What is quercetin used for?
Mar 11, 2021

What is quercetin used for?

Quercetin is a plant pigment (flavonoid). It is found in many plants and foods, such as red wine, onions, green tea, apples, berries, Ginkgo biloba, St. John's wort, American elder, and others. Buckwheat tea has a large amount of quercetin. People use quercetin as a medicine.

Quercetin is most commonly taken by mouth to treat conditions of the heart and blood vessels and prevent cancer. It is also used for arthritis, bladder infections, and diabetes. But there is limited scientific evidence to support these uses.

Coronavirus disease 2019 (COVID-19): Quercetin may have benefit for some airway infections, but there is no good evidence to support using it for COVID-19. Follow healthy lifestyle choices and proven prevention methods instead.

what is quercetin used for in dogs

What is quercetin used for in dogs?

Quercetin is a plant-derived flavonoid found naturally in many fruits and vegetables, such as kale, green tea, blueberries, and broccoli. It’s technically considered a plant pigment, which is why you’ll find it in richly pigmented fruits and vegetables.

In human nutrition and wellness, quercetin is used extensively for its anti-inflammatory properties and is also thought to improve endurance and athletic performance. But in our pets, quercetin is most often used to help with the itchiness, inflammation, and discomfort caused by allergies.

It is commonly referred to as “nature’s Benadryl” due to its natural anti-inflammatory, antioxidant, and antihistamine properties. Histamine is released from inflammatory cells when our dogs are exposed to allergens and it’s part of the cause of itchy, puffy eyes and irritated, itchy skin.

What is zinc quercetin used for?

So what is missing from this viral protection plan? Zinc. Zinc is vital for immune system function. Zinc controls immune system messaging within the cells and is also an anti-oxidant (prevents cell damage) and is anti-inflammatory. In cellular lab cultures, zinc has been shown to stop viral reproducing in minutes. One study showed that zinc inhibited SARS coronavirus in test tubes. For zinc to work effectively in the body to boost immune system function, zinc has to be pushed into the cells which would require an ionophore.

An ionophore is a substance that transports particles across the cell wall barrier into the center of the cell. The center of the cell is where zinc needs to be to have the immune system effect. Viruses reproduce in the center of the cells. Zinc needs to be in the center of the cell to stop viral reproduction. An all-natural zinc ionophore is quercetin. Quercetin is a plant pigment found in red wine, onions, apples, berries and green tea. Quercetin is one of the most abundant anti-oxidants found in our diet and itself has strong anti-viral properties. The major benefit of taking quercetin with zinc is that the quercetin will push the zinc into the center of the cell where the zinc can stop the virus from reproducing.

What is quercetin used for

What is quercetin plus vitamin c used for?

Quercetin, which is considered as a health-promoting antioxidant, belongs to the broad flavonoids group. Numerous experimental studies have proved that quercetin and vitamin C provide anti-inflammatory and antioxidant properties. The aim of this study is to assess the effects of both quercetin and vitamin C on lipid profile and muscle damage in human subjects.

Quercetin and vitamin C supplementation may not be beneficial in lipid profile improvement, although it may reduce induce muscle damage and body fat percent.

Is quercetin used for allergies?

Available research indicates that quercetin is a very effective treatment for allergic rhinitis. Studies have found that taking quercetin for at least 5 consecutive days can minimize instances of sneezing, and significantly reduce nasal itching, helping sufferers to live a more comfortable life.

Is quercetin used for interstitial cystitis?

Interstitial cystitis (IC) is a disorder of unknown etiology with few effective therapies. Oral bioflavonoid therapy utilizing quercetin recently proved to be clinically effective in men with chronic pelvic pain syndrome, a disorder with similarities to IC. We therefore tested in an open-label trial a quercetin-based supplement in patients with clinically proven IC.

quercetin food

Quercetin Foods

Foods with Quercetin

Quercetin is one of the most common flavonoids, and is present in many foods. It also appears in red wine, black tea, and green tea. When you get your quercetin from fruits and vegetables, you reap the other benefits of those foods. You also increase your intake of fiber, which is lacking in the standard American diet.

Quercetin is available as a supplement, often with a recommended dose of 500-1,000 mg per day. It’s considered safe to use, but may interact with several medications, including antibiotics and blood thinners. Doses over one gram may damage the kidneys.

There's no recommended daily allowance for quercetin, but these commonly eaten foods are good sources of it:

1. Onions

All onions contain quercetin, but since it's a pigment, red and yellow onions contain the most. To keep the quercetin, peel off as little as possible of the outer layers. Onions contain many other vitamins and minerals, and they are especially rich in the vitamin biotin.

2. Kale

Kale has a well-deserved reputation as a nutritional powerhouse. Besides quercetin, it’s also a rich source of vitamin A, vitamin C, and fiber. Half a cup contains only 18 calories.

3. Cherry tomatoes

All tomatoes are good sources of quercetin. Cherry tomatoes are the best because they have the highest ratio of skin to flesh. They make a great low-calorie snack, with only 37 calories per dozen.

