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cess with the intent of enhancing its transparency, especially in the face of uncertainties. Although this committee was mindful of the identified methodological gaps for enhancing the DRI process, it was not tasked with addressing them; in any case, virtually all of the relevant issues are complex and suggest a need to convene groups of individuals with specific expertise germane to the question at hand. Because this DRI report is an initial effort to set DRI development on the path of a risk assessment approach, its experience points to the importance of addressing several gap issues.

Specifically:

  • The identification of dose–response relationships for calcium and vitamin D relative to health outcomes was a major challenge. The gap issue1 (number 5-5 in Taylor, 2008) that is focused on methodologies for approximating dose–response relationships warrants attention, as it is likely that DRI efforts in the future will face the same challenges.

  • With the exception of the inclusion of osteoporosis within the bone health measures, the existing data precluded the use of a chronic disease such as cancer or heart disease as an indicator for DRI development. However, had it been possible, this DRI process would have benefited from guidelines specifying what, if any, differences may apply to using chronic disease endpoints versus other types of endpoints for DRI development (gap issue number 4-42 in Taylor, 2008).

  • In the committee’s judgment, sufficient new data were available to allow the development of EARs and RDAs, and it was no longer necessary to make use of AI estimates for calcium and vitamin D, except for infants. The AI is useful in that it allows the specification of some type of a reference value for use in public health settings—which is better than the absence of any value. However, it presents challenges in public health applications (gap issue num-

1

“New methodologies—many from other fields of study—are emerging and can be useful for examining and approximating dose–response relationships when available data are limited. These should be more closely examined and incorporated into the DRI process as appropriate” (Taylor, 2008).

2

“There is considerable interest—as well as more than 10 years of experience—surrounding the inclusion of chronic disease indicators within DRI development. A variety of perspectives were put forward. There is a need for focused discussions about how to include chronic disease indicators in the DRI process, including specific approaches for addressing their confounders, identification of appropriate biomarkers, and quantifying their effects” (Taylor, 2008).



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