Total Diet Studies in the United States (U.S.) are conducted yearly by the U.S. Food and Drug Administration (FDA) to monitor the safety and quality of the U.S. food supply and to monitor the dietary intakes of population subgroups with respect to pesticide residues, industrial chemicals, radionuclides, heavy metals, and nutrient minerals. The program has been ongoing since 1961 and has evolved over the years based on resources available to FDA and concerns about the food supply and dietary intake. Currently, the programs are based on a core food concept in which 265 core foods of the U.S. food supply are collected four times per year and analyzed individually for the analytes of interest. The core food approach has specific advantages and disadvantages with regard to monitoring the safety and nutritional adequacy of a national food supply.