evidencesignificant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect (this is the CancerChoices definition; other researchers and studies may define this differently) of better (fewer or less severe) urinary incontinence symptoms and lower impact on quality of life among males scheduled to undergo primary intensity-modulated radiotherapy for localized prostate cancer treated with curcumin, quercetin, hyaluronic acid, and chondroitin sulfate

Isoquercetin, ascorbic acid, and nicotinic acid: weak evidenceone or more case studies, supported by animal evidence OR small treatment effects of limited clinical significance OR studies with no controls OR weak trends of effects (this is the CancerChoices definition; other researchers and studies may define this differently) of better fatigue scores during treatment with sunitinib among people with kidney cancer treated with isoquercetin

Curcumin, quercetin, hyaluronic acid, and chondroitin sulfate: preliminary evidence of better (fewer or less severe) urinary incontinence symptoms and lower impact on quality of life among males scheduled to undergo primary intensity-modulated radiotherapy for localized prostate cancer treated with curcumin, quercetin, hyaluronic acid, and chondroitin sulfate

Better urinary incontinence symptoms and lower impact on quality of life (bother scores) at 1-year among males scheduled to undergo primary intensity-modulated radiotherapy for localized prostate cancer treated with hyaluronic acid (HA)/chondroitin sulfate (CS) weekly by intravesical instillation for 6 weeks and an oral formulation containing 200 mg CS, 20 mg HA, 200 mg quercetin, and 100 mg curcumin, one capsule twice a day for 12 weeks compared to controls (no treatment) in a small RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects¹⁸Redorta JP, Sanguedolce F et al. Multicentre International Study for the Prevention with iAluRil of Radio-induced Cystitis (MISTIC): a randomised controlled study. European Urology Open Science. 2021 Feb 23;26:45-54.

Isoquercetin, ascorbic acid, and nicotinic acid: weak evidence of better fatigue scores during treatment with sunitinib among people with kidney cancer treated with isoquercetin

Better fatigue scores during treatment with sunitinib among people with kidney cancer treated with 450 or 900 mg isoquercetin a day for a median of 81 days compared to baseline in small uncontrolled triala study in which a therapy is used, but without a comparison group against which to judge outcomes; an uncontrolled trial is considered a weak study design¹⁹Buonerba C, De Placido P et al. Isoquercetin as an adjunct therapy in patients with kidney cancer receiving first-line sunitinib (quasar): results of a phase I trial. Frontiers in Pharmacology. 2018 Mar 16;9:189.

Symptoms not specific to cancer

Modest evidencesignificant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observational studies), or several small studies aggregated into a meta-analysis (this is the CancerChoices definition; other researchers and studies may define this differently) of lower blood pressure among people treated with quercetin (not specific to cancer)

Preliminary evidence of less pain and joint stiffness among women with rheumatoid arthritis (not specific to cancer) treated with quercetin

Preliminary evidence of fewer symptoms among men with chronic pelvic pain syndrome treated with quercetin

Preliminary evidence of less severe numbness, jolting pain, and irritation among people with diabetic peripheral neuropathy treated with QR-333

Cardiovascular symptoms: modest evidence of lower blood pressure among people treated with quercetin (not specific to cancer)

Lower systolic and diastolic blood pressure, mostly at doses of 500 mg/day or higher, among people, mostly without high blood pressure, treated with quercetin compared to controls in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 7 RCTsrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects²⁰Serban MC, Sahebkar A et al. Effects of quercetin on blood pressure: a systematic review and meta‐analysis of randomized controlled trials. Journal of the American Heart Association: Cardiovascular and Cerebrovascular Disease. 2016 Jul 12;5(7):e002713.

Pain and joint stiffness: preliminary evidence of less pain and joint stiffness among women with rheumatoid arthritis (not specific to cancer) treated with quercetin

Less pain and joint stiffness among women with rheumatoid arthritis treated with 500 mg quercetin per day compared to placebo in a small RCT²¹Javadi F, Ahmadzadeh A et al. The effect of quercetin on inflammatory factors and clinical symptoms in women with rheumatoid arthritis: a double-blind, randomized controlled trial. Journal of the American College of Nutrition. 2017 Jan;36(1):9-15.

