The objective of this paper was to evaluate the students’ level of knowledge of the presence of foreign compounds in food. Moreover, the respondents were segmented into groups based on how they perceived threads. The subject of the research study constituted students of the Warmia and Masuria University in Olsztyn, Faculty of Food Sciences and Faculty of Veterinary Medicine. The knowledge of threads to food was focused on two food components: substances of chemical origin and substances of biological origin. A definitely more numerous was the segment representing students who were much more aware of the presence of substances of chemical than of biological origin in food.