Christopher C. Chang, MD, PhD, MBA, FAAAAI, FACAAI, Associate Professor of Medicine in division of Rheumatology, Allergy and Clinical Immunology at UC Davis
Like other allergic diseases, the incidence of food allergies has dramatically increased over the past several decades. When I was growing up years ago, food allergies in school hardly seemed to exist. Fast forward to when my children went to school, and about a handful of students in the entire school had food allergies. Allergy management for these students at school was done on a case-by-case basis.
Now, students with food allergies have actions plans, there are mandatory laws in many states for keeping and administering Epinephrine autoinjectors in the schools, and special peanut-free zones are set up in many schools.
But along with the increase in allergies and the information age, there is quite a lot of misinformation when it comes to food allergies. For one thing, allergies may mean different things to different people. When we allergists speak about allergies, we are talking about a specific disease whereby a person makes allergic antibodies to a specific molecule, usually a protein. These antibodies are known as Immunoglobulin E (IgE) and are a class of antibodies that causes the release of compounds, including but not limited to histamine, that can cause allergic reactions. These allergic reactions generally come on quite quickly, and symptoms include hives, flushing, wheezing, or vomiting.
Mild reactions can be treated by antihistamines, but the most severe forms of allergies known as anaphylaxis require epinephrine, usually administered in the field in the form of autoinjectors. But besides allergies, foods can cause other types of reactions, and some of these may involve the immune system and others may not. An example would be lactose intolerance. Some people experience this when they drink cow’s milk because the lack an enzyme to break down lactose. While this may cause stomach discomfort and diarrhea, this is not an allergy. Another example would be headaches that develop as a result of consuming monosodium glutamate, a flavoring agent which used to be much more widely used. Again, this is not an allergy, but an intolerance to the particular agent. In some cases, even food poisoning can mimic an allergic reaction.
It is important to look at the symptoms people are experiencing to determine if it’s an allergy. Typical allergies present as hives, flushing, wheezing, cough, a sensation of one’s throat closing up, vomiting, and stomach ache. These would be consistent with an allergic reaction. On the other hand, symptoms such as difficulty concentrating, loss of memory, fatigue, most headaches, weakness, depression, behavior problems are NOT the result of an allergy. Timing is important as well. Symptoms that occur inconsistently upon exposure to a specific food, or which occur days after ingestion are generally not allergic. In fact, in many of these cases, a food is not the culprit at all, but merely a red herring.
This becomes important when we talk about testing for a food allergy. In my next blog, I’ll discuss what to expect when you come to see an allergist about a suspected food allergy. Also, I’ll tell you more about controversial and unproven testing methods in allergy and immunology.