Nutritional Risk Assessment Perspectives, Methods, and Data Challenges: Workshop Summary (2007) / Chapter Skim
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3 An Examination of Current and Potential Nutritional Risk Assessment Methods
3 An Examination of Current and Potential Nutritional Risk Assessment Methods
Pages 25-48
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From page 25... ...
Robert Russell, an expert in human metabolism of retinoids and carotenoids, addressed how different groups have used risk assessment methods to establish upper intake levels for nutrients and identifies data gaps that impede the assessment of risk related to excessive nutrient intakes. Suzanne Murphy, an expert in dietary assessment methodology, covered potential connections between the establishment of nutrient requirements and Tolerable Upper Intake Levels (ULs)
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From page 26... ...
Robert Russell provided a brief review of the derivation of a UL and the sources of uncertainty and then focused on how three different expert groups arrived at different conclusions when they determined the upper levels1 for vitamin A, beta carotene, vitamin B6, and zinc. He concluded his presentation with a list of the kinds of data needed to improve the determination of upper levels for these four nutrients.
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From page 27... ...
Scientific Committee on Food for the European Union. He focused on the establishment of upper levels for vitamin A (EVM, 2003; IOM, 2001; SCF, 2002)
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From page 28... ...
Neither IOM nor the EU Scientific Committee on Food set an upper level for beta-carotene. The reasons that both expert groups gave for not setting an upper level were similar (IOM, 2000b; EC, 2000)
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From page 29... ...
. The resulting upper levels were as follows: • IOM = 40 mg/day • United Kingdom = 25 mg/day • European Union = 25 mg/day Despite the use of very different methods in the United Kingdom and the European Union, the result was the establishment of identical upper levels.
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From page 30... ...
POTENTIAL CONNECTIONS BETWEEN ESTABLISHING NUTRIENT REQUIREMENTS AND TOLERABLE UPPER INTAKE LEVELS Presenter: Suzanne P Murphy Although adverse health effects are associated with both nutrient inadequacy and nutrient excess, expert groups use very different approaches to set nutrient requirements and upper levels.
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From page 31... ...
Indeed, Murphy argued that there could be a very low (nearly zero) risk of excessive intake in the homeostasis area of intake (see "Applying Risk Assessment Methods to Nutritional Risk Assessment" in Chapter 2)
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From page 32... ...
It would be desirable to be able to provide a quantification of the risk of an adverse effect rather than being limited to a statement that a certain percentage of the population has intakes above the UL. Are Some Risk Assessment Methods Applicable to Both Nutrient Requirements and Upper Levels?
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From page 33... ...
Concluding Remarks To identify commonalities and to align the methods better, Murphy recommended a review of the models that have been used to set nutrient requirements and ULs. She suggested that a more consistent approach to the various methods for the establishment of the DRIs could increase
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From page 34... ...
The participants examined the long-standing scientific principles of risk assessment that had been established for nonnutrient substances, and taking into account the principles of nutrition science, they worked to adapt them for nutrient substances. The resulting publication, A Model for Establishing Upper Levels of Intake for Nutrients and Related Substances: Report of a Joint FAO/WHO Technical Workshop on Nutrient Risk Assessment (FAO/WHO, 2005)
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From page 35... ...
Despite the appearance of Figure 3-2, the curves are unlikely to be symmetrical. Nutritional Risk Assessment Needs a Multidisciplinary Perspective During the FAO/WHO technical workshop, it was noted that a range of expertise is essential to adapt risk assessment approaches to nutrient substances and to carry out the assessments appropriately.
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From page 36... ...
An expert's disciplinary background is likely to influence the way in which that expert views and discusses uncertainty, including variability. Thus, nutritional risk assessment needs to include and to give mutual respect and equal weight to a wide range of experts: risk assessors, nutritionists, clinicians, physiologists, pathologists, epidemiologists, biochemists, food scientists, statisticians, and, perhaps, others.
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From page 37... ...
Intake Assessments Uncertainties associated with intake assessments often play a minor role in classical risk assessment. To be conservative on the side of safety, classical risk assessment may use large correction factors (called default options in Chapter 2)
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From page 38... ...
Instead, nutritional risk assessors must usually rely on secondary data obtained from studies of the benefits or mechanisms of action of nutrients. The guidance and criteria needed for decision making in the face of limited data call for the use of a multidisciplinary approach to nutritional risk assessment.
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From page 39... ...
Overview of Current Assessment Methods Some background information is helpful in understanding the extent to which classical risk assessment paradigms are useful in nutritional and functional food evaluations, whether they are holding back progress (and if so, how) , and unique aspects of safety assessments for nutrients.
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From page 40... ...
Risk assessments are less conservative, and information about the benefits and the risks is communicated to consumers. Safety Assessments Typically, safety assessments involve a simple comparison of an Acceptable Daily Intake (ADI)
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From page 41... ...
In particular, they • do not address the degree of variability in dietary intakes, • do not balance the severity of the adverse effects of selected in takes of a nutrient against the biological benefits of the nutrient, and • do not help describe the benefits and adverse effects that operate over very different time scales or by different biochemical mechanisms. Beneficial Utility Index The Beneficial Utility Index (BUI)
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From page 42... ...
, the severity of the toxic effects from the nutrient, the amount of uncertainty in the data, the biological variability in the population, and the variability in intake of the nutrient. FIGURE 3-3 Beneficial Utility Index.
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From page 43... ...
FIGURE 3-4 Impact of the BUI: Incorporating the uncertainty into the effi cacy and toxicity curves: example of the impact on the BUI by using hypo thetical nutrient GYX. U = utility; LL = lower limit; UL = upper limit.
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From page 44... ...
Risk-Based Advice Risk-based advice may be based on a formal risk assessment or on a safety assessment. Formal Risk Assessment Formal risk assessments may be conducted on the basis of two rationales: a practical rationale or a public policy rationale.
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From page 45... ...
Public policy rationale In matters of public health, there is a desire for the use of a rationale that calls for decisions to meet a standard of reasonableness. What one is accountable for may determine whether a risk assessment or a safety assessment is the preferred approach.
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From page 46... ...
Risk assessment provides a structure for providing these elements in a defensible way. Risk assessment also opens a large multidisciplinary tool kit for analysis, clear and succinct presentation of the knowledge, and decision making.
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From page 47... ...
Challenges for Nutritional Risk Assessment Classical risk assessors address the risks associated with single very small events and thus tend to think in terms of precision and to have models with high specificities. In contrast, those who assess the risks of nutrient substances must take into account the fact that the substance may affect multiple systems or organs.
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From page 48... ...
48 NUTRITIONAL RISK ASSESSMENT OPEN DISCUSSION Moderator: Molly Kretsch The key points that were raised in the open discussion have been incorporated into Chapter 6, Perspectives on Challenges and Solutions: Summary Remarks and Suggested Next Steps.
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