Four to eight percent of the population are estimated to be food-allergic. Most food allergies in adolescents and adults are acquired on the basis of cross-reaction to pollen allergens. Theses allergens are ubiquitous in the plant kingdom. Therefore pollen-allergic patients might acquire a multitude of different plant food allergies, and even react to novel foods to which they have never previously been exposed. A curative therapy for food allergy does not yet exist. Food-allergic patients have to rely on strict avoidance diets, The widespread use of industrially processed foods poses a general problem for food-allergic patients. Although the most frequent allergens must be declared openly in the list of ingredients, involuntary contamination with allergy-provoking compounds can occur. The precautionary labelling "may contain" is sometimes applied even if the chance of contamination is very low; on the other hand, foods not declared to contain possible traces of allergenic components may actually contain relevant amounts of allergenic proteins. Switzerland is the only country in Europe with legal regulations on contamination by allergenic food; however, the allowance of 1 g/kg is too high to protect a relevant proportion of food-allergic individuals.