This information is specific to allergies and is designed for health professionals only. See here for general information on eggs for babies.
The frequency of all food hypersensitivity peaks in the first year of life and represents a serious health issue. Milk and egg are the two most common food allergens1.
Many estimates of prevalence of food allergies are based on self-reported data and therefore may overstate the issue. However, a 2007 meta-analysis that included both self-reported and more objective evidence of IgE-mediated reactions, such as skin prick and double-blind challenge data, suggested that food allergy affects about 4% of children2. The reported prevalence for egg allergy in young children based on symptomatic and skin prick/IgE tests in this analysis was 0.5% - 2.5%.
Egg allergy in infants
Egg allergy is most common in infants under the age of twelve months, but tends to resolve with time in most children by late childhood. The phenomenon of tolerance among children with food allergies is well-recognised. Therefore, although some food allergies, such as peanut allergy, persist into adult life, egg allergy frequently diminishes and disappears after a period of time. Estimates of persistence vary, but evidence suggests that by 10 years of age more than one third of children will have developed tolerance to egg and that at least two thirds of children will have outgrown their allergy by 16 years of age3. Those with other allergies or with a family history of allergy seem to be particularly vulnerable to persistent egg allergy.
Food allergy commonly presents in infants as atopic dermatitis (eczema) and egg is the most common food to cause eczema in babies. The presentation of an egg allergy in sensitised babies can be dramatic. The most common immediate way in which this allergy presents is with a red rash around the mouth within seconds of eating a meal containing egg, followed in a few minutes by angioedema - swelling around the mouth, on the face and also inside the mouth. Rapid onset of vomiting is also common. However, particularly in patients with non-IgE mediated reactions to egg, the symptoms may be delayed for many hours with slowly worsening eczema, abdominal pain and distension, diarrhoea and occasional constipation. Frequently, as they get older, children will also display respiratory symptoms such as sneezing, wheezing and asthma. Anaphylaxis may also occur, but is rarer than in milk or nut allergy.
Eggs in the mother's diet
It has been observed that more than half of the infants who develop egg allergy begin to have symptoms within minutes of ingesting egg for the first time. In infants with eczema, sensitisation can occur just through skin contact with very small amounts of egg. While it is possible that some may have unknowingly been exposed to and sensitised by small amounts of egg, for example, in a manufactured baby food, some may have been sensitised before birth or via breast milk. However, there is no evidence that the avoidance of egg during pregnancy or lactation, or delayed introduction at weaning, will reduce the incidence of egg allergy. The most recent Cochrane review of five trials of antigen avoidance in the maternal diet concluded such approaches were unlikely to substantially reduce the child's risk of atopic disease.4 In fact there is some evidence that infants whose mothers were exposed to higher levels of egg in pregnancy showed fewer egg allergic responses at 6 months than those whose mothers had minimal exposure to egg during pregnancy5. Therefore, the avoidance of egg in pregnancy does not appear to be the best strategy. Current government advice to pregnant and breastfeeding women does not recommend the exclusion of eggs or other allergenic foods to reduce the risk of allergies in their babies, and suggests that eggs can be consumed as part of a healthy, balanced diet, unless the woman is herself allergic to them6.
Eggs and weaning
The current recommended weaning advice from the Department of Health is to begin the introduction of solid foods at around 6 months of age and to include potentially allergenic foods such as eggs at that age7. However, in the UK many mothers delay the introduction of eggs until much later8.
There is growing evidence that the delayed introduction of potentially allergenic foods may indeed be counter-productive and more likely to be associated with subsequent development of allergies9,10. Two important studies, published in 2015 and 2016 respectively, have tested the hypothesis that the introduction of potential allergens into an infant's diet during a critical window, at around or slightly before six months, may result in greater tolerance to these proteins and therefore reduce the risk of allergic disease in the child. The results of both these studies - LEAP (Learning Early about Peanut Allergy) and the EAT (Enquiring About Tolerance) - support this hypotheis11,12.
