Egg allergy is one of the most common food allergies in young children affecting 2 – 3% of UK children. Predicting which infants and children will outgrow egg allergy is related to two key features: the severity of initial reactions to egg and the ability to tolerate baked egg. High skin prick tests and IgE blood values are strongly predictive for persistent egg allergy. Tolerance to baked egg at age 1 is predictive for around 50% of infants outgrowing their allergy by age 2.
Who gets allergy allergy?
Genetically susceptible individuals are those with atopic conditions such as eczema, asthma or hayfever in the immediate family. More strongly inherited on mum’s side, and in particular if mum has eczema, and which rises with atopic conditions and severity in both mum and dad. Infants can be become sensitised to eggs even although they have never eaten egg, both from egg proteins from mum’s diet crossing the placenta and transferred in breast milk. Maternal egg avoidance in pregnancy would not be advised as a public healthy policy, with the likely consequence of actually increasing prevalence of egg allergy in the general population.
Outgrowing egg allergy
Allergy to egg white is more common and takes longer to outgrow due to the composition of specific and more complex protein structures. Egg yolk may be tolerated entirely or at an earlier stage (than egg white) and can be a valuable addition to the diet. All egg proteins are heat labile, with higher cooking temperatures altering the proteins, making them less likely to cause allergic reactions with the less severe presentations of egg allergy. Continuing to consume oven-baked egg, provides useful exposures which serve to educate the immune system and develop tolerance, and is a useful practice to support outgrowing egg allergy. Complete avoidance of egg for those with less severe reactions will limit tolerance development and allergy to egg may be maintained. Immunotherapy for those with persistent allergy, can offer a treatment with tiny amounts to gradually educate the immune system, and is currently being offered by a small number of centres in the UK.