Supplements 101: What is Quercetin?

What is Quercetin?

Quercetin is a type of antioxidant called a flavonol, which is part of the flavanoid family. Flavonol is found in plant-based foods, such as red wine, tea, and coffee, as well as onions, broccoli, citrus fruits, dark cherries, dark berries (blueberries, blackberries, and bilberries), apples, and buckwheat.  

Quercetin is gaining popularity as a natural therapy for a variety of health conditions. Here is just the tip of the iceberg for potential uses of quercetin: 

Allergies, Asthma, Hay Fever and Hives

In test tubes, quercetin prevents immune cells from releasing histamines, chemicals that cause allergic reactions. On that basis, researchers think quercetin may help reduce symptoms of allergies, including runny nose, watery eyes, hives, and swelling of the face and lips. However, there is no evidence yet that it works in humans (1).

Metabolic Syndrome

A new study in rats suggests quercetin may help patients with Metabolic Syndrome (2). This condition is characterized by central obesity (excessive fat tissue in and around the abdomen), increased blood pressure, and insulin resistance (the body can’t properly use insulin or blood sugar).

Lung Health after Exercise

Other quercetin research has shown short-term quercetin use may be an effective strategy to lessen the impact of stressful exercise on people susceptible to respiratory infection (3). 


Numerous studies have been done on quercetin and blood pressure. These studies indicate quercetin supplementation decreases blood pressure in stage I hypertensive individuals (4).

Prostate pain and inflammation

Quercetin’s role in inhibiting the onset/growth of prostate cancer is currently being studied and progress is being made. One study found a 27% risk reduction of prostate cancer for those who consume at least 24 µg of quercetin a day (5). Taking quercetin seems to reduce pain and improve quality of life, but doesn’t seem to help urination problems in men with ongoing prostate problems that aren’t due to infection (6). 


An April 2013 study conducted on 26 badminton players for eight weeks showed quercetin may improve endurance exercise performance (7). Another study done on 60 male athletes found supplementation with quercetin and vitamin C for 8 weeks reduced muscle damage (8).


Quercetin was shown to inhibit tumor growth and therefore may possibly be a potential drug candidate for cancer therapy (9).


Quercetin is generally considered safe, but be cautious about taking quercetin with some types of medications, such as blood thinners. Always check with your health care provider prior to starting a new supplement.

In Health and Happiness,

Kelly Harrington, MS, RDN

Registered Dietitian Nutritionist for Healthy Goods


1.  Lee EJ, Ji GE, Sung MK.  Quercetin and kaempferol suppress immunoglobulin E-mediated allergic inflammation in RBL-2H3 and Caco-2 cells.  Inflamm Res.  2010 Oct;59(10):847-54.

2.  Panchal SK, Poudyal H, Brown L.  Quercetin ameliorates cardiovascular, hepatic, and metabolic changes in diet-induced metabolic syndrome in rats.

3.  Davis JM, Murphy EA, McClellan JL, Carmichael MD, Gangemi JD.  Quercetin reduces susceptibility to influenza infection following stressful exercise.  Am J Physiol Regul Intergr Comp Physiol.  2008 Aug;295(2):R505-9.

4.  Edwards RL, Lyon T, Litwin SE, Rabovsky A, Symons JD, Jalili T.  Quercetin reduces blood pressure in hypertensive subjects.  J Nutr.  2007 Nov; 137(11):2405-11.

5.  McCann SE, Ambrosone CB, Moysich KB, et al. Intakes of selected nutrients, foods, and phytochemicals and prostate cancer risk in Western New York.  Nutrition and Cancer. 2005;53(1):33–41.

6.  Wang G, Song L, Wang H, Xing N.  Quercetin synergizes with 2-methoxyestradiol inhibiting cell growth and inducing apoptosis in human prostate cancer cells.  Oncol Rep.  2013 Jul;30(1):357-63.

7.  Daneshvar P. et al.  Effect of eight weeks of quercetin supplementation on exercise performance, muscle damage and body muscle in male badminton players.  Int J Prev Med.  2013 Apr;4(Suppl 1):S53-7.

8.  Askari G. et al.  Does quercetin and vitamin C improve exercise performance, muscle damage, and body composition in male athletes?  J Res Med Sci.  2012 Apr;17(4):328-31.

9.  Pratheeshkumar P, et al.  Quercetin inhibits angiogenesis mediated human prostate tumor growth by targeting VEGRF-2 regulated AKT/mTOR/P70S6K signaling pathways.  PLoS One.  2012;7(10):e47516.

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