Food Allergies vs. Food Intolerances

by Carmen Roberts, M.S., R.D., L.D.N. Health Professional, Medical Reviewer

Over 15 million Americans have been diagnosed with food allergies. Chances are you know of someone who has a food allergy or claims that they have an intolerance to a certain food. But what is the difference between the two, and how can a food allergy or intolerance be identified?

Food Allergies

One in 13 children in the United States have been diagnosed with a food allergy. Though some will outgrow this condition, many will have to live with their food allergy for the rest of their life. A food allergy develops when your immune system mistakenly targets a food protein as a threat to your body and attacks it. What makes a food allergy unique compared to any other food intolerance is that your immune system creates an enormous amount of an antibody called immunoglobulin E (IgE) to help attack the food allergen. When this occurs, histamine and other chemicals are released in your body, causing an allergic reaction to occur. This reaction will occur each and every time the food is ingested.

Virtually any food can cause an allergic reaction; however, there are eight foods that are responsible for over 90 percent of all allergic reactions in the United States: peanuts, tree nuts, shellfish, soy, wheat, milk, fish, and eggs. Allergic reactions can affect many parts of the body, including the skin, respiratory system, gastrointestinal tract and cardiovascular system. Reactions vary greatly from mild to severe, and include hives, itching, sneezing, nausea, vomiting and diarrhea. The most severe allergic reaction can result in anaphylaxis, which may cause a decrease in blood pressure, difficulty breathing and loss of consciousness. A person who has both asthma and a food allergy is at a greater risk for anaphylaxis. Peanuts, tree nuts, fish and shellfish are the allergens that are most likely to cause this type of allergic reaction.

Add Lean Protein to your Favorite Dishes

Food Intolerances

With the exception of celiac disease, an intolerance to a specific food does not involve the immune system. Though some people can show symptoms similar to those seen with a food allergy, a food intolerance will not trigger anaphylaxis. Common food intolerances include lactose intolerance and celiac disease. When someone is lactose intolerant, their body does not produce enough lactase, which is the enzyme in your body that helps to break down lactose (the naturally occurring sugar in milk). Symptoms are usually seen within 30-120 minutes after consuming lactose. Common complaints of lactose intolerant individuals include bloating, cramping, diarrhea and nausea.

In the case of celiac disease, an immune response is seen after the ingestion of gluten (the protein found in wheat, barley, rye and some oats). This immune response does not involve IgE, so there is no risk of anaphylaxis. However, this immune reaction may damage the intestinal lining over time, so gluten-containing products must be avoided to prevent long-term damage to the small intestine. Common symptoms of celiac disease include bloating, gas and diarrhea.

Bottom Line

If you suspect that you have a food allergy or intolerance, make an appointment with a board-certified allergist. Do not try to diagnose a food allergy on your own; doing so may lead to unnecessary dietary restrictions and possible nutritional deficiencies. Proper testing is the only way to make a clear diagnosis, which will help you to manage and treat the food allergy or intolerance, minimize your symptoms and avoid potential life-threatening reactions.

Carmen Roberts, M.S., R.D., L.D.N.
Meet Our Writer
Carmen Roberts, M.S., R.D., L.D.N.

Carmen is a Registered Dietitian. In addition to writing for HealthCentral, she has spent her career working at Johns Hopkins and is also an adjunct faculty instructor for Excelsior College. Carmen has over 20 years of experience in nutritional counseling, education, writing, and program management and is a certified specialist in adult weight management. She enjoys educating her students and clients about how nutrition affects the body and its role in overall health and wellness.