Food allergy or food intolerance? A Q&A for parents

Allergies and intolerances to foods such as eggs, milk, peanuts, tree nuts, wheat, shellfish and soy are on the rise among children.

According to the U.S. Centers for Disease Control and Prevention, roughly 8% of children are affected by food allergies. The more you understand food allergies and intolerances, the more you can help your child navigate meal time.

What’s the difference between an allergy and an intolerance?

True food allergies are caused by an immune system response to a specific allergen in the food. Reactions occur quickly and every time the food is eaten. Most often, these reactions involve hives or swelling; vomiting, belly pain and trouble breathing may also occur. Typically, food allergies are discovered during childhood.

With food intolerances, the vast majority are not related to the immune system. However, food intolerances can cause symptoms similar to food allergies, such as diarrhea, nausea and belly pain. An allergy or gastroenterology specialist can help you distinguish between a food allergy and an intolerance.

What causes food allergies and intolerances?

Allergic reactions are caused by an immune system response to an allergen present in food, such as a specific protein in a peanut or in cow's milk. When a person with a food allergy is exposed to that protein, their immune system mistakenly thinks the protein is harmful and triggers an allergic reaction. Symptoms of an allergic reaction may involve just the skin and result in hives and swelling. Systemic reactions can include belly pain, vomiting, diarrhea, wheezing and difficulty breathing. Heredity and environment are some of the factors that affect a person’s risk for food allergies; researchers theorize our susceptibility to food allergies may be increasing due to decreased exposure to germs and infections early in life.

With food intolerances, the most common cause is an enzyme deficiency. For instance, a lactose intolerance is due to a deficiency in the lactase enzyme that lives on the surface of the small intestine. If you have a lactose intolerance, your body relies on bacteria within your gut to break down and digest lactase, which in the process can make you feel bloated, gassy and nauseous.

Another common sensitivity is gluten intolerance. Researchers are still unsure whether gluten causes this intolerance, but certain components of foods (such as wheat) that contain gluten may increase your intestine’s permeability. This means that microbes can cross the intestinal barrier and interact with the immune system, triggering a mild inflammatory reaction along with symptoms like abdominal pain, diarrhea and bloating.

It’s important to remember that many conditions can be mistaken for allergies and food intolerances, including acid reflux, irritable bowel syndrome, celiac disease and inflammatory bowel disease.

How do we diagnose food allergies and intolerances?

An individual's history of reaction(s) is most important in helping determine a true food allergy. Skin prick testing and blood testing are used to help detect antibodies to food allergens and assist in the diagnosis of food allergies.

It can be tempting to test your child for a broad range of food allergies. We don't recommend it. A person can test positive for a particular food but experience no problems with that food in real life. Unnecessarily eliminating a food from a child’s diet can affect their nutrition and development, create stress around sticking to a restrictive diet, and potentially lead to the development of a true food allergy.

It’s important to remember that many conditions can be mistaken for allergies and food intolerances, including acid reflux, irritable bowel syndrome, celiac disease and inflammatory bowel disease.

Food intolerances are much harder to diagnose. Breath and stool tests exist to diagnose lactose and other sugar intolerances, but most food intolerances are identified by a process of elimination. Usually, that means reviewing your child’s diet, removing suspect foods for two weeks, then reevaluating their symptoms.

If your child does better, you should contact your child’s doctor to consider additional testing for more harmful conditions before permanently eliminating the food from their diet.

Home test kits that are advertised online and on TV to diagnose allergies or intolerances are neither well-studied nor proven to provide accurate diagnoses. These tests can be misleading and result in unnecessary dietary eliminations which may cause more harm than benefit.

How are food allergies and intolerances treated?

There is currently no cure for food allergies; however, this is an active area of research.

Oral immunotherapy is a newer treatment that involves desensitizing the immune system so that small amounts of a food can be tolerated as a safety measure in case of accidental exposure to a food allergen. This slow process involves gradually increasing microdoses of the food over the course of months. This provides a layer of protection. When someone is accidentally exposed to that food, their body may not be as reactive.

Currently, peanuts are the only food for which an FDA-approved oral immunotherapy exists. However, doctors are often able to offer tailored oral immunotherapy for other food allergies.

Most food intolerances involve dietary eliminations or reductions to improve symptoms.