Implementing food-based dietary guidelines for - United Nations ...

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S54 Planning energy and macronutrient intakes Energy intakes for individuals may be planned using the NIV for the average energy requirement as a target. An INL x is not usually set for energy intake, because intakes above the mean requirement would result in weight gain, which is usually undesirable. The calculation of the planned mean energy intake should consider both the person’s body size and his or her activity level. An example of this approach is provided in the DRI report on macronutrient intakes [12]. If AMDRs have been set for percentages of energy from fat, protein, and carbohydrate, then the goal for planning an individual’s diet is to ensure that the usual intakes of these macronutrients by the individual fall within the ranges. Using NIVs for assessment and planning for groups Assessing nutrient intakes of groups Goal The goal of assessing intakes of groups is to determine the prevalence of inadequacy and the prevalence of potentially excessive intakes in the groups [2, 7, 8]. Prevalence of inadequacy The prevalence of inadequacy is the proportion of the group whose intakes do not meet their requirements. Alternatively, the prevalence of adequacy can be calculated as the proportion of the group who do meet their requirements based on a defined criterion of adequacy. The prevalence of adequacy (expressed as a percentage) is equal to 100 minus the prevalence of inadequacy. Such prevalences should correspond to the proportion of the group that exhibits the functional outcome (or criterion) that was used to set the requirement distribution. If, for example, the vitamin C requirement was set at a level to prevent scurvy, then the prevalence of inadequacy should correspond to the prevalence of scurvy within the group. If it was set at a higher level with the goal of maintaining near-maximal neutrophil concentrations with minimal urinary loss, as was done in the United States and Canada [13], then the prevalence of inadequacy should correspond to the proportion of the population that does not exhibit near-maximal concentrations in their neutrophils. There are two ways to determine the prevalence of inadequacy (or adequacy) for a group: the full probability approach and the cutpoint method. The full probability approach involves calculating the probability of inadequacy for each person within the group and then taking the average [14]. The average probability of inadequacy is then equal to the prevalence of inadequacy. The cutpoint method is a shortcut of the full probability approach. The prevalence of inadequacy is estimated as the proportion of the group with usual intakes below the ANR. Neither of these methods requires that intakes be normally (or even symmetrically) distributed, but other assumptions must be met, as described below. Full probability approach The full probability approach uses the same calculation that was described for estimating the probability of inadequacy for an individual. This probability calculation is performed by using the usual nutrient intake for each individual in the group and then determining the average probability. As noted above, the probability calculations assume that intake and requirements are independent, and of course, the distribution of requirements must be known. Cutpoint approach The cutpoint approach does not require the calculation of any probabilities and thus is easier to implement. The prevalence of inadequacy is simply estimated as the proportion of the group with usual intakes below the ANR (fig. 2). For example, if 35% of the group has usual intakes below the ANR, then the prevalence of inadequacy would be approximately 35%. However, the cutpoint approach still requires that intakes and requirements be independent. Although the requirement distribution does not have to be known for this method to be used, it must be approximately symmetrical. Therefore, the cutpoint approach cannot be used to determine the prevalence of inadequate iron intakes for menstruating women, because the distribution of requirements is skewed. Finally, this approach works best if the actual prevalence of inadequacy is neither very high nor very low, and if the variability in intakes among individuals in the group is greater than the variability in requirements of the individuals. This last assumption is met by almost all intake distributions, but it is possible that the variability of intakes could be very low for groups who are eating similar amounts of �� S. P. Murphy and H. H. Vorster �� FIG. 2. Graph of a hypothetical distribution of usual nutrient intakes for a group of people. The area to the left of the average nutrient requirement (ANR) represents an estimate of the proportion of the group with inadequate intakes (the prevalence of inadequacy)
Using nutrient intake values to assess intakes similar foods. In this case, the full probability approach should be used. As explained in more detail elsewhere [2], the cutpoint approach works for statistical reasons. It does not mean that the ANR is an appropriate cutpoint for screening individuals. That is, it cannot be assumed that the individuals with intakes below the ANR are the ones who should be targeted for dietary interventions. Although it is true that intakes below the ANR have at least a 50% probability of inadequacy, it is not true that all of these individuals have intakes below their requirements. Even at the ANR, an intake still has a 50% probability of adequacy. Furthermore, some individuals with intakes above the ANR are still not meeting their requirements. As noted above, screening at the individual level is difficult unless usual long-term intakes have been measured. At the group level, however, the