Nutrition is well-recognized as a necessary component of educational programs for physicians. This is to be valued in that of all factors affecting health in the United States, none is more important than nutrition. This can be argued from various perspectives, including health promotion, disease prevention, and therapeutic management. In all cases, serious consideration of nutrition related issues in the practice is seen to be one means to achieve cost-effective medical care. These modules were developed to provide more practical knowledge for health care providers, and in particular primary care physicians. This module is designed as a resource which will assist the primary care physician in understanding the functions of vitamins and trace minerals. Manifestations of deficiency and excess are presented as are concepts relevant to the evaluation of patient status. Information is provided to assist physicians in counseling their patients regarding the multitude of claims made concerning dietary supplements. Included are learning goals and objectives. A self-check of achievement with regard to goals references, and lists of resources for patients and physicians. Appendices include tables of recommended dietary allowances, safe and adequate dietary intake of selected vitamins and minerals, clinical nutrition examination findings, laboratory test interpretations, plasma and urine nutrient levels, healthy foods, and a food composition table for dietary analysis. (CW)