do occur with excessive intakes of potassium, sulfate, and water, as discussed in the nutrient chapter.

The assessment of nutrient adequacy for groups of people requires unbiased, quantitative information on the intake of the nutrient of interest by individuals in the group. Care must be taken to ensure the quality of the information upon which assessments are made so that they are not underestimates or overestimates of nutrient intake. Estimates of total nutrient intake, including amounts from supplements, should be obtained. It is also important to use appropriate food composition tables with accurate nutrient values for the foods as consumed.

To assess the intake of a group, several steps must be taken. First, the intake distribution must be adjusted to remove the effect of day-to-day variation of individual intake. The statistical adjustments are based on assumptions about the day-to-day variation derived from repeat measurements of a representative subset of the group under study (Nusser et al., 1996). The resulting adjusted intake distribution narrows, giving a more precise estimate of the proportion of the group with usual intakes below the estimated requirements (Figure 8-2). An explanation of this adjustment procedure has been presented in previous reports (IOM, 2000, 2003).

For nutrients with an EAR, the prevalence of inadequacy in the population group for the nutrient evaluated is approximately the percent of the population evaluated whose intakes fall below the EAR, provided certain critical assumptions are met (IOM, 2000). Thus it is preferable to be able to establish an EAR where requirement data are available. However, for the nutrients in this report, inadequate or insufficient data on requirements of these nutrients for the indicators of adequacy prohibited establishing EARs.

In this report, Adequate Intakes (AIs) are assigned for total water, potassium, and sodium for all life stage and gender groups. Groups with median intakes equal to or above the AI for total water, potassium, and sodium can be assumed to have a low prevalence of inadequacy as determined by the criteria used to evaluate adequacy (provided that intake variability does not exceed that of the healthy group used to establish the AI). This would be particularly true for water, as the AI was set as a median intake of a presumably healthy