For patients who suffer from allergies, it often feels like the treatment options are severely limited. The most commonly used pharmacological therapies—including antihistamines, corticosteroids, mast cell stabilizers, and decongestants—are not effective for all patients, and they often lead to side effects that disrupt everyday life. After years of frustration with oral antihistamines, nasal sprays, eye drops, inhaled corticosteroids, and other over-the-counter and prescription drugs, many patients are ready to explore other treatment options.
Over the last few decades, scientific research into the physiological underpinnings of allergies has suggested that inflammatory processes and oxidative stress may both mediate the most common symptoms. This has led to increased motivation within the research community to study anti-inflammatory and antioxidant supplements as potential allergy treatment options. In particular, curcumin has emerged as a non-pharmacological alternative with a strong base of biochemical and early clinical evidence, but there are also a few other options, including phytochemicals like quercetin, that have been implicated as potential all-natural therapeutics.
Understanding the Relationship Between Allergies, Inflammation, and Oxidative Stress
Antioxidants and anti-inflammatory supplements have come to the attention of the research community in light of biochemical and clinical evidence suggesting a distinct relationship between allergies, inflammation, and oxidative stress. It is well-known that exposure to allergens leads to systemic inflammation by increasing the circulation of immune cells and by triggering the release of certain proteins and other inflammatory factors. However, scientists have also observed “minimal persistent inflammation” in patients with allergic rhinitis—that is, these patients display chronic, slightly above-average levels of inflammatory markers, even when allergy triggers are not present. Not only can these chronically elevated levels of inflammation increase a patient’s susceptibility to the onset of severe allergy symptoms, it can also lead to an increase in oxidative damage—another potential mediator of allergy response.
Both internal inflammation and exposure to external allergy triggers can damage antioxidant enzymes and other key cell factors that play important roles in the cell signaling processes that mediate the manifestation of symptoms. As a result, oxidative stress levels are considerably higher in patients with allergic rhinitis. According to one recent study in children with chronic allergies, blood samples indicated that their total oxidant levels were significantly higher than those of their healthy peers. Based on this combination of chemical and clinical research, researchers are increasingly interested in the ways that anti-inflammatory and antioxidant supplements may prove to be effective allergy treatment options for patients.
Considering Curcumin as a Possible Allergy Treatment Option
As an anti-inflammatory and antioxidant supplement, curcumin has emerged as one of the most prominent potential allergy treatment options. This compound has long been known for its anti-inflammatory and antioxidant properties, and there are preliminary laboratory and clinical studies to suggest that it may help patients who suffer from allergies. For instance, in 2016, a group of researchers in Turkey conducted a rigorous study on the antioxidant effects of curcumin in rat models of allergic rhinitis. After 28 days of oral curcumin therapy, the researchers measured multiple tissue and serum markers of antioxidant activity (including the levels of seven different enzymes with known antioxidant activity) and observed significantly higher levels in the rats that had been treated with the supplement than the rats in their control population. Moreover, the researchers noted that serum markers of oxidation were reduced in the curcumin-treated rats, suggesting that curcumin not only upregulates antioxidant enzyme activity, but may also directly decrease oxidative stress in patients with allergic rhinitis.
Alongside these findings on the benefits of curcumin as an antioxidant, there is also evidence to suggest that curcumin can have a protective effect on acute airway inflammation in patients with respiratory allergy symptoms. In a 2014 study in the journal Inflammation, a group of researchers from China not only demonstrated that treatment with curcumin could reduce inflammation in mouse models, they were also able to elucidate the specific molecular mechanism through which the protective benefit is mediated. Through a series of genetic experiments, the researchers were able to show that the benefits of curcumin in mouse models required the functioning of the Notch1-GATA signaling pathway. When researchers can highlight a specific signaling pathway that directly explains the association between an intervention like curcumin supplementation and anti-inflammatory processes by implicating the activity of a particular cell signaling pathway, it strengthens the evidence that the supplement is truly having an effect—and indicates that further studies are warranted in patients.
So far, the clinical evidence for the benefits of curcumin for allergy patients is limited, but a pilot study from 2016 provided the first indication that curcumin may help modulate the immune response and ameliorate nasal and respiratory symptoms in patients. In a randomized, double-blind study of 241 patients who had previously been diagnosed with allergic rhinitis, a group of researchers in China found that treatment with curcumin led to lower serum levels of multiple inflammatory factors, as well as a decrease in the circulation of certain types of immune cells. In addition, the patients who took the curcumin supplements reported direct therapeutic effects, including reductions in nasal symptoms and improvements in nasal airflow resistance. For researchers, this study paves the way for more comprehensive clinical studies in the future. For patients and practitioners, it suggests that it may be worth trying a curcumin supplement to alleviate allergy symptoms.
The Potential Benefits of Phytochemicals and Other Anti-Inflammatory and Antioxidant Supplements
So far, curcumin is the anti-inflammatory and antioxidant supplement with the strongest laboratory and clinical evidentiary support when it comes to allergy treatment options, but there is also growing evidence that phytochemical supplements may also have positive effects for some patients. These plant-derived compounds may inhibit the nuclear transcription factor NF-kappa-B, which is known to mediate the anti-inflammatory response, as well as other transcription factors with similar activity. Some of the phytochemicals with antioxidant and anti-inflammatory processes that have been highlighted as potential research targets include quercetin, resveratrol, and magnolol.
Indeed, there have been several recent studies highlight quercetin as a possible alternative to antihistamines, including two animal studies in which quercetin supplementation in rat models of rhinitis led to both symptomatic and molecular improvements in anti-inflammatory and antioxidant processes. There is even growing evidence to suggest that there may be other ways in which quercetin supplementation may help reduce the allergy-related immune response—that is, beyond the transcription factor inhibition described above. Specifically, quercetin may also suppress the creation of certain types of immune cells (which can help with chronically elevated systemic inflammation), prevent the release of inflammatory proteins like cytokines, and limit the formation of certain types of antibodies.
Clinical evidence on the benefits of phytochemicals for patients with allergies is still lacking. However, because they have the same antioxidant and anti-inflammatory properties as curcumin, they are increasingly under consideration as potential allergy treatment options. For patients and practitioners who are ready to look beyond the prescription and over-the-counter drugs, supplements like curcumin and quercetin present promising possibilities.
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