Public health advocates, government agencies, and commercial organizations increasingly use nutritional science to guide food choice and diet as a way of promoting health, preventing disease, or marketing products. We argue that in many instances such references to nutritional science can be characterized as nutritional scientism. We examine three manifestations of nutritional scientism: the simplification of complex science to increase the persuasiveness of dietary guidance, superficial and honorific references to science in order to justify cultural or ideological views about food (...) and health, and the presumption that nutrition is the primary value of food. This paper examines these forms of nutritional scientism in the context of biopolitics to address bioethical concerns related to the misuse of scientific evidence to make claims regarding the effect of diet on health. We argue that nutritional scientism has ethical implications for individual responsibility and freedom, concerning iatrogenic harm, and for well-being. (shrink)