4. Broccoli

Along with quercetin, broccoli is rich in vitamin K and vitamin C. It also contains another flavonoid, kaempferol, that offers potent antioxidant capabilities. A one-cup serving provides 5 grams of fiber.

5. Blueberries

Blueberries are antioxidant superstars. On top of quercetin, they contain 17 different phytochemicals including resveratrol, the antioxidant best known for appearing in red wine.

6. Apples

Apples contain four different phytochemicals along with the beneficial fiber known as pectin. To get the benefits of quercetin, eat your apples unpeeled. Apple juice doesn’t provide the same benefits as the whole fruit.

quercetin benefits

Quercetin Benefits

1. Fighting free radicals

Quercetin has antioxidant properties.Antioxidants work to protect the body from free radicals. Free radicals are unstable molecules in the body that can increase the risk of disease and quicken aging.

Many different factors can contribute to more free radicals, including:

  • pollution

  • cigarette smoke

  • radiation

  • chemical toxins

  • greenhouse gases

  • Quercetin is a more powerful antioxidant than vitamin C, vitamin E, or beta carotene.

2. Reducing inflammation

Inflammation is the body’s natural response to stress and injuries and usually helps the body heal. However, chronic inflammation can be harmful to the body and may contribute to certain health conditions.

However, quercetin might help reduce inflammation. One study on animals found that quercetin prevented both acute and chronic inflammation, in addition to showing anti-arthritis properties.

Results from human studies have provided mixed results, however. While research on healthy male athletes found that quercetin could reduce inflammation, it did not have the same effect in women with rheumatoid arthritis.

3. Reducing the risk of cancer

Quercetin occurs naturally in onions.

Quercetin may contain anticancer properties that might help prevent the spread of cancerous cells and tumor growth.

Research has shown that a diet high in flavonoids, such as quercetin, can help prevent cancers. Fruits and vegetables are full of flavonoids, so increasing intake of these foods might reduce the risk of many types of cancer.

A 2015 report found that quercetin restricted the growth of prostate cancer cells in mice and rats.

A 2018 in vitro study indicated that quercetin showed promise in both the treatment and prevention of prostate cancer. In vitro means the researchers performed the experiment outside of a living thing, for example, in a test tube.

Researchers still need to find out more about the anticancer properties of quercetin in humans and to ensure the body can absorb high doses of quercetin effectively.

4. Preventing neurological diseases

Quercetin may help to prevent neurodegenerative diseases, such as Alzheimer’s or Parkinson’s disease.

Oxidative stress contributes to the development of neurodegenerative diseases. Oxidative stress occurs when there is an imbalance of free radicals in the body. The antioxidant properties of quercetin may help fight free radicals.

Research on rats showed that quercetin could protect against oxidative stress. It also showed quercetin could protect against the toxic effect of certain metals on the nervous system.

5. Relieving allergy symptoms

Research suggests that quercetin might be an effective antihistamine, as it restricts histamine from being released from cells.

These anti-allergy properties indicate that quercetin might help treat bronchitis and asthma.

6. Preventing infections

Quercetin has antibacterial properties, which are effective against almost all types of bacteria, particularly those linked to:

stomach and intestines




Quercetin, along with other flavonoids, might help fight off viruses, such as:


herpes simplex virus

Japanese encephalitis

respiratory syncytial virus

7. Reducing the risk of heart disease

Diet plays an essential role in reducing the risk of cardiovascular diseases, such as heart disease and strokes. Because fruit and vegetables contain flavonoids, eating more of them can reduce the risk of these diseases.

Quercetin may improve blood vessel cell health and blood flow through arteries in people with heart disease.

8. Lowering high blood pressure

According to a 2016 study by the American Heart and Stroke Association, taking quercetin supplements could be an effective way to reduce blood pressure.

Other research showed that people who were overweight and took a quercetin supplement of 150 milligrams (mg) per day had lower levels of harmful cholesterol in their blood, as well as reduced systolic blood pressure, which measures the pressure in the blood vessels during a heartbeat.

Quercetin Covid

In cell cultures, quercetin has been shown to prevent viral entry and reduce the cytopathic effects of many viruses, including rhinovirus and poliovirus. In a 2016 animal study, rodents administered quercetin before being exposed to a lethal load of Ebola virus survived.

COVID-19 has been associated with high levels of interleukin-6, depleted levels of interferons, and a cytokine storm that damages the body and is related to respiratory failure, said Ruben Colunga Biancatelli, MD, of Old Dominion University in Norfolk, Virginia, and first author of a paper on quercetin and vitamin C as a potential therapy for treating SARS-CoV-2 in Frontiers in Immunology.

Using this rationale, researchers are postulating that vitamin C should be administered with quercetin because it can recycle oxidized quercetin, producing a synergistic effect and enhancing quercetin's antiviral capability, Biancatelli added.

After the 2003 SARS-CoV-1 coronavirus outbreak, researchers in China found quercetin and other small molecules bound to the spike protein of the virus, interfering with its ability to infect host cells.

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