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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 0.5 (50%) to an individual. The Recommended Dietary Allowance (RDA) is the intake at which the risk of inadequacy is very small—only 0.02 to 0.03 (2% to 3%). The Adequate Intake (AI) does not bear a consistent relationship to the EAR or the RDA because it is set without being able to estimate the average requirement. It is assumed that the AI is at or above the RDA if one could be calculated. At intakes between the RDA and the Tolerable Upper Intake Level (UL), the risks of inadequacy and of excess are both close to 0. At intakes above the UL, the risk of adverse effects may increase.

in half of the healthy individuals in a life stage or gender group (see Figure 1-1). At this level of intake, the other half of a specified group would not have its nutritional needs met. The general method used to set the EAR is the same for all the B vitamins. The details, which are provided in Chapters 4 through 9, differ because of the different types of data available.

Method for Setting the RDA

The EAR is used in setting the RDA as follows. If the standard deviation (SD) of the EAR is available and the requirement for the


Three considerations prompted the choice of the term EAR: data are rarely adequate to determine the distribution of requirements, precedent has been set by other countries that have used EAR for reference values similarly derived (COMA, 1991), and the type of data evaluated makes the determination of a median impossible or inappropriate.

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