Medical Edge Newspaper Column

Difference Between Food Allergy and Food Intolerance

April 17, 2008
Readers:
What's the difference between food allergy and food intolerance? And why is it important to know the difference?

If you have a food allergy, eating even the smallest amount of that food may trigger a serious reaction. With food intolerance, you may be able to eat small amounts of problem foods without a reaction.

With an allergy, the immune system mistakenly identifies a food as harmful, triggering immunoglobulin E (IgE) antibodies to fight the substance. Signs and symptoms usually develop within minutes and may include tingling in the mouth; hives; swelling of the lips, face, tongue and throat; wheezing or breathing difficulties; dizziness; abdominal pain; diarrhea; nausea or vomiting.

Food intolerance, where a symptom is triggered by a food or substance, is much more common than food allergy. Only about 2 percent of adults and 6 percent of children have a food allergy. Food intolerance doesn't involve the immune system but can cause some of the same gastrointestinal symptoms as food allergy. For example, lactose intolerance, where people don't have the digestive enzymes to fully digest sugar in milk products, can cause bloating, cramping or diarrhea.

If you have concerns or questions about your reaction to certain foods, consult with a doctor. Allergies can be diagnosed with skin and blood tests. Diagnosing food intolerance is a bigger challenge, requiring a thorough health history.