The interplay between risk and preventive factors explains why some children develop allergies to certain foods and others show tolerance

Aim A number of studies have clarified the tolerance mechanisms and risk factors for food allergies. Our aim was to explore food allergy symptoms by target organs, together with the risk factors and how to prevent food allergies and induce tolerance. Methods We carried out a thorough review of studies on paediatric food allergies published in the last decade. Results Food allergy symptoms may affect the skin, nasal and oral mucosa, conjunctivae, gastrointestinal tract or, in severe cases, the respiratory tract and cardiovascular organs. Immunoglobulin E (IgE)‐mediated symptoms appear rapidly after exposure to the offending allergen, whereas non‐IgE‐mediated symptoms are typically delayed. The immunological processes involved in non‐IgE‐mediated allergic reactions are poorly understood, but T‐cell activation is probably involved. There are several factors that influence the food sensitisation process: genetic predisposition, disruption of oral tolerance development, impaired skin barriers in atopic eczema and the influence of microbiomes. Conclusion The symptoms and intensity of reactions vary considerably with regard to food allergies, and these depend on the individual's concomitant immunological and regulatory mechanisms. There is strong evidence that dietary diversity is important for children, even when they come from families with high allergy risks.