It is now generally agreed that the impact of the current nature, purpose and extent of food processing on human well-being, health and disease needs to be better understood and explained, in order to improve public health. The special issue of Public Health Nutrition devoted to the concept of ultra-processing of food, and the NOVA classification of which ultra-processed foods are one category, is a great step forward in this work. Coincidentally, a polemical ‘critical appraisal’ of ultra-processing was recently published in another journal. Debate and discussion are an essential part of the scientific endeavour. In this commentary, we correct inaccurate statements made about NOVA in the ‘appraisal,’ rebut points raised, and discuss the larger issue of scientific responsibility for publishing opposing views on controversial topics.