The Development of DRIs 1994-2004 Lessons Learned and New Challenges: Workshop Summary (2008) / Chapter Skim
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4 General Guidance for Users of DRIs: Session 3
4 General Guidance for Users of DRIs: Session 3
Pages 99-122
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From page 99... ...
Susan Barr of the University of British Columbia on the issues and options for enhanced guidance in terms of planning and assessing the total diet. The final presentation was given by Dr.
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From page 100... ...
For guidance for planning for groups, the goal is identified as a low prevalence of inadequate intakes and consideration is given to definitions of acceptable prevalence of inadequate intakes. For assessing individuals, the guidance contains both qualitative and quan
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From page 101... ...
A set of questions about ease of use, practicality, and the need for simpler guidance Specific questions raised included what further work needs to be pursued to address the emerging world of statistical methods and their application to DRI guidance for users (particularly individuals) , and to what extent guidance is limited by lack of research on relevant methodologies.
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From page 102... ...
A second concern is harmonizing the DRIs, food labels, and MyPyramid advice with respect to chronic degenerative disease risk, especially when the focus is on counseling individuals. A third issue is the application of DRIs to those with treated diseases (e.g., those taking high blood pressure medication)
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From page 103... ...
However, estimating the distribution of total intake for a population is challenging, and current estimates of intake suggesting low or high intakes in North America may be questionable. Are these findings due to uncertainties in estimating the requirements, difficulties in obtaining accurate dietary intake information, the unintended consequences of applying the values incorrectly, or some other factor?
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From page 104... ...
A comment was made that application of the risk analysis paradigm to DRI development elevates the question of "uses." She suggested it will frame the set of issues important to sponsors and other stakeholders. Chronic Disease Considerations A participant asked whether planning for groups should return to focusing solely on non-chronic disease endpoints or whether it should continue to embrace the chronic disease question.
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From page 105... ...
For nutrients with an AI, neither probability nor prevalence can be FIGURE 4-2 Relationship of the AI to the EAR and RDA. NOTE: EAR = Estimated Average Requirement; RDA = Recommended Dietary Al 4-2.eps lowance; AI = Adequate Intake; UL = tolerable upper intake level.
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From page 106... ...
In practice, one option for estimating the probability of inadequacy is to assign approximate probabilities for a range of intake levels, based on an evaluation of the data used to set the AI. For example, the following probabilities shown in Table 4-1 might be used to assess persons over 50 years of age for calcium.
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From page 107... ...
Planning the Total Diet Presenter: Susan Barr Given that the goals of dietary planning for individuals using DRIs are to achieve intakes with a low risk of prevalence of inadequacy or excess, the suggested approach is fairly straightforward. Unless there are special
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From page 108... ...
The goal of a low prevalence of inadequacy is met if the proportion with usual intake below the EAR is minimal. If the baseline assessment has revealed a high prevalence of inadequacy, as estimated by the proportion below the EAR, planning would be done to shift the distribution upward to minimize the prevalence of inadequacy.
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From page 109... ...
. Although the approach used to develop Canada's Food Guide was based in part on the planning paradigm outlined in the planning report, it did not use a baseline usual intake distribution as the starting point.
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From page 110... ...
For example, before using this approach, a dietitian working in an assisted living facility would need to obtain 24-hour recalls from the residents, obtain repeat recalls on a subsample, analyze the food records to derive nutrient intakes, and then use sophisticated software to obtain the usual nutrient intake distributions. This would require access to software and the time and ability to the software.
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From page 111... ...
The confidence of adequacy approach for assessing individual diets seemed impractical, and the probability of adequacy approach would require knowledge of an individual's long-term nutrient intake, which is impossible to measure accurately. Other USDA efforts demonstrated that the guidance relevant to group planning was impractical because the shapes of the target nutrient intake distributions were difficult, if not impossible, to determine in an environment where intervention is intended to change the distribution of the nutrient intake.
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From page 112... ...
She suggested that dietitians do not just use food guides; some situations require nutrient reference values, such as when working with a population that has specific nutrient needs, so they must be able to adjust the nutrient intake recommendations. A second presenter agreed, but a discussant disagreed, saying that when she was a clinical dietitian counseling patients with a need for dietary modification (e.g., someone with renal disease)
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From page 113... ...
Skewed Distributions An audience member remarked on the conceptual advances and new tools offered by the Subcommittee on Interpretation and Uses of Dietary Reference Intakes. However, he highlighted a problem in the approach for predicting the shape of the intake distribution given an intervention that shifts the distribution -- the assumption that there will be a shift and no skew when the intent of the intervention is to skew the distribution results in a target value well above the RDA for many nutrients.
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From page 114... ...
4. Planning -- either for the usual intake with a low risk of inadequacy for an individual or for a distribution of usual intakes with an ac ceptably low prevalence of inadequacy for groups -- is fundamentally an extension of assessment.
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From page 115... ...
Thus, the goal in planning for groups is to achieve a distribution of usual intakes that has a low prevalence of nutrient inadequacy and a low proportion of intakes above the UL (IOM, 2003a)
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From page 116... ...
To develop food intake patterns, it calculated the nutrient profile for each food group or subgroup from the weighted average of the nutrient content of foods in the group, based on National Health and Nutrition Examination Survey (NHANES) food consumption data, then used an interactive process of modeling to determine the amounts from the food group composites required to meet nutrient and energy goals.
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From page 117... ...
is an oversimplification of what is needed to apply those core concepts appropriately, and its interface between individuals and populations must be evolved further. We need to separate the needs of the dietetic profession and others who engage in nutritional counseling from applications of the DRIs for public policy purposes (e.g., food guides, fortification, labeling)
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From page 118... ...
One is that modeling food patterns to achieve the AIs for selected nutrients had a strong impact on the final guidance in both countries. In addition, multiple nutrient goals were translated into food servings for five population groups, so there was a blunting effect for some of the distinctions.
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From page 119... ...
She endorsed a continuing dialogue between risk managers and risk assessors. Finally, she underscored her perspective that ensuring reality checks -- for instance, using examples of policies or programs to validate newly revised DRI values -- is needed and would be valuable in accomplishing risk communication.
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From page 120... ...
In terms of reaching out to practitioners and consumers, she stated that, in her own experience with the National Cholesterol Education Program, the "know your number" public education campaign was extremely successful. Perhaps a similar approach could be used for teaching about DRIs.
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From page 121... ...
A panel member posited that the safety factor need not be two SDs as currently used to develop the RDA, but could be one SD or a value anywhere between the EAR and the UL. Another panel member suggested that once a risk curve is established the determination can be made, and remarked that the key point is that the DRI process should specify risk curves.
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From page 122... ...
One participant noted that the focus was on an "apparently healthy" person to reduce confounders, such as those who need blood pressure medication. Another audience member said using healthy persons as study subjects simplifies research protocols.
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