Food-dependent exercise-induced anaphylaxis: clinical and laboratory findings in 54 subjects.

BACKGROUND: In some subjects, specific foods trigger anaphylaxis when exercise follows ingestion (specific food-dependent exercise-induced anaphylaxis, FDEIAn). Skin test and/or RAST positivity to foods suggest an IgE-mediated pathogenic mechanism. Others suffer from anaphylaxis after all meals followed by exercise, regardless of the food eaten (nonspecific FDEIAn). We sought to identify the culprit foods with a diagnostic protocol.

METHODS: We collected detailed histories and performed skin prick tests (SPT) with 26 commercial food allergens, prick plus prick tests (P+P) with 15 fresh foods (including 9 assessed with SPT), and RAST for 31 food allergens. Treadmill stress tests were administered after a meal without any positive food (food plus exercise challenge, FEC).

RESULTS: Among the 54 patients, 6 could not recall any suspect food. The other 48 suspected a specific food in at least one episode. The most frequent were tomatoes, cereals and peanuts. Fifty-two subjects were positive to at least one food (22 to more than 20), whereas 2 showed no positive results. All suspect foods were positive. SPT, P+P and RAST displayed different degrees of sensitivity. Each test disclosed some positivities not discovered by others. Two subjects reacted to FEC. Overall, 48 patients probably had specific FDEIAn and the other 6 nonspecific FDEIAn.

CONCLUSION: It is useful to test both in vivo and in vitro an extensive panel of foods. Avoidance of foods associated with skin test and/or RAST positivity for at least 4 h before exercise has prevented further episodes in all our patients with specific FDEIAn.