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7 Implications anc! Recommenciations While developing the guidance for use of the Dietary Reference Intakes (DRIB) in planning cliets for groups and inclivicluals, several crucial areas have been iclentifieci for which ciata and techniques do not exist or for which aciclitional knowledge is neecleci. This chapter synthesizes and prioritizes these neecis. Research recommendations to improve the uses of the DRIs as applied to clietary assessment have been clelineateci (IOM, 2000a). As part of a necessary cycle of assessment, planning, implementation, and reassessment, a number of the research recommendations proposed for clietary assessment apply to dietary planning as well. These recommendations, which aciciress issues such as the neeci to improve estimates of nutrient requirements and the quality of clietary intake ciata, are reiterated here. The recommendations in this chapter have been prioritized, and those presented uncler the first heacling should be given the highest priority for research and development funding. DIETARY PLANNING FOR GROUPS Pilot test the proposed approach to planningfor a low group prevalence of inadequacy. The approach to group planning proposed in this report focuses on planning for intakes rather than meals offered or served and on the distribution of usual intakes rather than on mean intake. This approach aims to achieve a low prevalence of inacloquate and exces- sive intakes of nutrients. However for some nutrients, achieving a 147
148 DIETARY REFERENCE INTAKES low prevalence of inacloquacy may require a considerable reposi- tioning of the usual nutrient intake distribution, thus targeting a higher meclian intake than may have been customary when previous planning activities focused on the Recommencleci Dietary Allow- ance. Before large-scale implementation of such changes, practical pilot testing of this approach will be useful to assess whether a low prevalence of inacloquacy can be achieved while meeting other important goals (e.g., avoiding excessive consumption of energy, maintaining nutrient intakes below the Tolerable Upper Intake Level FULL, and avoiding unnecessary food waste). Determine how different nutrition interventions a;f/7ect intake distributions. It cannot be assumed that an intervention clesigneci to increase the intake of a nutrient will result in a simple upward shift in nutri- ent intakes without changing the shape of the intake distribution or the between-person variation in usual nutrient intake. Different types of nutritional interventions may have very different effects on both the magnitude and shape of the intake distribution. A nearly complete distribution shift may be possible with interventions involv- ing mandatory fortification of whole cliets that have limited variety, such as emergency relief rations, or cliets with a limited number of widely consumed staple foocis in economically clepresseci areas of the world. Successful government-sponsoreci fortification of varied cliets, as is the case in the United States and Canada, clepencis on an appro- priate selection of food vehicles that are similarly consumed by most people. Other nutritional interventions, baseci on supplementation recommendations, inclustry-initiateci fortification of specific foocis, increased food choices, or nutrition education approaches, have less predictable effects on the nutrient intake distribution. Some interventions may move the meclian intake while expanding the range and variation, resulting in little improvement or movement up or clown at the extreme tails of the distribution. It is also possible that targeted interventions may affect primarily inclivicluals in the tail of a distribution, thus changing the shape and benefiting those in greatest need of dietary improvement. Examination and publica- tion of intake distributions before and after an intervention, with a systematic collection of this type of ciata, would allow a more informed selection of methods for planning a clietary intervention.
IMPLICATIONS AND RECOMMENDATIONS Determine the intake distributions of specific population groups. 149 Methods have been outlined in this report to estimate the clistri- bution of usual intakes in a group and apply this estimate to posi- tion or target the distribution of usual intakes so that there is a low prevalence of clietary inacloquacy or excess. Data on clietary intakes may be available for large groups, either from national population surveys or surveys of large groups (e.g., participants in the National School Lunch Program; the Supplemental Nutrition Program for Women, Infants, and Children; or specific branches of the mili- tary). However, often such information has not been reported in a manner that facilitates the estimation of variation in the usual in- take of inclivicluals. Information is generally minimal or lacking on the nutrient intake distributions of other groups such as children in different ciaycare settings, hospitalized patients, or residential long- term care homes or other institutional settings (with or without selective menus). For smaller settings where the on-site assessment of intake distributions may not be practical, planning for a low prev- alence of inacloquate intakes can be facilitated by descriptive ciata on the size and shape of intake distributions associated with similar settings. In aciclition, there is a paucity of population-level clietary intake ciata in Canada and on some unclerserveci subgroups in the United States (e.g., Native Americans on reservations or inner city populations) . c, . .. Conduct;further research on the relationship between foods offered and nutrient intake in the content of group planning. Although the framework for group planning focuses on the distri- bution of nutrient intakes as the ultimate goal, planners generally can control only what is offered and served to inclivicluals in the group. More work is neecleci to provide guidance to planners on how food and nutrient offerings relate to food and nutrient intakes in various populations and how the relationship between offering and intake varies according to planning contexts. Develop and evaluate dietary planning strategies for heterogeneous groups, including a nutrzent~ensity approach to dietary planning. Groups may be heterogeneous in ways (e.g., life stage and gentler) that result in multiple requirement levels within the same group. The nutrient density approach is suggested here as a method to plan diets to achieve adequate amounts of nutrients for all group
