Holistic Health Supplements The Health Benefits of Quercetin The flavonoid may help to reduce blood pressure By Cathy Wong facebook twitter Cathy Wong is a nutritionist and wellness expert. Her work is regularly featured in media such as First For Women, Woman's World, and Natural Health. Learn about our editorial process Cathy Wong Medically reviewed by Medically reviewed by Arno Kroner, DAOM, LAc on July 08, 2020 facebook twitter linkedin Arno Kroner, DAOM, LAc, is a board-certified acupuncturist, herbalist, and integrative medicine doctor practicing in Santa Monica, California. Learn about our Medical Review Board Arno Kroner, DAOM, LAc on July 08, 2020 Print Verywell / Anastasia Tretiak Table of Contents View All Table of Contents Health Benefits Possible Side Effects Dosage and Preparation What to Look For Quercetin is a chemical found naturally in a number of foods including apples, onions, teas, berries, and red wine. This flavonoid is also found in some herbs such as ginkgo biloba and St. John's wort. Quercetin acts as an antioxidant, neutralizing free radicals—the chemical by-products that harm cell membranes and damage DNA. Available as a dietary supplement, quercetin also possesses antihistamine and anti-inflammatory properties. Health Benefits In alternative medicine, quercetin is said to help with the following conditions: AllergiesCardiovascular diseaseInflammationColds So far, results to support the benefits of quercetin are mixed—with some conditions examined only in test tubes or on animals. Here's how the research shakes out: Allergy Relief Quercetin is thought to prevent the release of histamine—an inflammatory chemical involved in allergic symptoms such as sneezing and itching—from certain immune cells. Although lab experiments suggest that quercetin may help fight allergic conditions like allergic rhinitis, most have been performed in vitro or in animals. Researchers recommend further studies on humans to prove a correlation. High Blood Pressure A 2016 review of randomized controlled trials found quercetin significantly reduced both systolic and diastolic blood pressure, particularly in diabetics who were given at least 500 milligrams per day. It's still unclear the precise dosage and duration to see the most benefits. Athletic Endurance Quercetin may be no better than a placebo when it comes to enhancing athletic performance, according to a 2011 review of 11 previous studies. All studies showed a boost in exercise endurance via VO2 max—oxygen consumption during physical activity—when people ingested quercetin but the effect was minimal. Another study found a more impressive link. A 2013 study analyzing 60 male students who've participated in athletics for at least three years saw improved lean body mass, total body water, basal metabolic rate, and total energy expenditure after taking quercetin. Cancer Studies on cell cultures have shown that quercetin may help slow the growth of some types of cancer cells. Some in vitro and animal-based research indicates that quercetin may protect against certain types of cancer, such as leukemia and lung cancer. For example, a 2010 study looked at the relationship between quercetin intake and lung cancer risk in 38 non-tumor lung tissues and found an inverse correlation—the higher the intake of quercetin, the lower the risk. However, since there is currently a lack of human studies on quercetin's cancer-fighting effects, it's too soon to tell whether quercetin might play a significant role in cancer prevention. Possible Side Effects Quercetin is generally well-tolerated when used in appropriate amounts. Some have reported tingling in the arms and legs, as well as upset stomach and headaches when taking quercetin orally. Very high doses—greater than 1 gram per day—might cause kidney damage. Supplements haven't been tested for safety and due to the fact that dietary supplements are largely unregulated, the content of some products may differ from what is specified on the product label. Also keep in mind that the safety of supplements in pregnant women, nursing mothers, children, and those with medical conditions or who are taking medications—particularly antibiotics—has not been established. Verywell / Anastasia Tretiak Dosage and Preparation Under the care of medical supervision, quercetin has been safely used in amounts up to 1,000 mg twice daily for 12 weeks. There is not enough evidence to know if it is safe for long-term use. The appropriate dose for you may depend on factors including your age, gender, and medical history. Speak to your healthcare provider to get personalized advice if you choose to take this supplement. What to Look For Food sources of quercetin include teas, onions, apples, buckwheat, and pau d'arco. When taking quercetin in supplement form, it may be beneficial to choose a product that also contains papain and/or bromelain. These are plant-derived enzymes (fruit extracts) shown to increase the intestine's absorption of quercetin. Due to the lack of supporting research, it's too soon to recommend quercetin for any health purpose. If you're considering using it, consult your primary care provider first. Self-treating a condition and avoiding or delaying standard care may have serious consequences. Was this page helpful? Thanks for your feedback! Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit Article Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Memorial Sloan Kettering Cancer Center. Quercetin. Updated December 6, 2016. Mlcek J, Jurikova T, Skrovankova S, Sochor J. Quercetin and its anti-allergic immune response. Molecules. 2016;21(5):623. doi:10.3390/molecules21050623 Serban MC, Sahebkar A, Zanchetti A, et al. Effects of quercetin on blood pressure: a systematic review and meta-analysis of randomized controlled trials. J Am Heart Assoc. 2016;5(7). doi:10.1161/JAHA.115.002713 Kressler J, Millard-stafford M, Warren GL. Quercetin and endurance exercise capacity: a systematic review and meta-analysis. Med Sci Sports Exerc. 2011;43(12):2396-404. doi:10.1249/MSS.0b013e31822495a7 Askari G, Ghiasvand R, Paknahad Z, et al. The effects of quercetin supplementation on body composition, exercise performance and muscle damage indices in athletes. Int J Prev Med. 2013;4(1):21-6. Lam TK, Rotunno M, Lubin JH, et al. Dietary quercetin, quercetin-gene interaction, metabolic gene expression in lung tissue and lung cancer risk. Carcinogenesis. 2010;31(4):634-42. doi:10.1093/carcin/bgp334 Penn State Hershey Milton S. Hershey Medical Center. Quercetin. Updated October 19, 2015. Jin F, Nieman DC, Shanely RA, Knab AM, Austin MD, Sha W. The variable plasma quercetin response to 12-week quercetin supplementation in humans. Eur J Clin Nutr. 2010;64(7):692-7. doi:10.1038/ejcn.2010.91 Additional Reading Zhang M, Swarts SG, Yin L, et al. Antioxidant properties of quercetin. Adv Exp Med Biol. 2011;701:283-9. doi:10.1007/978-1-4419-7756-4_38