An ad hoc expert committee will undertake a study to assess current relevant data and update as appropriate the Dietary Reference Intakes (DRI) for vitamin D and calcium. The review will consider vitamin D in relation to the reduction in risk of cancer and other chronic diseases as well as the evidence related to vitamin D and bone health. It will also incorporate systematic evidence-based reviews of the literature and an assessment of potential indicators of adequacy and of excess intake. Indicators for adequacy and excess will be selected based on the strength and quality of the evidence and the demonstrated public health significance, taking into consideration sources of uncertainty in the evidence. Specifically, in carrying out its work, the committee will:(1) Review evidence on indicators of adequacy and on indicators of adverse effects from excess intake relevant to the general North American population, including for groups whose needs for or sensitivity to the nutrient may be affected by particular conditions which are widespread in the population such as obesity or age-related chronic diseases. Special groups under medical care whose needs or sensitivities are affected by rare genetic disorders or diseases and their treatments will be excluded. (2) Consider systematic evidenced-based reviews including those made available by the sponsors as well as others and carefully document the approach used by the committee to carry out any of its own literature reviews. (3) Regarding selection of indicators upon which to base DRI values for adequate intake, give priority to selecting indicators of adequacy for the various age, gender, and lifestage groups that will allow for the determination of an Estimated Average Requirement. (4) Regarding selection of indicators upon which to base DRI values for upper levels of intake, give priority to examining whether a critical adverse effect can be selected that will allow for the determination of a so-called benchmark intake. (5) Update DRI values, as appropriate, Using a risk assessment approach that includes (i) identification of indicators of adequacy and hazard, (ii) selection of the indicators of adequacy and the critical adverse effect, (iii) intake-response assessment, (iv) dietary intake assessment, and (v) risk characterization. (6) Identify research gaps to address the uncertainties identified in the process of deriving the reference values and evaluating their public health implications.The project is sponsored by the U.S. Department of Health and Human Services (National Institutes of Health, Food and Drug Administration, Office of Disease Prevention and Health Promotion), U.S. Department of Agriculture (Center for Nutrition Policy and Promotion, Agricultural Research Service), U.S. Department of Defense (Telemedicine and Advanced Technology Research Center), and Health Canada. The approximate start date for the project is September 29, 2008.A report will be issued at the end of the project in approximately 24 months.