Nutrition

What Is Quercetin? Foods, Benefits, Dosage and Side Effects

What is Quercetin?

 Quercetin is the most abundant natural pigment found in plants. It is an antioxidant flavonoid that protects your cells from unstable reactive molecules. (1)

The best sources of quercetin are:

  • Onions
  • Apples
  • Asparagus
  • Red leaf lettuce
  • Tomatoes
  • Broccoli
  • Peppers
  • Peas
  • Grapes
  • Cherries
  • Berries
  • Apples
  • Tea
  • Coffee
  • Red wine

 Possible Health Benefits of Quercetin

Quercetin protects you from these cells. Damage to your cells caused by reactive molecules is linked to chronic disease and illnesses such as high blood pressure, heart disease, inflammation, diabetes, dementia and some cancers.(2)

May lower inflammation related to chronic disease:
When your cells are damaged your immune system kicks in and causes inflammation. Studies have shown that quercetin protects your cells from damage and may stop or slow the release of several inflammatory cells.  (4)(5)(6)

May help lower blood pressure and heart disease risk:
Studies have shown that quercetin not only has blood pressure lowering effects, but can also help your arteries pump blood out of your heart. (7)(8)(9)

Lower risk for developing chronic brain disorders (Alzheimer’s and dementia):
Research suggests that quercetin protects your brain cells from damage and can enhance brain cell energy so they function correctly.(10)

It may have anticancer properties:
High levels of inflammation have been linked to some cancers. Quercetin has strong anti-inflammatory effects and several studies found direct anticancer and antitumor effects.. (7)(11)(12)

May slow the aging process and prevent skin damage:
UV-rays from the sun can increase oxidative stress in skin cells which lead to wrinkles and dark spots. Quercetin is a potent antioxidant and may help prevent premature aging in skin. (11)

May help reduce allergy symptoms:
Research suggests it stimulates the immune system, has antiviral activity, and stops your body from releasing histamine and inflammation causing immune cells. (12)

Summary: The antioxidant effects of quercetin may help lower inflammation throughout the body. Lower inflammation and less oxidative stress is linked to a reduced risk of developing heart disease; cancer; dementia or Alzheimer’s Disease. It may also help slow the aging process and reduce allergy symptoms. 

Dose and Possible Dangers:

US adults consume approximately 14-17 mg of quercetin per day. (2) The best way to consume more quercetin is to eat lots of fruits and vegetables. Supplements can be found in doses ranging from 500-1,000 mg/day.

Quercetin is considered to be generally safe and when taken in reasonable doses, it has not shown to have any obvious toxic effects. (13) As with any supplement, it is best to speak with your healthcare provider before adding it to your diet.

Summary: It is best to consume quercetin through increasing your fruit and vegetable consumption. Supplements are available and doses range from 500-1000 mg per day. Quercetin supplements are seen as generally safe, but you should consult your doctor before adding it, or any supplement, to your diet.

Written by: Marguerite Drowica, Dietetic Intern, Hunter College

Reviewed by: Nazirber Maduro, RDN, CDN, CDCES

Nazirber Maduro is a bilingual registered dietitian and nutritionist who believes that healthy and delicious food should be enjoyed at any stage in life. She helps people transform the way they eat and find joy in food through the practice of food and lifestyle medicine.

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