Estimated Average Requirement1

The Estimated Average Requirement (EAR) is the daily intake value that is estimated to meet the requirement, as defined by the specified indicator

*The definition of EAR implies a median as opposed to a mean, or average. The median and average would be the same if the distribution of requirements followed a symmetrical distribution and would diverge if a distribution were skewed.

INTRODUCTION TO DIETARY REFERENCE INTAKES 23

or criterion of adequacy, in half of the apparently healthy individuals in a life stage or gender group (see Figure 1-1). A normal or symmetrical distribution (median and mean are similar) is usually assumed for setting the EAR. At an intake level equal to the EAR, half of a specified group would not have their nutritional needs met. This is equivalent to saying that randomly chosen individuals from the population would have a 50:50 chance of having their requirement met at this intake level. This use follows the precedent set by others who have used the term "Estimated Average Requirement" for reference values similarly derived but meant to be applied to population intakes (COMA, 1991).

The EAR's usefulness as a predictor of an individual's requirement depends on the appropriateness of the choice of the nutritional status indicator or criterion and the type and amount of data available. The general method used to set the EAR is the same for all nutrients. The specific approaches, which are provided in Chapters 5 through 10, differ since each nutrient has its own indicator(s) of adequacy, and different amounts and types of data are available for each.

The EAR serves three major functions: as the basis for the Recommended Dietary Allowance (RDA), as the primary reference point for

Observed Level of Intake

FIGURE 1-1 Dietary Reference Intakes. This figure shows that the Estimated Average Requirement (EAR) is the intake at which the risk of inadequacy is estimated to be 0.5 (50 percent) to an individual. The Recommended Dietary Allowance (RDA) is the intake at which the risk of inadequacy would be very smallâ€”only 0.02 to 0.03 (2 to 3 percent). At intakes between the RDA and the Tolerable Upper Intake Level (UL), the risk of inadequacy and of excess are both estimated to be close to 0.0. At intakes above the UL, the potential risk of adverse effects may increase.

Observed Level of Intake tn o ^

o be

FIGURE 1-1 Dietary Reference Intakes. This figure shows that the Estimated Average Requirement (EAR) is the intake at which the risk of inadequacy is estimated to be 0.5 (50 percent) to an individual. The Recommended Dietary Allowance (RDA) is the intake at which the risk of inadequacy would be very smallâ€”only 0.02 to 0.03 (2 to 3 percent). At intakes between the RDA and the Tolerable Upper Intake Level (UL), the risk of inadequacy and of excess are both estimated to be close to 0.0. At intakes above the UL, the potential risk of adverse effects may increase.

24 DIETARY REFERENCE INTAKES

assessing the adequacy of estimated nutrient intakes of groups (IOM, 2000a), and, together with estimates of the variance of intake, in planning for the intake of groups (see Chapter 13).

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