Food Allergies

Frequently Asked Questions About Food Allergies

The allergy and immunology specialists at CHOC understand the struggles that families with food allergies face at home and in their communities. With this in mind, they have created these frequently asked questions about food allergies.

What is food allergy?

A food allergy is an abnormal response of the body to a certain food.

What causes food allergy?

Before having a food allergy reaction, a sensitive child must have been exposed to the food at least once before. After a subsequent exposure, the body makes a protein called an IgE antibody. This antibody will now activate every time the allergic food is eaten and allergic symptoms can occur with future exposures to that food. IgE antibodies react with the food which helps release allergic inflammatory chemicals that can cause your child to have hives, asthma, itching or swelling in the mouth, trouble breathing, stomach pains, vomiting, itchy or runny nose and/or diarrhea.

What is the difference between food allergy and food intolerance?

Food allergy causes an immune system response, causing symptoms in your child that range from uncomfortable to life-threatening. Food intolerance does not affect the immune system, although some symptoms may be the same as in food allergy.

What foods most often cause food allergy?

Approximately 90 percent of all food allergies are caused by the following eight foods:

Eggs, milk, and peanuts are the most common causes of food allergies in children, with wheat, soy, and tree nuts also included. Peanuts, tree nuts, fish, and shellfish commonly cause the most severe reactions. Although most children “outgrow” their allergies, allergies to peanuts, tree nuts, fish and shellfish may be lifelong.

What are the symptoms of food allergy?

Allergic symptoms may begin within minutes to an hour after ingesting the food. The following are the most common symptoms of food allergy:

According to the National Institute of Allergy and Infectious Disease, it does not take a large amount of the food to cause a severe reaction in highly allergic people. In fact, trace amounts of peanut kernel can cause an allergic reaction for a severely peanut allergic individual.

Allergies to milk and soy are usually seen in infants and young children. Often, these symptoms are unlike the symptoms of other allergies, and may include:

• Colic (fussy baby)
• Blood in your child’s stool
• Poor growth.

Often, your child’s health care provider will change your baby’s formula to a hypoallergenic one if it’s thought he or she is allergic to milk.

The symptoms of food allergy may look like other problems or medical conditions. Always consult your child’s doctor for a diagnosis.

How are food allergies diagnosed?

There are different types of tests used to diagnose allergies in children. These tests include:

Skin tests. The skin test is a very accurate test that measures your child’s level of IgE antibodies in response to certain allergens or triggers. Using small amounts of solutions that contain different allergens, your child’s doctor will apply the allergens with a small scratch to the skin. A reaction would appear as a small, raised red area. A reaction to the skin test does not always mean your child is allergic to the allergen that caused the reaction. This will be determined by your child’s doctor. Learn more about skin tests at CHOC.

Skin testing may not be performed on children who have had a severe life-threatening reaction to an allergen or have severe dry skin (eczema).

Blood tests. Blood tests for allergies measure IgE antibodies to specific allergens in the blood. The blood test most commonly used is called RAST (radioallergosorbent test). Blood tests may be used when skin tests cannot be performed. As with skin testing, it is important to remember that a positive blood test does not always mean your child is allergic to that allergen.

Challenge test. A test supervised by an allergist who administers a very small amounts of an allergen taken orally and is closely monitored.

How are food allergies treated?

There is no medication to prevent food allergy. The goal of treatment is to avoid the foods that cause the symptoms. After seeing your child’s health care provider and finding which foods your child is allergic to, it is very important to avoid these foods and other similar foods in that food group. If you are breastfeeding your child, it is important to avoid foods in your diet that your child is allergic to. Small amounts of the food allergen may be transmitted to your child through your breast milk and can cause a reaction.

It is also important to give vitamins and minerals to your child if he or she is unable to eat certain foods. Discuss this with your child’s health care provider.

For children who have had a severe food reaction, your child’s doctor may prescribe an emergency kit that contains epinephrine, which helps stop the symptoms of severe reactions. Your child’s doctor can provide more information on whether or not your child may need an emergency kit.

Some children, under the direction of his or her health care provider, may be given certain foods again after 3 to 6 months to see if he or she has outgrown the allergy. Many allergies may be short-term in children and the food may be tolerated after the age of 3 or 4.

How can I prevent food allergies?

The development of food allergies cannot be prevented, but can often be delayed in infants by following these recommendations:

• Your baby’s only source of nutrition during their first 6 months of life should be breastmilk or formula. If possible, breastfeed your infant exclusively for the first 6 months.
• Gradually introduce solid foods to your baby at 7 months of age.
• Introducing commonly allergenic foods early may also provide protection. Speak with your child’s health care provider about when and what types of foods to introduce.