The new DRIs are more complex and differ considerably from the earlier RDAs and RNIs. They also represent a much broader conceptual approach from the earlier RDAs and RNIs, and they employ very specific modeling and statistical designs:
Where specific data on safety and a role in health exist, reduction in the risk of chronic degenerative disease or developmental abnormality, rather than just the absence of signs of deficiency, is included in the formulation of recommendations. The concepts of probability and risk underpin the determination of the EAR, RDA, and UL, and inform their application in assessment and planning. (IOM, 2003, p. 17)
An important change in DRIs from a public health perspective is the inclusion of the UL. As intake increases above the UL, there is the potential for an increased risk of adverse effects. This is the first time a reference value that deals with toxicity has been ascribed to nutrients. The DRI Standing Committee cited the potential for the overconsumption of specific nutrients due to high levels of discretionary fortification (sometimes over 100 percent of the Daily Value), coupled with the widespread use of dietary supplements, as rationales for developing the UL (IOM, 1997). In the DRIs, the ULs for children for some nutrients overlap with new recommended intakes for adults (for children ages 1–3 years: vitamin A, zinc, manganese, folate, and niacin; for children ages 4–8 years: vitamin A, niacin, and folate). The committee was charged with considering the best way to use the UL in developing reference values for nutrition labeling given this overlap and the resulting implications for discretionary food fortification. The challenge of these charges in the context of appropriate values for nutrition labeling is addressed in the next two chapters.