Dietary Reference Intakes
Dietary Reference Intakes and Chronic Disease Endpoints Workshop
The Dietary Reference Intakes (DRI) Committees of the U.S. and Canadian governments held a workshop entitled “Options for Consideration of Chronic Disease Endpoints for Dietary Reference Intakes” on March 10 – 11, 2015. The objective of the workshop was to critically evaluate key scientific issues involved in using chronic disease endpoints for setting dietary reference intakes and, in this context, to provide information for future decisions as to whether and/or how chronic disease endpoints can be incorporated into the setting of DRI values.
View the workshop webcasts:
The current DRI approaches for selecting indicators of adequacy and toxicity and for estimating dose-response relationships between nutrient intakes and selected outcomes derive from several Food and Nutrition Board committee reports published by the Institute of Medicine (IOM) in 19941 and 19982. These committees recommended that DRIs for adequacy be expressed as Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs, representing 97.5% of population requirements). They also recommended that reference values for Tolerable Upper Intake Levels (ULs) be included in future DRI evaluations. Additionally, the 1994 IOM committee concluded that future RDA processes (now called DRIs) should include the concept of chronic disease risk reduction in addition to the classical nutrient deficiency endpoints. The approaches recommended by the 1994 and 1998 committees were applied, with a few additions (e.g., Adequate Intakes, Acceptable Macronutrient Distribution Ranges), for all seven of the DRI reviews published from 1997 to 2011. View these reports on the National Agricultural Library website.
It has become apparent that a number of unanticipated challenges were encountered when chronic disease endpoints were considered as indicators for setting DRI reference values. Many of these challenges were discussed in a 2007 “lessons learned”` workshop conducted by the IOM after the first six DRI reports were published3. Other scientific publications have also discussed the challenges, but approaches for addressing the identified challenges have not yet been adequately explored.
Recently, the DRI Committees of the U.S. and Canadian governments called for nominations for nutrients to be considered for future DRI reviews. Many of the nominated nutrients cited new data on chronic disease relationships as the justification for new DRI reviews, including three of the four nutrients selected by the DRI Committees for further consideration based on the availability of sufficient new and relevant evidence. Given the clear need for more in-depth evaluation of the challenges involved in incorporating chronic disease endpoints into DRI processes prior to initiating a new DRI review, the two government committees sponsored the March 10 – 11, 2015 workshop to address whether, and how, chronic disease outcomes can be incorporated into the process of setting DRI values.
1 Food and Nutrition Board, Institute of Medicine. 1994. How Should the Recommended Dietary Allowances Be Revised? National Academy Press, Washington, D.C.
2 Dietary Reference Intakes: A Risk Assessment Model for Establishing Upper Intake Levels for Nutrients. National Academy Press, Washington, D.C.
3 The Development of DRIs 1994-2004: Lessons Learned and New Challenges, Workshop Summary, November 30, 2007. Available from: http://www.iom.edu/Reports/2007/The-Development-of-DRIs-1994-2004-Lessons-Learned-and-New-Challenges-Workshop-Summary.aspx.
Nutrient Assessment for DRI Review
The US and Canadian governments have each established Federal DRI Committees that work collaboratively to identify DRI needs and to coordinate government sponsorship of DRI reviews and related activities. The DRIs—which reflect nutrient reference values essential to national nutrition policies and to professionals working in the field of nutrition and health—have been developed under the auspices of the Institute of Medicine with funding from the US and Canadian governments.
Dietary Reference Intake Nomination Process
The US and Canadian governments accepted nutrient nominations from April 29, 2013 to July 31, 2013. Nominations consisted of:
- Cover letters: Rationale and description of why the nominator believes that a review is warranted and how it would address a current public health concern.
- Literature Search: Description of the search strategy and list of new, relevant literature since the last nutrient DRI review.
Prioritization of DRI Reviews
The two government DRI Committees are jointly responsible for prioritizing nutrients for government-funded reviews and subsequent commissioning of an expert review to establish reference values. The committees prioritize new reviews based on evidence of significant, new, and relevant data since the last DRI review, as well as relevance to current public health concerns. They also work to determine that any methodological issues that could impede a new review, especially those identified previously, have been resolved. The availability of funds is also a factor in the initiation of DRI reviews.
Significant, new, and relevant data are characterized as follows:
- “Significant” data refers to the overall scientific quality of the evidence, number of new studies, consistency of the results and whether the new study results appear to expand the DRI-related information available to the original DRI expert panel. Of particular interest are randomized controlled trials of high scientific quality.
- “New” refers to research that was unlikely to have been available to the previous DRI expert panel.
- “Relevant” means that the study results are generalizable to the North American population and to DRI development.
Decision to Seek Input Regarding Nutrients of Interest
As the DRI Committees consider future reviews of the current DRIs, they are cognizant of the broad range of uses of the DRIs. Because of this, the DRI Committees recognize the importance of input from individuals and organizations both within and outside the government in making future DRI prioritization decisions. Therefore, the DRI Committees have established a nomination process to help in planning for new DRI reviews of nutrients and related substances reviewed in previous DRI reports.
Status of the DRI Nomination Process, August 15, 2014
In total 26 nominations were received for the following 16 nutrients:
- Arachidonic acid
- Docosahexaenoic acid (DHA)
- Eicosapentaenoic acid (EPA)
- Fiber (specifically, viscous fibers and fermentable fibers)
- Saturated fat
- Stearic acid
- Vitamin B6
- Vitamin E
All received nominations were screened for completeness to ensure all requirements were met. To avoid any bias in the screening and assessment process, submitter’s names were removed from all nomination documents. Each country’s DRI committee was asked to select their top three priority nutrients based on public health and/or policy importance. Combining the priorities of both countries, four nutrient areas were selected: omega-3 fatty acids, sodium, magnesium, and vitamin E.
Nutrient assessment working groups were formed comprising staff from both the U.S. and Canada. Each group was tasked with evaluating whether there was new science published since the last DRI review that would be relevant to the development of a new DRI review. Government agencies jointly prioritized the nutrients and decided that a workshop on the potential use of chronic disease endpoints in setting DRI values was needed before a nutrient DRI review would be undertaken.
The federal governments conducted a workshop in March 2015 to address whether, and how, chronic disease outcomes can be incorporated into setting DRI values. It is expected that this will lay the foundation for an expert report on this aspect of public health.
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