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From page 19...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 19 APPLYING THE DIETARY REFERENCE INTAKES T he goal of dietary assessment is to determine if the nutrient intakes of an individual or group are meeting the needs of that individual or group. The goal of dietary planning is to recommend a diet that provides adequate, but not excessive, levels of nutrients.
From page 20...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 20 BOX 1 Definitions Associated with Assessing and Planning Nutrient Intakes Distribution of requirements: The distribution that reflects the individual to-individual variability in requirements. Variability exists because not all individuals in a group have the same requirements for a nutrient, even if the individuals belong to the same life stage and gender group.
From page 21...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 21 STATISTICAL FOUNDATION The DRIs and their applications are based on the statistical concept of a distribution. A distribution is an arrangement of data values showing their frequency of occurrence throughout the range of the various possible values.
From page 22...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 22 EAR 50% 50% 34% 34% RDA 13.5% 13.5% 2.5% 2.5% –3 SD –2 SD –1 SD 0 +1 SD +2 SD +3 SD Mean Median Percentile Rank 2.5 16 50 84 97.5 FIGURE 2 Normal requirement distribution of hypothetical nutrient showing percentile rank and placement of EAR and RDA on the distribution. One important use of the normal distribution is the way it can be used to con vert scores into percentile ranks, or probabilities.
From page 23...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 23 TABLE 1 Probability of Adequacy for Selected Z- Scores z-score Probability of Adequacy 2.00 0.98 1.65 0.95 1.50 0.93 1.25 0.90 1.00 0.85 0.86 0.80 0.68 0.75 0.50 0.70 0.00 0.50 –0.50 0.30 –0.85 0.20 –1.00 0.15 Applying the DRIs Makes Use of Two Distributions In applying the DRIs, two distributions are used simultaneously. The first is the distribution of requirements.
From page 24...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 24 When working with individuals, this variability is taken into account in the formulas used for assessment. When working with groups, statistical proce dures should be used to adjust the distribution of observed intakes by partially removing the day-to-day variability in individual intakes so that the adjusted distribution more closely reflects a usual intake distribution.
From page 25...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 25 Panel A AI Median intake Theoretical requirement distribution Distribution of usual intakes 0 1 2 3 4 5 6 7 Nutrient X (mg/d) AI Median intake Panel B Theoretical Distribution of requirement usual intakes distribution 0 1 2 3 4 5 6 7 Nutrient X (mg/d)
From page 26...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 26 in this chapter. Thus, assessment of dietary intakes should be used as only one part of a nutritional assessment, and the results must be kept in context.
From page 27...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 27 Therefore, the fall-back assumption is that the individual's requirement will be close to the average, in which case the EAR is the best estimate for an individual's unobservable requirement. It is important to note that there is variation in nutrient requirements between different individuals, and this needs to be taken into account when conducting an assessment.
From page 28...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 28 For nutrients with a UL: • Observed mean intake less than the UL is likely to be safe. • Observed mean intake equal to or greater than the UL may indicate a potential risk of adverse effects.
From page 29...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 29 The use of this equation requires the following information: • Mean observed intake: The mean nutrient intake of an individual is the best estimate of an individual's usual intake. • EAR: The EAR is the best estimate of an individual's requirement for a nutrient.
From page 30...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 30 BOX 2 Example: Using the Quantitative Approach for Individual Assessment for a Nutrient with an EAR Suppose a 40-year-old woman had a magnesium intake of 320 mg/day, based on 3 days of dietary records. The question is whether this observed mean intake of 320 mg/ day indicates that her usual magnesium intake is adequate.
From page 31...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 31 • Within-person SD of intake: The variation in day-to-day nutrient intake within the individual is an indicator of how much observed intake may deviate from usual intake (see Appendix I) • The number of days of intake records or recalls Solving for the equation gives the confidence with which one can conclude that usual intake is greater than the AI.
From page 32...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 32 Solving for the equation yields the confidence with which one can conclude that usual intake is less than the UL. Intakes less than the UL are likely to be safe; and intakes equal to or greater than the UL may indicate a potential risk of adverse effects.
From page 33...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 33 Quantitative vs. Qualitative Approaches to Dietary Assessment of Individuals Box 2 provides a brief example of a quantitative assessment for a nutrient (magnesium)
From page 34...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 34 Individual Are there "special considerations"? No Yes e.g., smoker (vitamin C)
From page 35...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 35 seling an individual, a practitioner must consider whether there is any recognizable benefit to increasing an individual's current intake level. The likelihood of the benefit must be weighed against the cost, monetary and otherwise, likely to be incurred by increasing the intake level.
