Quercetin for Immune Support and Allergies: Here’s What You Need to Know

As one of the most abundantly available antioxidants on the planet, quercetin has proven to be a potent anti-inflammatory and immune-enhancing supplement. Plus, it’s a natural antihistamine to combat allergies. With allergy season in full swing, what exactly is quercetin? And how does this natural supplement support our health and longevity? 

What is Quercetin, and Why Do We Need It?

Quercetin is a flavonoid, a group of plant compounds containing pigment naturally found in a wide variety of plants and foods such as red wine, green tea, fruits, vegetables, and grains. 

Research shows that flavonoids play a beneficial role in disease prevention by working as an antioxidant, protecting the body from free radical damage most typically understood as the normal aging process.

Well-stocked in high levels of antioxidants, quercetin contributes to a large range of benefits that ultimately may assist in disease prevention. Let’s take a look at some of the most-studied and well-researched benefits. 

5 Benefits of Quercetin

1. It Promotes Proper Immune Function.

According to the Journal of Immunology, quercetin has an immunosuppressive effect on dendritic cells, which are responsible for sending messages amongst cells in the body. T cells, which play a major role in the productivity of the immune system, are especially affected. When the dendritic cell function is altered, so is its role in curbing allergic and autoimmune diseases where hyperactive signaling is seen, such as in Lupus and Crohn's. These inflammatory conditions caused by an overactive immune response are tempered by quercetin, providing a calmer ground for healthy communication within the immune system. 

That’s not all, though. Quercetin also works on underactive immune responses by improving T cell activity and suppressing interleukin (IL-4) production, synthesized by T-helper 2 (Th2) cytokines. This can best be demonstrated by a study in HIV patients where this imbalanced cytokine response between Th1 and Th2 leads to impaired immunity and reverses with the suppression of Th2 synthesized IL-4. Quercetin may be a useful tool in modulating the immune system. 

2. It has Antiviral Qualities.

Flavonoids are encouraging compounds when it comes to antiviral activity, and quercetin is one of the most plentiful dietary sources of flavonoids. The average person consumes up to 100 mg of these flavonoids naturally through quercetin-rich food sources such as citrus, berries, broccoli, leafy vegetables, tomatoes, red grapes, and tea.

But when taken alone as a supplement, quercetin is not readily absorbed, which is why it’s best when combined with vitamin C or digestive enzymes, like bromelain, to increase bioavailability. Quercetin has broad antiviral properties and inhibits heat shock proteins required for viral assembly, making it a powerful addition to any immune-protecting cocktail.

3. It Lessens the Severity of Allergy Symptoms.

Skin, food, and respiratory allergies have been globally increasing at a rapid rate over the last three decades. A 2016 review in the journal Molecules shares how quercetin, acting as an anti-allergy and anti-inflammatory, inhibits the release of histamine, decreases inflammatory cytokines, and inhibits enzymes and inflammatory mediators responsible for mast cell activation.

Histamine, in particular, is a major contributor to allergic reactions such as anaphylaxis, hives, and other bronchial asthmatic responses. It’s responsible for causing a range of seasonal allergy symptoms that can make you feel miserable: sneezing, watery or itchy eyes, stuffy or runny nose, throat irritation, rashes, and other skin conditions, and more. However, quercetin’s histamine-lowering qualities have shown to be as effective as some over-the-counter antihistamines, minus the undesirable side effects, such as dry eyes and sedation.   

Another study showed that quercetin has the ability to calm gastrointestinal hypersensitivity due to food allergy, thereby protecting the digestive tract from injury. The studies suggest that quercetin may be a viable therapeutic option for easing allergy symptoms. 

4. It Lowers Blood Pressure.

A study on antihypertensive effects of quercetin found that a single daily dose of the bioflavonoid reduced the blood pressure and heart rate of hypertensive rats. Rats were given quercetin every day for five weeks, and their systolic and diastolic blood pressure values decreased by 18% and 23%. Furthermore, a 2016 review concluded that doses equalling more than 500 mg per day significantly reduced blood pressure, marking quercetin as a worthy addition to an antihypertensive regimen. 

