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The Allergic Alarm ⋅ Where to Find Quercetin ⋅ Other Benefits of Quercetin ⋅ 7 Sources of Allergy Relief

Ah, spring! Time to open the windows and welcome in the fresh air.

Well, maybe.

If you’re among the more than 50 million people in the United States with allergic rhinitis, better known as allergies, spring can be a miserable time. Pollen from trees, grasses, and weeds can trigger itchy eyes, nasal congestion, and other indignities. Spring’s arrival may make you more likely to close up the house and submit to a groggy few months of allergy medication.

Yet many integrative– and functional-medicine practitioners believe there are better — and safer — options. “Inhaled, nasal, and topical steroids are very handy and effective, but they’re not without adverse effects,” says functional-medicine physician Gregory Plotnikoff, MD, MTS, FACP.

The occasional use of anticholinergic, antihistamine drugs isn’t likely to lead to problems aside from drowsiness, but long-term use may be another story. “Anticholinergic drugs such as Benadryl act by blocking a neurotransmitter in our brains called acetylcholine, which is involved in allergic reactions — as well as learning and memory,” explains naturopathic practition­er Kara ­Fitzgerald, ND, IFMCP.

She points to a study published in JAMA Internal Medicine in 2015 indicating drugs with anticholinergic effects may increase the risk of dementia. Other studies also suggest there may be a connection between long-term use of these medications and cognitive decline.

Further, says Fitzgerald, “antihis­tamine medications don’t address the root cause of immune dysfunc­tion, which, if left unaddressed, can ­promote further immune ­dysregulation and development of other sensitivities.” (Learn more about the functional-medicine ­approach to treating allergies at
“Taking On the Allergy Epidemic“.)

Fortunately, drugs are not your only option. You can support your immune system and relieve the misery of seasonal-allergy symptoms through targeted nutrition.

One especially useful nutrient to consider is quercetin. This natural antihistamine can provide drug-free relief, both from seasonal-allergy symptoms and from allergic reactivity to perennial triggers, such as dust and dander.

The Allergic Alarm

Nutritionally, quercetin is classified as a flavonoid — a group of naturally occurring compounds that give vegetables, fruits, and flowers their colorful hues. Flavonoids also act as antioxidants, which neutralize the oxidative stress behind virtually all chronic disease.

To understand how quercetin reduces allergic reactivity, consider how allergens activate our immune systems. In sensitized people, pollen and other substances in our environment trigger the production of IgE antibodies. These immune molecules cause mast cells and basophils to release histamine and other allergy-mediating molecules.

Mast cells are in all parts of the body that come into contact, directly or indirectly, with the outside world — eyes, ears, sinuses, mouth, throat, gastrointestinal tract, and skin. Imagine these as sentinels on a ship scanning the horizon for icebergs, or in a tower scouting for forest fires, ­Plotnikoff suggests. “If they ­detect something, they sound the alarm.”

Drugs are not your only option. You can support your immune system and relieve the misery of seasonal-allergy symptoms through targeted nutrition.

This alarm leads to inflammation of nasal passages and eyes, as well as itching, swelling, and mucus production. But the response doesn’t end here.

Histamine molecules dock at receptor sites in these affected areas, triggering mast cells to keep releasing histamine and other chemicals. “This is where people get stuck in a non­resolving, detrimental, proinflammatory loop,” Plotnikoff says.

Quercetin helps relieve these symptoms by stabilizing the mast-cell membranes, which inhibits histamine release. “It interrupts the loop,” he adds. “It raises the threshold by which mast cells would release more histamines and other chemicals.”

This nonsteroidal way of moderating histamine response takes a while to get up to speed, he adds. It can be several weeks before the ­effects kick in. “So, it’s not going to be nearly as quick as taking a Zyrtec or a Benadryl, which actually block the histamine receptor.”

While a lot of research has been done on quercetin, it’s mostly been in lab environments rather than clinical ones. But Plotnikoff and other practitioners consider this research in the context of clinical observation and patient reporting as well.

“Quercetin is well known and overall safe,” he says. “It represents a logical option for those who would prefer not to take medications.”

Where to Find Quercetin

If you’re already eating a plant-forward, rainbow-colored diet, you’re likely getting quercetin nearly every day. It’s found in colorful produce, including red onions, dark cherries, cranberries, blueberries, blackberries, and grapes. Apples (with the skin), citrus fruits, and yellow onions are also good sources of quercetin, as are broccoli, spinach, kale, asparagus, peppers, scallions, and fennel.

“Capers, in particular, are off the charts compared with other foods for their quercetin content — they are a quercetin superfood!” says Fitzgerald.

You can find the nutrient in your morning tea — especially green, black, and oolong — and in your ­evening red wine as well.

Herbs (including parsley, sage, thyme, oregano, chives, and dill) are good sources, too.

Still, the bioavailability of quer­cetin varies widely among foods, says Plotnikoff. Onions deliver more bioavailable quercetin than apples, for example. Because quercetin is a lipophilic compound (meaning it dissolves more easily in fat than water), pairing these foods with dietary fat — think cooking onions in olive oil — may improve absorption. “A salad with olive oil would also be ideal,” he says.

“I always encourage people to focus on food first for quercetin absorption,” adds functional dietitian Cindi Lockhart, RDN, LD, IFNCP, but she notes that “there’s a lower potency. When you talk about therapeutic doses, you almost have to supplement.”

If you’re trying to reduce your dependence on allergy medication, Lockhart says, try synergistic quercetin supplements that include nutrients such as bromelain, an enzyme mixture found in pineapples that can enhance the body’s ability to absorb quercetin.

