It has been revealed that nanoparticles, for example, titanium dioxide particles, can be detected in different foodstuffs. Small particles in the nano range possess altered physico-chemical properties compared to the respective bulk materials, which is the underlying cause for a suspected increased toxicity of such compounds. This chapter reflects applications of nanoparticles in the food sector, and focuses on toxicological and analytical issues with regard to the oral ingestion of food-derived nanomaterials. Oral uptake of nanoparticles can be divided into four main parts, as schematically delineated: interaction of nanoparticles with the food matrix, interaction of nanoparticles with intestinal fluids, intestinal uptake and bioavailability of nanoparticles, and toxicity and metabolism. Despite the availability of a large number of experimental studies on various aspects of the toxicology of many different nanoparticles, only a few risk assessments of nanomaterials are currently on hand.