Update on food allergy

Overview

This review, published in Pediatric Allergy and Immunology in 2021, summarizes recent advances in IgE-mediated food allergy. Food allergy is a growing public health problem in the urbanized world. Beyond the risk of allergic reactions, it affects nutrition, family finances, quality of life and mental health, and many children with food allergy experience bullying.

Epidemiology and mechanisms

Food allergy is most common in infancy and early childhood. Egg and cow's milk allergy often resolve, whereas peanut and tree nut allergy tend to persist. Prevalence varies widely between and within countries and is lower in rural areas. Early, severe eczema is probably the strongest known risk factor, possibly because a damaged skin barrier allows sensitization through the skin. New research highlights Th2-skewed T-cell responses, a follicular helper T-cell subset that drives high-affinity IgE, IgE class switching in gut tissue, and the roles of IgE glycosylation and basophil responses.

Diagnosis

Diagnosis rests on the clinical history plus evidence of allergen-specific IgE, with the double-blind placebo-controlled food challenge as the gold standard. Skin prick tests and specific IgE are safe and inexpensive, but many sensitized children tolerate the food. Component-resolved diagnostics, such as IgE to the peanut component Ara h 2, the basophil activation test and the mast cell activation test improve accuracy. The authors propose using them as second-line tests after equivocal conventional results to reduce the need for oral food challenges.

Management and prevention

There is no cure. Management is based on allergen avoidance and access to emergency medication, which many patients do not carry consistently. Oral immunotherapy is now an established treatment for milk, egg and peanut allergy and lowers the risk of reactions after accidental exposure, but it increases allergic reactions during treatment, and tolerance is often lost when regular intake stops. Sublingual and epicutaneous routes are safer but less effective. Biologics such as anti-IgE are mainly studied as adjuncts to immunotherapy. For prevention, introducing peanut and egg into the infant diet at weaning, alongside breastfeeding, is the one widely recommended strategy. Management plans should reflect patient and family preferences.