Advances in pharmacokinetics and pharmacodynamics require new competencies related to pharmaceutical prescribing. First, both physicians and pharmacists need to recognize the potential negative impact of nutrients and dietary supplements on the absorption, metabolism, and utilization of prescription drugs. Second, physicians, even more than pharmacists, need to recognize the potential negative effects of pharmaceuticals on the absorption, metabolism, and utilization of nutrients. This article discusses common drug-nutrient interactions and presents a case that illustrates how unrecognized nutrient disruption may negatively affect a patient's health and potentially result in unnecessary prescribing of medications. In presenting the case, we also provide a conceptual framework for assessing and treating this patient and a summary of current knowledge regarding drug-nutrient interactions.