Advice concerning the appropriate timing for introduction of potentially allergenic foods, including eggs, is currently under review by the government. The Scientific Advisory Committee on Nutrition (SACN) is reviewing the appropriate age for introduction of complementary feeding and has published a draft report13. As part of this the Committee on Toxicity (COT) was asked to review the optimal age for the introduction of allergenic solids and a systematic review and meta-analysis of the evidence was comissioned10. A COT opinion, based on the review was published in 2016, concluding that for peanut and for egg, there was moderate evidence that earlier introduction (at 4-11 months for peanut at and 4-6 months for egg) reduces the likelihood of subsequently developing an allergy to those foods14. However, following a further benefit-risk assessment, carried out by SACN/COT, it was suggested that there were insufficient data to suggest that introduction of egg or peanut between 4-6 months reduced the risk of allergy to those foods to a greater extent than introducing them at around 6 months15 and that the earlier introduction of solid foods may displace breast milk13. Importantly though, it was concluded from these data that the deliberate exclusion or delayed introduction between 6-12 months of egg or peanut may increase the risk of allergy to these foods later on15.
Final advice is awaited from SACN, but in the meantime it is generally important that a wide range of foods are introduced into the infant diet from six months. For the majority of children, provided that there has been no evidence of eczema or other symptoms of egg allergy. as discussed above, eggs should be introduced from around six months.7, 13.
Diagnosis of egg allergy, as with other food allergies, requires confirmation by the presence of antigen-specific IgE, using skin prick tests and immunoassay of serum antigen-specific IgE concentration.1 Management involves the removal of all sources of egg, with subsequent periodic reviews of the child’s allergic status to assess evidence of developing tolerance.1 When there is evidence of a diminishing skin test reaction or levels of circulating egg specific IgE, challenge with egg protein would be attempted under controlled medical conditions, initially using baked egg and ultimately with raw egg. Subject to the results of such challenges, in most children eggs would be gradually re-introduced at some time in later childhood, initially as small amounts in baked goods. However, in small proportion of people, the egg allergy will persist into adult life.
In patients with suspected non-IgE mediated reaction to egg there is currently no reliable test to confirm the diagnosis. Thus a trial of an egg free diet followed by controlled challenge is the only strategy for management.
1 Longo G, Berti I, Burks AW et al (2013) IgE-mediated food allergy in children. Lancet. 2013 Jul 8. pii: S0140-6736(13)60309-8. doi: 10.1016/S0140-6736(13)60309-8
2 Rona RJ, Keil T, Summers C et al (2007) The prevalence of food allergy: a meta-analysis. Journal of Allergy and Clinical Immunology, 120:638-46
3 Savage JH, Matsui EC, Skripak JM et al (2007) The natural history of egg allergy. Journal of Allergy and Clinical Immunology, 120:1413-7
4 Kramer MS, Kakuma R (2012) Maternal dietary antigen avoidance during pregnancy or lactation, or both, for preventing or treating atopic disease in the child. Cochrane Database of Systematic Reviews 2012, Issue 9. Art. No.: CD000133.DOI:10.1002/14651858.CD000133.pub3.
5Vance GHS, Grimshaw KEC, Briggs R et al (2004) Serum ovalbumin-specific immunoglobulin G responses during pregnancy reflect maternal intake of dietary egg and relate to the development of allergy in early infancy. Clinical & Experimental Allergy 34: 1855-61
8 Gray J, Gibson S (2014) Egg consumption in pregnancy and infant diets: How advice is changing. Journal of Health Visiting, 2(4): 198-206
9 Koplin JJ, Osbourne NJ, Wake M et al (2010) Can early introduction of egg prevent egg allergy in infants? Journal of Allergy and Clinical Immunology, 126:807-13
10 Ierodiakonou et al. (2016) Timing of allergenic food introduction to the infant diet and risk of allergic or autoimmune disease: a systematic review and meta-analysis. Journal of the American Medical Association. 316 (11) 1181- 1192
11 Du Toit G et al (2015). Randomized trial of peanut consumption in infants at risk for peanut allergy. New England Journal of Medicine. 372(9):803-13
12 Perkin MR et al. EAT Study Team. (2016) Randomized Trial of Introduction of Allergenic Foods in Breast-Fed Infants. New England Journal of Medicine 374:1733-1743