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Best Quercetin Supplement

The products featured in this article have been independently reviewed by a holistic health practitioner.

Are you feeling run down and out of energy? Are you struggling with seasonal allergies or inflammation? Quercetin could be the natural solution you’re looking for. Studies have shown that this powerful antioxidant plant flavonoid boosts immunity, reduces inflammation, fights free radicals, and more.

In this article, we’ll explain what quercetin is, why you should consider taking a quercetin supplement, and how to choose the best quercetin supplement for your needs. We’ll also answer some frequently asked questions about this popular antioxidant supplement.

What Is Quercetin?

Quercetin is a naturally occurring flavonoid – a plant nutrient found in nearly all fruits, vegetables, grains, tea, wine, and other plant-based foods and beverages. Over 6,000 flavonoids have been identified across different plant sources. Some common flavonoids include quercetin, catechins, anthocyanidins, hesperidin, and rutin.

Flavonoids act as antioxidants in the body, neutralizing free radicals – unstable molecules that can damage cells. These antioxidants have anti-inflammatory, antiviral, and anticancer effects. Researchers believe flavonoids may be partly responsible for the health benefits of diets high in fruits, vegetables, teas, and wines. Increasing flavonoid intake through whole foods or supplements may help prevent chronic illnesses and diseases.

Also known as a “flavonol,” quercetin is part of a group of antioxidant compounds called polyphenols. It is considered one of the most abundant antioxidants in the human diet.

Structurally, quercetin consists of a flavone backbone with several hydroxyl groups attached. This unique chemical structure allows quercetin to neutralize free radicals and protect cells from oxidative damage.

Quercetin acts as a potent anti-inflammatory agent in the body. It helps stabilize cell membranes, regulate the immune system, and support cardiovascular health.

Natural Sources

Many healthy food sources naturally contain quercetin. The following items are notably high in quercetin content:

Fruits and Vegetables

  • • Apples – The highest nutrient concentration is in the skin, which contains 4–10 times more quercetin than the flesh.
  • • Onions – High concentrations of quercetin are found in red, yellow, and white onions.
  • • Cruciferous veggies – Broccoli, cabbage, kale, and Brussels sprouts are in this classification.
  • • Berries – Blueberries, blackberries, raspberries, and cranberries are particularly beneficial.
  • • Parsley – This vegetable is one of the best herb sources, providing over 30mg of quercetin per 100 grams.
  • • Green tea – Camellia sinensis leaves used to make green tea are high in quercetin.


  • • Buckwheat – This source is a gluten-free grain with high quercetin content.
  • • Capers – The unripened flower buds used as a seasoning contain significant quercetin.


  • • Red wine – High quercetin levels are in red grape skins, making red wine a rich source.
  • • Cocoa – The processing of cocoa powder and chocolate retains their quercetin content.
  • •Black and green olives – The skins contain a high nutrient concentration.

A diet high in fresh fruits, vegetables, teas, herbs, and other whole foods provides a healthy way to consume quercetin and other polyphenols regularly. However, research shows that typical dietary intake levels are often low. Targeted quercetin supplements can offer higher therapeutic dosages.

A History of Quercetin Supplementation

Quercetin was first isolated as a compound and identified as a component of plants in the early 20th century. Research began on its potential therapeutic properties, eventually leading to notable discoveries. In the 1970s, scientific studies demonstrated quercetin’s antioxidant and anti-inflammatory activities. These findings sparked interest in its medicinal potential.

In the 1980s, quercetin became widely available in supplement form as an over-the-counter antioxidant. Clinical trials were conducted in the 1990s, showing its bioavailability and ability to produce physiological effects in the body.

At the dawn of the 21st century, enhanced forms of quercetin, like quercetin phytosome, were introduced to improve absorption. Combinations with bromelain and vitamin C also became popular.

In the 2010s, numerous studies confirmed the key benefits of quercetin for immunity, allergies, endurance, heart health, and more. Usage increased among health-conscious consumers. In the 2020s, high-potency quercetin supplements with additional absorption enhancers have become prevalent. Quercetin gained popularity for its antiviral properties during the COVID-19 pandemic.

