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for vitamin K, chromium, and manganese. Accordingly, individuals should use the AI as their goal for intake of these nutrients.


Using the Estimated Average Requirement and the Tolerable Upper Intake Level for Groups

For those nutrients with Estimated Average Requirements (EARs), the EAR may also be used as a basis for planning or making recommendations for the nutrient intakes of groups. The mean intake of a group should be high enough so that only a small percent of the group would have intakes below the EAR, thus indicating a low prevalence of dietary inadequacy. Traditionally, a prevalence of inadequacy below 2 to 3 percent has been used as a target. For nutrients with a statistically normal requirement distribution, this goal would be attained by planning for a group mean intake equal to the EAR plus 2 standard deviations (SD) of the intake distribution. Because the variability of intakes generally exceeds the variability of requirements, this target group mean intake will usually exceed the Recommended Dietary Allowance (RDA) (which equals the EAR plus 2 SDs of the requirement distribution). Prevalences of inadequacy more or less than 2 to 3 percent could also be considered, and mean intakes needed to attain these prevalences would be estimated by determining the number of SDs of intake that would result in the desired prevalence below the EAR. This is done by consulting tables that list areas of the standard normal distribution in relation to standard deviation scores (z scores).

When it is known that requirements for a nutrient are not normally distributed (for example, iron requirements) and one wants to ensure a low group prevalence of inadequacy, examination of the distributions of both intakes and requirements would be needed to determine a median intake at which the proportion of individuals below the EAR is low.

Using the EAR and Tolerable Upper Intake Level (UL) in planning intakes of groups involves a number of key decisions and the analysis of issues such as the following:

  • determination of the current nutrient intake distribution of the group of interest;

  • an evaluation of possible interventions to shift the current distribution, if necessary, so there is an acceptably low prevalence of intakes below the EAR, as well as an acceptably low prevalence of

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