Can giving infants egg powder prevent allergies?

Parents and healthcare providers are increasingly concerned with the high prevalence of food allergies in children, especially in countries like Australia, where rates of food allergies in 1-year-old children are as high as 10%. In the United States, the Centers for Disease Control and Prevention (CDC) estimates that prevalence of food allergies in children is 4-6%, with an increase of 18% between 1997 and 2007. While significant efforts are made to assess why food allergies have become so common, understanding how to prevent them remains a research priority.

In 2000, the American Academy of Pediatrics recommended that children at risk for food allergies avoid contact with allergenic foods like peanuts tree nuts and fish until at least age 3^[1], and eggs until age 2, in an effort to reduce allergy prevalence. However, recent studies show this recommendation may have been misguided.

Recent news has made much of findings from a randomized controlled trial (RCT) showing that early introduction of peanuts lowers the incidence of peanut allergy in infants with severe eczema or egg allergy. In fact, the National Institute of Allergy and Infectious Diseases issued an addendum to their 2010 Guidelines for the Diagnosis and Management of Food Allergy in the United States to add advice for early exposure to peanuts in infants.

While most people have heard of severe allergies to peanuts, another common^[2] food to which children develop allergies is eggs. And preliminary research suggests that egg allergies may be preventable like peanut allergies. Observational evidence has shown decreased incidence^[3] of egg allergy in infants exposed to egg between 4 to 6 months compared with those first given egg after 6 months.

It has become popular to use the term “allergy” as a stand-in for food intolerance or even to simply express a preference. But in the case of studying childhood allergy, researchers are focused on reactions mediated by immunoglobulin E (IgE, shown in Figure 1), which cause symptoms soon after ingestion and can cause anaphylactic reactions.

Figure 1: IgE-mediated food allergy in a nutshell

Reference: Waserman et al. Allergy Asthma Clin Immunol. 2011 Nov

RCTs have examined the effect of adding egg to the diets of infants, with mixed results. In a recent study, researchers tested early introduction of multiple foods associated with childhood allergies. Across all participants, even those who were less adherent to trial guidelines, infants with early introduction to egg were 30% less likely to experience an allergic reaction, although the difference was not statistically significant. In the per-protocol analysis (following only those who were adherent) researchers found a 75% reduction in relative risk among the early-introduction group.

A second study also found a nonsignificant reduction in egg allergy among an early-introduction group, but the trial was never fully enrolled due to a lack of funding. This study examined early-introduction of eggs in infants who had eczema, a condition strongly correlated with incidence of childhood allergies. While the study didn’t have statistically significant outcomes, it also experienced a roadblock as part of its early introduction plan. Thirty-one percent of the infants in the early introduction group experienced an allergic reaction to the pasteurized raw egg powder used as the treatment and could not continue with the trial. This further handicapped the trial’s outcomes.

In the current study, researchers in Japan sought to test the same hypothesis but circumvent the issues that plagued the previous two studies. It also restricted participants to those who had eczema. Furthermore, their methodology tried to ease infants into eating eggs by dispensing cooked egg amounts in two phases, starting with a small amount and increasing.

Incidence of childhood food allergies seems to be growing and researchers are interested in how early dietary interventions may prevent these allergies from developing. Observational evidence shows that infants given allergenic foods before 6 months of age had lower incidences of food allergies. There have been a couple RCTs testing early introduction of egg that have not reached statistical significance. The current study examines administering egg powder in two phases, with varying doses, as a way to prevent egg allergy.