Radionuclides of both natural and human made origin exist throughout the environment. These radionuclides can be transferred to plants and animals that are consumed by humans, thereby resulting in exposure to ionizing radiation and an internal radiation dose. This Safety Report provides information on the observed distributions of concentrations of natural radionuclides in various food products, on the use of 'total diet' and other studies to assess ingestion doses, and on radionuclide concentrations in natural mineral waters. Different dose assessment methodologies are presented and the advantages and disadvantages of each is discussed, along with approaches used for managing non-radioactive contaminants in food. This publication is jointly sponsored by the IAEA, the Food and Agriculture Organization of the United Nations and the World Health Organization. It is intended to support Member States in the assessment and management of radionuclides in food, and the alignment of national policies with Requirement 51 of IAEA Safety Standards Series No. GSR.