Primary Prevention of Food Allergy in Infants

Editor(s):
Dr Lee Bee Wah

In children, allergic diseases – including food allergy – are among the most common non-communicable diseases. In this article, Dr Lee Bee Wah, Adjunct Professor at the National University of Singapore specialising in clinical paediatric immunology and allergy, discusses the latest updates in the primary prevention of food allergies.

Drivers of food allergy – New insights

In Western countries, challenge-diagnosed food allergy has been reported to be as high as 10%; In Asia, the overall prevalence of food allergy appears to be lower compared to that in the West, and the types of food allergy differ in order of relevance, e.g. egg and cow’s milk allergy appear to be as common as in the West, while peanut allergy appears to be less common in Singapore. , Recent studies suggest, however, that a shift towards an urbanized lifestyle, either as a result of rising economic growth or migration, contribute to the development of food allergy. In Australia, it was reported that infants with parents of East Asian ethnicity had a three-fold higher risk of food allergy compared with infants of non-East Asian descent, and children of Asian mothers who migrated to Australia had a lower risk of nut allergy than children of Asian mothers born in Australia.1 These findings suggest that genetic factors, as well as migration and exposure to a Western environment early in life may contribute to allergy risk.

Mounting evidence also now point to the skin as a site for allergic sensitisation to foods, thus suggesting that atopic dermatitis – characterised by skin barrier impairment and inflammation – may be a strong risk factor for food allergy. While the exact mechanism is still unclear, current evidence suggests that food allergy may develop through transcutaneous sensitisation to allergenic peptides.

Primary prevention of food allergy – Latest developments

Many official guidelines – including those of the Asia Pacific Association of Pediatric Allergy, Respirology and Immunology (APAPARI) – now encourage the early introduction of allergenic food into diets of infants at risk of developing food allergy.6

Peanut allergy

The Learning Early About Peanut Allergy (LEAP) study showed that early introduction of peanuts in infants with severe eczema, egg allergy or both drastically reduced the risk of developing allergy at 5 years of age. The protective effect of peanut consumption persisted after 12 months of avoiding peanuts, suggesting that the early exposure was sufficient to induce durable tolerance. The protective effects also appears to be allergen-specific; early consumption of peanuts does not prevent the development of other allergic disease, sensitization to other foods and allergens.

Egg allergy

Similar findings have been reported for egg allergy: the step-wise introduction of heated egg, combined with aggressive eczema treatment, helped prevent egg allergy in high risk infants.

Milk allergy

The prevention of cow’s milk allergy appears to be complex. Partially hydrolysed (pHF) and extensively hydrolysed (eHF) formulas have been suggested to be effective in preventing allergic diseases and atopic eczema. However, many of these trials lack methodological rigor, and underscores the importance of recommending only those formula of documented evidence of safety and efficacy from well-designed randomized control trials. , , , Contrary to the AAAAI, EAACI, ASCIA whose consensus guidelines have removed pHF and eHF as a strategy to prevent allergy based on a 2016 meta-analysis, professional medical societies in Hong Kong, Malaysia and Singapore recognise the role of hydrolysed formula in preventing allergy among high-risk infants if exclusive breastfeeding is impossible.” 

Summary

Our understanding of the epidemiology, risk factors and primary prevention of food allergies continue to evolve. It is established that atopic dermatitis is associated with food allergy in early life, particularly egg allergy. Exclusive breastfeeding for 3-4 months and continued breastfeeding beyond that is recommended to help prevent eczema and wheezing in early life. Complementary foods, such as egg and peanut, early, should also be introduced one at a time, no earlier than 4 months and up to 6 months once babies are able to tolerate solids. There is consensus from experts from Hong Kong, Malaysia and Singapore that in formula-fed infants at high allergy risk, the use of a clinically proven partially hydrolysed formula may be useful.

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20. Persatuan Alergi dan Imunologi Malaysia, Obstetrical and Gynaecological Society of Malaysia. Persatuan Pediatrik Malaysia. Malaysian Allergy Prevention (MAP) Guidelines for Healthcare Professionals. Available at: https://www.ogsm.org.my/docs/MAP-Guidelines.pdf.

21. Academy of Medicine Singapore, College of Obstetricians & Gynaecologists, Singapore, and College of Paediatrics and Child Health, Singapore. Primary prevention of allergy in at-risk infants – Consensus Statement. 2019. Available at: https://www.ams.edu.sg/view-pdf.aspx file=media%5c5649_fi_819.pdf&ofile=Consensus+Statement+on+Primary+Prevention+of+Allergy+in+At-Risk+Infants+(FINAL).pdf Assessed Feb 2021