Quercetin Benefits for Immune Health

Curious about antioxidants and immunity? Quercetin is a plant flavonoid with antioxidant activity that has drawn research interest for immune and allergy support.

Most of the evidence so far comes from lab, animal, and small human studies, so quercetin has not been shown to prevent or treat colds, allergies, or any disease. Read on to learn what quercetin is, what the research says, and which supplement we like.

What is Quercetin?

New to quercetin? You’re not alone. This flavonoid isn’t the most well-known dietary supplement, and its benefits in people are still being studied.

Quercetin is a plant pigment naturally found in foods such as onions, apples, berries, green tea, and red wine. Plant phenols like quercetin act as antioxidants in lab studies. Research on quercetin’s antiviral effects found it blocked influenza viruses in cell experiments, which does not prove the same effect in people.

Researchers are studying quercetin for allergy symptoms like watery eyes and runny nose, but good human trials are limited. It is not a substitute for allergy medicine, an inhaler, or a doctor’s care for breathing problems.

Recommended Quercetin Dosage

Foods supply small amounts of quercetin, while supplements provide much more. A 12-week study gave adults 500 to 1,000 milligrams of quercetin per day and found blood levels rose, though very unevenly from person to person.

There is no official recommended dose. A safety review found side effects in human studies were rare and mild, but long-term data on doses of 1,000 mg or more beyond 12 weeks are lacking.

The same review flags possible concerns for people with kidney disease or estrogen-sensitive cancers, and notes quercetin can change how some drugs are absorbed. Ask your doctor or pharmacist before taking it, especially if you are pregnant, breastfeeding, or on prescription medicine.

Supplements often pair quercetin with vitamin C. That pairing is popular, but there is little evidence that it fights infections better than either nutrient alone.

Quercetin is also sold alongside other plant compounds like resveratrol, catechins, and genistein. These are being studied for effects on inflammation and oxidative stress, but none is proven to strengthen immunity.

Best Quercetin Supplement

Pure Encapsulations Quercetin

Pure Encapsulations makes a simple quercetin supplement. According to the label, it contains only these ingredients:

• Quercetin
• Hypoallergenic plant fiber
• Vegetarian capsule

We like this quercetin supplement for its short ingredient list. Keep in mind that the FDA does not approve dietary supplements before they are sold, so claims about heart health, blood pressure, or blood sugar have not been reviewed by the agency.

Label directions: Follow the dose on the current product label, and check with your clinician first.

Quercetin for Colds, Allergies, and Beyond!

Quercetin is a promising plant compound, but it is not proven to clear airways, stop allergies, or prevent colds. A diet rich in fruits and vegetables already provides some quercetin along with many other nutrients.

If you want to try a supplement, talk with your clinician first, especially if you take other medicines. See a doctor for a cough, fever, or allergy symptoms that don’t improve. Check out a health food store for the best natural supplements to boost your immunity.

Sources

• Safety Aspects of the Use of Quercetin as a Dietary Supplement, Molecular Nutrition & Food Research (PubMed)
• Quercetin as an Antiviral Agent Inhibits Influenza A Virus Entry, Viruses (PMC)
• Questions and Answers on Dietary Supplements, FDA