Surviving Seasonal Allergies

As spring approaches, tree pollen counts soar–and so does the influx of patients with congestion, itching, sneezing and watery, irritated eyes. Inflammation plays a prominent role in the development and progression of those aggravating symptoms, and research suggests herbs, supplements and nutrients can modulate inflammation, stabilize mast cells, reduce histamine levels, boost immunity and help manage the misery of season allergies.

Seven science-backed nutraceuticals shown to tame inflammation, support immunity and ease suffering, all season long:

Olive leaf extract. Various components of the olive tree (Olea europaea) have been used for centuries in traditional medicine for their potential health benefits. Olive leaves are an especially concentrated source of bioactive compounds, including oleuropein, oleic acid and hydroxytyrosol, all with proven antioxidant, anti-inflammatory and immune-enhancing properties.

Olive leaf extract has been shown to stimulate macrophages and natural killer cells, modulate T-cell function and cytokine production and promote a balanced immune response. Its rich concentration of polyphenol antioxidants further supports immune health, regulating immune cell activation and signaling pathways, and influencing lymphocytes, macrophages and natural killer cells.^{1, 2, 3}

Studies also highlight the anti-inflammatory properties of olive leaf extract and point to its potential for controlling and treating inflammatory responses. Hydroxytyrosol, one of the key bioactive components of olive leaf, suppresses the expression of proinflammatory mediators, and may play a central role in mitigating seasonal allergies. Hydroxytyrosol improves endothelial dysfunction, known to be involved in the development and progression of inflammatory processes, including allergic reactions. Other studies suggest hydroxytyrosol inhibits mast cell degranulation and reduces histamine release, with a stronger inhibitory effect that what was seen in similar compounds, like oleuropein.^{4, 5, 6, 7}

Vitamin C. Recognized for its potent antioxidant and anti-inflammatory properties and its role in supporting immune health, vitamin C offers promise for managing symptoms of seasonal allergies. Increased intake of vitamin C and other antioxidants are known to improve overall immune response. In studies of children with allergic rhinitis, those with higher vitamin C intake had fewer symptoms, and research suggests supplementing with vitamin C can prevent or treat various allergic disorders.^{8, 9, 10}

Vitamin C may also protect the airways, shielding lung cells from oxidative damage and supporting lung function. By easing inflammation, vitamin C helps alleviate airway irritation caused by allergens. Vitamin C interventions have been linked with reduced lung and airway inflammation, and supplementing with vitamin C has been shown to mitigate upper respiratory symptoms from pollen, mold and other allergens.^{11, 12, 13, 14}

Additionally, vitamin C plays a part in regulating histamine levels.  Research links low plasma vitamin C with higher levels of histamine and supplementing with vitamin C may decrease histamine production after exposure to environmental allergens and reduce bronchial passages spasms in patients with allergic rhinitis. Other studies show vitamin C interventions improved allergic rhinitis, lessened nasal congestion, sneezing, itching and allergy-related symptoms.^{15, 16, 17}

Garlic extract. Garlic (Allium sativum) is rich in compounds offering a broad spectrum of beneficial effects, including anti-inflammatory, antioxidant and immunosupportive properties, and garlic extracts show promise in alleviating the symptoms of seasonal allergies.^{18, 19}

Organosulfur constituents of garlic appear to modulate immune function and its response to allergens through various mechanism, stimulating macrophages, lymphocytes and natural killer cells, regulating cytokines, and influencing immunoglobulin production, phagocytosis and macrophages. Other research points to the ability of garlic to enhance immune cell activity and improve immune-system-stimulating gut bacteria, including Lactobacillus and Clostridia species.^{20, 21}

Garlic extracts also have powerful antioxidant and anti-inflammatory properties, potentially alleviating the severity of allergic inflammation. In studies, garlic inhibited the release of pro-inflammatory substances and decreased inflammatory response in the airways, possibly reducing nasal congestion, sneezing, itching and other symptoms associated with seasonal allergies.^{22, 23}

Although garlic does not directly suppress histamine release, studies examining its benefits in allergic responses show garlic extracts inhibit β-hexosaminidase, a marker of mast cell activation, closely correlated with histamine release. Other research suggests a protective role of garlic extracts on allergen-induced airway inflammation, demonstrating a significant decrease in total inflammatory cell counts and eosinophil infiltration.^{24, 25}

