Seasonal Allergies and Immunity: What the Research Shows

As allergy season hits full stride, plenty of your patients likely present with litany of miserable symptoms like congestion, sneezing, itchy watery eyes, postnasal drip, coughing and fatigue. Allergic rhinitis is the fifth most common chronic disease in the United States overall, and an estimated 25 percent of the adult population suffers from seasonal allergies. But symptomatic treatment is limited, especially for persistent and severe allergies, and current medications are linked with a range of adverse effects, including drowsiness, blurred vision, nausea, headaches, irregular heartbeat and other troubling complications.^{1, 2, 3, 4}

“Symptomatic relief, though helpful, leaves open the triggered and over-reactive immune system that has perceived pollen and/or other allergens as invaders,” says Chris D. Meletis, Naturopathic Physician. “The goal is to mitigate symptoms that can often be accomplished by some simple diet and lifestyle hacks and ensuring the immune system is supported but not overstimulated.”

Instead of treating symptoms, focus on the foundations. “Our immune systems are, without question, defenders, but when they overreact or become over​‌whelmed​‌, the symptoms of seasonal allergies can arise,” Meletis says. “The goal is to support year-round immune competence.”

Alleviating seasonal allergies begins with a healthy immune system, and new research suggests science-backed natural ingredients offer safe and effective solutions.  A comprehensive protocol that targets immune support through dietary interventions, lifestyle changes and evidence-based supplements can lessen symptoms, ease suffering and help patients survive allergy season.

Food, Nutrition and Gut Health.

Nutrition plays a pivotal role in seasonal allergies, impacting immune response and modulating inflammation. The typical Western diet is associated with a greater incidence of allergic disease, and studies link a high-protein, high-fat diet to a significantly increased risk of allergic rhinitis. Nutrients and dietary components influence immune cells in all stages of allergic inflammation, and a broad range of vitamins, minerals, fatty acids and phytochemicals have been shown to support immunity, regulate allergic inflammation and mitigate the development and severity of allergies.^{5, 6, 7, 8}

Diet is also critical in shaping the composition, function and diversity of the gut microbiome, maintaining gut barrier integrity and gut immune homeostasis, and microbiome disruptions increase the risk of allergic diseases. Poor nutrition adversely affects the production of bacterial metabolites involved in various immune pathways and allergic inflammation, and research suggests short-chain fatty acids, bile acid conjugates and other metabolites have the ability to modify allergic reactions.^{9, 10, 11, 12}

“A leaky gut increases the absorption of larger food molecules, which contribute to the total allergenic burden and also increase the risk of cross-reactivity,” Meletis says. “A healthier gut supports a less-reactive immune system overall.”

Lifestyle Influences—Stress, Sleep and Allergies.

Besides basic lifestyle changes to lessen exposure to allergens, minimizing stress and encouraging restorative sleep are essential for surviving seasonal allergies. Research continues to validate strong ties between stress, mood, mental health and allergies, especially in women. Emotional stress aggravates allergies, and chronic stress and impaired mood are associated with more frequent allergy flares. Seasonal allergies are also linked to generalized anxiety, and studies demonstrates a significant relationship between emotional stress, frequency of allergy flares, and severity of symptoms.^{13, 14, 15, 16}  

Deep, restorative sleep is likewise vital for maintaining immune function integrity. Sleep deprivation interferes with immune response and drives inflammation, and research shows insufficient sleep increases the risk of developing seasonal allergies and worsens symptoms. In studies, allergic rhinitis was linked with insomnia, poorer sleep quality, interrupted sleep, longer sleep latency and lower sleep efficiency, as well as negative consequences  like difficulty waking up and daytime sleepiness.  Common allergy medications can further disrupt sleep, impair mood and heighten anxiety. Meanwhile, lack of sleep fuels stress and mood disturbances, in a frustrating, hard-to-break cycle.^{17, 18, 19, 20}

Science-Backed Supplements: Research Highlights.

Along with dietary interventions and lifestyle modifications, certain supplements have been shown to support immunity, minimize inflammation and ease seasonal allergies. What to include in a comprehensive protocol:

Astragalus root. Astragalus membranaceus has been used for centuries in traditional Chinese medicine to strengthen resilience, and modern science validates its ability to modulate immune response and tame inflammation. Astragalus is rich in bioactive compounds that target specific immune cells, influencing cytokines and improving the function of natural killer cells. Astragalus also has powerful anti-inflammatory and antioxidant properties, and may positively impact the gut microbiome, further supporting immunity. Research suggests its potential for relieving symptoms of seasonal allergies and alleviate allergic asthma. In one study of patients with allergic rhinitis, those who took astragalus root extract showed improvements in symptoms like runny nose and itchy eyes compared to placebo, and both patients and researchers judged astragalus treatment as significantly more effective than placebo.^{21, 22, 23, 24, 25, 26, 27, 28}

Berberine. Naturally occurring in goldenseal, barberry and other plants, berberine has a long history of use in Ayurveda and  Chinese medicine for a wide range of ailments, including infections and inflammation, and current research confirms its anti‐inflammatory and immunomodulatory effects. Berberine influences the proliferation and activity of lymphocytes, inflammatory cytokines and various immune cells, and some studies compare its antioxidant effect to that of vitamin C. Additional research suggests berberine positively affects gut microbiota composition and diversity, critical for immune health. Its anti-inflammatory properties are well documented, with studies showing berberine suppresses inflammatory responses through different pathways, including inhibiting pro-inflammatory cytokines and impact leukocytes. These combined actions point to its promise for managing seasonal allergies and minimizing the severity of symptoms, and animal models found berberine significantly reduced allergic inflammation.^{29, 30 31, 32, 33, 34, 35, 36}

