May 18, 2010
Is it a Food Allergy or Food Intolerance?
A recent article in the New York Times (available online at http://www.nytimes.com/2010/05/12/health/research/12allergies.html) sheds light on the misconceptions of food allergy. As practicing allergists, we see many patients who think they have a “food allergy” when in reality they have a “food intolerance.”
A food allergy occurs when the immune system reacts to a certain food. The body creates allergic antibodies to the food, known as immunoglobulin E (IgE), which react with the food and cause histamine and other chemical mediators to be released. A true food allergic reaction usually involves hives, asthma, angioedema (swelling) or other symptoms.
Food intolerance, on the other hand, does not involve the immune system and is not life-threatening. A common example is lactose intolerance, which is caused by a deficiency in the enzyme needed to break down milk sugars. Symptoms may include abdominal cramps, bloating and diarrhea. Another example is headache due to sulfite-containing foods such as processed cheeses and certain wines.
It’s very important to know that a positive allergy skin or blood test (both detect food specific IgE levels) does not always mean you’re allergic to a food. Many times you can eat a food without symptoms despite a positive test. In addition, a positive test does not tell you how severe an allergy is. That’s why it’s very important to be seen by an allergist who can skillfully put together the clinical history of food reactions with appropriate testing to obtain an accurate diagnosis and minimize false positive results.
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