There is increasing consensus that limiting consumption of meat and dairy products can contribute to lowering the environmental impact of diets. At the same time, the market for ultra-processed plant-based substitutes for meat and dairy (ie. ‘milk’, ‘cheese’ and ‘yoghurt’) is expanding to meet changing consumer demands. This shift far outpaces the revision of dietary guidelines and other nutritional guidance. Here, we identify significant knowledge gaps in the nutritional composition of meat and dairy substitutes as well as the extent to which they comprise modern diets in many countries in the WHO European Region. We also highlight that most dietary models are not based on real-life dietary patterns.