Berberine. An isoquinoline alkaloid found in some plants like goldenseal, Oregon grape and Indian barberry, berberine has a long history of use in traditional medicine, especially Chinese and Ayurvedic systems. Modern research validating its anti-inflammatory, immune-supportive and antioxidant properties hints at potential applications for seasonal allergies.^{26, 27}

Studies examining berberine’s immunomodulatory effects show it can impact the activity and function of immune cells, influencing the proliferation and differentiation of lymphocytes. Berberine also affects gut microbiota composition and diversity, which plays a key role in overall immune health.^{28, 29, 30}

As an anti-inflammatory, berberine has been shown to regulate the production of cytokines, suppress inflammatory responses and possibly reduce the intensity and severity of allergic symptoms. It’s known for its antioxidant properties, and research suggests berberine can enhance the activity of antioxidant enzymes, including superoxide dismutase and catalase, and increase levels of glutathione peroxidase.^{31, 32}

Citrus flavonoids. Abundant in oranges, lemons, grapefruits and other citrus fruits, the antioxidant, anti-inflammatory and immunomodulatory benefits of citrus flavonoids are well established. Studies of patients with allergic disorders also highlight citrus flavonoid therapy as a promising strategy for treating seasonal allergies, alone or in combination with antiallergic drugs.^{33, 34, 35, 36}

An exacerbated inflammatory response plays a central role in the development and progression of allergic reactions, and the powerful anti-inflammatory and anti-allergic properties of flavonoids  have potential for managing symptoms of seasonal allergies. Flavonoids work in part by regulating Th1/Th2 cells and blunting the activation of mast and basophil cells, exerting natural antihistamine actions, and in one clinical trial, citrus flavonoids demonstrated a significant inhibitory effect against IgE-induced histamine release after pollen exposure.^{37, 38}

Citrus flavonoids are involved in Th-2-mediated immune responses related to allergic inflammation and have been shown to suppress synthesis of IL-4 and IL-13 cytokines, and some studies suggest they can reduce IgE-mediated allergic immune responses. Hesperidin, naringin and other citrus flavonoids bolster overall immunity and enhance the body’s resistance to environmental triggers. They appear to work synergistically with vitamin C, protecting against oxidative damage, maintaining capillary health, reducing swelling and inflammation related to pollen and other allergens, and easing symptoms of seasonal allergies.^{39, 40, 41}

Quercetin. A type of flavonoid found in foods like apples, berries, onions and green tea, quercetin is well known for its antioxidant, anti-inflammatory and immune-supportive benefits, offering a valuable strategy for treating seasonal allergies.

Studies examining the immunomodulatory effects of quercetin have identified various possible mechanisms of action. Quercetin influences the function and activity of T cells, B cells, macrophages and other immune cells, modifies signaling pathways regulating the expression of genes involved in immune cell activation, impacts the production and release of cytokines, inhibiting pro-inflammatory cytokines and potentially enhancing the production of anti-inflammatory cytokines.^{42, 43}

Quercetin’s antioxidant properties contribute to its immunomodulatory benefits, reducing oxidative stress and protecting immune cells from damage. Research shows quercetin suppresses inflammatory mediators, including prostaglandins and leukotrienes, stabilizing mast cells and preventing the release of histamines. In vitro studies of patients with allergic rhinitis found quercetin inhibited histamine release, reducing inflammation and airway hyper-responsiveness associated with allergies.^{44, 45}

Zinc. Zinc plays a vital role in various physiological processes, especially numerous aspects of immune function, and deficiencies impair cellular mediators of innate immunity such as phagocytosis, natural killer cell activity and the generation of oxidative burst. The immunomodulatory effects of zinc impact the body’s response to allergens, and zinc deficiency is a known risk factor for the development of asthma. Zinc insufficiency is also implicated in the development of allergic diseases, and supplementation can lessen the severity of symptoms.^{46, 47}

Zinc may indirectly influence histamine metabolism and modulate the allergic response. It’s involved in regulating inflammation, inhibiting the activation of signaling pathways, impacting the production and balance of cytokines and reducing pro-inflammatory cytokines and other inflammatory mediators.^{48, 49, 50}

Zinc’s anti-inflammatory properties show promise for improving allergic rhinitis. Research suggests zinc can temper the response to allergens and decrease airway inflammation, and one interventional study found patients with allergic rhinitis who supplemented with zinc experienced a significant reduction of symptoms and improved quality of life.^{51, 52, 53}

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