Dietary Reference Intakes Applications in Dietary Assessment (2000) / Chapter Skim
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From page 1... ...
It is hoped that this use of stanciarci deviations of estimates of usual intake, nutrient inacloquacy, nutrient requirements, or any other parameter of interest will become the norm in nutritional analyses. Throughout this report the Subcommittee on Interpretation and Uses of Dietary Reference Intakes distinguishes between methods of evaluating the nutrient intakes of inclivicluals (Chapter 3)
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From page 2... ...
where specific data on safety and efficacy exist, reduction in the risk of chronic degenerative disease is included in the formulation of the recommendation rather than just the absence of signs of deficiency; (2) upper levels of intake are established where data exist regarding risk of adverse health effects; and (3)
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From page 3... ...
Like the former RDAs and RNIs, each DRI refers to the average ciaily nutrient intake of apparently healthy inclivicluals over time. The amount of intake may vary substantially from clay to clay without ill effect in most cases.
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From page 4... ...
Recommencleci intakes for the nutrients examined to ciate are presented at the end of this book. The introduction of multiple clietary reference intakes the EAR, RDA, AI, and UL requires that applications for each be carefully clevelopeci and clearly explained.
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From page 5... ...
USING DRIs TO ASSESS NUTRIENT INTAKES OF INDIVIDUALS It can be appropriate to compare intakes of inclivicluals with specific Dietary Reference Intakes (DRIs) , even though clietary intake ciata alone cannot be used to ascertain an incliviclual's nutritional status.
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From page 6... ...
However, a statistically baseci hypothesis testing procedure for comparing observed intake to the AI may be used. This is a simple z-test, which is constructeci using the stanciarci deviation of ciaily intake of the nutrient.
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From page 7... ...
Another basic question is, What proportion of the group has a usual intake of a nutrient so high that it places them at risk of adverse health effects? The assessment of intake of groups requires obtaining accurate data on intake, selecting the appropriate Dietary Reference Intakes (DRIs)
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From page 8... ...
Because there is a range of usual intakes in a group, the prevalence of inadequacy the average group risk is estimated as the weighted average of the risks at each possible intake level. Thus, the probability approach combines the two distributions: the requirement clistribution which provides the risk of inadequacy at each intake level, and the usual intake distribution which provides the intake levels for the group and the frequency of each.
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From page 9... ...
-1— Adjusting Intake Distributions Regardless of the method chosen to assess prevalence of inacleauate nutrient intakes in a group of inclivicluals, information is required about the distribution of usual intakes of the nutrient in the group. The distribution of those usual intakes in the group is referred to as the usual intake distribution or the adjusted intake distri~btion.
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From page 10... ...
Cut-Point Method for Assessing the Prevalence of Inacloquacy for Groups Established DRIsa Meets th Variance Intake is Greater Variance Nutrient EAR RDA AI UL Requirer Magnesium + + + Yes Phosphorus + + + Yes Selenium + + + Yes Thiamin + + Yes Riboflavin + + Yes Niacin + + + Yes Vitamin B6 + + + Yes Folate + + + Yes Vitamin B12 + + Yes Vitamin C + + + Yes Vitamin E + + + Yes Calcium + + Fluoride + + Biotin + Choline + + Vitamin D + + Pantothenic Acid + a RDA = Recommended Dietary Allowance; AI = Adequate Intake, cannot be used with the cut-point method; UL = Tolerable Upper Intake Level. b Due to little information on the variance of requirements, published DRIs have assumed a coefficient of variation (CV)
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From page 11... ...
, by definition, is an intake level that exceeds the requirements of 97 to 98 percent of all inclivicluals when requirements in the group have a normal clistribution. Thus, the RDA should not be used as a cut-point for assessing nutrient intakes of groups because a serious overestimation of the proportion of the group at risk of inacloquacy would result.
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From page 12... ...
of people, similar groups with mean intakes at or above the AI can be assumed to have a low prevalence of inadequate intakes for the defined criteria of nutritional status. For AIs that were either experimentally derived or developed from a combination of experimental and intake data, a similar assessment can be made, but with less confidence.
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From page 13... ...
Difficulties arise in attempts to quantify the risk Likelihood of adverse health effects in the general population from ciaily nutrient intakes exceeding the UL. The use of uncertainty factors to arrive at the UL reflects inaccuracies in reported nutrient intake ciata, uncertainties in the close-response ciata on adverse health effects, extrapolation of ciata from animal experiments, severity of the adverse effect, and variation in incliviclual susceptibility.
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From page 14... ...
Percentage with usual intake greater than the Tolerable Upper Intake Level (UL) Vitamins: niacin, B6, folate, choline, C, D, and E Elements: calcium, phosphorus, magnesium, fluoride, selenium Are there differences in nutrient intakes and differences in nutrient adequacy for different subgroups of the population?
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From page 15... ...
SUMMARY 15 Comments In acln, am, line, In acln, am, line, Mean nutrient intake should not be used to assess nutrient adequacy This measure is not appropriate for food energy, given the correlation between intake and requirement This measure is not appropriate for calcium, vitamin D, pantothenic acid, biotin, and choline, since they currently do not have an EAR There currently is no UL for thiamin, riboflavin, vitamin B12, pantothenic acid, and biotin, thus no conclusion can be drawn regarding potential risk of adverse effects. Conduct multiple regression analyses of nutrient intakes; compare regressionadjusted mean intake for the different subgroups Regression-adjusted mean nutrient intake should not be used to assess nutrient adequacy Statistical tests of significance can be used to determine if the differences across subgroups in percentages less than the EAR are statistically significant This measure is not appropriate for food energy, given the correlation between intake and requirement This measure is not appropriate for calcium, vitamin D, fluoride, pantothenic acid, biotin, and choline, since they currently do not have an EAR Statistical tests of significance can be used to determine if the differences across subgroups in percentages greater than the UL are statistically significant This measure is not appropriate for nutrients for which a UL has not been set (thiamin, riboflavin, vitamin B12, pantothenic acid, and biotin)
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From page 16... ...
Research to Improve Estimates of Nutrient Requirements Even for nutrients for which an Estimated Average Requirement (EAR) is available, the EARs and Recommencleci Dietary Allowances (RDAs)
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From page 17... ...
. Research should be undertaken to allow Tolerable Upper Intake Levels (ULs)
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From page 18... ...
In particular, further research is neecleci to apply the methods inclucleci in this report to estimate differences in the prevalence of inacloquacy between subgroups after controlling for other factors that affect nutrient intake. Ways to assess the performance of methods to estimate prevalence of inacloquacy should be investigated.
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