Food allergy and atopic dermatitis

Abstract

Food allergies are an important cause of atopic dermatitis. While the association between eczema and food allergies is well established, effective guidelines for dietary modifications in children with eczema remain unavailable. Food allergies can be IgE or non-IgE mediated and food allergies should be approached for both IgE-mediated food allergy and non-IgE-mediated food allergy. But tests based on IgE levels cannot predict the likelihood of all eczematous reactions, as some reactions occur in the absence of detectable food-specific IgE levels. Oral food challenges are the gold standard for food allergy testing and can allow for recognition of both early and late cutaneous reactions, including eczematous reactions. An elimination diet should precede the oral food challenge, along with appropriate control of other allergens such as dust mites, aggravating factors and infections. Reduced serum eosinophil levels following an elimination diet protocol strongly suggest food allergy as a cause of atopic dermatitis. After allergenic foods resulting in atopic dermatitis are determined through oral food challenge using a relevant protocol for IgE-mediated food allergy and non-IgE-mediated food allergy, allergenic foods can be managed by avoidance or by tolerance induction of the allergenic foods. Oral immunotherapy for food allergies is remarkably advanced, and specific oral tolerance induction is actively recommended for food allergies when indicated. Specific oral tolerance induction using IFN-γ has been particularly well established. A definitive distinction between IgE-mediated food allergy and non-IgE-mediated food allergy is absolutely necessary because the diagnostic and therapeutic procedures differ significantly. This chapter highlights the conceptual immunologic background and the practical effective control of food allergies in atopic dermatitis, including the diagnosis and management of these conditions.