Some foods are more liable than others to provoke allergic reactions in susceptible people because of the kind of proteins they contain. The size of the protein molecule can be important and some proteins are more digestible, absorbable and stable than others.
Eggs contain proteins that, in the raw state, are of the right size and stability to cause allergies, but in most cases these proteins cannot withstand the effect of heat. This explains why people with an allergy to eggs may tolerate some forms of well-cooked eggs, such as in baked products like cakes, even when they contain relatively large quantities of egg, but may still react to raw or lightly cooked egg proteins1.
In Europe and elsewhere a significant proportion of the population report adverse reactions to food which they regard as 'allergy', but generally few of these perceived reactions are true IgE-mediated reactions. An analysis of the prevalence of sensitisation to 24 foods, among a random sample of over 4500 young adults in 13 countries, found overall rates to be highly variable across different countries, although sensitisation rates to specific foods were similar in all countries.
Sensitisation rates to egg were generally low, at an average of 0.2% in the overall sample population; the figure for egg sensitisation in the UK was 0.5%2.
In a study published in 2016 the incidence of confirmed egg allergy in a sub-group of children studied from birth to 24 months was just over 2%, compared with 1.23% in Europe as a whole; about half the children in the overall study were shown to tolerate eggs within one year of diagnosis3.
1Lack G (2012) Update on risk factors for food allergy. Journal of Allergy & Clinical Immunology 129: 1187-97
2Burney P, Summers C, Chinn S, Hooper R, van Ree R, Lidholm J, (2010) Prevalence and distribution of sensitization to foods in the European Community Respiratory Health Survey: a EuroPrevall analysis, Allergy 2010; 65, 1182-1188
3 Xepapadaki et al. (2016) Incidence and natural history of hen's egg allergy in the first 2 years of life-the EuroPrevall birth cohort study. Allergy. 2016 Mar;71(3):350-7.