NHD CPD eArticle Volume 9.05 9th May 2019
FOOD ALLERGY EXAMINED: WHERE WE ARE NOW Food allergy (FA) is a dynamic area, with advances continuing to be made in the understanding, diagnosis, prevention and treatment. The following article includes updates on prevalence, incidence, causes, management and treatment. In 2010, an Expert Panel Report sponsored by the National Institute of Allergy and Infectious Diseases (NIAID), defined FA as ‘an adverse health effect arising from a specific immune response that occurs reproducibly on exposure to a given food’, and food intolerance as ‘non immune reactions that include metabolic, toxic, pharmacologic and undefined mechanisms’.1 Any reaction to food that results in objectively reproducible signs or symptoms should be described as food hypersensitivity. If immunological mech-anisms are involved, then it should be described as a FA. Where immunoglobulin E (IgE) is involved, then the terminology IgE mediated FA should be used and where immune mediated reactions not mediated by IgE, the term non-IgE mediated FA is the correct term. PREVALENCE AND INCIDENCE
Data suggests that FA is common, with the prevalence of clinically proven FA as high as 10%, in preschool children in developed countries.2 In countries such as Asia and China, where societies are large and rapidly increasing and there are documented increases in FA, the prevalence of oral food challenge (OFC) proven FA is now approximately 7% in preschoolers. This figure is comparable to European reported prevalence.
It also appears to affect those in industrialised/westernised regions disproportionately, more common in children as opposed to adults and only a few foods accounting for most of the more serious reactions, namely peanut, tree nuts, fish, shellfish, egg, milk, wheat, soy and seeds.1,3,4 In children, FA affects up to 6% to 8%5,6 and the incidence has increased significantly over the past 20 years.7 All prevalence data, outside of non-IgE mediated cow’s milk protein allergy (CMPA), is based on IgE mediated allergies. Determining prevalence statistics remains difficult, however, due to a number of reasons: many manifestations of FA with varying degrees of severity; different allergy definitions being used; evaluation of specific study populations; focus on specific foods; different methodologies; geographic variations; diet exposure effects; and differences according to age, race and ethnicity.8 Self-reported FA rates are substantially higher compared to those by medically supervised OFCs.9 The systematic review and meta-analysis of FA to ‘common foods’ in Europe, by Nwaru et al, looked at 42 studies, finding an overall lifetime self-reported prevalence of 6% (95% CI, 5.7% to 6.4%). A EuroPrevall birth cohort study involving nine countries enrolled 12,049
Jacqui Lowdon Paediatric Dietitian, Leeds Children’s Hospital Jacqui is a Clinical Specialist in paediatric cystic fibrosis at Leeds Children’s Hospital. She previously specialised in gastroenterology and cystic fibrosis. Although her career to date has focused on the acute sector, Jacqui has a great interest in paediatric public health.
This article has been peer reviewed by Dr Rosan Meyer, RD,PhD Paediatric Research Dietitian, Honorary Senior Lecturer, Imperial College, London.
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