This information on babies and egg allergy 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%. More recently, an analysis of data from the EuroPrevall study, which examined a cohort of children from birth to 24 months in 9 European countries, reported an incidence of just over 2% (2.18%) in the UK compared with a mean incidence of 1.23%.3 The incidence reported in Australia is 9%.
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 age4. In the EuroPrevall study around half of the children were able to tolerate egg within one year of diagnosis.3 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.
It is worth noting that some babies and children who are unable to tolerate lightly cooked egg may be able to tolerate well-cooked, extensively heated egg as in baked goods such as small muffins and that over time tolerance to egg protein may develop.5 This approach is used to manage egg allergy.6
A recent study from the US suggests that oral immunotherapy using egg white powder might be superior to baked egg in helping baked egg-tolerant children achieve sustained unresponsiveness to egg protein. However, whether or not such an approach is appropriate would need to be assessed by the medical team on an individual basis. The authors also conclude that their data add weight to the idea that egg-allergic subjects who can tolerate baked egg have a less severe and distinct phenotype of egg allergy.23
Eggs in the mother's diet
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 them.7
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 and in fact there is evidence to the contrary.
A 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.8 There are limited studies on maternal exposure to eggs in pregnancy and infant egg allergy but there is evidence from one study 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 pregnancy.9
More recently, as part of the SACN (Scientific Advisory Committee on Nutrition) review of infant feeding10, a systematic review and meta-analysis of the effects of maternal diet during pregnancy and lactation and risk of development of subsequent food-allergic disease in childhood was commissioned. The authors concluded that there was little evidence for any effect of maternal diet on subsequent risk of childhood allergy.11 However, emerging evidence from recent studies in both animal models and humans suggests that exposure to egg proteins, as measured by ovalbumin in breast milk, may be associated with a reduced risk of egg allergy in childhood.12
Eggs and complementary feeding
Following a review of infant feeding by SACN, it has been emphasised that babies can be given eggs from around 6 months of age when complementary feeding is introduced and delayed introduction could result in a higher risk of allergy later in childhood13. The government has also advised that babies can be given raw or runny eggs safely, as long as the eggs have the British Lion mark on.14
The current recommended weaning advice from the government is to begin the introduction of solid foods at around 6 months of age whilst continuing to breast feed if possible and to include potentially allergenic foods such as eggs at that age.15 However, in the UK many mothers delay the introduction of eggs until much later.16
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 allergies.17 Two important studies, published in 2015 and 2016 respectively, 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 hypothesis18, 19.
The Scientific Advisory Committee on Nutrition (SACN) has reviewed the appropriate age for introduction of complementary feeding and published their findings in a report ‘Feeding in the first Year of Life.10 As part of SACN’s deliberations, 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 comissioned17. 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 foods.20 However, following a further benefit-risk assessment, carried out by SACN/COT, it was concluded 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 months and that the earlier introduction of solid foods may displace breast milk.21
The final SACN report recommends that babies are breastfed exclusively until around 6 months and that breastfeeding should continue for at least the first year of a child’s life. In line with previous advice, SACN recommends that the introduction of complementary foods can begin at around 6 months, but not before 17 weeks. Importantly SACN has also recommended stronger advice concerning the introduction of both hens’ eggs and peanuts, so that these foods are introduced from around 6 months when weaning begins and are not differentiated from other foods. Furthermore, SACN emphasises that the deliberate exclusion or delayed introduction of egg or peanut beyond 6-12 months may increase the risk of allergy to these foods later on10. Once these foods are introduced and tolerated, they should remain part of the baby’s regular diet because if consumption is not maintained after first exposure, this may also increase the risk of sensitisation and future allergy.10
The British Society of Allergy and Clinical Immunology (BSACI), together with the British Dietetic Association (BDA) Food Allergy Specialist Group, have published guidance for healthcare professionals and parents on preventing food allergy in higher risk infants, which also includes advice for non-allergic babies22. Their advice for infants who may be at higher risk of developing food allergies because, for example, they may be exhibiting early onset moderate or severe eczema, differs from the conclusions of SACN. Based on the results of the various research studies, including LEAP and EAT16, 17, they recommend considering the introduction of egg and peanut from 4 months, alongside other complementary foods.22 However, these foods must be introduced carefully, in very small amounts, one by one, and once tolerated should be included at least once per week to ensure immune tolerance; if any reaction occurs the food should be stopped and medical advice should be sought.22
In 2021, the British Society of Allergy and Clinical Immunology published new guidelines on managing egg allergy, with a detailed egg ladder for re-introduction of egg after diagnosis of egg allergy
Allergy diagnosis
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. Therefore, a trial of an egg-free diet followed by controlled challenge is the only strategy for management.
References
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 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.
4 Savage JH, Matsui EC, Skripak JM et al (2007) The natural history of egg allergy. Journal of Allergy and Clinical Immunology, 120:1413-7
5 Upton J, Nowak-Wegrzyn A (2018) The impact of baked egg and baked milk diets on IgE and non-IgE-mediated allergy. Clin Rev Allergy Immunol. 2018 Oct;55(2):118-138. doi: 10.1007/s12016-018-8669-0.
6 Leonard SA et al. (2015) Naked milk- and egg-containing diet in the management of milk and egg allergy. J Allergy Clin Immunol Pract. 2015 Jan-Feb;3(1):13-23; quiz 24. doi: 10.1016/j.jaip.2014.10.001.
7 http://www.nhs.uk/Conditions/pregnancy-and-baby/pages/healthy-pregnancy-diet.aspx
8 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.
9 Vance 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
10 Scientific Advisory Committee on Nutrition (2018) Feeding in the First Year of Life
11 Garcia-Larsen V et al. (2018) Diet during pregnancy and infancy and risk of allergic or autoimmune disease: A systematic review and meta-analysis.
12 Verhasselt V et al. (2019) Ovalbumin in breast milk is associated with a decreased risk of IgE‐mediated egg allergy in children. https://onlinelibrary.wiley.com/doi/full/10.1111/all.14142
13 https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/725530/SACN_report_on_Feeding_in_the_First_Year_of_Life.pdf14 https://cot.food.gov.uk/committee/committee-on-toxicity/cotstatements/c…
14 webarchive.nationalarchives.gov.uk
15 www.nhs.uk
16 Gray J, Gibson S (2014) Egg consumption in pregnancy and infant diets: How advice is changing. Journal of Health Visiting, 2(4): 198-206
17 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
18 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
19 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
20 https://cot.food.gov.uk/committee/committee-on-toxicity/cotstatements/cotstatementsyrs/cot-statements-2016/statement-on-the-timing-of-introduction-of-allergenic-foods-to-the-infant-diet-and-influence-on-the-risk-of-development-of-atopic-outcomes-and-autoimmune-disease
21 https://cot.food.gov.uk/sites/default/files/jointsacncotallergystatementfinal2.pdf(link is external)
22 bsaci.org