Published on in Children's Doctor
Food allergy (FA) is defined as an adverse health effect caused by a specific immune response that occurs reproducibly on exposure to a given food. IgE-mediated food allergies are a specific type of FA characterized by various symptoms ranging from cutaneous symptoms (pruritis, urticaria, angioedema), gastrointestinal (nausea, abdominal pain, vomiting, diarrhea), respiratory (sneeze, nasal congestion, cough, wheeze), neurologic (dizziness, sense of doom), to hypotension and anaphylaxis. Food allergy is the most common type of anaphylaxis in pediatrics.
The prevalence of food allergy has increased steadily over the past 20 years and now affects 6% to 8%, or 4.5 million to 6 million children. It shapes many aspects of life for these children, including a dramatic effect on quality of life for both patients and their caregivers.
Diagnosis of food allergy can be challenging. Clinical history remains one of the strongest components of diagnosis, as clinicians identify typical symptoms of IgE-mediated food allergy and rule out other conditions that mimic it. Unfortunately, both skin and blood testing carry a high rate of false positivity, which can make diagnosis of food allergy frustrating in some cases. But there is a very low rate of false negatives.
The gold standard for diagnosis of food allergy is a double-blinded placebo-controlled food challenge, although open (unblinded) oral food challenges (OFC) are more practical in most clinical settings. An OFC is helpful in determining if a food allergy has been outgrown or if clinical history and diagnostic testing are asynchronous.
Outgrowing a food allergy can dramatically change a patient’s life, removing the anxiety and fear associated with the diagnosis. Families often report a huge sense of relief, both when a food allergy has resolved completely, freeing the patient’s diet, but also when food challenges are not successful, as families leave with a greater sense of clarity and understanding about their child’s allergy to the food.
The procedure involves administering small, increasing amounts of food by mouth over set intervals of time and monitoring very closely for signs of an allergic reaction. Allergic reactions can include any of the symptoms listed above, including anaphylaxis, which requires the use of epinephrine. At CHOP, we perform among the highest number of food challenges in the country. Our dedicated team of doctors and nurses are highly skilled at performing food challenges to countless foods, even in patients who are considered at high risk of severe reaction due to their allergic history or history of other medical conditions.
For more information about our Oral Food Challenge program and process, please visit this helpful interactive guide.
Until very recently, the only treatment for children with food allergy was strict avoidance. Fortunately, last year CHOP launched our Oral Immunotherapy (OIT) Program to help desensitize children to the foods to which they are allergic. Eventually, children are given small quantities of the allergenic food every day at home. Gradually doses are increased under medical supervision in the hospital until patients reach their “maintenance” dosing, which has been shown to decrease a child’s sensitivity to the food and protect children from anaphylaxis after accidental exposures. Currently, children can perform OIT with up to five different foods at the same time.
After an initial intake visit, patients complete a specialized low-dose food challenge to each food to determine where initial dosing for each individual patient should start. Patients then take doses at home and return to the clinic for bi-weekly dosing. This up-dosing phase typically lasts 6 months before the maintenance dosing is reached. Patients then have follow-up visits every 3 months, and maintenance dosing is to be continued indefinitely at home.
Side effects of OIT are usually mild and include oral or throat itching, abdominal pain, or a few hives. About 10% of patients have anaphylaxis to the food and 5% also may go on to develop eosinophilic esophagitis (EoE) to the food. Approximately 20% to 30% of patients who start OIT will not reach maintenance due to intolerance of taste, abdominal pain, anaphylaxis, or suspected EoE.
For more information about our dedicated Oral Immunotherapy program click here.
Early food introduction
For the treatment of food allergy, the ideal case is to prevent it from starting. Several studies over the last 10 years have shown that early introduction of foods into the diet is both safe and can prevent food allergies.
The initial pivotal study done by Gideon Lack showed that early introduction of peanut reduced the rate of peanut allergy in infants from 4 to12 months of age by 80% in a high-risk group. This reduction confirms some retrospective studies on food introduction in large cohorts. Since publication of the key pivotal studies, similar studies have shown benefit for early introduction of peanut, egg, milk, and, most recently, cashew. Therefore, based on these publications, the national Allergy Associations-AAAAI, ACAAI, National Institutes of Health, and pediatric and allergy societies throughout the world, including United States and Canada, have revised the recommendation of food introduction.
Early this year, U.S. Department of Agriculture, as part of its newly issued dietary guidelines, also recommend early introduction of foods (see chart).
The guidelines do not recommend avoidance of any foods in the diet or in the mother’s diet during pregnancy or breast feeding unless specifically recommended by her physician or the child’s physician.
Early Introduction of Food
- All infant should be introduced to peanut protein in the first year of life
- Peanut protein should be given in a powder or puff form to prevent choking.
- When the child can eat the food, it should be introduced at 4 to 12 months of life.
- Infants should be introduced to egg protein in the first year of life.
- It should be first introduced in baked good form like bread, cake, muffin, pancake, etc.
- Egg protein should also be introduced in the first 4 to 12 months of life.
- Milk protein (not plain milk) in the form of yogurt or cheese can be introduced in the first year of life.
U.S. Department of Agriculture