What is Quercetin? How Much You Need and Where to Find It

Quercetin is a plant pigment that belongs to a group of plant compounds known as flavonoids and has antioxidant and anti-inflammatory effects. The antioxidant properties in this plant pigment protect our body from cellular damage and support cardiovascular health, blood circulation and the immune system. It may be beneficial for treating medical conditions like hay fever, asthma, heart disease, hypertension, allergies, high cholesterol, cancer and inflammatory disorders like prostatitis, interstitial cystitis and rheumatoid arthritis.

Let us understand why quercetin is important for us and how can we maintain our health effectively with the help of this flavonoid.

What is Quercetin?

Quercetin is most commonly present in broccoli, apples, grapes, berries, onions, citrus fruits, green tea, red wine, grains and capers. It is often linked to health benefits like reducing the risk of heart disease, degenerative brain disorders and cancer.

Antioxidants are compounds in our bodies that can neutralize free radicals which may cause cellular damage. Quercetin functions as an antioxidant inside our bodies and may prevent the cellular damage caused by free radicals.

Like other flavonoids, quercetin may have anti-inflammatory properties which prevent chronic inflammation and clear out dangerous free radicals from the body. You can gain the potential antioxidant and anti-inflammatory benefits of quercetin through natural sources. However, if not possible to do the same, this flavonoid is also available as a supplement in powder form and as a capsule.

Sources and Dosage of Quercetin

Quercetin is found naturally in plant-based foods and is present particularly in the outer layer of these foods or the peel of fruits.

Plant-based sources of quercetin include −

  • Capers

  • Peppers (yellow and green)

  • Shallots

  • Onions (red and white)

  • Cooked asparagus

  • Tomatoes

  • Broccoli

  • Peas

  • Kale

  • Red leaf lettuce

Quercetin can also be found in fruits like −

  • Cherries

  • Berries

  • Red apples

  • Grapes

  • Citrus fruits

Along with the above-mentioned sources, quercetin can also be found in green tea, coffee, and red wine. The amount of quercetin in foods may vary as per the conditions in which the food was grown.

Quercetin Supplements

Quercetin had a low bioavailability and hence, your body may not absorb it properly. This is when quercetin supplements can help you which are also inclusive of other compounds like vitamin C and digestive enzymes like bromelain to increase its absorption. Quercetin supplements are available in powder form and as a capsule. These can be purchased online or from health food stores.

Quercetin supplements may interact with certain medications and may not suit everyone. When consumed in food, quercetin is safe for pregnant and breastfeeding women, but when it comes to taking quercetin supplements, you must always consult a doctor before taking them.

Quercetin Dosage

The typical dosage of quercetin can range from 250 to 1,000 milligrams per day. Doctors may prescribe quercetin supplements for adults as 1 gram daily for up to 12 weeks at a time. Quercetin when consumed from natural sources is safe. Also, as a supplement, it is usually safe, but taking more than 1000 mg of quercetin per day may cause mild side effects like headache, tingling sensation or stomach ache in certain individuals.

Health Benefits of Quercetin

As quercetin acts as an antioxidant in our body, in general, it may contribute to treating many ailments and diseases. May reduce inflammation

High levels of free radicals may activate genes that promote inflammation. Persistent inflammation is often associated with cardiovascular and kidney diseases as well as certain types of cancer. Quercetin may reduce the markers of inflammation and thus act as a cardio protective. Research has also shown that the anti-inflammatory properties of quercetin may protect our bodies against oxidative stress, endothelial cell dysfunction and atherosclerosis. In rheumatoid arthritis, quercetin may reduce early morning stiffness, morning pain and after-activity pain.

May Lower Blood Sugar

Quercetin may promote blood sugar management in the body and is thereby determined safe for diabetes management. Quercetin may modulate glucose levels, improve glucose metabolism and enhance insulin function. Thus, it could be considered an important factor in potential diabetes therapy.

May Prevent Cancer

Because of its antioxidant properties, quercetin may have cancer-fighting properties. This flavonoid may suppress cell growth and induce cell death in the prostate, liver, lung, breast, bladder, colon, adrenal, ovarian, colon and lymphoid cancer cells. It may thus be recommended as an alternative treatment for certain cancers.

May Ease Allergies

Quercetin found in many sources may act as a mast cell stabilizer which supports in easing the symptoms of allergies. Quercetin may block enzymes responsible for inflammation and suppress inflammation-promoting chemicals like histamine. This may provide allergy symptom relief.

May Lower the Risk of Chronic Brain Disorders

Quercetin-rich diet may reduce markers of degenerative brain disorders like Alzheimer's disease and dementia. Moreover, research shows that quercetin present in coffee may protect against the effects of Alzheimer's.

May Reduce Blood Pressure

High blood pressure puts you at risk of heart disease and many other health problems. Research has shown a positive effect on systolic and diastolic blood pressure values after consuming 500 mg of quercetin in supplement form daily. However, it is important to consult your healthcare provider before adopting a quercetin supplement as an alternative therapy for high blood pressure.

Some of the other potential health benefits of quercetin may include improved endurance in exercise performance and rejuvenating ageing cells to combat premature ageing. Quercetin may support the functioning of the immune system, but there is currently no evidence that quercetin supplements can be used to treat or prevent Covid-19.

Side Effects of Quercetin

If have kidney problems or estrogen-dependent cancer or are currently on certain prescribed drugs like antibiotics and blood pressure medicines, you should always consult your doctor before taking quercetin supplements. These supplements may make certain medications less effective as they interact with certain drugs. Anti-diabetes and anti-hypertensive medications may interact with quercetin supplements.

Furthermore, drugs like cyclosporine, diclofenac, pravastatin, warfarin, midazolam, quetiapine, certain herbs and quinolone antibiotics may also interact with quercetin supplements and hence, if you are currently taking any of these medicines, consult your doctor before taking quercetin supplements.


Due to its antioxidant and anti-inflammatory properties, it's ideal to eat foods containing quercetin. As this flavonoid is readily available in plant foods, fruits and other sources like tea, coffee or red wine, you can maintain your health naturally. However, if your doctor recommends quercetin supplements as per your medical condition, you can buy them online or at any health food store.