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Food Allergies: Why Are They So Common and What Can You Do About Them?

State of the Art Pediatrics - May 2023

Column Authors: Aarti P Pandya, MD, Jodi A. Shroba, APRN, CPNP and Jay M. Portnoy, MD | Pediatric Allergy & Immunology

Column Editor: Amita Amonker, MD, FAAP | Pediatrics; Pediatric Hospitalist; Assistant Professor of Pediatrics, University of Missouri-Kansas City School of Medicine; Clinical Assistant Professor of Pediatrics, University of Kansas School of Medicine

 

Quick Quiz: Which of these represents a case of food allergy? Check your answer at the end of the article. 

  1. An 8-month-old occasionally vomits after drinking a full bottle of infant formula but is otherwise happy and growing normally. 

  1. A 2-year-old with severe eczema that periodically flares up. The mother blames foods for the flare ups but can’t figure out which ones. 

  1. A 3-year-old who reproducibly develops generalized hives, wheezing, and then vomits shortly after eating peanut butter. 

Food allergy is an IgE-mediated reaction that occurs following ingestion of a food. Manifestations may include hives, wheezing, stridor, vomiting, hypoxia, hypotension and even death. Other non-IgE types of reaction to food are usually referred to as “food intolerance.” 

The prevalence of food allergy in children has increased over the last 20 years. We don’t really know why. Virtually any food can cause food allergy. However, the most common food allergies are caused by milk (2.5%) and egg (1.3%), which are usually outgrown, as well as peanut (0.8%) and tree nuts (0.2%). 

Many parents are quick to believe that any unwanted symptom that does not have an obvious cause is due to food allergy, including rashes, hives, abdominal pain, constipation/diarrhea, behavior problems, nasal symptoms and even autism. A patient or parent who suspects that a “hidden” or “unknown” food is the cause of their symptoms does not have food allergy. Patients with food allergy will tell you that they ate a specific food and had a specific reaction. The cause of the reaction is usually obvious. 

Tests for food allergy 

 

Tests for food allergy are performed to confirm the diagnosis when it is uncertain, to confirm the IgE mechanism and to monitor disease activity. Because false positive food tests are common, tests should be performed only for foods suspected to have caused a reaction.  

Though sometimes the parents insist on them, screening tests for food allergy should be avoided. Food panels (other than defined ones such as panels for nuts, shellfish and fish) should also be avoided. You should test only for a food that is suspected of having caused an IgE-mediated reaction. 

The goal of testing is to determine if it is safe to eat the food. A patient who can eat a food without a reaction is not allergic to that food and does not need a test.

Food avoidance

 

A patient who is allergic to a food should avoid it. A few facts about food avoidance: 

  • Food avoidance can severely harm a child’s quality of life. Children often face bullying, isolation, depression and anxiety due to excessive fear of a specific food. 

  • Casual contact with a food will not cause anaphylaxis. Only eating the food causes anaphylaxis. Patients who are allergic to peanuts do not need to avoid airplane flights that serve peanuts, and their schools do not need to be peanut-free. 

  • Skin contact with certain foods commonly causes a rash. However, the food does not need to be avoided as a rash is not life-threatening. 

  • Peanut oil (refined) does not have peanut allergen so foods fried in peanut oil can safely be eaten. 

Treatment of food allergy 

 

Patients who are at increased risk of anaphylaxis should avoid the food and be given an epinephrine autoinjector, instructions for its use along with proper training, and an anaphylaxis action plan. Children’s Mercy recently updated its clinical practice guideline for treatment of anaphylaxis. Remember: the treatment for anaphylaxis is epinephrine.  

Antihistamines may prevent progression to anaphylaxis, but they do not treat anaphylaxis once it has occurred. H2 blockers have no proven benefit for treatment of anaphylaxis. In addition, systemic steroids have no proven benefit for treatment of anaphylaxis. They also have not been shown to reduce the risk of a late-phase reaction. 

Oral immunotherapy (OIT) for peanut 

 

The Food Allergy Center currently offers peanut OIT with an FDA-approved product called Palforzia. This treatment provides desensitization but is not a cure for peanut allergy. Patients treated with OIT are at lower risk of peanut-induced anaphylaxis, but they still need to avoid peanuts and carry epinephrine. 

What about early introduction? 

The LEAP study showed that introduction of peanut into children between 5 and 11 months of age reduces their risk of developing peanut allergy. Children at high risk of developing food allergy (e.g., those with severe eczema or who already have a food allergy) should be fed age-appropriate forms of peanut at least several days per week. This method would probably be helpful for egg allergy as well. The allergy clinic routinely provides early introduction of peanut to children whose parents are anxious. 

 

Summary points regarding food allergy: 

 

  1. Food allergy is a common complaint. 

  1. The most common food allergies in children are milk, eggs, peanuts and tree nuts. 

  1. The best test for food allergy is a history of what happens when the food is ingested. 

  1. A test for food IgE should be performed to determine the risk of anaphylaxis if a food is ingested, to confirm the reaction mechanism, and to monitor the allergy over time. 

  1. A patient who can eat a food without a reaction does not have food allergy. A test is unnecessary and can be misleading. 

  1. If the patient or parent suspects that a hidden or unknown food is the cause of symptoms, it is not a food allergy. These symptoms include chronic hives, abdominal pain and severe eczema. 

  1. A food must be eaten to cause anaphylaxis. Casual contact does not cause anaphylaxis. 

  1. Do not order food panels that contain foods that are not of concern. 

  1. Because food avoidance can cause significant harm to the patient’s and family’s quality of life, it should not be recommended unless there is clearly an increased risk of anaphylaxis. 

  1. Treatment choices for food-allergic patients include: 

  • Avoid the food and carry epinephrine if the risk is high. 

  • Consider oral immunotherapy (OIT) for peanut allergy. 

  • Perform an oral challenge if the risk is unclear. 

  • Introduce the food into the diet (either at home or in the clinic) if the risk is low. 

  1. Early introduction of peanut (and probably egg) between 5 and 11 months can reduce the risk of developing peanut (or egg) allergy. 

Answers to the three patients above: 

  1. An 8-month-old occasionally vomits after drinking a full bottle of infant formula but is otherwise happy and growing normally. This probably represents normal spit-up.
  2. A 2-year-old with severe eczema that periodically flares up. The mother blames foods for the flare ups but can’t figure out which ones. Food allergy rarely is a trigger for eczema. 
  3. A 3-year-old who reproducibly develops generalized hives, wheezing, and then vomits shortly after eating peanut butter. This patient has peanut allergy. 
 

If you have questions, feel free to contact the Food Allergy Center at Children’s Mercy Kansas City. 

 

References:

 

  1. Du Toit G, Roberts G, Sayre PH, et al. Randomized trial of peanut consumption in infants at risk for peanut allergy. N Engl J Med. 2015;372(9):803-813.
  2. Greenhawt M, Shaker M, Wang J, et al. Peanut allergy diagnosis: a 2020 practice parameter update, systematic review, and GRADE analysis. J Allergy Clin Immunol. 2020;146(6):1302-1334.
  3. Portnoy J, Shroba J, Tilles S, et al. Real-world experience of pediatric patients treated with peanut (Arachis hypogaea) allergen powder-dnfp. Ann Allergy Asthma Immunol. 2023;130(5):649-656.e4. doi:10.1016/j.anai.2023.01.027
  4. Shaker MS, Wallace DV, Golden DBK, et al. Anaphylaxis-a 2020 practice parameter update, systematic review, and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) analysis. J Allergy Clin Immunol. 2020;145(4):1082-1123.

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