Quercetin: Health benefits, dosage, and side effects

Quercetin: Health benefits, dosage, and side effects

Quercetin is a pigment found in many plants, fruits, and vegetables. It may have some health benefits and help prevent a range of conditions.

People can get quercetin through a balanced diet or by taking a supplement.

This article details the possible benefits of quercetin. It also looks at the potential side effects.

What is quercetin?

Close up of grapes which contain Quercetin
Grapes contain quercetin.

Quercetin is a flavonol, which is a sub-category of flavonoids.

Flavonoids are a particular chemical in plants, called phytonutrients, and have a wide range of health benefits.

Humans cannot make quercetin in their body, but many fruits, vegetables, and drinks contain it.

Foods and drinks that contain quercetin include:





citrus fruits






red wine

black tea

Quercetin is also present in herbal remedies, such as ginkgo biloba and St John’s wort. People can also take quercetin as a supplement.

Quercetin is one of the most common and well-researched flavonoids.

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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.


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