Today, quercetin remains one of the best-selling flavonoid supplements, widely used for its research-backed health benefits. Next-gen delivery methods continue to optimize its bioavailability. Over the past 50 years, quercetin has built up substantial scientific support and popularity as a safe and effective natural supplement.

The Potential Benefits of Quercetin Supplementation

Quercetin supplements can provide a concentrated dose of this beneficial antioxidant to promote several aspects of health:

1. Boosts immunity

Quercetin stimulates immune function and suppresses inflammation. Some research indicates it may help reduce susceptibility to illnesses like the common cold and flu.

2. Fights inflammation

Multiple studies demonstrate quercetin’s potent anti-inflammatory properties. It inhibits inflammatory enzymes and signaling pathways in the body. This can help relieve chronic inflammatory conditions.

3. Supports Heart Health

Through its anti-inflammatory and antioxidant effects, quercetin promotes cardiovascular function. It also helps relax blood vessels and may lower blood pressure.

4. May Provide Antiviral Properties

Experimental studies show quercetin can inhibit the replication of certain viruses, including hepatitis and influenza. More research is needed to confirm the effects in humans.

5. Improves Endurance

Some evidence suggests quercetin enhances athletic performance and endurance capacity by boosting mitochondria function.

6. Supports Brain Function

Quercetin appears to have neuroprotective effects. Animal studies show it may help protect against neurodegenerative diseases.

7. Relieves Allergies

Quercetin may block enzymes that release histamine, helping stabilize mast cells and easing allergy symptoms for some people. It is most effective against allergies when used as a preventative measure before allergen exposure.

8. Aids Weight Management

Research suggests that quercetin may aid weight management. One study demonstrated that ingesting the nutrient affected decreases in weight and waist, hip, and thigh measurements. More study is needed to determine how quercetin works with other factors affecting weight loss.

9. And more

A report published by Icahn School of Medicine at Mount Sinai suggests that quercetin may also prove effective in fighting high cholesterol, interstitial cystitis, prostatitis, and rheumatoid arthritis.

Advice from Angela Halderson RDN, CMST, an Integrative & Functional Nutritionist with Natural Healthy Concepts:

1. Why Take a Quercetin Supplement?

"Quercetin is a potent antioxidant found in onions, grapes and berries that has potent anti-inflammatory effects on the body. It also acts as an ionophore – meaning it helps shuttle zinc ions into the cells,” says Halderson. “Someone may want to take extra quercetin if they believe their diet is not providing them enough quercetin. Other people may be sick and need extra nutritional support that is provided from a supplement. Quercetin is commonly taken to support heart and artery health. People repairing their microbiome may also want to consider taking extra quercetin through supplementation. I will often pair zinc with quercetin for someone who has a low zinc status. This can help ensure the zinc is being absorbed into the body.”

2. Which Quercetin Supplement is Best Absorbed?

"There are many varieties of quercetin. Different manufacturing processes can add quercetin to lipids to create a 'LipoMicel' structure. This creates a closed lipid monolayer with a lipid at the very core and a polar surface, or a polar core with a lipid layer of quercetin. This can be easier for cell absorption,” Halderson says. “There is also liposomal quercetin. This is quercetin attached to a lipid bilayer. Liposomal supplements are also easier for the body to absorb. Either of these manufacturing processes also for faster uptake of the quercetin into the cell. 'Regular' quercetin which has not been enzymatically altered or turned into a liposome does take the body longer to break down and absorb. Each has their benefits for the body."

3. What Are Some Tips on How to Choose a Quercetin Supplement?

"If you are new to quercetin supplementation and showing symptoms of sickness like a sore throat, runny nose or cough you may want to reach for a liposomal or isoquercetin,” Halderson says. “These allow for quicker absorption into the body, which can help the body with acute illness. If someone is supplementing quercetin to help replete their mineral status, and is using it for longer term GI repair or heart health, I simply have them reach for regular quercetin."