5. It Promotes Longevity. 

Aging is largely attributed to cellular senescence, or cell death, which is a phenomenon that occurs when cells cease to divide. As we age, these dead cells accumulate in our tissues and organs, contributing to the aging process if not removed. Quercetin clears senescent cells from obese mice when in combination with the senolytic drug, dasatinib, according to researchers at the Mayo Clinic in Rochester, MN. Clearing senescent prevents cell damage and delays physical, age-related degenerative dysfunction, thereby extending lifespan. A 2017 study displayed that eliminating senescent cells can improve cardiovascular function, and can even prevent age-related bone loss and reduce frailty. 

Perhaps the most exciting anti-aging discovery in the last 20 years, quercetin has been proven to activate sirtuins, the “longevity genes.” Out of the seven sirtuins in our cells, all carry a variety of duties, but the overarching role of them is to maintain cellular homeostasis. In other words, their job is to slow down or halt the aging process.

While quercetin does activate sirtuins, increasing NAD+ (nicotinamide adenine mononucleotide) levels is needed to truly benefit from increased sirtuin activity. NMN and NR are the precursors to NAD+ and recommended as adjunct supplementation alongside trans-resveratrol and quercetin. 

How Can You Increase Your Quercetin Levels?

There are a number of ways you can get a balanced intake of quercetin to regulate your immune system, ward off allergies, and feel younger. Quercetin accounts for about 75% of your daily flavonoid consumption, which can range anywhere between 50-800 mg/day, depending on your diet. Quercetin is available through a balanced diet, herbs, and supplements. The following list contains a variety of quercetin-rich items.  

1. Diet

• Apples
• Berries
• Black tea
• Buckwheat
• Capers
• Citrus fruit
• Grapes
• Kale
• Nuts
• Onions
• Red wine
• Seeds
• Shallots
• Tea
• Tomatoes

2. Herbs

• Ginkgo biloba
• St. John’s wort (Hypericum perforatum)
• American elder (Sambucus canadensis)

3. Supplements

One of the major drawbacks that has been found with supplemental quercetin is its poor bioavailability and absorption. Finding a blend that incorporates phytosomes, tiny spheres made out of plant-derived phospholipids, will increase bioavailability, making it easily absorbed by the body. The quercetin phytosome provides 50 times greater bioavailability than traditional quercetin. A study conducted on a product using phytosomes proved an increase of bioavailability in the plasma up to 20 times more than a standard quercetin dose.

Dosage: When it comes to quercetin, it’s important to note that people often take between 500 mg to 1,000 mg per day. However, dosages may vary depending on the bioavailability of the product and the needs for which you are using it.   

Contraindications: When using quercetin supplements, please consult with your physician if you are undergoing treatment for a medical condition, are pregnant or lactating, or have general questions and concerns.

Takeaways

• Quercetin has an immune-modulating effect on the body, acts as a natural antihistamine, natural antiviral, eases allergies, and reduces inflammation.
  
  
• Quercetin promotes longevity by clearing away cell death accumulation and activating sirtuins, our “longevity genes.” 

• It may lower systolic and diastolic (upper and lower) blood pressure.
  
  
• You can consume quercetin via a well-balanced diet of fruits, vegetables, grains, red wine, and tea.
  
  
• Supplementing with the more bioavailable forms, including ones with phytosomes, is the best way to get adequate amounts of quercetin and optimize absorption.

References:

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Chirumbolo S. The role of quercetin, flavonols and flavones in modulating inflammatory cell function. Inflamm Allergy Drug Targets. 2010;9(4):263‐285. doi: 10.2174/187152810793358741 

Duarte J, Pérez-Palencia R, Vargas F, et al. Antihypertensive effects of the flavonoid quercetin in spontaneously hypertensive rats. Br J Pharmacol. 2001;133(1):117‐124. doi:10.1038/sj.bjp.0704064

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Meyaard L, Hovenkamp E, Keet IP, et al. Single cell analysis of IL-4 and IFN-gamma production by T cells from HIV-infected individuals: decreased IFN-gamma in the presence of preserved IL-4 production. J Immunol. 1996;157(6):2712‐2718.

Mlcek J, Jurikova T, Skrovankova S, Sochor J. Quercetin and Its Anti-Allergic Immune Response. Molecules. 2016;21(5):623. Published 2016 May 12. doi: 10.3390/molecules21050623 

Ogrodnik M, Zhu Y, Langhi LGP, et al. Obesity-Induced Cellular Senescence Drives Anxiety and Impairs Neurogenesis [published correction appears in Cell Metab. 2019 May 7;29(5):1233]. Cell Metab. 2019;29(5):1061‐1077.e8. doi: 10.1016/j.cmet.2018.12.008

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