From page 36...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 36 For most nutrients, intakes at or above the UL would rarely be attained from unfortified food alone. PLANNING NUTRIENT INTAKES FOR AN INDIVIDUAL USING THE AMDR In addition to meeting the RDA or AI, and remaining below the UL, an individual's intake of macronutrients should be planned so that carbohydrate, fat, and pro tein are within their respective acceptable ranges.
From page 37...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 37 priate body weight. Additionally, self-reported energy intake should not be relied on to determine a person's energy needs, since underreporting of intakes is a serious and pervasive problem.
From page 38...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 38 TABLE 2 Common Reasons for Adjustment in DRI Values When Planning Dietary Intake Consideration Nutrient Adjustment Recommended Folic acid for women of It is recommended that all women consumption from childbearing age capable of becoming pregnant take 400 mg folic acid every day from fortified synthetic sources foods, supplements, or both, in addition to the amount of food folate found in a healthful diet. Vitamin B12 for those It is advisable for those older than 50 older than 50 years of years to meet the RDA mainly by age consuming foods fortified with vitamin B12 or a supplement containing vitamin B12.
From page 39...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 39 KEY POINTS FOR WORKING WITH INDIVIDUALS ASSESSING NUTRIENT INTAKES The goal of assessing an individual's nutrient intake is to 3 determine if that intake is meeting his or her nutrient requirements. Assessment requires using the individual's observed or 3 reported mean intake as an estimate of usual intake and using the EAR of the appropriate life stage and gender group as an estimate of the individual's requirement.
From page 40...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 40 For nutrients with an EAR and an RDA, the probability of 3 inadequacy is 50 percent at the EAR and 2–3 percent at the RDA. Thus, the RDA is often used as a guide for planning for individuals.
From page 41...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 41 Percentage of Individuals Adjusted (usual intake) distribution Unadjusted (1-day intake)
From page 42...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 42 • For nutrients with an EAR, the EAR can be used to estimate the preva lence of inadequate intakes using the probability approach or a shortcut derived from the probability approach called the EAR cut-point method. • The RDA is inappropriate for assessing nutrient intakes of groups be cause the RDA is the intake level that exceeds the requirements of a large proportion of individuals in a group.
From page 43...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 43 USING THE EAR CUT-POINT METHOD TO ASSESS PREVALENCE OF NUTRIENT INADEQUACY IN A GROUP The EAR cut-point method is a shortcut derived from the probability approach. When certain conditions are satisfied, the proportion of the group with intakes below the EAR will be similar to the proportion that does not meet their requirement.
From page 44...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 44 requirements will have inadequate intakes (their usual intake, although above the EAR, is below their own requirement)
From page 45...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 45 BOX 3 Assessing Group Nutrient Intakes -- The RDA Is Inappropriate The EAR for vitamin B6 for women aged 51–70 years is 1.3 mg /day and the RDA is 1.5 mg/day. Shown below is a distribution of dietary vitamin B6 intakes for a group of women 51–70 years of age.
From page 46...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 46 point method in that the proportion of the group with intakes above the UL is determined. Because ULs for nutrients are based on different sources of intake, the ap propriate usual intake distribution must be used in the assessment.
From page 47...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 47 excessive. This can be challenging because the amount and selection of foods that group individuals eat will vary, even if the same meal is offered.
From page 48...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 48 What Is a Target Usual Nutrient Intake Distribution? Suppose a practitioner is interested in planning a group diet with a high prob ability of nutrient adequacy (e.g., such that the prevalence of inadequacy in the group is no more than 2–3 percent)
From page 49...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 49 Panel A EAR Median Requirement Distribution Frequency Intake Distribution 30% Baseline Usual Intake Panel B EAR Median Requirement Distribution Intake Distribution Frequency 2.5% Target Usual Intake FIGURE 6 Concept of a target usual intake distribution. Panel A shows the baseline usual nutrient intake distribution with 30 percent prevalence of inadequate intakes.
From page 50...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 50 Panel A Median of the Target EAR RDA Intake Distribution Frequency Requirement Distribution Intake Distribution 2.5% 50 65 86 Usual Intake Median of the Target Panel B Intake Distribution EAR RDA Frequency Requirement Distribution Intake Distribution 2.5% 101 50 65 86 Usual Intake Panel C RDA = Median of the Target Intake Distribution EAR Frequency Requirement Distribution Intake Distribution 28% 50 65 86 Usual Intake FIGURE 7 Target usual intake distributions. Panel A: Low group prevalence of inadequacy: 2.5 percent of the population has usual intake below the estimated average requirement.
From page 51...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 51 where Z comes from a table of areas under the curve of a normal distribution and SDusual intake is the standard deviation of the intake distribution. Table 3 reproduces part of a table of z-scores.
From page 52...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 52 that the percentile of usual intake associated with this specified prevalence of inadequate intake equals the EAR. Using the DRIs to Plan a Group's Nutrient Intakes The summary below explains how DRIs are appropriately used in planning a group's nutrient intakes.
