reference values, are used by various stakeholders, ranging from those who set national nutrition policy to health practitioners in community settings. Such reference values specify, for normal, healthy persons, an average daily requirement for the nutrient, known as the Estimated Average Requirement (EAR). They also identify levels of intake that are likely to meet the needs of about 97.5 percent of the population (the Recommended Dietary Allowance, or RDA). Further, they include a Tolerable Upper Intake Level (UL) above which the potential for harm increases.

The two governments requested that the IOM conduct a study to assess current data and to update as appropriate the DRIs for vitamin D and calcium. The study was to include consideration of chronic disease indicators (e.g., reduction in risk of cancer or diabetes) and other (non-chronic disease) indicators/outcomes, and to assess the ability of each to serve as the basis for specifying adequate intake or excess intake. The final DRI indicators were to be selected based on the strength and quality of the evidence.

To carry out the request, the IOM established an ad hoc consensus committee of 14 scientists. The committee met eight times, held a public workshop and open sessions to gather information and receive input on the nature of the available data, maintained a website that accepted comments and data from stakeholders, conducted a review of existing data, and developed a report that included the specification of DRI values. Committee members had expertise in the areas of vitamin D and calcium or a related topic area, with specific expertise related to pregnancy and reproductive nutrition, pediatrics and infant nutrition, minority health and health disparities, cellular metabolism, toxicology and risk assessment, dermatology, immunology, endocrinology, skeletal health, oncology, cardiovascular health, epidemiology; nutrition monitoring, and biostatistics. Three members of the committee had served on other DRI committees.

This report marks the first DRI review since the completion of the 1997-2004 DRIs, which in contrast with their predecessors were based on a different approach to respond to expanded uses of the values and newer understandings of the role of nutrients. The DRIs now incorporate the statistical concept of a distribution, including the distributions of requirements and intakes. The major components of the DRIs are shown in Box S-1.

The first DRIs, contained in six volumes, are now used in both the United States and Canada. The governments of these two countries have