ThE ROLE OF FOOD ALLERGY IN ALLERGIc AIRWAY DISEASES

Food allergies have been increasing over the last decades, in parallel with a general increase of allergy worldwide. however, epidemiological studies on food allergy are difficult to perform (especially when using questionnaires), and contain a number of pitfalls because of a considerable amount of false negative and false positive results. This is mainly because food can induce a number of abnormal reactions which are not food allergic reactions (i.e. food intolerance, aversion). The prevalence of food allergy is lower than inhalant allergy (such as house dust mite allergy). Only a few population based studies on food allergy in Asia have been published, showing higher prevalence in young children than in older children or adults. clinical manifestations are variable, but are usually skin symptoms (urticaria, angioedema). Other symptoms can be rhinitis, asthma, and gastrointestinal symptoms (FTT, vomiting and diarrhea). Symptoms resulting from other organs (especially psychological or neurological symptoms) are usually not due to food allergy. Diagnosis of food allergy is based on history – clinical examination, allergy testing (IgE and skin prick testing) and provocation testing. The doubleblind placebo-controlled food challenge (DbPcFc), (performed in a hospital setting, under strict observation and with all emergency facilities available) is still the golden standard for the diagnosis. SFP2009; 35(2): 18-24 DEFINITION OF FOOD ALLERGY Any abnormal reaction that results from the ingestion of food is considered an adverse food reaction. A number of types of adverse reactions are distinguished. The terminology is not always clear, as different researchers use different definitions. Usually, adverse reactions to food are divided into three groups: food intolerance, food allergy (including IgE-mediated reactions) and food aversions or phobias. Most researchers consider the term “food allergy” as an abnormal reaction from the human body in which the immune system is involved. The term “food allergy” is here used for all abnormal immunological reactions, not only for the IgE-mediated reactions. This definition is therefore different from all other allergic reactions, in which the involvement of IgE is pivotal. Any abnormal reaction to food in which the immune system is not involved is not considered as food allergic reactions. Food Intolerance Food intolerances are the most common type of adverse reactions to foods. It is a general term describing an abnormal physiologic response to an ingested food. A number of underlying causes have been identified which may be due to either the food or the host. Usually, the symptoms are diarrhea, tummy pain and vomiting. The most common types are: a. Intolerance caused by toxic contaminants of food Examples: high histamine in scombroid fish poisoning, toxins from bacteria, such as Salmonella, Shigella and Campylobacter. b. Intolerance caused by pharmacologic properties of the food Examples: alcohol, caffeine in coffee, tyramine in aged cheeses or food poisoning by foods containing heavy metals or pesticides. c. Intolerance caused by infected food Examples: food containing bacteria, parasites or viruses (such as rotavirus infection, by drinking contaminated water) d. Intolerance caused by characteristics of the host Example: metabolic disorders, such as lactase deficiency, causing intolerance to milk.