Food-dependent exercise-induced anaphylaxis

Background. Food-dependent exercise-induced anaphylaxis (FDEIAn) is a severe reactive syndrome that can be triggered by any type of physical activity a short while after a meal. Two forms are distinguished: "specific" and "non-specific ". The former follows the ingestion of a particular food for which allergological tests are usually found to be positive. In the latter, the reactions are triggered by physical activity after any intake of food and the allergological examination for food types is often negative. The main purpose of our diagnostic protocol is to identify the food allergens responsible. Methods. We studied 54 adults who had presented one or more episodes of FDEIAn with: a detailed personal history, prick tests with commercial food allergens, prick+prick tests with fresh vegetables, prick tests with the main aeroallergens. We also carried out: measurement of total IgE (PRIST) and specific IgE (RAST), objective examination integrated by electrocardiogram, echocardiogram and respiratory function tests, maximal exercise test on the treadmill 90 minutes after intake of a meal not containing the incriminated food or any of the foods for which skin- and/or RAST positivity had been identified (Food Exercise Challenge-FEC). Results. The allergological examination was positive for at least one food in 52 patients; 14 presented an oligosensitisation and 38 polysensitisation. The prick+prick technique revealed positivity of vegetable foods not picked up by the diagnostic extracts on the market. RAST highlighted numerous cases of positivity proving, with a few exceptions, to be a much more sensitive test than skin-reactions with vegetable foods. All in all, 48 patients presented a probable "specific" form of FDEIAn and 6 a "non-specific" form, although only 2 of the latter had presented symptoms following the FEC. The "specific" form of FDEIAn should be considered a particular type of food allergy that occurs in association with physical exercise. Polysensitisation to trophoallergens seems to be an important characteristic of most subjects with FEDIAn. Conclusions. It is vital to avoid intake of foods that have proved positive to allergological examination at least 4 hours before physical activity. This interval of time is sufficient to prevent reactions even in patients with the "non-specific" form