Why zinc may be the missing nutrient in childhood asthma care

By Dr. Liji Thomas, MDReviewed by Lauren HardakerAug 19 2025

Scientists explain how zinc deficiency may fuel childhood asthma and allergies, and why supplements could become a safe, low-cost add-on treatment once clinical trials confirm the benefits.

Study: The Role of Zinc in Pediatric Asthma and Allergic Rhinitis: Mechanisms and Clinical Implications. Image credit: New Africa/Shutterstock.com

Both asthma and allergic rhinitis in children are driven by chronic inflammation, the result of genetic and environmental forces. A literature review, published in Nutrients, explored available evidence on the role of the trace element zinc in preventing such illnesses via its effect on oxidative stress and immunomodulation.

Introduction

Among the most common chronic illnesses worldwide are asthma and allergies. Asthma affected 262 million people in 2019, with 455,000 deaths. It is also a leading cause of disability.

Asthma affects nearly 6.5% of children aged 6-11 years, and the prevalence is increasing. The factors responsible could be urbanization, increased focus on hygiene, higher rates of environmental pollution, and unhealthy ‘Westernized’ dietary patterns. Asthma management aims to control symptoms, allow the patient to live normally, and prevent acute exacerbations. Simultaneously, the adverse effects of asthma treatment need to be minimized.

There are sometimes misplaced fears regarding conventional steroid- and anti-allergic therapies for asthma and allergic rhinitis, so patients are exploring complementary medicine and the role of nutrition as treatments. Trace elements like zinc and iron, and vitamins like A, C, and D, can alter the immune response and enhance the body’s antioxidant capacity. These are often deficient in children suffering from atopy, with zinc and vitamin A deficiency linked to airway inflammation.

In adults, zinc deficiency is generally defined by levels below 74 µg/dL and 70 µg/dL in males and females, respectively. In children aged ≥10 years, thresholds are below 70 µg/dL in males and 66 µg/dL in females. However, these can vary with age and sex, inflammation, and individual body rhythms.

Zinc is second only to iron in body abundance and is found in multiple tissues, including muscle and bone, skin, and liver. It is involved in over 300 enzyme-mediated reactions, gene transcription, and protein structure. Up to 20% of people worldwide may be zinc-deficient. Signs and symptoms include retarded growth, repeated infections, impaired wound healing, and imbalanced immune reactions.

Zinc functions

The redox cycle is the site of zinc’s most essential functions. It restricts the production of hydroxyl radicals by competing with iron, copper, and other transition metals with high redox potential. It is the coenzyme for copper-zinc superoxide dismutase, which opposes lipid peroxidation within the cell membranes, thus countering inflammation.

Zinc keeps the thymus gland healthy and maintains thymulin activity at normal levels, allowing T cell differentiation and immune tolerance. Zinc deficiency causes poor T cell development and a Th2-skewed phenotype shift. The presence of a Th2-dominant picture after exposure to non-noxious environmental stimuli is characteristic of asthma.

The Th2-dominant phenotype is pro-inflammatory and stimulates B lymphocyte activation, causing a flood of immunoglobulins (Ig), especially IgE, interleukin release, and eosinophil activation, the markers of allergy-related inflammation.

Low zinc levels are linked to increased airway eosinophilia, which is opposed by zinc supplementation. Zinc also regulates the proliferation and inflammatory activity of group 2 innate lymphoid cells. Additionally, zinc controls dendritic cell maturation and enhances the tolerogenic states of these antigen-presenting cells. Without enough zinc, these cells become hyperactive, and the individuals develop a Th2-skewed picture with allergic sensitization.

Zinc maintains epithelial barrier integrity by stabilizing the tight junction molecules. It also activates a signaling cascade that increases junctional complex assembly. Zinc deficiency can allow allergens to get through the epithelial barrier, triggering overactive immune responses and long-lasting inflammation.

Zinc alters apoptosis, helping prevent excessive cell loss while supporting tissue repair and recovery in the presence of oxidative stress or toxins. This knowledge of zinc's actions supports its role in preventing atopy.

Study findings

Multiple observational and interventional studies have shown that low zinc levels in children with asthma correlate with more symptoms, poorer lung function, and higher levels of oxidative stress, even without meeting the threshold for clinical deficiency.

Children with allergic rhinitis were more likely to have inflamed nasal mucosal membranes and lower serum zinc levels. At the same time, acute allergic inflammation is associated with increased zinc in the mucosa. This could be due to the movement of zinc from the blood to the allergy site. This hypothesis is supported by preclinical experiments and by the known role of zinc in maintaining epithelial barrier integrity and its immunomodulatory activity.

Some but not all interventional trials in children with asthma indicate that zinc supplementation may provide benefits for symptoms (wheezing, cough, shortness of breath) and lung function. Still, findings remain inconsistent due to differences in study design, supplementation protocols, and populations studied.

Adequate zinc levels in pregnancy were linked to better lung function and a lower risk of asthma in the offspring. Intranasal zinc in mice reduced allergic symptoms like sneezing and mucin-secreting goblet cells in the nasal mucosa.

In mice, zinc deficiency activates the p38 MAPK signaling pathway, while supplementation reduces this effect, dropping elevated IgE and inflammatory cytokine levels.

Conclusion

Zinc homeostasis affects many children with asthma and allergic rhinitis, acting through multiple pathways. The most important roles appear to be its ability to prevent aggressive inflammation immune reactions and keep the mucosa healthy. Being safe and readily available, zinc supplementation could be a valuable add-on for children with allergic airway disease.

However, this is mainly observational data, with significant heterogeneity and non-standardized supplementation protocols. The formulation of clinical guidelines on zinc supplementation requires well-designed randomized controlled trials to ensure that zinc is clinically useful and to establish the mode, dosage, duration, and conditions of use for optimal benefit. Hair zinc levels rather than serum zinc could be a better marker of zinc adequacy. The intranasal route offers much promise.

“Integrating zinc status assessment into routine clinical evaluation, especially in children with severe or poorly controlled allergic disease, may offer a pathway toward more personalized and effective treatment strategies.”

Download your PDF copy now!