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20 Fredericksburg Parent and Family • March 2020 Ask the Expert a sk t h e e x p e rt The National Institutes of Health estimates that food allergies affect approximately 5 percent of children and 4 percent of adults in the United States. Awareness and knowledge about food aller- gies is important for most any parent these days, whether it's to help them manage their own or their child's allergies, or to help them understand how to safely pack snacks and treats for school, sports, birthday parties or other group activities. Allergy Partners of Fredericksburg has helped many families on the jour- ney of diagnosing, treating and managing food allergies. As our March Expert, Allergy Partners' Dr. Nicholas Klaiber, a Board Certified Allergy Immunology Physician who treats both pediat- ric and adult allergy and immunol- ogy patients, offers knowledge on the latest research about food allergies in children. Q: What are the most common food allergens in children? The biggest foods causing allergic reactions in children are: Sesame is on the rise as an allergen, and we may see that added to the list of allergens that must be listed in bold at the end of nutritional information on food packaging. Q: Are we seeing an increase in the prevalence of food allergies? We have seen a huge increase in the prevalence of food allergies over the last 50 years. Part of the cause of this increase is the practice of delaying the introduction of allergenic foods to infants. This was recommended in the past, but recent research shows that these recommendations were actually counter- productive and have contributed to the increasing prevalence of food allergy. Another reason for the dramatic increase in food allergy prevalence is explained by the hygiene hypothesis. The hygiene hypothesis is based on the notion that a lack of exposure to particular infec- tions during early childhood hinders the development of the immune system. Without these infectious exposures, the immune system never learns to regulate itself properly. All allergies are an overreaction of the immune system to harmless molecules from the environment. The most common type of food allergies are dependent upon a molecule produced by the immune system called IgE. IgE production is stimulated by a type of white blood cell called a TH2 cell. One of the primary roles of TH2 cells is to fight off intestinal parasites called helminths. Infections with the helminths used to be ubiquitous across the globe. Through public hygiene programs however, we have virtually eliminated helminth infections within the USA and other industrialized nations. It is in precisely these countries (industrial- ized nations) where we have observed the largest increases in food allergy, asthma, eczema and allergic rhinitis. TH2 cells from individuals growing up in modern environments are no longer exposed to the parasitic worms they would normally be fighting off. Foods that are the most common allergens share certain molecular characteristics that may essentially trick the immune system into thinking they are parasites, thus leading to IgE production and a subsequent allergy against these substances. INTERVIEWED BY EMILY FREEHLING • Peanuts • Tree nuts • Eggs • Milk • Soy • Fish • Shellfish • Wheat