Considerations on the allergy-risks related to the consumption of fruits from urban trees in Mediterranean cities

Food provision is designated as one of the ecosystem services provided by urban forests which are comprised of numerous fruit trees. In cities with a Mediterranean climate, the use of fruit trees has a long historical tradition, although its main function has been ornamental. In turn, the consumption of the fruits from these urban trees can lead to some tradeoffs or negative impacts on health. One of the main ecosystem disservices associated with the implementation of urban fruit forests are the allergic reactions caused by plant allergens. This study has two main objectives: 1) to establish a list of urban fruit trees in Mediterranean cities, and 2) to review the allergic reactions associated with the consumption of fruits from urban trees. The catalog of urban fruit trees begins with the species present in the city of Granada (southern Spain), which has resulted in a list of 70 species of 30 botanical families. The family Rosaceae is the most abundant, with 23 species. Of this family, the genus Prunus appeared most prominently, with 7 species, followed by the genus Citrus of the family Rutaceae, with 6 species. As for allergenicity, the species of the families Oleaceae, Fagacecae, Moraceae and Juglandaceae have allergenic pollen with different degrees of incidence in the population, while in others these allergens are found in the fruit, specifically in nuts, berries, citric fruits and species within the Rosaceae family. There are also cross reactions between common allergens in Mediterranean plants and commonly consumed fruits. It can be concluded that the results of this study address the existing knowledge gap when discussing the ecosystem service of food provision, particularly in relation to pollen and fruit allergens.