prevalence of inadequacy could be reduced by shifting the distribution of intakes so that fewer intakes fall below the ANR; this approach is described below in the section on Planning Nutrient Intakes for Groups. Adjusting intake distributions Both the full probability approach and the cutpoint approach require that the distribution of intakes represents usual intakes for the group of interest. Usual intakes could be obtained by having many days of observation for each individual, but this type of data is seldom available. Alternatively, the distribution can be statistically adjusted to remove the effect of day-today variation (fig. 3). Several methods are available for making these adjustments [2, 14–17], but all require an estimate of the day-to-day variation in nutrient intakes for the group. These methods may be used even if data from only one day are available for each person, as long as a second day of dietary data is collected for at least a representative subset of the group of interest. Alternatively, an estimate of day-to-day variation may be obtained from multiday data for a similar population. The ability to statistically adjust intake distribution to remove the effect of day-to-day variation in intakes, rather than collecting many days of data for each � �� FIG. 3. Comparison of a distribution of one-day nutrient intakes with a distribution of usual nutrient intakes. The proportion of the group with intakes below the average nutrient requirement (ANR) is greater for the one-day distribution S55 person, makes the assessment of groups more feasible than the assessment of individuals. Assessing intakes with an AI For nutrients without an ANR, it is possible to evaluate the intake of a group if an adequate intake (AI) has been set based on the mean intake of a healthy population. If the group’s mean intake approximates the AI, then the group can be assumed to have a low prevalence of inadequacy. However, no such qualitative judgment can be made if mean intake is below the AI. Because the distribution of requirements is not known, it is possible that mean intakes below the AI are also associated with a low prevalence of inadequacy. For this type of assessment, the intake distribution does not need to be adjusted for day-to-day variation, because only the mean intake is being examined. Assessing the prevalence of potentially excessive intakes To assess the prevalence of potentially excessive intakes, the proportion of the group with usual intakes above the UNL should be estimated. Because the UNL includes an uncertainty factor, it should not be assumed that everyone with an intake above the UNL is at risk for adverse effects. However, as the prevalence of intakes above the UNL increases, the likelihood that the group is at risk also increases. Prior to this evaluation, the intake distributions must be adjusted to remove the effect of day-to-day variation, as described above. Assessing energy intakes As was the case for assessing individuals, the probability approach cannot be used to evaluate the energy intakes of a group. Instead, the average energy intake of the group can be compared with the estimated average energy requirement for the group, taking into consideration the ages, sexes, and physical activity levels of the individuals within the group. If the average energy intake exceeds the estimated average requirement, then the group, on average, is likely to be gaining weight, assuming that the requirements and intakes have been accurately calculated. If the reverse is true, then the group may be, on average, losing weight. This type of comparison does not require adjusting the intake distribution for day-to-day variation, since only the mean is being evaluated. Energy balance can also be measured by weight changes, which can assist in assessing whether a group’s energy intake is inadequate or excessive. Assessing macronutrient intakes If AMDRs have been set, then the group’s macronutrient intakes may be assessed using these standards. The proportion of the group with intakes outside the AMDR is a measure of how well the group is meeting these standards. These would be interpreted as the prevalence of intakes that are too high or too low. If
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Contents International harmonizatio
Page 3 and 4: Executive summary Harmonization of
Page 5 and 6: Executive summary [11]. These are l
Page 7 and 8: Executive summary and converted to
Page 9 and 10: Executive summary very rapidly and
Page 11 and 12: Executive summary References Concep
Page 13 and 14: Introduction Janet C. King and Cutb
Page 15 and 16: Introduction References 1. King JC,
Page 17 and 18: Terminology and framework for nutri
Page 27 and 28: Nutrient risk assessment: Setting u
Page 29 and 30: Setting upper levels for nutrient r
Page 39 and 40: Establishing nutrient intake values
Page 51 and 52: Methods for using nutrient intake v
Page 53: Using nutrient intake values to ass
Page 57 and 58: Using nutrient intake values to ass
Page 59 and 60: Using nutrient intake values to ass
Page 61 and 62: Determining life-stage groups and e
Page 63 and 64: Life-stage groups and nutrient inta
Page 77 and 78: The role of diet- and host-related
Page 79 and 80: Diet- and host-related factors in n
Page 101 and 102: Human nutrition and genetic variati
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Human nutrition and genetic variati
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Application of nutrient intake valu
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Beyond recommendations: Implementin
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Dietary guidelines and nutrient int
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International Dietary Harmonization
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