Comparing allergies vs. intolerance

Recently I have been asked several questions about the difference between a food allergy and a food intolerance. One in three people believe they have a food allergy, yet only a small percentage of adults suffer from true food allergies. More likely, they are suffering from an intolerance. Unfortunately, it doesn’t make the symptoms any less unpleasant.

The term “food allergy” often defines a variety of adverse physical reactions to foods. A true food allergy is an abnormal response of the body’s immune system to certain foods or food ingredients. For some people, eating even a little of the offending food can cause a life-threatening reaction. Less sensitive people may be able to tolerate small amounts of the food to which they are allergic.

Unlike a food allergy, a food intolerance does not involve the immune system. However, the physical symptoms of a food intolerance, such as intestinal discomfort, can resemble those of a true food allergy. For this reason, a food intolerance reaction may be easily confused with an allergic reaction. It is important that the symptoms be evaluated and diagnosed by a board-certified allergist.

Common physical responses to allergic food substances include:

Skin reactions: swelling, hives, rashes.

Nose/lung reactions: nasal congestion, asthma.

Stomach/intestinal reactions: nausea, diarrhea, gas.

Symptoms can develop immediately, within two hours, or may appear one to two days after eating a food. Persons who believe they have experienced an adverse reaction should seek medical evaluation. Many typical symptoms could be caused by other illnesses such as the flu or food poisoning.

The most severe type of food allergy reaction is called anaphylaxis. This reaction can occur within moments after eating the offending food, and typically involves several parts of the body. Symptoms may include hives, difficulty breathing, and loss of consciousness. Without immediate medical attention, death may occur. Common foods that cause anaphylaxis are peanuts, nuts, eggs, and shellfish.

The most common food allergies in adults include reactions caused by fish and shellfish, peanuts and nuts such as walnuts or pecans, and eggs. In children common food allergy culprits are milk, egg, peanuts, wheat, and soy.

Diagnosing a food allergy requires a physical examination by an allergist who may recommend you consult with a registered dietitian to help you manage your diet.

Food intolerances may cause people to react adversely to foods for a number of reasons. These include digestive and other physical conditions that can mimic food allergy symptoms. Also, an enzyme deficiency, such as when the body cannot digest lactose (a milk sugar) often produces symptoms of gas, cramps, and bloating. This is known as a lactose intolerance, and is not a milk allergy.

For information visit to view the American Academy of Allergy and Immunology’s website. They can help you find a list of allergists in your area, as well as general information on food allergies, other allergies, and asthma. You can also visit the Food Allergy Research and Education website at for information and resources.

Mary Koch is a Registered Dietitian at Banner Churchill Community Hospital and the VA Lahontan Valley Outpatient Clinic. Send your nutrition questions to Mary at


Use the comment form below to begin a discussion about this content.

Sign in to comment