It is hard to open a newspaper or lifestyle magazine now without finding the concept of ‘ultra-processed food’ somewhere mentioned. Based on the idea that not only a product’s content but the processes involved in its manufacture determine its health value, UPF has captured public attention. How useful is the classification, and what can its use achieve? In this TABLE Letterbox Exchange, Rob Percival, Anthony Warner and Mike Rayner were asked to consider in their debate i) the multiple understandings of the UPF concept, ii) the context and conditions of its successful or unsuccessful use, and iii) the relative goals and outcomes of i) and ii). The Letterbox will feature a total of nine letters. Read more about the origins and terms of the concept in TABLE’s UPF Explainer.