Delayed-Onset Food Allergies

I n 1906, Clemens Von Pirquet, M.D., the noted Austrian pediatrician, coined the term allergy from the Greek “allos” (meaning changed or altered state) and “ergon” (meaning reaction or reactivity) to describe patients with excessive physiologic responses to substances in their environment. Currently, 50 million Americans suffer from allergies on a yearly basis, with allergy ranking as the sixth leading cause of chronic disease and costing the U.S. health care system $18 billion per year.1 In fact, 16.7 million office visits to health care providers are attributed to allergic rhinitis alone.2 At all ages, allergic rhinitis without asthma is reported by nearly 90 people of every 1000.3 In 1996, estimated U.S. health care expenditures attributable to sinusitis were more than $5.8 billion.4 Two recent estimates of allergy prevalence in the United States were 9 and 16 percent,5 while the prevalence for specific allergic conditions, such as allergic rhinitis and atopic dermatitis, have increased over the last 15 years.6,7 What is even more alarming is the fact that these numbers continue to increase at a rapid rate. These statistics reflect the prevalence of clinically diagnosed, commonly established allergic conditions. Food allergy is one type of condition that is not always easy to recognize and, therefore, treat appropriately. Food allergy is a complex of clinical syndromes resulting from sensitization to one or more foods whereby symptoms manifest locally in the gastrointestinal (GI) tract or elsewhere in the body as a result of immunologic reactions. Numerous food-based allergic syndromes with manifestations other than classical allergic symptoms are misdiagnosed and are, therefore, medically mismanaged. Delayed patterns of food allergy are not always clinically obvious and are generally unrecognized, because of the delay in symptom onset of hours to days. The relative neglect of food as an allergenic factor in conventional medical practice has led to a gap in the management of patients with these allergies and a void in the understanding of the disease process involved. Because of this, food allergies other than type I, immediate-onset allergies are often unacknowledged in clinical medicine and research. Yet, food allergies that are attributable to type III, delayed-onset allergies have been implicated in numerous medical conditions, ranging from childhood hyperactivity to migraine headaches. The concept of delayed-onset food allergies is not new. In the 1920s, reactions to food were linked, via experiments, to such physical symptoms as colitis, diarrhea, bladder pain, and Meniere’s syndrome.8,9 Other experiments were performed, demonstrating the ability of ingested food antigens to penetrate the GI barrier and become affixed to dermal mast cells.10,11 Food allergies other than type I were described in the 1930s, with reports of delayed symptoms of hours to days following the ingestion of suspect foods.12