If you’re trying to reduce your dependence on allergy medication, Lockhart says, try synergistic quercetin supplements that include nutrients such as bromelain, an enzyme mixture found in pineapples that can enhance the body’s ability to absorb quercetin.

She explains that many supplements have a “loading dose,” to be taken initially. As you notice a dampening of symptoms, you can reduce to a lower “maintenance dose.” (Turn to a healthcare provider for ­dosage guidance. Also, some ­providers recommend starting supplements well before pollen season begins, to prevent symptoms.)

You may even be able to wean yourself from pharmaceutical support altogether.

“It usually takes a few weeks ­before you notice improvements, during which time you may still need to use antihistamine medications if your symptoms are severe enough to impede your daily activities,” says Fitzgerald. “However, after that time you may start to notice reduced symptoms and have less or no need for medication.”

Beyond Allergies: Other Benefits of Quercetin

In addition to helping tame the allergy response, quercetin has anti-inflammatory, antiviral, and anticancer properties, and it provides mitochondrial protection, says Gregory Plotnikoff, MD, MTS, FACP. Its protective and therapeutic potential keeps researchers busy investigating its ability to support a range of health conditions.

• Brain health: Several ­studies have identified quercetin’s neuro­protective benefits. As an antioxidant, it may mitigate age-related ­degenerative processes, for example, and its anti-inflammatory properties may protect against the progression of inflammation-mediated neuro­degenerative disorders.
• Heart health: Along with other flavonoids, such as resveratrol and catechins, quercetin may help reduce the risk of atherosclerosis, the plaque accumulation in arteries that can lead to heart attack and stroke. It may also prevent damage from LDL cholesterol and reduce blood pressure in people with hypertension.
• Cancer: In lab studies, quercetin has inhibited many types of cancer cells. Plotnikoff cautions, however: “In some types of cancers, quercetin enhances the activity of chemotherapy, and in others it actually blocks the effectiveness of chemotherapy.”
• COVID-19: The Institute for Functional Medicine notes that “quercetin has been shown to have antiviral effects against both RNA viruses (e.g., influenza and coronavirus) and DNA viruses (e.g., herpes).” Although clinical evidence is limited, says Plotnikoff, “for some people, quercetin has been helpful for both acute and long COVID.”

7 Sources of Allergy Relief

To address allergies, “one of the most powerful leverage points we have is diet,” says Kara Fitzgerald, ND, IFMCP, who recommends a whole-foods diet with plenty of colorful vegetables and fruits, herbs and spices, nuts and seeds, and fish rich in omega-3 fatty acids. She also suggests avoiding inflammatory foods that can drive allergy symptoms, including sugars, refined grains, vegetable oils, trans fats, and processed foods.

Several botanicals may support you during allergy season. “They usually take a little longer to act than medications, and you must be consistent about taking them before and during allergy seasons, but they are much safer for long-term use,” she says.

Consider adding these to your antiallergy arsenal:

2. Stinging Nettle

A long-revered herbal remedy, stinging nettle contains quercetin and other flavonoids as well as a host of vitamins, including vitamin C. Research is limited, but studies suggest it may reduce seasonal-allergy symptoms by acting as an anti-inflammatory and antihistamine. More long-term human studies are needed to confirm efficacy and safety.

Best Food Sources:

You can find stinging-nettle tinctures and capsules at most natural grocery stores and pharmacies. Some people make a tea or tincture from dried leaves or flowers, or add roots to soups. “I would not recommend making a tincture on your own unless you’re an experienced herbalist or professional,” cautions McKinney.

How to Supplement:

“The most common dose for allergies is 300 mg twice daily for a total of 600 mg of a supplement from the stinging-nettle leaf, not the root,” says McKinney.

4 & 5. Probiotics and Prebiotics

With 70 to 80 percent of our immune cells living in the gut — and an increasing understanding of how the gut microbiome affects systemic immunity — it makes sense to feed and repopulate our microbiota to reduce allergic reactivity. Several studies have shown that probiotic support can improve symptoms of allergic rhinitis.

Best Food Sources:

“Food is how you really shift things in the microbiome,” says Lockhart, noting that “a supplement is more like a placeholder.” Probiotic foods that populate your gut with healthy bacteria are fermented fare, such as natural sauerkraut, kimchi, yogurt, miso, and kombucha. Prebiotic foods — which feed the bacteria in your gut — include asparagus, cabbage, garlic, Jerusalem artichokes, and onions.

How to Supplement:

McKinney suggests that a broad-spectrum probiotic supplement may be helpful for allergies. “I typically recommend both food-based strategies and periodic probiotic supplementation. Look for options that have at least 30 billion CFU (colony-forming units) that include both Lactobacillus and Bifidobacterium species.”

(Learn more at “Everything You Need to Know About Probiotics” and “Why Prebiotics Are as Important as Probiotics.”)

7. Black Cumin Seed

Nigella sativa (N. sativa), also known as black cumin seed, has a long history as a traditional food and folk medicine. Limited but promising research suggests the seed’s antihistamine, anti-inflammatory, and immune-boosting properties may reduce respiratory allergy symptoms.

Best Food Sources:

Black cumin seeds are commonly used throughout the Middle East, North Africa, and South Asia. They’re often added to bread, yogurt, pickles, sauces, and salads.

How to Supplement:

Many studies used 500 mg of black-cumin-seed oil taken three times daily. Fitzgerald recommends looking for formulations with 0.7 percent or greater thymoquinone (TQ) content.

This article originally appeared as “Seasonal Allergies? Discover Quercetin” in the April 2023 issue of Experience Life.