What’s a Food Allergy?

According to Food Allergy Research and Education (FARE), up to 15 million Americans have food allergies. Food allergies affect 1 in every 13 children under 18 years of age. That’s roughly two in every classroom. We all probably know someone who avoids certain foods for one reason or another, be it gluten-intolerance or a full blown shellfish allergy, and this IFT Food Facts Video explains what exactly a food allergy is.

What is a Food Allergy?

A food allergy occurs when the immune system mistakes an ingredient in food as harmful and creates antibodies to fight it. These antibodies create the symptoms of a food allergy, such as rash or hives, nausea, stomach pain, diarrhea, itchy skin, shortness of breath, chest pain and anaphylaxis.

Food allergies, which can be genetic, affect about 4 percent of teens and adults and 5 percent of children, while food intolerances are much more common. Though most people will experience an unpleasant reaction to a certain type of food at some point in their lives, the only way to diagnose a true food allergy is by visiting a medical doctor.

What is Food Intolerance?

While the symptoms are similar to food allergy, food intolerance occurs when an ingredient or compound in food irritates a person's digestive system or when a person is unable to properly digest the food. Symptoms of food intolerance are primarily gastrointestinal and include stomach pain, gas cramps or bloating, heartburn, vomiting and diarrhea. Intolerance to lactose, an ingredient in most milk and dairy products, is the most common food intolerance and affects about 10 percent of Americans.

There are a number of factors that may influence food intolerance. In some cases, as with lactose intolerance, the person lacks the enzyme to properly digest lactose, a type of sugar (disaccharide) found in milk and dairy products. While food allergies can be triggered by a smallest amount of the food in question, food intolerances are sometimes dose related and may not occur unless the person allergic consumes a large portion of the food. For example: a person with lactose intolerance may be able to drink milk in coffee, but will become sick if she drinks an entire glass of milk. 

Keeping a food journal and tracking what you ate when symptoms occur can generally help diagnose food intolerances. Another way to diagnose food intolerance is to go on an elimination diet, which involves completely eliminating any suspect foods from your diet until you are symptom-free. You then begin to reintroduce the foods, one at a time. This can help you pinpoint which foods cause symptoms. Seek the advice of your health care provider or a registered dietitian before beginning an elimination diet to be sure your diet provides adequate nutrition.

What is Food Sensitivity?

Food sensitivity is the least understood and most difficult to diagnose of the three afflictions. Generally, food sensitivity means that a person has a negative reaction to certain foods that do not always occur in the same way.

With a food sensitivity, a person might be able to consume a certain food occasionally without feeling any ill effects, but will sporadically develop symptoms such as acid reflex, nausea, abdominal cramps. These symptoms are unpredictable and the medical field is largely uncertain as to why they occur some times, but not others.