Zinc and childhood allergies: how the trace element affects asthma and rhinitis

Asthma and allergic rhinitis are two of the most common chronic diseases in children. They are formed at the intersection of genetics, environment, and nutrition. In a new review in Nutrients, scientists analyze the role of zinc, a trace element that affects immunity, oxidative stress, and the integrity of mucous membranes. The conclusion is short: zinc is involved in all key nodes of allergic inflammation, and deficiency is more common in children with asthma; zinc supplements show promising, but so far inconsistent clinical effects - rigorous RCTs are needed.

Background of the study

Asthma and allergic rhinitis are the most common chronic inflammatory diseases of the respiratory tract in children. Their development is influenced by genetics, environment and nutritional characteristics, and symptom control is influenced by the state of the mucous barrier and oxidative stress. Against this background, microelements with immunomodulatory properties attract attention, primarily zinc, which is involved in the work of hundreds of enzymes and transcription factors, maintains antioxidant protection and the integrity of the epithelium.

Observational studies indicate that a proportion of children with asthma and rhinitis have lower circulating zinc levels, which is associated with greater inflammation and poorer lung function. Mechanistically, zinc deficiency shifts the immune response toward Th2 dominance, impairs antioxidant systems (including Cu/Zn-SOD), and impairs epithelial repair, theoretically enhancing allergic airway inflammation.

Clinical interventions provide promising but inconsistent signals: zinc supplementation has been shown to reduce symptoms, inflammatory markers, and improve spirometry in asthma in a number of studies, but results have varied due to differences in dose, duration, inclusion criteria, and endpoints. This calls for careful interpretation and highlights the need for standardized RCTs in pediatric patients.

A separate issue is the assessment of zinc status: serum levels are influenced by age, circadian oscillations, and inflammation, so thresholds for deficiency in children must be interpreted in the clinical context. Taken together, the accumulated data make zinc a logical target for adjuvant therapy of childhood airway allergies, but translation into routine recommendations requires a more uniform evidence base.

What data array was analyzed?

The authors conducted a targeted search of PubMed and Cochrane (2015–2025) and included observational and interventional studies in children with asthma or allergic rhinitis that assessed zinc status and/or supplementation. The review also included mechanistic studies on how zinc affects Th1/Th2 balance, oxidative stress, and the airway barrier epithelium.

Key to interpretation:

• Asthma in children is often associated with low blood zinc levels, which correlates with poorer symptom control and lower lung function;
• In allergic rhinitis, a decrease in zinc in the nasal mucosa and an increase in local inflammation are observed (during an exacerbation, paradoxical fluctuations in levels in the secretion are also possible).

What does zinc do at the mechanical level?

Normally, the body contains 2-4 g of zinc; it participates in hundreds of enzymatic reactions and regulates gene transcription. In immunity, it is needed for thymulin activity, T-cell differentiation and maintenance of tolerance. When there is little zinc, the balance "shifts" towards the Th2 response, characteristic of allergies. At the same time, antioxidant systems and the epithelial barrier suffer.

More specifically, by nodes:

• Oxidative stress: Zinc competes with iron/copper to reduce hydroxyl radical generation and is a component of Cu/Zn-SOD, which reduces lipid peroxidation and proinflammatory signals (e.g., 8-iso-PGF₂α).
• Adaptive immunity. Deficiency → thymic atrophy, decrease in thymulin activity → shift of CD4⁺-response to Th2 (↑IL-4/IL-5/IL-13, ↑IgE, ↑eosinophils).
• Innate immunity and barrier. Zinc influences ILC2, epithelial “alarmins” and epithelial repair, helping to keep the mucosal “gate” closed to allergens.

What clinical studies show

The picture is uneven, but trends can be seen.

• Observational data:
  • Children with asthma are more likely to have low circulating zinc;
  • deficiency is associated with higher oxidative stress and worse lung function.
• Interventional work:
  • Zinc supplements often improved symptoms, reduced inflammation, and improved spirometry;
  • but the results are inconsistent, due to differences in dose/duration, inclusion criteria, and outcome assessment methods.

The conclusion of the review: zinc is a multifactorial modifier of allergic inflammation. Supplements look promising as an adjunct to standard therapy, but high-quality RCTs are needed to determine who, how much, and for how long they are truly beneficial.

How to understand if there is a shortage

Diagnosis of zinc status is challenging: serum levels are influenced by age, gender, circadian rhythms, and inflammation. Guidelines for pediatric populations ≥10 years use values of ≈66-70 mcg/dL as a lower limit, but context is important—levels must be interpreted in conjunction with clinical presentation and risk factors.

Practical meanings

If a child with asthma/rhinitis is often ill, recovers slowly from exacerbations, eats selectively - the zinc status should be discussed with a doctor. The review suggests several directions:

• Nutrition as a base:
  • food sources: lean meat, fish, eggs, dairy, legumes, whole grains, nuts/seeds;
  • For vegetarian diets, ensure variety and bioavailability.
• When thinking about supplements:
  • there is evidence, but it is not unified;
  • discuss dosage/timing/monitoring with a pediatric allergist, especially if asthma and recurrent respiratory infections are combined.
• Combinations of strategies: nutrition + standard therapy (ICS, antihistamines, etc.) + work with sleep, allergens and physical activity.

What else is near zinc?

In the introduction, the authors briefly remind us that vitamins A, C, D, E, selenium, iron and a number of bioactive molecules (e.g. lactoferrin, resveratrol/β-glucan in intranasal forms) are also studied in childhood allergies and sometimes show a clinical effect. But the focus of the review is zinc and its mechanistic "architecture".

Limitations that are honestly stated

• much heterogeneity between studies (age, severity, doses, duration, endpoints);
• zinc biomarkers are variable and there are no screening standards for all children with asthma/rhinitis;
• Some effects may depend on concomitant deficiencies (vitamin D, etc.) and diet in general. Conclusion: large, well-designed RCTs with standardized outcomes are needed.

Conclusion

Zinc is not a silver bullet, but it is a significant cog in the mechanism of childhood airway allergies. Deficiency is common and is associated with poorer disease control; supplements may help some children, but the evidence is still inferior to standard drug therapy. The best approach is to assess status, strengthen diet, and make personalized decisions.

Source: Dinardo G. et al. The Role of Zinc in Pediatric Asthma and Allergic Rhinitis: Mechanisms and Clinical Implications. Nutrients. 2025;17(16):2660. Published August 17, 2025. https://doi.org/10.3390/nu17162660