Red onions. Green leafy kale. Garlic and tomatoes. What do these veggies have in common? Bioflavonoids, members of the antioxidant family with loads of healthful benefits. You’ll also find them in fruits, too. That’s why getting several servings a day is so good for you!  

Quercetin is one of those helpful bioflavonoids you need to know about. It quenches specific biochemical agents that incite inflammation and provoke reactions to pollen, trees, grasses, ragweed, mold spores and environmental pollutants. Being indoors doesn’t protect you either. There’s formaldehyde in carpets and furniture, pet dander and the most common allergen, dust mites. 

What is an allergen? Tiny substances in food, water, plants, air and other materials that your immune system raises a red flag as being a threat. Like skin contact with allergens in poison ivy and oak that cause hives and intensely itchy skin. Most allergens are airborne and involve the respiratory tract. Symptoms of a runny or stuffy nose, scratchy throat, wheezy cough and even difficulty breathing. Eyes that water, feel irritated and are sensitive to light. Severe reactions may require the use of an injectable device that delivers a dose of epinephrine. The drug rapidly open blood vessels and airways to prevent a drop in blood pressure and anaphylactic shock. Thankfully, most reactions are more annoying than life threatening.

Avoiding the offending allergen is your best defense to reduce an allergen “attack”. Check local pollen, tree and grass reports for your environmental irritants. Air quality also affects respiratory health. Close doors and windows during your peak allergy season. Food can be an allergen source for some. You may need allergy testing to help you find your particular allergens to help avoid or reduce them.

Quercetin is well known in its ability to intercept specific immune mast cells. These  cells are “sentinels” for the immune system that watch out for invading pathogens and allergens. Mast cells release histamine, a chemical that helps flush out the “invader” and causes the sneezing, sniffling and stuffy symptoms associated with allergies. Quercetin also interferes with prostaglandins, hormone-like substances that incite inflammation and swelling. Like many bioflavonoids, quercetin is target specific, aiming its  antioxidant activity to the upper respiratory system where most allergy symptoms occur.

About 1 in 3 Americans have some form of allergies, evidenced by the rows of remedies you’ll find in any local drug store. Sufferers reach for antihistamines to calm the “attack” and decongestants to open airways. Prescription medications are also available taken when allergies are most severe. What about quercetin?

There’s much research on quercetin. In a 2016 review, Mlcek and colleagues state allergic disorders (skin, food and respiratory) have been increasing rapidly for three decades. Thus, “there is a need for new, bioactive compounds” with a focus on bioflavonoids, especially quercetin. Its “anti-allergic mechanism of action through the inhibition of enzymes and inflammatory mediators has also been extensively studied”. They conclude that the “results of the studies prove a unique position of quercetin in the treatment of allergic disorders”. Another published review in 2024 led by Dr. Vishakha looked at quercetin to “explore the therapeutic potential and clinical efficacy “. They reviewed data from “PubMed, Science Direct, ClinicalTrails. gov, and from many reputed foundations”. They concluded: “the results of the studies prove the unique position of quercetin in the treatment of various disorders”. They further state “as evidenced by the numerous published reports on human interventions …quercetin intake significantly improves disease conditions with minimal adverse effects”. Per the reviews, quercetin is effective and safe! 

Study subjects took 500 mg once or twice a day. That’s why most supplements are available in 500 mg doses. Getting enough from fruits and veggies will be difficult as they are not high in quercetin content and the average American does not consume enough of them. A bunch of dark red grapes or bowl of broccoli offers 3 mg and small red onion about 40 mg. Quercetin is also water soluble so it is not stored in the body, which means consistent, daily use is needed to maintain systemic levels. Quercetin does not act as quickly as drugs do. Give it time to “work” and consider taking it 4-6 weeks before allergy season. 

Quercetin is often paired with bromelain, an enzyme from pineapple that supports quercetin’s activity. Bromelain is proteolytic, meaning it clears out cellular debris to help cellular function and health. 

Taking proactive steps may lessen and even eliminate the sneezing, sniffling, reach-for-the-tissues reactions before they gets out of control. Keeping your immune system healthy is a must. One more note on quercetin. Due to its antioxidant role in quenching inflammation, studies include benefits for heart and brain well-being, too. Quercetin is really your year round health helper! 

RESOURCES

1. National Institutes of Health,www.niaid.nih.gov/publications/ allergies.htm
2. American Academy of Allergy, Asthma & Immunology.  www.aaaai.org
3. American College of Allergy, Asthma & Immunology.  www.acaai.org
4. PDR for Health. www.pdr.health.com
5. Herb Research Foundation (member research materials)
6. Mleck J  et al. Quercetin and its Anti-Allergic Immune Response, Molecules 2016, 21, 623.
7. Vishakha D et al. Therapeutic Potential and Clinical Effectiveness of Quercetin: A Dietary Supplement. Recent Adv. Food, Nutr. Agric.V15, Iss.1.

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