(May 14, 2009 - Insidermedicine)
At the American Academy of Allergy Asthma and Immunology’s annual meeting in Washington, we had a chance to speak with Dr. Leslie Grammer. Dr. Grammer is a professor of medicine in the division of allergy at Northwestern University’s Feinberg School of Medicine.
If I Had A Food Allergy
Dr. Grammer: Adverse reactions to foods come in two major categories. One is food allergy, wherein your body has developed an immune response to a food and that immune response causes food allergy. As opposed to food intolerances that are not immunologically mediated. They are mediated in a variety of other ways. For instance, people who don’t have certain enzymes. If you don’t have the enzyme called lactase in your GI tract then you can’t break down lactose, which is the sugar in milk and other dairy products, causing severe abdominal cramps and diarrhea. Which is a very distressing syndrome to have, but it is not a food allergy. Other kinds of intolerance include people with migraine headaches. Certain things like coffee or chocolate will bring on their migraine headaches, just as examples. The majority of adverse food reactions in adults are intolerances and not allergies.
How do allergies and intolerances present themselves?
Dr. Grammer: There is overlap between intolerance and allergy. Having said that in a patient who comes to you with hives, itching, flushing, trouble breathing after ingestion of a food, that probably is food allergy. As opposed to a patient who comes to you who says that they have severe migraine headaches after ingesting a food.
What foods can cause allergies?
Dr. Grammer: The three different diseases that are manifestations of food allergy include: Anaphylaxis, which is a generalized severe allergic reaction that can include things like hives, asthma, swelling of the back of the throat, and severe cardiovascular problems like cardiac arrest. Another disease that can be caused by food allergies, primarily in children, is Eczema (atopic dermatitis). Whether food actually causes atopic dermatitis in adults is unclear. If it does it is certainly in a very small percentage of patients. A disease that has been recognized in probably only the last decade is Eosinophilic Esophagitis. Wherein the esophagus, which is the tube that leads from your mouth to your stomach, gets inflamed by allergic reactions to food. Most commonly in adults it presents as food getting stuck in the esophagus when the patient swallows.
Will reactions always manifest themselves in the same way?
Dr. Grammer: Whatever the person’s manifestation is of food allergy to a given food, that’s what it always is. There are people who have anaphylaxis from peanuts. Every time they eat peanuts they get anaphylaxis. That same person, again this is mostly children, can also have allergy let’s say to egg and soy, where their reaction is worsening of their atopic dermatitis. They don’t get anaphylaxis to that food because that’s not their immunologic mechanism.
How are different reactions treated?
Dr. Grammer: Food allergies, whether they are anaphylactic or not, have one common treatment and that’s avoidance. The secondary treatments however can be quite different. The medication regime for patients who have atopic dermatitis from food allergy, is quite different from people with anaphylaxis. Patients with food anaphylaxis need to carry their anaphylactic emergency medicines with them at all times. Whereas people whose food allergy manifests itself as atopic dermatitis or eosinophilic esophagitis don’t need emergency treatment but they do need to avoid the foods if possible.
If I had…
Dr. Grammer: If I had an adverse reaction to a food, I would want to figure out if it were an intolerance or an allergy. If it were an intolerance, depending upon the problem I might see a GI doctor or a neurologist. If it is a food allergy then of course I’d see an allergy specialist. I would work with my doctor to figure out which food or foods I was allergic to, so that I could avoid them. If I had an anaphylactic reaction to foods I would be sure that I had emergency medications to take and be sure that I knew how and when to take the medicines. And I would have those emergency medicines with me at all times.