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Seasonal Allergies? Focus on Antioxidant Support

Seasonal Allergies? Focus on Antioxidant Support

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Vitamin C and quercetin may help

Although spring brings the joys of warmer days and colorful flowers, it’s also the beginning of allergy season for many (over 19 million of us, to be exact!)[1]For some of us, allergies hit us worse in the fall. Unfortunately, if you have an allergic disposition, it may never seem to end!

Also known as allergic rhinitis, hay fever is a truly irritating condition that occurs when the sinuses and lungs overreact to airborne allergens, including pollen. If you’ve ever had allergies, you know that the symptoms include nasal congestion, sneezing, itchy eyes, coughing, and a runny nose, all of which can lead to headache, sleep disturbances, and fatigue. Living with allergies can be challenging, especially when symptoms are at their worst.

And it’s not just hay and grasses that cause seasonal allergies. Early-season hay fever sufferers tend to react to tree pollens, such as alder and ash, which are carried in the wind. Late-season hay fever sufferers react more to specific grasses and agriculture crop pollens, which start to emerge early May and continue to around mid-August. It’s not surprising, then, that many people resort to antihistamine and/or steroid medications for most of the spring and summer. Unfortunately, these pharmaceuticals also have side effects such as drowsiness, dizziness, dry mouth, nausea, and more.

So can anything be done to increase one’s resilience to hay fever, without the side effects of pharmaceutical treatments? The answer is ‘yes!’ Targeted nutritional support can help. Today we’ll discuss the importance of antioxidant support with quercetin and vitamin C.


Quercetin is a flavonoid found in many fruits and vegetables, including onions, green tea, apples, cherries, broccoli, tomatoes, berries, and green tea.[2] Owing to its antioxidant properties, quercetin is one of the most powerful flavonoids for protecting the body against reactive oxygen species.[3],[4]

Quercetin is perhaps best known for its role in taming the histamine response seen in allergic conditions.

The consumption of quercetin is associated with a wide range of immune system benefits, including modulation of allergic responses.[2],[5] Quercetin is perhaps best known for its role in taming the histamine response seen in allergic conditions. If you have an allergy, your immune system overreacts to an allergen by producing a type of antibody called immunoglobulin E (IgE). These antibodies bind to mast cells, causing the release of histamine, which triggers allergic symptoms.[6]

Quercetin counteracts the allergic response by suppressing antigen-specific IgE antibody formation, thereby acting at a very early step in the allergic response.[7],[8],[9] Additionally, quercetin inhibits the release of histamine and proinflammatory substances implicated in allergic reactions.[2],[10]

Along with modulating allergic responses, laboratory studies have shown that quercetin can reduce infectivity of a wide variety of respiratory viruses,[11] including coronaviruses,[12],[13] which have been in the headlines recently due to an outbreak in China. Interestingly, vitamin C appears to enhance the activity of quercetin, in part by stabilizing the quercetin molecule itself.[14] Vitamin C also has independent and potent effects on immune cells, as discussed below.

Vitamin C

Maintaining adequate-to-high levels of vitamin C (ascorbate) intake may help reduce one’s susceptibility to allergies.[15],[16],[17] Vitamin C modulates the immune system in multiple ways: it promotes immune tolerance (decreasing reactivity) to allergens, prevents excessive inflammation of sinus tissues, lowers blood levels of histamine,[18],[19] and reduces oxidative stress (more about this later).[20],[21] Low dietary and circulating ascorbate levels are associated with allergy susceptibility.[22] Moreover, clinical investigations have shown that histamine levels increase exponentially as ascorbate levels decline.[23],[24]

We humans are one of the few species on earth that cannot synthesize vitamin C and must therefore rely on nutritional sources – food, beverages, and supplements – to meet the body’s ascorbate needs.[25] Diets that are high in vitamin C-rich fruits and veggies may theoretically provide enough vitamin C, yet studies show that up to 20% of the population may have suboptimal vitamin C levels.[26],[27],[28],[29]

Vitamin C status can be suboptimal even with dietary intakes that are generally regarded as adequate.

