Food allergy occurs when your child’s immune system mistakenly sees and responds to a normal protein found in some foods as an invader. The immune system releases an antibody called immunoglobulin E (IgE) to attack the protein the same way it releases normal antibodies to attack viruses and bacteria.
IgE causes an exaggerated or hyper-response to something that would not ordinarily cause a problem. The IgE that your child’s body produces attaches to many cells in the body. These are special cells called mast cells. Mast cells are found in the skin, the digestive tract, the respiratory system and the circulatory system. When the IgE antibody on the mast cell meets the food protein, a reaction occurs.
Most food allergies are linked to eight specific foods. Those foods are:
Food allergies are most common in babies and children, but they can appear at any age. Children may outgrow a food allergy, particularly one to milk or eggs. In the past, it was thought that peanut, tree nut, fish and shellfish allergy would last forever. Now, 20 percent of children with peanut allergy and 10 percent of children with tree nut allergy may outgrow these allergies, too.
Having a food allergy may also mean that your child is at risk for other allergies. For example, a child who is allergic to bananas or melons may also be allergic to ragweed because the proteins that trigger the allergy are similar. This is called cross-reactivity. Another example of cross-reactivity is the occurrence of positive allergy tests to legumes in a child with a peanut allergy.
Cross-reactivity happens when different allergens contain shared proteins or proteins that your child’s immune system sees as being very similar. Directed allergy testing may determine if a reaction to a food is due to cross-reactivity with pollen or another allergen.
Common symptoms of a food allergy include:
With a food allergy, symptoms occur right away. The amount of the trigger food does not matter—even a small exposure can cause a reaction. These symptoms occur every time your child eats the allergenic food.
In some cases, you may think your child has a food allergy, when he or she actually has a food intolerance. With food intolerance, the reactions that occur do not involve the immune system. Small amounts of the food are usually fine, but larger quantities may cause digestive symptoms like gas, cramps or bloating.
Diagnosing a food allergy starts with a doctor’s appointment with a Riley at IU Health allergy specialist. During this appointment, the doctor will learn about your child's health history and perform a physical exam. Make sure to tell the doctor about any cause and effect relationships you have noticed with your child’s symptoms and certain foods.
Skin tests or blood tests help confirm a suspected food allergy diagnosis. A food challenge can also help confirm diagnosis. Once a suspected food is confirmed as an allergen, a treatment plan is created.
The best way to treat a food allergy is for your child to avoid the foods that trigger an allergic reaction. You will have to read nutritional labels carefully to learn whether a food contains your child’s allergens.
Your child may also need the following to treat food allergy:
Based on your child’s allergy symptoms and allergy test results, your child’s allergist may also recommend a food challenge. There is hope on the horizon for treating food allergies. We will see this in the near future.
Visit the trusted websites below to learn more about food allergies.
Riley at IU Health offers a broad range of supportive services to make life better for families who choose us for their children's care.
This website provides in-depth information for families of children with food allergies.
The American Academy of Allergy, Asthma & Immunology provides additional information about food allergies, including diagnosis and treatment.
The American College of Allergy, Asthma & Immunology provides additional information about food allergies, including diagnosis and treatment.
This resource from the National Institutes of Health provides clinical recommendations for healthcare professionals on how to diagnose and manage food allergy and how to treat acute food allergy reactions.