Image courtesy of Freerange Stock.
As the prevalence of food allergies has increased in recent decades, research on allergies has also been rapidly developing. Egg allergies are one of the most common allergies in young children. Consuming muffins containing baked eggs, which are generally more tolerable for those with allergies, is a common method of gradually improving tolerance to eggs. However, there are exceptions to this trend. Stephanie Leeds MHS ’23, a pediatrician and researcher at the Yale School of Medicine, encountered a patient who had a severe allergic reaction to a slight change in a baked muffin recipe. “This patient, who had tolerated baked egg in a specific recipe that we had given many times, went into anaphylaxis after substituting half the flour in the recipe with banana mash, trying to make it a bit healthier,” Leeds said.
The experience prompted Leeds to reach out to collaborators to explore the matrix effect, or how interactions between different ingredients in a food can affect the allergenicity of a single ingredient such as egg. In a recent study involving Northwestern University researcher Stephanie Eisenbarth GSAS ’03, MD ’05, Leeds and allergy and immunology instructor Elise Liu MD ’14, GSAS ’22, led a team of researchers at the Yale School of Medicine to examine how various ingredient substitutions in muffins affected how much egg allergen could be extracted. “My hypothesis was that somehow the matrix effect was disrupted with [the] substitution of large amounts of ingredients,” Leeds said.
The researchers cooked plain baked egg, as well as three variations of a baked egg muffin that uses wheat flour: the original recipe, one with wheat flour substituted for rice flour, and a wheat flour and banana puree mix. The muffins were chopped and centrifuged, meaning the substances in the muffin pieces were separated through high-speed spinning to isolate the food allergen particles. The researchers analyzed the concentrations of two major proteins responsible for egg allergies, ovalbumin and ovomucoid, in the samples. To verify the validity of the proteins they extracted, the researchers checked their results using blood serum samples from pediatric patients with egg allergies.
In their study, the researchers found that there were indeed differences in the amounts of egg allergen proteins present in the variations of muffins. Compared to raw eggs, all of the baked egg varieties contained much lower amounts of the allergen proteins ovalbumin and ovomucoid. However, the three muffin variations baked with wheat flour, rice, or the banana puree mix had much more ovalbumin than the plain baked egg, which could explain the unexpected anaphylaxis experience of Leeds’ patient and others.
“The take-home message from our study is that we have to be really careful when we start making substitutions in recipes. Even if we think it’s not going to have an effect on the allergenic content of a food, it actually might,” Liu said. “It’s hard to know what a particular substitution will do.” This study strongly suggests that the food matrix affects egg allergens, emphasizing that those with egg allergies should be mindful of the other ingredients in their food that could alter the severity of an allergic reaction. With this information, physicians can give more specific instructions for patients dealing with egg allergies, minimizing the risk of dangerous allergic reactions.