Professional Supplement Picks

What are the best quercetin supplements? The following are a few of our professional picks:

Bioclinic Naturals (EMIQ Activated Quercetin)

EMIQ Activated Quercetin by Bioclinic Naturals offers a highly bioavailable form of the popular antioxidant quercetin. It uses enzymatically modified isoquercitrin (EMIQ) technology to enhance absorption in the body. Studies show EMIQ quercetin has up to 40 times greater bioavailability than regular quercetin supplements.

Each veggie capsule provides 167mg of EMIQ, delivering 50mg of pure quercetin. This is attached to sugar molecules through a natural enzymatic process, making it more soluble and easier to absorb. EMIQ Activated Quercetin also contains 50mg of vitamin C, further boosting quercetin absorption when taken together.

This professional-grade product adheres to strict quality standards. It is manufactured in an NSF-certified facility and is non-GMO, gluten-free, and vegan. Suggested use is 1–2 capsules daily or as recommended by a health professional. EMIQ Activated Quercetin provides antioxidant and immune support, especially during seasonal changes. It’s an excellent option if you’re looking for a highly bioavailable quercetin supplement.

  • • Form: Veg capsules
  • • Dose: 1 capsule daily
  • • Servings per container: 60 servings

Pure Encapsulations (Quercetin)

Quercetin by Pure Encapsulations is a high-potency 500 mg quercetin supplement made with hypoallergenic ingredients. As a natural plant pigment and phytoestrogen, quercetin provides antioxidant support and helps maintain healthy histamine levels. This makes it an excellent option for seasonal allergy relief.

Each serving of two veggie capsules provides 500mg of pure quercetin. This powerful antioxidant helps scavenge free radicals while supporting healthy inflammation pathways. Quercetin helps maintain cellular, cardiovascular, immune, and estrogen health.

Produced by the reputable supplement brand Pure Encapsulations, this product adheres to strict quality standards. It is free of GMOs and common allergens like gluten. The suggested usage is two capsules, 1-2 times daily between meals. For those seeking natural allergy relief, Pure Encapsulations Quercetin is a great way to get a concentrated daily dose of this beneficial plant flavonoid.

  • • Form: Veg capsules
  • • Dose: 2 capsules, 1–2 times daily, between meals
  • • Servings per container: 120 capsules, 60 servings

Bluebonnet (Super Quercetin)

Super Quercetin produced by Bluebonnet delivers a powerful blend of quercetin with absorption-boosting cofactors. Each 2-capsule serving provides 500 mg of quercetin and 500 mg of vitamin C to enhance bioavailability.

This formula also contains bromelain, rose hips, acerola cherry, citrus bioflavonoids, hesperidin, and rutin. Together, these ingredients provide antioxidant support to help maintain immune function. The high 500 mg quercetin dosage also promotes seasonal wellness.

Produced by the reputable supplement brand Bluebonnet, Super Quercetin is vegan, gluten-free, non-GMO, and Kosher. The suggested use is two vegetable capsules daily. For those seeking targeted immune support, Bluebonnet’s Super Quercetin provides an evidence-based blend of quercetin and botanicals.

  • • Form: Veg capsules
  • • Dose: 2 capsules daily
  • • Servings per container: 90 capsules, 45 servings

Frequently Asked Questions

Which quercetin supplement is best absorbed?

The bioavailability of quercetin depends on the form in which it is ingested. Here are some key considerations when choosing a quercetin supplement for optimal absorption:

  • • Quercetin aglycone – This form of quercetin consists of the quercetin molecule without attached sugar groups.

  • • Quercetin phospholipids – Attaching quercetin molecules to sunflower-derived phosphatidylcholine significantly improves absorption compared to regular quercetin. These lipid-bound forms help boost bioavailability.

  • • Enzyme-treated quercetin – Some supplements use enzymatically modified isoquercitrin (EMIQ) technology to break down quercetin from plant sources into smaller molecules. This process helps increase absorption rates in the digestive tract.

  • • Quercetin with vitamin C – Taking quercetin along with vitamin C has been shown in studies to enhance plasma quercetin levels by up to 50%. Vitamin C helps optimize absorption.

  • • Nanoparticle/liposome quercetin – Reducing quercetin compounds into tiny nano-sized particles or enclosing them in liposomes may help further enhance absorption and bioavailability.

