This article explores the process of consolidating technical and historically contingent ideas about nourishment into seemingly straightforward terms such as vitamins and minerals. I study the adoption of scientific principles of abstraction and reduction as a strategy of nutrition education in three Guatemalan highland sites: an elementary school classroom, a rural clinic, and the obesity outpatient center of Guatemala’s third-largest public hospital. I show that despite its pretense of simplicity, the reductionism of nutritional black-boxing produces confusion. Moreover, dietary education not dependent upon simplified and fixed rules and standards may be more intelligible to people seeking nourishment in their lives.