Reactivity to potential cross-reactive foods in fruit-allergic patients: implications for prescribing food avoidance.

BACKGROUND: Prescribing therapeutic elimination diets in patients with fruit allergy should include recommendations on which other foods of the same family or group may be safely consumed. Evidence-based data on the management of fruit allergy are lacking; therefore, advice may vary from just avoiding the offending fruit, to overly restrictive diets of the entire botanical family. The aims of this investigation were to assess clinical reactivity to potential cross-reactive foods in fruit-allergic patients, and the implications for prescribing specific therapeutic elimination diets.

METHODS: Sixty-five adults diagnosed with clinical allergy to one or more fruits were evaluated for IgE-mediated allergy to other related foods, which might share cross-reactive antigens. Those with actual allergy to some Rosaceae fruit (including peach, apple, apricot, plum, and almond) underwent skin prick testing (SPT), food-specific IgE assessment by the Pharmacia CAP-FEIA system, and oral challenges with the entire group. For those with allergy to other fruits (chestnut, melon, banana, kiwi, or avocado) immunologic and clinical reactivity to all five were evaluated. Since a number of people in the study also had proven clinically allergy to some nut or legume (peanut, sunflower seed, walnut, pistachio, or hazelnut), the reactivity to the entire set was investigated.

RESULTS: Thirty-four of those tested (52%) were found to be clinically allergic to more than one fruit, so 125 allergic reactions occurred in the 65 patients. Peach, melon, kiwi, apple, and banana accounted for 72% of allergic reactions. Forty-two (65%) had sensitization to pollens, causing seasonal allergic rhinitis and/or asthma, and 18 (28%) were sensitized to latex. The 65 with IgE-mediated fruit allergy underwent 351 additional SPT and food-specific IgE determinations with potential cross-reactive foods considered in this study; 223 (64%) of these results were positive. The routine challenges with potential cross-reactive foods uncovered 18 further reactions in 14 (22%) out of 65 (to avocado in seven; apricot in three; plum in one; almond and peanut in one; banana and hazelnut in one; avocado, banana and kiwi in one). Only 8% (18/223) of positive results for SPT, or food-specific IgE levels of greater than 0.35 kU(A)/l to potential cross-reactive foods investigated in this study, were clinically relevant.

CONCLUSION: Elimination diets that rely on total group avoidance, or only on the results of allergy testing, might have resulted in unnecessary restriction of 205 foods in the 65 people studied. The lack of routine oral challenges with related fruits--before prescribing dietary restriction--may have allowed 18 food reactions in one-fifth (14/65) of patients to be overlooked.