• How should I select a quercetin supplement?

When choosing a quercetin supplement, there are several key factors to consider:

  • • Form of quercetin – Look for products with enhanced bioavailable forms. These options optimize absorption compared to standard quercetin.

  • • Potency – Opt for supplements with a high potency of 500–1,000 mg quercetin per serving. This level of concentration provides a therapeutic dosage.

  • • Additional ingredients – Some products add vitamin C, bromelain, or black pepper extract to boost quercetin absorption further. This combination can be beneficial.

  • • Third-party testing – Verify the product has been third-party tested for label accuracy and purity. This qualifying factor ensures potency and safety.

  • • Clean ingredients – Choose supplements without unnecessary fillers, binders, or additives. Steer clear of artificial ingredients.

  • • Reputable brand – Purchase from established supplement brands that follow Good Manufacturing Practices (GMP). This standard ensures quality control.

  • • Positive reviews – Read reviews from other consumers to help identify products that are highly rated for their value and results.

  • • Affordability – Compare prices to find a high-quality quercetin supplement that fits your budget. Sales and promotions can offer good value.

These guidelines will help you choose a high-quality, research-backed quercetin product to support your health goals. Always consult your doctor before taking any new supplements.

Where can I buy quercetin?

Quercetin supplements can be purchased from a variety of retailers:

  • • Online – Many online supplement retailers and distributors carry a wide selection of quercetin products. Shopping for supplements online lets you quickly compare different brands, prices, and formulas.

  • • Health food stores – Local health food stores and chains offer quercetin supplements. A knowledgeable staff can guide product selection.

  • • Pharmacies – Major pharmacy retailers sell quercetin capsules and soft gels. Availability may vary by location.

  • • Specialty supplement shops – Stores focused on supplements may have a more extensive quercetin selection and niche brands not found elsewhere. Staff can provide recommendations. Natural Healthy Concepts offers a wide variety of quercetin supplements.

  • • Direct from manufacturers – Some supplement companies sell quercetin products directly from their websites.

  • • Doctor’s offices – Health practitioners like naturopaths or nutritionists may offer medical-grade quercetin supplements for patients.

When purchasing quercetin, always verify the product uses a highly bioavailable form like quercetin phytosome and check reviews for quality. Buying from reputable retailers can help ensure you get an authentic, high-potency supplement to support your health goals. Consult a health professional if you have questions about dosage and safety.

What is the best quercetin dosage?

When taking a quercetin supplement, finding the dosage that’s right for your needs is crucial. The optimal dosage can vary based on the desired therapeutic benefits. Here are some general dosage guidelines:

  • • General health: 250-500 mg daily
  • • Seasonal allergies: 500-1,000 mg daily
  • • Chronic inflammation: 1,000-1,500 mg daily
  • • Athletic performance: 1,000 mg daily
  • • Antiviral/illness prevention: 500-1,000 mg daily

For allergies and inflammation, research shows benefits with higher doses around 1,000 mg daily. However, lower doses, around 500mg, may be suitable for basic immune and antioxidant support.

Always start at the lowest recommended dosage when beginning quercetin. Give your body time to adjust for a week before increasing the dose. The maximum suggested dosage is 1,500 mg per day. There is insufficient evidence to recommend exceeding this amount.

Pay attention to how you feel on a given quercetin dosage. Minor side effects like headaches may indicate the dose is too high. Consulting a healthcare practitioner can help determine the optimal dosage for your health goals. Ramping up slowly can allow you to find the right amount where you experience the most benefits with minimal side effects.

How can I maximize the benefit from quercetin?

To maximize the benefits of quercetin supplementation, there are some best practices to follow:

  • • Take with vitamin C – Research shows taking quercetin along with vitamin C increases plasma quercetin levels by up to 50%. Vitamin C boosts bioavailability for optimal absorption. Look for quercetin supplements that contain vitamin C, or take them together.

  • • Split your dosage – Since quercetin stays in the body for only 4 to 7 hours, splitting your dosage into smaller amounts twice or three times daily can help maintain consistent levels. For example, instead of one 1,000mg dose, take 500mg in the morning and 500mg in the evening.

