Food Allergies and Best Practices for RDNs

Millions of Americans are estimated to have an allergy to one or more foods. The prevalence of food allergies has been difficult to estimate in the past due to variations in its definition and diagnosis. Even today, people may mistake a food intolerance for a food allergy. In 2010, a panel of experts sponsored by the National Institutes of Health's National Institute of Allergy and Infectious Diseases (NIAID) developed criteria for the diagnosis and management of food allergies in the United States in order improve the consistency of their identification and treatment.

According to the guidelines, the definition of a food allergy is an "adverse health effect arising from a specific immune response that occurs reproducibly on exposure to a given food." In individuals who are affected, contact with a certain protein in the food, called an allergen, causes the body to produce an immunoglobulin E (IgE) antibody, which can result in a wide range of symptoms that can vary in terms of their onset and severity. There is also a classification of food allergies which cause a delayed non-IgE mediated response, such as food protein-induced enterocolitis syndrome, also known as FPIES; whereas eosinophilic esophagitis (EoE) is thought to involve a mix of IgE and non-IgE-mediated responses.

Unfortunately, it is not uncommon for people to self-diagnose a food allergy and severely restrict their diet or a child's, putting them at risk for nutritional deficiencies. In other cases, the allergy testing results may be misinterpreted due to a food-specific IgE being detected in the blood, causing people to avoid certain foods even though no allergic reaction has occurred. According to the NIAID-sponsored report, measuring total serum IgE or allergen-specific serum IgE should not be used as the sole basis for diagnosing a food allergy.

If a food allergy is suspected, the Expert Panel recommends an in-depth medical history and physical examination be performed, which will aid in determining the appropriate diagnostic test. The following list of procedures are not recommended for the routine evaluation of the IgE-mediated food allergy due to being non-standardized and unproven, according to the NIAID-sponsored guidelines:

• Basophil histamine release/activation
• Lymphocyte stimulation
• Facial thermography
• Gastric juice analysis
• Endoscopic allergen provocation
• Hair analysis
• Applied kinesiology
• Provocation neutralization
• Allergen-specific IgG4
• Cytotoxicity assays
• Electrodermal test (Vega)
• Mediator release assay (LEAP diet)

More than 170 foods have been reported to cause IgE-mediated reactions; however eight foods have been responsible for the majority of all food allergies in the U.S. These eight major food allergens include egg, milk, peanuts, tree nuts, wheat, fish, crustacean shellfish and soy. The declaration of these ingredients on food packaging has been required since the inception of the Food Allergen Labeling and Consumer Protection Act (FALCPA) of 2004. Sesame officially became the ninth major allergen in the U.S. in 2021, with the passing of the Food Allergy Safety, Treatment, Education, and Research (FASTER) Act, and will be required to be listed on food labels starting on January 1, 2023.

Label reading is considered one of the important focus areas for registered dietitian nutritionists when providing education to patients and clients with food allergies. The NIAID-sponsored guidelines emphasize the importance of addressing how to interpret ingredients on food labels. They state that if a food label contains precautionary labeling, such as "this product may contain trace amounts of allergen," the food should be avoided.

The Expert Panel does not recommend restricting the maternal diet during pregnancy or lactation as a strategy for preventing the development of a food allergy and recommends that all infants be exclusively breast-fed until 4 to 6 months of age, unless breastfeeding is contraindicated for medical reasons. In addition, there are specific recommendations for the use of soy infant formula, cow's milk and hydrolyzed formulas, and for the introduction of solid foods, which should not be delayed beyond 4 to 6 months of age.

The introduction of potentially allergenic foods to infants who are developmentally ready has been established by more recent research. An addendum to the NIAID-sponsored guidelines, published in 2017, addresses the significance of the early introduction of peanut-containing foods (after other solid foods are introduced) in preventing peanut allergy. Evidence reviewed for the 2020-2025 Dietary Guidelines for Americans prompted its recommendation to offer age-appropriate, potentially allergenic foods when other complementary foods are introduced to infants, with the exception of cow’s milk which should be delayed until twelve months of age.

Children who have already been diagnosed with an egg allergy, severe eczema, or both conditions are at an increased risk of peanut allergy. Although the early introduction of peanut-containing foods is still recommended for these individuals, additional guidance and precautions will be needed. Children who are at increased risk of food allergy may require allergy testing prior to the introduction of potentially allergenic foods or supervision in a clinical setting while doing so.

RDNs are uniquely positioned to assist patients and clients who have been diagnosed with food allergies by creating strategies for avoidance of food allergens, while focusing on the nutritional adequacy of their overall eating pattern. In addition to label reading, education on safe and nutritious food substitution, advice for dining out in restaurants, managing food allergens in schools, and preventing cross-contamination when preparing foods at home will be beneficial. RDNs can additionally support parents and caregivers who are concerned about the timing and safe introduction of complementary foods.

References:

• Food Allergy Research & Education. Facts and Statistics. Accessed July 1, 2022.
• NIAID-Sponsored Expert Panel, Boyce JA, Assa'ad A, et al. Guidelines for the diagnosis and management of food allergy in the United States: report of the NIAID-sponsored expert panel. J Allergy Clin Immunol. 2010;126(6 Suppl):S1-S58. doi:10.1016/j.jaci.2010.10.007.
• U.S. Food and Drug Administration. Food Allergies. Accessed July 1, 2022.
• Togias A, Cooper SF, Acebal ML, et al. Addendum Guidelines for the Prevention of Peanut Allergy in the United States: Report of the National Institute of Allergy and Infectious Diseases-Sponsored Expert Panel. J Pediatr Nurs. 2017;32:91-98. Doi:10.1016/j.pedn.2016.12.006.
• U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025. 9th Edition. December 2020.