Quercetin
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.
Quercetin at a glance
The flavonoid quercetin is found in several foods.
- Apples
- Black, green, and buckwheat tea
- Onions
- Red grapes
- Cherries
- Raspberries
- Citrus fruits
- Broccoli
- Coffee
- Red wine
- Capers
Quercetin is also found in some medicinal plants such as ginkgo biloba and St. John’s Wort, and it is available as a supplement.
As a natural antioxidanta molecule that can cause a free radical molecule to stabilize and become less reactive; an antioxidant can reduce harmful oxidation from free radicals, quercetin’s main benefit related to cancer is better body terrain, and especially lower inflammation. People eating higher levels of quercetin in foods may have lower risks of some types of cancer.
CancerChoices ratings for quercetin
We rate quercetin on seven attributes, with 0 the lowest rating and 5 the highest.
See how we evaluate and rate complementary therapies ›
Improving treatment outcomes
See More- 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
- See How can quercetin help you? What the research says ›
Optimizing your body terrain
See More- 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 treated with quercetin
- 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 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 HbA1c levels or a marker of insulin resistancea condition in which cells in your muscles, fat, and liver don’t respond well to insulin and can’t efficiently take up glucose from your blood for energy, among people with metabolic syndrome and related disorders treated with quercetin
- 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 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)
- No evidence of an effect on measures of body weight among overweight or obese people 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
- See How can quercetin help you? What the research says ›
Managing side effects and promoting wellness
See More- 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 incidence of oral mucositisinflammation and ulceration of the mucous membranes lining the digestive tract, usually as an adverse effect of chemotherapy and radiotherapy treatment for cancer among people with blood malignancies treated with quercetin
- 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 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 less pain and joint stiffness among women with rheumatoid arthritis (not specific to cancer) treated with quercetin
- See How can quercetin help you? What the research says ›
Reducing cancer risk
See More- 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
- 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
- Preliminary evidence of lower risk of gastric adenocarcinoma among people eating foods with the highest levels of quercetin, with stronger effects for female smokers
- 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
- 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
- See How can quercetin help you? What the research says ›
Use by integrative oncology experts
See More- Not mentioned in integrative cancer clinical practice guidelines
- Used in several of our program sources
- Used in traditional Chinese medicine treatments
- See How do experts use quercetin? ›
Safety
See More- Quercetin showed few and generally mild side effects in clinical trials.
- Quercetin may interact with some prescription drugs; moderate caution is needed and supervision by a medical professional is highly recommended by anyone taking these drugs.
- An increased risk of distal colon cancer is seen among people with low levels of fruit intake eating the highest levels of foods with quercetin.
- See Safety and precautions ›
Affordability and access
See More- Widely available without restriction
- Generally inexpensive (less than $500 US/year)
- See Affordability and access ›
Keep reading about quercetin
Author
Ms. Hepp is a researcher and communicator who has been writing and editing educational content on varied health topics for more than 20 years. She serves as lead researcher, program manager, and writer for CancerChoices. Her graduate work in research and cognitive psychology, her master’s degree in instructional design, and her certificate in web design have all guided her in writing and presenting information for a wide variety of audiences and uses. Nancy’s service as faculty development coordinator in the Department of Family Medicine at Wright State University also provided experience in medical research, plus insights into medical education and medical care from the professional’s perspective.
Reviewer
Laura Pole is senior clinical consultant for CancerChoices. Laura is an oncology clinical nurse specialist who has been providing integrative oncology clinical care, navigation, consultation, and education services for over 40 years. She is the co-creator and co-coordinator of the Integrative Oncology Navigation Training at Smith Center for Healing and the Arts in Washington, DC. Laura also manages the “Media Watch Cancer News That You Can Use” listserv for Smith Center/Commonweal. In her role as a palliative care educator and consultant, Laura has served as statewide Respecting Choices Faculty for the Virginia POST (Physician Orders for Scope of Treatment) Collaborative as well as provided statewide professional education on palliative and end-of-life care for the Virginia Association for Hospices and Palliative Care.
For CancerChoices, Laura curates content and research, networks with clinical and organizational partners, brings awareness and education of integrative oncology at professional and patient conferences and programs, and translates research into information relevant to the patient experience as well as clinical practice.
Laura sees her work with CancerChoices as a perfect alignment of all her passions, knowledge and skills in integrative oncology care. She is honored to serve you.
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.