Olive leaf extract. Derived from the leaves of the olive (Olea europaea) tree, olive leaf extract contains bioactive compounds known to decrease inflammation, combat oxidative stress and promote balanced immune response. Olive leaf regulates immune cell activation, modulating cytokine production, enhancing natural killer cells and other mechanisms. It’s also a potent antioxidant, and research highlights its ability to mitigate the inflammatory response and histamine release that characterize allergic reactions. Olive leaf extract has been shown to reduced histamine in human mast cells and inhibit pro-inflammatory cytokine expression in allergic responses. Hydroxytyrosol in particular may play a central role in combating allergies, with studies demonstrating its ability  to inhibit histamine release more strongly than other olive leaf constituents.^{37, 38, 39, 40 41, 42, 43}

Garlic extract. Garlic is a concentrated source of bioactive compounds known to support immune function and reduce inflammation, and some studies hint at its potential to ease symptoms of seasonal allergies. Organosulfur substances in garlic modulate the body’s response to allergens, stimulating the activity of immune cells, increasing natural killer cells, regulating cytokine production and improving gut bacteria associated with immune-system stimulation. Garlic also directly and/or indirectly modifies the functions of mast cells, impacting the release of histamine, a key mediator of allergic reactions. Research points to garlic’s promise in protecting against allergen-induced airway inflammation and managing seasonal allergies, with studies showing garlic extract lead to a significant decrease in total inflammatory cell counts and eosinophil infiltration.^{44, 45, 46, 47, 48, 49}

Vitamin C. Widely recognized as a powerful antioxidant, vitamin C is vital for healthy immune response, mitigating inflammation and relieving symptoms of seasonal allergies. Vitamin C enhances immunity through various mechanisms, supporting cellular functions of both the innate and adaptive immune system, and deficiencies are linked with impaired immunity. Low vitamin C status is also associated with higher levels of histamine and research suggests vitamin C supplementation can decrease in serum histamine concentration, especially in people suffering from seasonal allergies. In studies of allergic rhinitis patients, vitamin C improved sneezing, watery eyes, itching and malaise. In other research, vitamin C combined with exercise significantly reduced congestion, sneezing, itching, runny nose and other symptoms.^{50, 51, 52, 53, 54, 55, 56, 57}

Zinc. Critical for immune system development and function, zinc affects multiple immune cells, supporting both innate and acquired immune responses, and deficiencies alter a range of immunological pathways and disrupt immune function. Insufficient zinc intake has been linked with the development of allergic diseases and research shows supplementation positively impacts the immune system and lessens the severity of symptoms. Zinc is also indirectly involved in histamine metabolism and zinc signaling dysregulation is implicated as a primary factor in inflammatory disorders and allergies. Because airway epithelial cells are especially high in zinc, deficiencies are known to increase allergic eosinophilic inflammation, which can be alleviated by zinc supplementation. Zinc’s role in regulating inflammation helps mitigate the response to allergens and reduce airway inflammation and in one study, allergic rhinitis patients who supplemented with zinc reported a significant decrease in symptoms and improved quality of life.^{58, 59, 60, 61, 62, 63, 64}

EpiCor. Derived from Saccharomyces cerevisiae yeast, EpiCor is rich in beta-glucans, mannans and other naturally occurring bioactive compounds with documented immunosupportive, antioxidant and anti-inflammatory properties. EpiCor has been shown to enhance natural killer cell activity and numbers, increase IgA levels, strengthen mucosal immunity and bolster immune function. EpiCor is a powerful antioxidant with the potential for rapid impacts on antioxidant levels, cytokine levels and  immune response. In one study, a single dose of EpiCor resulted in a significant increase in serum antioxidant protection and immune surveillance after only two hours, compared to placebo. Other research suggests EpiCor may alleviate allergies: a clinical trial of patients with grass allergies found EpiCor treatment significantly reduced the incidence and duration of common seasonal allergy symptoms like nasal congestion and runny nose compared to placebo. ^{65, 66, 67, 68, 69, 70, 71}

Citrus flavonoids. Hesperidin, naringenin, quercetin and other flavonoids in citrus fruit have been shown to support immunity, tame inflammation and promote resistance to environmental allergens. Various citrus flavonoids are involved in Th-2-mediated immune responses related to allergic inflammation, inhibiting the activation of mast and basophil cells, suppressing inflammatory cytokines and blunting histamine release. Studies suggest citrus flavonoids can reduce IgE-mediated allergic immune responses and offer a viable strategy for managing seasonal allergies. One clinical trial found a significant inhibitory effect against IgE-induced histamine release after pollen exposure, and citrus flavonoids appear to mitigate pollen-allergy symptoms like itching eyes, sneezing, nasal discharge and disrupted sleep. Vitamin C appears to boost their effects, decreasing swelling and inflammation, and lessening allergy symptoms.^{72, 73, 74, 75, 76, 77, 78, 79}

N-acetyl-L-cysteine. NAC, an acetylated derivative of the amino acid L-cysteine, has a range of biological activities, including antioxidant, anti-inflammatory, immunosupportive and mucolytic properties. NAC promotes glutathione synthesis, modulating T cell function and influencing lymphocytes, mast cells and other immune cells, and studies demonstrate its ability to improve cell-mediated immunity, and enhance immune response. Other research validates its anti-inflammatory effects, linking NAC supplementation with reduced serum levels of CRP and IL-6. NAC’s positive effects on respiratory health are well-documented, and its ability to loosen mucous in the lungs and airways and decrease the frequency and severity of coughing, wheezing and other respiratory symptoms make it especially beneficial for managing seasonal allergies.^{80, 81, 82, 83, 84, 85, 86, 87}

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