Dietary Reference Intakes Research Synthesis Workshop Summary (2007) / Chapter Skim
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10 Tolerable Upper Intake Levels
10 Tolerable Upper Intake Levels
Pages 113-126
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and WHO to describe a model for nutrient risk assessment. TOLERABLE UPPER INTAKE LEVELS Sanford A
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Figure 10-1 illustrates this point. In the DRI reports, the definition for UL is, "the highest level of daily nutrient intake that is likely to pose no risk of adverse health effects for almost all individuals in the general population." Dr.
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Instead, the DRI process has used the safe level model, while calling it a risk assessment model.
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A reasonable public health goal is to recommend the consumption of the nutrient at a level that minimizes the total expected loss of health -- the dotted line in Figure 10-2. Recommending a "safe level" (defined here as 0 expected loss of health)
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The classic example of this type of risk is a deficiency disease related to a nutrient, such as osteopo rosis and vitamin D The dotted line represents the total expected loss of health (sum of the expected losses from Risk 1 and Risk 2)
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UPPER LEVEL RESEARCH RECOMMENDATIONS WITHIN THE CONTEXT OF AN INTERNATIONAL MODEL FOR NUTRIENT RISK ASSESSMENT Presenter: Christine Taylor This presentation addressed UL research recommendations from the perspective of work conducted recently by the WHO in cooperation with the FAO. The work resulted in the release of report of a Joint FAO/WHO Scientific Workshop on Nutrient Risk Assessment (FAO/WHO, 2005)
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Those principles are modified, however, for special considerations related to nutrient substances, such as the following: • One-of-a-kind homeostatic mechanisms • Metabolic differences for age, sex, and life stage • Dual risk curves -- deficiency and excess • Need to deal with inadequate data sets The nutrient risk assessment model has at least three underlying themes: 1. Outcomes are based on available evidence, even if it is limited, not on "developed data sets." 2.
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Dealing with Existing Data Sets The workshop participants found the existing reports on nutrient risk assessment lacking in transparency regarding the scientific judgments made and reasons for the decisions made. The participants regarded the practice of scientific judgments to be a researchable area and thus the report calls for guidelines for approaches to scientific judgment (establishing upper levels is a researchable issue)
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Dealing with the Need for Human Intervention Data Although it was emphasized that limited human data sets should not remain the norm, the ability to fulfill research needs faces certain ethical issues as well as the costs and difficulties associated with human trials and intervention studies. Because of these challenges, there is a need to do the following: • Develop innovative methodologies including animal models, in vitro techniques, and computer simulations • Explore more fully at least three areas: 1.
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• Factors affecting uptake and absorption (456-H) Improving and Harmonizing Dietary Intake Assessments In the comparison of the three major risk assessments, a major source of inconsistencies was in the approach to dietary intake assessment.
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Is the risk assessment model equally applicable to essential and nonessential nutrient substances? • Some nutrient substances have no threshold response.
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According to the FAO/WHO nutrient risk assessment report, when there is an array of truly adverse health effects, one examines the end points from a public health protection filter and selects the effect seen at the lowest level of intake. The focus is not necessarily on the effect that is most severe or even the effect for which the weight of the evidence is strongest.
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The FAO/WHO Working Group was aware of the need to ensure that risk assessment outcomes were usable by risk managers. Participants recognized that failing to set an upper level in the face of insufficient data was problematic because risk managers often must make regulatory decisions that provide some measure of safety.
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