FAQs

What Is a Food Allergy?

A food allergy is an immune system response. It occurs when the body mistakes an ingredient in food - usually a protein - as harmful and creates a defense system (antibodies) to fight it. Food allergy symptoms develop when the antibodies are battling the "invading" food. The most common food allergies are peanuts, tree nuts (such as walnuts, pecans and almonds), fish, and shellfish, milk, eggs, soy products, and wheat.

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What Is Food Intolerance?

Food intolerance is a digestive system response rather than an immune system response. It occurs when something in a food irritates a person's digestive system or when a person is unable to properly digest or breakdown the food. Intolerance to lactose, which is found in milk and other dairy products, is the most common food intolerance.

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How Common Are Food Allergies and Intolerances?

Food allergies affect nearly 4% of teens and adults and 5% of children. Food intolerances are much more common. In fact, nearly everyone at one time has had an unpleasant reaction to something they ate. Some people have specific food intolerances. Lactose intolerance, the most common food intolerance, affects about 10% of Americans.

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What Causes Food Allergies and Intolerances?

Food allergies arise from sensitivity to chemical compounds (proteins) in food. They develop after you are exposed to a food protein that your body thinks is harmful. The first time you eat the food containing the protein, your immune system responds by creating specific disease-fighting antibodies (called immunoglobulin E or IgE). When you eat the food again, it triggers the release of IgE antibodies and other chemicals, including histamine, in an effort to expel the protein "invader" from your body. Histamine is a powerful chemical that can affect the respiratory system, gastrointestinal tract, skin, or cardiovascular system.

As a result of this response, food allergy symptoms occur. The allergy symptoms you have depend on where in the body the histamine is released. If it is released in the ears, nose, and throat, you may have an itchy nose and mouth, or trouble breathing or swallowing. If histamine is released in the skin, you may develop hives or a rash. If histamine is released in the gastrointestinal tract, you likely will develop stomach pains, cramps, vomiting or diarrhea. Many people experience a combination of symptoms as the food is eaten and digested.

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How Can You Tell the Difference Between a Food Allergy and Intolerance?

Food allergies can be triggered by even a small amount of the food and occur every time the food is consumed. People with food allergies are generally advised to avoid the offending foods completely. On the other hand, food intolerances often are dose related.

People with food intolerance may not have symptoms unless they eat a large portion of the food or eat the food frequently. For example, a person with lactose intolerance may be able to drink milk in coffee or a single glass of milk, but becomes sick if he or she drinks several glasses of milk.

Your health care provider can help determine if you have a food allergy or intolerance, and establish a plan to help control your symptoms.

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