A rise in both prevalence and public awareness of food allergy in developed countries means that clinicians and researchers are frequently asked to explain reasons for the increase in food allergy, and families are eager to know whether they can take steps to prevent food allergy in their children. In this review, we outline leading theories on risk factors for early life food allergy. We summarize the leading hypotheses to explain the increase in food allergy as "the 5 Ds": dry skin, diet, dogs, dribble (shared microbial exposure), and vitamin D. We discuss currently available evidence for these theories and how these can be translated into clinical recommendations. With the exception of dietary intervention studies, evidence for each of these theories is observational, and we describe the implications of this for explaining risk to families. Current infant feeding recommendations are that infants should be introduced to solids around the age of 4 to 6 months irrespective of family history risk and that allergenic solids do not need to be avoided, either by infants at the time of solid food introduction or by mothers whilst pregnant or lactating. Additional potential strategies currently being explored include optimization of early life skin barrier function through a decrease in drying soaps and detergents and an increase in the use of nonallergenic moisturizers. The investigation of the role of microbiota and vitamin D is ongoing and cannot yet be translated into clinical recommendations.
Keywords: Eczema; Food allergy; Hygiene hypothesis; Microbial exposure; Migration; Peanut allergy; Vitamin D.
Copyright © 2016 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.