From page 53...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 53 TABLE 4 Method Used to Estimate Adequate Intake (AI) for Groups of Healthy Adults Estimation Method Nutrient Experimental derivation Biotin Calcium Choline Vitamin D Fiber, total Fluoride Potassium Sodium and chloride Mean intake Chromium Median intake Vitamin K Manganese Pantothenic acid n-6 Polyunsaturated fatty acids n-3 Polyunsaturated fatty acids Water, total study met the criterion of adequacy.
From page 54...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 54 mean and median intake of healthy groups. Practitioners who want to compare their target groups to the groups used to set the AIs can obtain this information in each of the individual nutrient profiles found in Part III.
From page 55...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 55 CASE STUDIES Case Study One: Using the Probability Approach to Assess Intakes in a Group Using a group of 650 adult men aged 19 to 30 years and a hypothetical nutrient with an EAR of 7 mg/day for this age and gender group illustrates the probability approach. Individuals in this group, even though they are similar in age and gender, differ in both their requirements for the nutrient and their usual intakes of the nutrient.
From page 56...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 56 1.2 5 mg/d 1.0 Probability = 0.9 0.8 Probability of Inadequacy 0.6 7 mg/d (EAR) Probability = 0.5 0.4 0.2 9 mg/d Probability = 0.1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Usual Intake (mg/d)
From page 57...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 57 1.2 Usual Intake Distribution Risk Curve 1.0 Probability of Inadequacy 0.8 0.6 0.4 0.2 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Usual Intake (mg/d) FIGURE 9 Comparison of the risk curve to a usual intake distribution.
From page 58...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 58 TABLE 5 Using the Probability Approach to Estimate Group Prevalence of Inadequacy in a Group of 650 Adult Men Ages 19 to 30 Years for a Nutrient with an EAR of 7 mg/day Probability ¥ Usual Intake Level Probability of Number of Numbera (mg/day) Inadequacy People 2 1.0 10 10 3 1.0 10 10 4 0.97 20 19.4 5 0.90 20 18.0 6 0.73 30 21.9 7 0.50 50 25.0 8 0.27 60 16.2 9 0.10 80 8.0 10 0.03 100 3.0 11 0 100 0 12 0 80 0 13 0 60 0 14 0 30 0 Total 650 131.5 = probability ¥ number/total Average probability = 131.5/650 = 0.20 (20 percent)
From page 59...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 59 typical omnivorous diet. The first and second columns of this table are based on information in Appendix Tables G-4 and G-7.
From page 60...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 60 equacy of 16.5 percent. It is important to remember that this approach does not identify the specific women with inadequate intakes, but is rather a statistical calculation of the prevalence of inadequate intakes.
From page 61...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 61 8 EAR Intake = Requirement 2 7 Intake < Requirement 6 Requirement (mg/d) 5 EAR 4 3 2 Intake > Requirement 1 1 0 0 2 4 6 8 10 12 Usual Intake (mg/d)
From page 62...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 62 When the above conditions are met, the individuals in triangle 1 (with intakes below the EAR but above their own requirements) are similar in number to the individuals in triangle 2 (with intakes above the EAR and below their own requirements)
From page 63...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 63 planner proceed to determine the target intake distribution of vitamin B6 needed to attain an acceptable prevalence of inadequacy?
From page 64...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 64 TABLE 8 Identification of the Target Median Intakea of Vitamin B 6 to Obtain a 10 Percent Prevalence of Inadequacy in Older Women Intake Difference Target at 10th (EAR – intake Median Median EAR Percentile at 10th Intake Intake Study (mg/day)
From page 65...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 65 of the target usual intake distributions are quite similar, as shown in Table 8. Assuming that a 10 percent prevalence of intakes below the EAR was considered acceptable, a median intake for vitamin B6 of 1.7 to 1.8 mg/day would be the planning goal.
From page 66...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 66 The UL can be used to estimate the proportion of a group at 3 potential risk of adverse effects from excessive nutrient intakes. The RDA should not be used in the assessment of a group's 3 nutrient intakes.
From page 67...
... PART I: APPLYING THE DIETARY REFERENCE INTAKES 67 SUMMARY The DRI values can be used by nutrition professionals to assess and plan the nutrient intakes of individuals and of groups. Table 9 summarizes the chapter discussions on the appropriate uses of each of the DRI values to achieve these goals.
From page 68...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 68 TABLE 9 Using the DRIs to Assess and Plan the Nutrient Intakes of Individuals and Groups EAR RDA AI UL When Assessing Diets For individuals: Usual intake Not recommended Usual intake at Usual intake above below the EAR for use when or above the AI the UL may place an likely needs to assessing nutrient has a low individual at risk of be improved. The intakes of probability of adverse effects.

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