Contrary to earlier advice, new research suggests introducing infants to potential allergens early may reduce risk of developing allergies to those foods
Food allergy, defined as an inappropriate immune response after exposure to foods that cause no problems in most individuals, is a widespread and growing challenge in Western countries and a global concern.1-3 Experts partially attribute the surge in cases to genetics but have identified epigenetic (heritable changes in gene function without a change in DNA sequence) and environmental factors as well. Traditional management has been simple in theory and difficult in practice: avoidance of the offending food and use of rescue medication.
Individuals can develop food allergies at any age, but they are most common in children. Eggs, fish, milk, peanuts, sesame, shellfish, soy, tree nuts, and wheat are most often implicated.4 Food allergies present in numerous ways and in varying severities (Table 1). Most, but not all, children outgrow or become tolerant of egg, milk, soy, and wheat allergies, but fish, peanut, shellfish, and tree nut allergies can be persistent. Children with non-immunoglobulin E (IgE)–mediated food allergies often outgrow them early in life,5 but only approximately 20% of children outgrow peanut allergy by the time they start school.4 Any food can lead to anaphylaxis in allergic individuals, but peanuts, tree nuts, fish, and shellfish are most often associated with severe anaphylaxis.6
MECHANISMS REVEAL POTENTIAL TREATMENT APPROACHES
Information about the mechanisms of food allergies and new prevention strategies is growing, as are available treatments. Better understanding of immune tolerance and induction of regulatory T (Treg) cells, T-helper type 2 (Th2) cell–driven responses, and subsequent proinflammatory cytokine production has been key.
The FDA has approved an oral immunotherapy, peanut (Arachis hypogaea) allergen powder-dnfp (PTAH; Palforzia), to mitigate allergic reactions, including anaphylaxis, pursuant to accidental exposure to peanuts.7 PTAH is approved for children aged 4 to 17 years with confirmed peanut allergy, and patients who use PTAH must continue to avoid peanuts. Its mechanism of action has not been established.
Administration consists of 3 phases: initial dose escalation, up-dosing, and maintenance.7 Real-world data indicate most patients have successfully navigated the 3 phases, and adherence tends to be excellent.8 Available through a Risk Evaluation and Management Strategy program, the most common adverse reactions associated with PTAH are abdominal pain, vomiting, nausea, and various allergic symptoms including anaphylaxis.8
Research is underway to determine whether monoclonal antibodies targeting interleukin (IL)-4, IL-5, and IL-13 that disrupt Th2 cell–related pathways can help. Omalizumab (Xolair; Genentech and Novartis), approved in several atopic conditions, is considered investigational in food allergy. Ligelizumab (Novartis) and dupilumab (Dupixent; Sanofi and Regeneron) are also being studied in food allergy.9
Currently, food allergy is considered incurable. It is also a unique response, and pharmacists should note that food allergy differs from other food-related concerns (Table 2).
Until recently, pediatricians advised new parents to withhold potentially allergenic foods from infants until after their first birthday or even later. Recent research changes that advice: Introducing infants to potential allergens at an early age may reduce the risk of developing allergies to those foods.10,11 In patients who continue to have food allergies, strict avoidance of the offending food is essential. Avoidance can be difficult, as many foods may contain or are cross-contaminated with allergens.
Patients can use antihistamines to relieve mild symptoms like itching or hives, but antihistamines are not appropriate to treat severe allergic reactions. Patients who have food allergies, especially if they have had or are at risk for anaphylaxis, should carry epinephrine autoinjectors. Patients with the most severe reactions may need corticosteroids.
Although food allergy is increasing in incidence, scientific developments are finding new ways to mitigate its effects. The next few years should produce better interventions. For now, pharmacists should counsel patients carefully and ensure they have rescue measures available in the unfortunate event of anaphylaxis.
About the Author
Jeannette Y. Wick, RPH, MBA, FASCP, is the director of the Office of Pharmacy Professional Development at the University of Connecticut, in Storrs.