Food allergy remains a significant paediatric health concern, but a positive allergy test alone does not always indicate true clinical allergy. Many children develop food sensitization, in which allergen-specific immunoglobulin E (IgE) antibodies are detectable without experiencing allergic symptoms when the food is consumed. Differentiating transient sensitization from persistent allergy is essential for prognosis, counselling, and therapeutic decision-making.^1,2

A recent longitudinal study published in Allergy investigated the natural evolution of allergen sensitization during early childhood using data from the Canadian Healthy Infant Longitudinal Development (CHILD) Cohort Study.³ Researchers aimed to better understand how sensitization patterns change between infancy and preschool age, providing valuable insights into the progression of allergic disease.

Changing Patterns of Sensitization During Early Childhood

The study evaluated 500 mother–child pairs, with maternal blood collected during pregnancy and children's blood samples obtained at 1 year and 5 years of age. Nearly 300 allergen extracts and molecular allergen components were analysed using component-resolved diagnostics to identify sensitization profiles over time.³

At one year of age, 25.3% of children demonstrated sensitization to at least one allergen-specific IgE. By five years of age, this proportion had increased to 40.4%, indicating that sensitization becomes more common as children grow older.³

The profile of allergens also evolved with age. During infancy, egg and peanut were the predominant food allergens associated with sensitization. By five years, sensitization shifted mainly toward peanut and tree nuts, while sensitization to inhalant allergens—including cat and dog dander, house dust mites, and grass pollens—became increasingly prevalent.³

Different Allergens Follow Different Courses

The investigators observed important differences in the persistence of sensitization among food allergens.

Peanut sensitization frequently developed early and tended to persist. Approximately half of the children sensitized to major peanut allergen components at one year remained sensitized at five years, suggesting greater stability of peanut-specific IgE responses.

In contrast, sensitization to important allergenic proteins from cashew, hazelnut, walnut, and pistachio often appeared later in childhood, indicating that sensitization to several tree nuts may develop progressively rather than during infancy.

Interestingly, sensitization was not always permanent. Approximately 25% of children lost sensitization to 2S albumin proteins over the four-year follow-up period. These storage proteins are major allergenic components of peanut, sesame, and several tree nuts and are commonly associated with systemic IgE-mediated allergic reactions. Loss of sensitization to these components may therefore indicate changing immune responses over time, although it does not necessarily confirm resolution of clinical allergy.⁴

Clinical Implications for Management

Understanding whether allergen sensitization is persistent, newly acquired, or resolving has become increasingly important as treatment options for food allergy continue to evolve. Current international guidelines recognize oral immunotherapy (OIT) as a treatment option for selected patients with IgE-mediated food allergy, with accumulating evidence suggesting that earlier intervention may improve treatment success and long-term outcomes.^5,6

Longitudinal assessment of molecular sensitization profiles may therefore help clinicians counsel families regarding prognosis, determine the need for further evaluation, and identify children who may benefit from emerging therapeutic strategies.

Study Limitations

The authors emphasize that the study evaluated IgE sensitization rather than clinically confirmed food allergy. Oral food challenges, which remain the gold standard for diagnosing food allergy, were not performed. Consequently, the findings should not be interpreted as evidence that one-quarter of children outgrow established food allergy. Instead, they demonstrate that allergen-specific IgE sensitization is dynamic during early childhood and may either persist, emerge, or disappear over time.

References

1. Middleton's Allergy: Principles and Practice. Elsevier; 2020.

2. European Academy of Allergy and Clinical Immunology. Muraro A, et al. EAACI guidelines on the diagnosis and management of IgE-mediated food allergy. Allergy. 2014;69(8):1008-1025.

3. Wong T, Eiwegger T, et al. Longitudinal changes in allergen component sensitization during early childhood in the Canadian CHILD Cohort Study. Allergy. 2026. doi:10.1111/all.70516.

4. American Academy of Allergy, Asthma & Immunology. Sampson HA, et al. Food allergy: A practice parameter update. J Allergy Clin Immunol. 2014;134(5):1016-1025.

5. Global Allergy and Asthma European Network, European Academy of Allergy and Clinical Immunology. Managing food allergy: GA²LEN ANACARE consensus recommendations. Allergy. 2024.

6. European Academy of Allergy and Clinical Immunology. EAACI Guidelines on IgE-mediated food allergy: Oral immunotherapy. Allergy. 2024.