Pain and symptoms from chronic prostatitis: preliminary evidence of fewer symptoms among men with chronic pelvic pain syndrome treated with quercetin

Fewer symptoms among men with category IIIa and IIIb chronic pelvic pain syndrome treated with 500 mg quercetin twice a day for 1 month compared to placebo in a small RCT²²Shoskes DA, Zeitlin SI, Shahed A, Rajfer J. Quercetin in men with category III chronic prostatitis: a preliminary prospective, double-blind, placebo-controlled trial. Urology. 1999 Dec;54(6):960-3.

Quercetin in combination with other therapies

QR-333, a topical compound containing quercetin, ascorbyl palmitate, and vitamin D3: preliminary evidence of less severe numbness, jolting pain, and irritation among people with diabetic peripheral neuropathy treated with QR-333

Less severe numbness, jolting pain, and irritation among people with diabetic peripheral neuropathy treated with QR-333 3 times a day for 4 weeks compared to placebo in a small RCT²³Valensi P, Le Devehat C et al. A multicenter, double-blind, safety study of QR-333 for the treatment of symptomatic diabetic peripheral neuropathy. A preliminary report. Journal of Diabetes Complications. 2005 Sep-Oct;19(5):247-53.

Reducing cancer risk

Is quercetin linked to lower risks of developing cancer or of recurrence? We present the evidence.

Breast cancer

Preliminary evidencesignificant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect (this is the CancerChoices definition; other researchers and studies may define this differently) of lower incidence of recurrence among people with breast cancer, especially obese people, eating higher levels of foods containing quercetin

Colorectal cancer

Modest evidencesignificant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observational studies), or several small studies aggregated into a meta-analysis (this is the CancerChoices definition; other researchers and studies may define this differently) of lower risk of proximal colon cancer, but only among people with high fruit intake or Healthy Eating Index scores, among people eating the highest levels of foods with quercetin, including tea

Gastrointestinal cancer

Preliminary evidence of lower risk of gastric adenocarcinoma among people eating foods with the highest levels of quercetin, with stronger effects for female smokers

Gynecological cancer

Weak evidenceone or more case studies, supported by animal evidence OR small treatment effects of limited clinical significance OR studies with no controls OR weak trends of effects (this is the CancerChoices definition; other researchers and studies may define this differently) of lower risk of endometrial cancer among people eating the highest amounts of foods with quercetin

Ovarian cancer

No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on risk of ovarian cancer among women eating foods with higher levels of quercetin in 2 very large studies

Prostate cancer

Preliminary evidence of lower risk of prostate cancer among men with the highest intake of quercetin in foods

No evidence of an effect on prostate specific antigen (PSA) or PSA doubling time among men with elevated PSA levels treated with quercetin in a small study

Quercetin in combination with other therapies

Curcumin and quercetin: weak evidence of fewer and smaller polyps among people with familial adenomatous polyposis treated with curcumin and quercetin

Keep reading about quercetin

See all our reviews of complementary therapies

Author

Nancy Hepp, MS

Lead Researcher and Program Manager

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Reviewer

Laura Pole, RN, MSN, OCNS

Senior Clinical Consultant

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Last update: March 26, 2023

Last full literature review: January 2023

We are grateful for research assistance from Adriana Rocio Gutierrez Galvis and Ma Victoria Acuña.

CancerChoices provides information about integrativein cancer care, a patient-centered approach combining the best of conventional care, self care, and evidence-informed complementary care in an integrated plan cancer care. We review complementaryin cancer care, complementary care involves the use of therapies intended to enhance or add to standard conventional treatments; examples include supplements, mind-body approaches such as yoga or psychosocialtherapy, and acupuncture therapies and self carelifestyle actions and behaviors that may impact cancer outcomes; examples include eating health-promoting foods, limiting alcohol, increasing physical activity, and managing stress practices to help patients and professionals explore and integrate the best combination of conventionalthe cancer care offered by conventionally trained physicians and most hospitals; examples are chemotherapy, surgery, and radiotherapy and complementary therapies and practices for each person.

Our staff have no financial conflicts of interest to declare. We receive no funds from any manufacturers or retailers gaining financial profit by promoting or discouraging therapies mentioned on this site.

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