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7 Specific Applications: Assessing Nutrient Intakes of Groups Using the Dietary Reference Intakes
Pages 127-144

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From page 127...
... . The applications consiclereci in this chapter are clesigneci to analyze information about the distribution of average daily intakes over time, referred to as usual nutrient intakes.
From page 128...
... Data available: 24-hour dietary recall data on a nationally representative sample of individuals, with two or more nonconsecutive days of data collected for at least a subsample of individuals. This discussion assumes that clietary recall ciata are available from a nationally representative sample of inclivicluals and have been used to estimate the usual nutrient intakes of the population from food and supplements.
From page 129...
... d Mean and median intake expressed as mg of oc-tocopherol. e Dietary intake data for selenium and vitamin E are from the Third National Health and Nutrition Examination Survey, 1988-1994.
From page 130...
... have not yet TABLE 7-2 Assessing Nutrient Intakes of Children 4 through 8 Years of Age What Proportion Has Inacloquate Intake? What Proportion Is Potentially at Risk of Excessive Intake?
From page 131...
... , assessment of acloquacy or potential risk of excess is not possible because these nutrients are not inclucleci in the national intake surveys. Common Mistakes in Evaluating Dietary Survey Data Some of the most common mistakes in evaluating clietary survey ciata arise from inappropriate conclusions drawn from comparing mean nutrient intakes with Recommencleci Dietary Allowances (RDAs)
From page 132...
... When mean usual nutrient intake of a group is less than the AI, however, nothing can be inferred about the probability of inadequacy (see Chapter 5~. In short, comparing mean intake either to the EAR or RDA or simply looking at mean intake levels should not be used to assess or imply relative nutrient adequacy.
From page 133...
... This sample includes both FSP participants and low-income nonparticipants. Descriptive Analyses of Nutrient Intakes Descriptive analyses would examine the mean, meclian, and other selected percentiles of the usual nutrient intake distribution.
From page 134...
... Similarly, to describe differences in the percentage potentially at risk from excessive nutrient intakes by subgroup, the percentages of FSP participants and low-income nonparticipants with usual nutrient intake greater than the UL (for nutrients with a UL) should be calculated and compared.
From page 135...
... In aciclition, just as the mean of observed nutrient intake is an unbiased estimate of mean usual nutrient intake, these regression-acljusteci differences in mean observed intakes are unbiased estimates of regression-acljusteci mean usual nutrient intake. Multiple regression analysis of nutrient intakes has been used to assess the relationship between program participation and nutrient intakes in FSP eligible inclivicluals (Gorclon et al., 1995; Oliveira and Gunclerson, 2000; Rose et al., 1998~.
From page 136...
... In the context of the FSP, the question is whether the proportion of inclivicluals with usual intakes below the EAR is different between FSP participants and nonparticipants, after controlling for other factors that affect nutrient intake. A proposed approach that enables users to cantrolfor Affects of potentially confounding variables through regression analysis is outlined below, using the FSP as an example.
From page 137...
... Step 3. Next, the effect of day-to-day variability is removed from the stanciarclizeci preclicteci intakes to produce an acljusteci usual intake distribution.
From page 138...
... The hypothetical example below (see also Table 7-3) illustrates the first four steps of this approach to assess whether FSP participation affects the mean intake of the group or the prevalence of inaciequacy of nutrient A
From page 139...
... Step 4. Finally, the proportion of inclivicluals with intakes below the EAR in each age-acljustecT usual intake distribution can be comparecT to determine whether FSP participation affects the prevalence of nutrient inadequacy.
From page 140...
... Therefore, some inclivicluals will be classified as below the EAR on the basis of observed nutrient intake although their usual nutrient intake would put them above the EAR, and vice versa. In general, because of underreporting, using observed nutrient intake ciata overstates the proportion of individuals with usual nutrient intakes less than the EAR.
From page 141...
... Answers to many of the descriptive questions such as those regarding the characteristics of the distribution of usual nutrient intake and differences in mean nutrient intakes between population subgroups do not clepenci on the DRIB. However, determining the proportion of a group with inacloquate usual nutrient intake is only possible for nutrients with Estimated Average Requirements (EARs)
From page 142...
... Mean nutrient intake for subgroups All nutrients under consideration Median usual nutrient intake for subgroups Percentiles of the usual nutrient intake distribution for subgroups Percentage with usual intake less than the EAR for subgroups Percentage with usual intake greater than UL for subgroups This me. intake This me.
From page 143...
... 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.


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