The best way to assess vitamin C adequacy is to measure blood (plasma) ascorbate concentrations.[30] Based on this measure, a far greater percentage of the population may have suboptimal vitamin C levels.[30] Low ascorbate levels can be triggered by exposures to air pollution (ozone and particulate matter), smoking (including secondary smoke exposures),[29],[31],[32] and nicotine itself.[33] These exposures induce oxidative stress, which causes ascorbate depletion, since vitamin C helps mop up excess free radicals (the oxygen species that damage cells, including white blood cells).[34],[35] Infections,[36],[37] diabetes,[38] and many other disease conditions also induce oxidative stress and reduce ascorbate levels.[39] Thus vitamin C status can be suboptimal even with dietary intakes that are generally regarded as adequate.[29],[40],[41] Studies suggest that additional vitamin C may be needed during infections, for example, and that an extra daily dose helps shorten the duration of the common cold.[42]

Physical and mental stresses also deplete ascorbate and exacerbate allergies.[43],[44],[45] This connection is known as the “adrenal-vitamin C axis.”[46] Here’s how it works: the adrenal glands are responsible for producing cortisol, the hormone that helps us react to and deal with stress.[47],[48] The adrenal glands contain high levels of ascorbate, and the same stress-driven signals that cause the adrenals to secrete cortisol also cause them to release ascorbate into the blood.[47] The more stress we experience, the more likely we are to become deficient in vitamin C. This is why people dealing with high stress levels may benefit from some extra vitamin C in the diet and/or supplement regimen. Vitamin C supplementation is associated with a decreased cortisol response after psychological or physical stress.[49],[50],[51] (For more information on adrenal support, check out our article on adrenal fatigue.)

In addition to diet and environmental exposure, genetics plays a role in vitamin C requirements. Scientists have discovered that human genetic variations can impair vitamin C transport and antioxidant enzyme function.[52],[53] Individuals who are carrying these gene variants might require higher-than-normal vitamin C intakes to achieve adequate blood ascorbate levels.[53]

Clearly, regular intake of vitamin C supports good health, in the allergy season and beyond.[47] Because vitamin C is water soluble, it is not stored in the body (unlike fat-soluble vitamins such as vitamin D), so it is important to consume vitamin C every day.[54] However, when vitamin C is provided as the crystalline form in a tablet or aqueous (water) solution, it is susceptible to degradation in the gastrointestinal tract.[53] Moreover, the absorption of vitamin C in the gut is easily saturated, meaning we may not get all we need from a single dose of plain vitamin C.[55]

To address these problems, scientists have developed liposomal formulations of vitamin C, which provide more effective and long-lasting delivery of the active molecule.[56],[57],[58] Liposomes are tiny spherical sacs of phospholipid molecules enclosing a water-soluble droplet, which are formulated to carry substances (such as drugs or nutrients) into the tissues. The vitamin C is dissolved in the water-soluble droplet, and then surrounded by the protective phospholipid layer, which protects the ascorbate from premature degradation and improves absorption. Liposomes have been shown to protect vitamin C during transit through the gastrointestinal tract; to minimize potential irritation of the GI tract, which typically accompanies large oral doses of ascorbate; and to increase bioavailability.[57] One clinical study showed 68% higher blood levels of ascorbate after consumption of a liposomal form of vitamin C, compared with an aqueous solution.[57] In addition, the liposomal vitamin C increased the length of time the ascorbate persisted in the blood (measured as the half-life), giving it more time to take action within cells.


Quercetin and vitamin C are important natural antioxidants worth considering as part of your daily supplementation regime, particularly during allergy season. The liposomal form of vitamin C helps boost blood levels of this nutrient. Vitamin D3 supplementation is also crucial, as pre-clinical and clinical studies suggest that insufficient vitamin D is associated with allergy symptoms. For more information on nutrition and allergies, see these additional articles:

Note: The information in this post was previously published under the title Nutritional Support for Seasonal Allergies.

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