What are Food Allergies?

Our immune system plays a very important role in defending us from harmful external invaders like viruses, bacteria, and parasites.  It also protects us often from internal threats like cancer cells.  Cancers grow only when our immune defenses are overwhelmed and defeated.

Occasionally due to unknown causes, our immune system turns against our own organs and damages them resulting in a variety of “autoimmune” disorders.  Some examples of autoimmune disorders include systemic lupus erythematosus (i.e., SLE), Sjögren’s syndrome, scleroderma, polymyositis, polymyalgia rheumatica, Churg-Strauss, Behçet’s disease, microscopic polyangiitis, myasthenia gravis, mixed connective tissue disease, bullous pemphigoid, pemphigus vulgaris, giant cell arteritis (i.e., temporal arteritis), Wegener’s granulomatosis, and polyarteritis nodosa.  Note that there are many more autoimmune disorder other than the ones’ listed.  Another way the immune mechanisms can go awry is when they mistake innocuous substances in the air (e.g., dust mites, molds, pollen, pet dander) and certain proteins in our food as potentially dangerous and mount a defensive attack on them.

There are three ways that foods can cause adverse effects in humans:

1. “Food allergy” commonly refers to the condition where specific IgE antibodies react with specific proteins in the food.  This causes a release of chemical mediators which then in turn may cause systemic or generalized reactions.  The tendency to form specific antibodies against the food proteins is often genetically determined.  Though any food can potentially cause systemic reactions, peanut, tree nuts, fish, shellfish, egg, milk, soy, and wheat are the most commonly involved foods.  Symptoms involving many organ systems usually begin within a few minutes (except for mammalian meat allergy-related symptoms which usually begin several hours after ingestion) and rapidly progress unless aggressively treated.  Simple skin tests and/or laboratory tests can identify the specific foods an individual is sensitized to, so that they can be avoided in the future.
2. There is another type of food-related adverse effect which is caused by an immunological mechanism but does not involve an immediate type hypersensitivity reaction which is mediated by IgE antibodies.  An example of this type of food-related adverse effect is celiac disease.  In celiac disease, the mechanism involves an adverse reaction to a group of proteins called gluten which is present in grains like wheat, rye, and barley.
3. A non-immunological food “intolerance” refers to a condition where a difficulty in processing the food results in primarily gastrointestinal symptoms.  A common example of a food intolerance is lactose intolerance.  In this condition, there is a relative deficiency of an enzyme called lactase.  Lactase is needed to break down the sugar called lactose that is found in dairy products.  As a result of not having enough lactase, there is a build-up of undigested lactose in the digestive system.  This undigested sugar (i.e., lactose) becomes fermented in the intestines and leads to symptoms which generally include abdominal bloating, flatulence, and/or diarrhea. This condition can be managed by the substitution of lactose with dairy-free products or the supplementation of the lactase enzyme (e.g., Lactaid milk, Lactaid pills) when dairy products are consumed.

The board certified allergists at Black & Kletz Allergy have been diagnosing and treating food allergies and food intolerances in both adult and pediatric patients for more than 5 decades.  We have 3 office locations with onsite parking in the Washington, DC, Northern Virginia, and Marylandmetropolitan area.  Our offices are in Washington, DC, McLean, VA (Tysons Corner, VA), and Manassas, VA and our Washington, DC and McLean locations are Metro accessible.  If you have food allergies or intolerances or think you may have them, please call our office to schedule an appointment.  You can also click Request an Appointment and we will respond within 24 hours by the next business day.  Black & Kletz Allergy strives to provide excellent state of the art allergy, asthma, and immunology care to the greater Washington, DC community in a convenient and friendly environment.