  • • Take between meals – Consuming quercetin supplements between meals on an empty stomach can further increase bioavailability. Food can compete for absorption and reduce plasma quercetin levels.

  • • Pair with bromelain – Bromelain is a digestive enzyme found in pineapples that may enhance the absorption of quercetin. Taking quercetin with bromelain supplements can amplify the effects.

  • • Avoid high-calcium foods – Calcium-rich foods can interfere with quercetin absorption when eaten simultaneously. Avoid taking quercetin supplements alongside dairy, antacids, or other calcium sources.

  • • Minimize alcohol – Alcohol consumption can decrease plasma quercetin concentration in the blood. Limit alcohol, especially around the time of taking quercetin.

  • • Increase bioflavonoids – Eating foods high in bioflavonoids, like oranges, lemons, and berries, can help raise quercetin levels for better absorption and utilization.

  • • Consider chelated forms – Quercetin chelated to an amino acid may increase bioavailability. Look for quercetin supplements bonded to compounds like lysine or methionine.

  • • Stick with a routine – To promote steady levels of quercetin, try to take it at the same times each day and stick with a consistent daily regimen. This regularity helps your body get into a rhythmic absorption pattern.

You can get the most out of your quercetin supplement by being mindful of these optimization strategies. Always follow dosage directions carefully and discuss quercetin use with a healthcare provider.

What are the side effects of quercetin?

Quercetin is generally well-tolerated, especially when taken at recommended dosages. However, there are some potential side effects to be aware of:

  • • Headaches – Some people report headaches after taking high doses of quercetin. This typically goes away after the body adjusts. Lowering the dosage can help.

  • • Tingling sensations – Numbness or tingling in the arms and legs has occurred in some cases. Discontinuing use should eliminate this effect.

  • • Upset stomach – Stomach pains, nausea, and diarrhea are possible if quercetin is taken on an empty stomach. Take with food to minimize GI upset.

  • • Kidney dysfunction – There have been isolated case reports of kidney damage in those with pre-existing kidney disorders. Consult a doctor before use if you have reduced kidney function.

  • • Thyroid interaction – Quercetin may interfere with thyroid hormone synthesis when taken in very high doses for long periods. Monitor thyroid function if taking long-term.

  • • Pregnancy concerns – Not enough research exists to recommend quercetin in pregnant or breastfeeding women. It is best avoided as a precaution.

  • • Medication interactions – Quercetin may interact with some antibiotics, blood thinners, NSAIDs, statins, and chemotherapy drugs. Seek advice from a healthcare professional before use.

For most healthy individuals, quercetin side effects are mild at suggested dosages of 500-1,000 mg per day. However, consult a doctor before use if you have underlying medical conditions or take any medications.


Quercetin acts as a potent anti-inflammatory and antioxidant in the body. It became popular as a supplement in the 1970s due to research showing its medicinal potential. Today, quercetin remains one of the best-selling flavonoid supplements.

Evidence for the health benefits of quercetin supplementation is abundant. It effectively boosts immunity, fights inflammation, supports heart health, improves endurance, deals with allergies, and more. Quercetin may also help protect against certain neurodegenerative diseases and viruses, though more research is needed.

To get the most benefits from quercetin, nutritionists and other health professionals suggest choosing supplements that use enhanced bioavailable forms like EMIQ or combining quercetin with vitamin C. When selecting a product, it is important to verify potency, purity, and quality through third-party testing and purchasing from reputable brands like Bioclinic Naturals, Pure Encapsulations, and Bluebonnet.

While generally well-tolerated, potential side effects can include headaches, tingling, and stomach upset. Quercetin may also interact with certain medications. As with any new supplement, consult a doctor before use, especially if you have underlying medical conditions. Overall, quercetin is a safe and effective antioxidant supplement offering a variety of science-backed health benefits.

How We Chose the Best Quercetin Supplements

For the ranking, the editorial team consulted with an accredited nutrition expert. Ratings were based on user satisfaction, cost, and third-party certification, and determined solely by the editorial team.

All product prices are accurate as of publication and are subject to change.