Egg Exposure and Allergy Incidence in Children

Controversy surrounds the ideal time to introduce infants to solid foods. Naturopathic physicians often see parents who wait until long after the commonly recommended 4 to 6 months. This study and others suggest later introduction may not be the best approach.

By Dr Matthew Baral

Reference
Palmer DJ, Metcalfe J, Makrides M, et al. Early regular egg exposure in infants with eczema: A randomized controlled trial. J Allergy Clin Immunol. 2013;132(2):387-392.

Design
Double-blind, randomized, controlled trial

Participants
Term infants with a diagnosis of moderate to severe eczema who had no ingestion of egg in their lifetime. The study cohort consisted of 49 participants, and the control group had 37 participants.

Key Findings
More children who were exposed daily to small amounts of whole egg powder between 4 to 8 months of age showed a decreased incidence of IgE-mediated egg allergy when compared to those in the control group who received a placebo of daily rice powder. Not surprisingly, IgG4 levels to egg were higher in the egg consumption group at 8 and 12 months of age.

Practice Implications
Controversy has always surrounded the subject of solid food introduction in infants. The atopic population is unique in these discussions, both for the concern of a higher risk of anaphylaxis during initial solids exposure and the development of life-threatening food allergies. Conventional medical approach has been to introduce solid foods between 4 and 6 months of age. It is interesting to note that this is the age range where the human infant begins to experience tooth eruption, the diminishing of tongue-thrust and gag reflexes, the pincer-grasp (allowing the child to bring solid food to the mouth), and sitting up independently.¹

As a naturopathic physician specializing in pediatrics, I most commonly interact with parents who are particularly concerned with inducing allergies to foods by introducing them too early. As a result, these parents don’t start solids with their children until later than the general population does, often after 9 months. There is an appreciable amount of evidence now showing specifically that introduction of most foods past this age can increase the risk of allergy to these foods, including those that are particularly allergenic such as wheat, dairy, eggs, fish, and nuts.^2–5 It is daunting to consider introducing these foods to an infant too early, especially in those with current atopy or a strong family history of allergic sensitization. Indeed, this is contrary to recommendations of the American Academy of Pediatrics as recent as a decade ago.⁶ The evidence available now is certainly strong enough to consider small challenges with foods once thought to be dangerous. However, one must always consider the risks in severely atopic infants and prepare accordingly for rare but strong reactions.

In addition, this article cites eggs as the most common allergy in Australia, and one might surmise this is due to sensitization from vaccines. The vaccines on most standard schedules worldwide that contain some amount of egg protein used in the processing include measles/mumps/rubella (MMR-II), influenza (Afluria, Fluvirin, Fluzone, FluMist, Flulaval), yellow fever (YF-Vax), rabies (Imovax, RabAvert), and Smallpox (Vaccinia – ACAM2000)7. MMR and the flu are the only immunizations from this list that are routinely administered to healthy infants and children, so it is feasible that they cause some sensitization. However, it is important to note that the conventional vaccination schedule starts the influenza vaccine at 6 months of age and the MMR vaccine at 12 months, and egg allergy certainly exists in patients younger than 6 months. Therefore, it is feasible that genetic programming for egg allergy occurs outside the realm of egg exposure.

Nevertheless, it appears that early food introduction can decrease sensitivity later in life. It is still unclear whether early food introduction to those severely sensitive or anaphylactic to eggs or other foods may be alleviated with early introduction, since the safety of a challenge cannot be guaranteed.

References
1. Center for Disease Control and Prevention. Learn the Signs. Act Early. Available at: https://www.cdc.gov/ncbddd/actearly/milestones/index.html. Accessed December 3, 2013.
2. Alm B, Aberg N, Erdes L, et al. Early introduction of fish decreases the risk of eczema in infants. Arch Dis Child.2009;94:11-5.
3. Filipiak B, Zutavern A, Koletzko S, von Berg A, Brockow I, Grubl A. Solid food introduction in relation to eczema: results from a four-year prospective birth cohort study. J Pediatr. 2007;151:352-358.
4. Koplin JJ, Osborne NJ, Wake M, et al. Can early introduction of egg prevent egg allergy in infants? A population-based study. J Allergy Clin Immunol. 2010;126:807-813.
5. Frank R. Greer, Scott H. Sicherer, A. Wesley Burks and the Committee on Nutrition and Section on Allergy and Immunology. Effects of early nutritional interventions on the development of atopic disease in infants and children: The role of maternal dietary restriction, breastfeeding, timing of introduction of complementary foods, and hydrolyzed formulas. Pediatrics 2008;121;183-191
6. American Academy of Pediatrics, Committee on Nutrition. Hypoallergenic infant formulas. Pediatrics. 2000;106:346-349.
7. Center for Disease Control and Prevention. Vaccine Excipient & Media Summary. Available at: https://www.cdc.gov/vaccines/pubs/pinkbook/downloads/appendices/B/excipient-table-2.pdf. Accessed Dec