150 DIETARY REFERENCE INTAKES members baseci on those with the highest requirements. This approach involves planning for a minimum nutrient density in pro- portion to the energy content of the cliet. Research is neecleci to determine the practical usefulness of planning for a target nutrient density, to determine if the applicability of the nutrient density approach is limited to situations with precletermineci food alloca- tions or restricted food choices (e.g., emergency relief rations), and to determine if this approach would be practical in situations offer- ing a wicle variety of food choices where the nutrient density is more clepenclent on food selection than on total food access to meet energy neecis. For situations in which nutrient density approaches are cleemeci useful, further development of ciata and methods is neecleci to esti- mate the meclian and distribution associated with nutrient require- ments when expressed as a proportion of energy, either by statistical derivation from the present Estimated Average Requirements (EARs), or as a goal for future revisions of the Dietary Reference Intakes. Further research is also necessary to determine how intake clistri- butions for all nutrients are affected when plans for heterogeneous groups involve targeting the aggregate or average requirement of specific nutrients for all inclivicluals within a group versus targeting the maximum incliviclual requirement for the whole group. Criteria are neecleci to determine when to apply each of these approaches baseci upon current knowledge used to derive the EARs and ULs, studies of intake distributions, and the effects of interventions (see the analysis of folate intake distributions by Lewis and colleagues 1999. These criteria should consider the impact of such goal setting on the food supply and resulting distribution of intakes. RESEARCH TO IMPROVE THE QUALITY OF DIETARYINTAKE DATA As cliscusseci in the prececling chapters, planning cliets, at either the incliviclual or group level, involves setting goals for what nutri- ent intakes should be. Thus, in order to plan effectively, high-quality ciata are neecleci on clietary intake of nutrients. Much has been written about ways to improve the quality of the intake ciata on which assessments are baseci (IOM, 2000a); some of the topics are revisited here along with specific areas in which research is still neecleci. Important advances to improve the application of human nutri- ent requirement estimates have been macle with the further clevel-
IMPLICATIONS AND RECOMMENDATIONS 151 opment and refinement of statistical procedures to recluce, if not eliminate, the distorting effect of random error in clietary ciata (Nusser et al., 1996~. The remaining issue of paramount impor- tance in clietary ciata collection and analysis is the presence and true extent of bias (such as uncler- or overreporting of food intake) and the accuracy of food composition databases. Research is needed to develop and validate statistical procedures to identify and correctfor both under- and overrep~ing in self- reported intake data for energy and other nutrients. This is a relatively unexplored field. Methods for directly estimat- ing bias regarding energy intake have been clevelopeci and used to demonstrate that the problem is serious. While the underreporting of energy has now been well clocumenteci, it is unclear how this affects the accuracy of self-reporteci nutrient intakes. Research into this question has been limited by the absence of reference bio- markers of intake for many nutrients. Efforts have begun in the management of bias cluring ciata analysis, but these are far from satisfactory at present. Unfortunately, the methods available to recluce bias caused by energy underreporting do not provide an appropriate correction of underreporting for clietary intake ciata to be used in assessment and planning applications of the Dietary Reference Intakes (DRIs). The handling of bias is a high-priority area of research awaiting new initiatives and innovative approaches. Better ways to quantify the intake of supplements are needed. Methods for collecting accurate supplement intake ciata have not been widely investigated. For the Third National Health and Nutri- tion Examination Survey, different instruments were used to collect food intake ciata and supplement intake ciata, and the correct meth- oclology for combining these ciata is uncertain. Furthermore, the intake distribution from supplements usually cannot be acljusteci because the ciata do not permit the estimation of the ciay-to-ciay variability in supplement intake. Plans for the Fourth National Health and Nutrition Examination Survey attempt to aciciress some of these issues. Despite the difficulties in maintaining a supplement composition database for the rapidly changing market, investiga- tion of better methods of quantifying supplement intakes is a high- priority research area.
152 DIETARY REFERENCE INTAKES Food composition databases need to be updated to include the forms and units that are specified by DR]s. Analysis of various forms of certain nutrients (e.g., or- versus y-tocopherol) may be required. The DRI recommendations also imply that databases need to separate nutrients inherent in foods from those provided by fortification, particularly when intakes are compared with the Tolerable Upper Intake Level for nutrients (e.g., niacin). It has been suggested (IOM, 1998a, 2000b) that food com- position databases report nutrients by weight and by equivalents to allow for rapid updates when more is known about bioavailability. Thus, it may also be necessary to change the units of measurement (e.g., dietary folate equivalents, as suggested for folate tIOM, 1998a]; the milligrams of oc-tocopherol, suggested for vitamin E in place of oc-tocopherol equivalents tIOM, 2000b1, and new biological conversion rates for ,3-carotene to vitamin A as suggested for retinal activity equivalents in place of retinal equivalents tIOM, 20011). GUIDANCE FOR DIETARY PLANNING Review and, where necessary, revise e~istingfoodF guides. Changes in recommended intakes of various nutrients, combined with rapid changes in the amount and number of nutrients and types of foods that are fortified (particularly in the United States), necessitate review of existing food guides and continuation of the periodic review of dietary guidance such as the Dietary Guidelines for Americans and Canada's Guidelines for Healthy Eating. Develop technical tools for the professional. There is a need to develop analytical tools that support imple- mentation of recommendations for using the Dietary Reference Intakes (DRIB) for professional dietary assessment and planning, as well as for general guidelines for professionals to evaluate such tools. Industry and academia should explore development and produc- tion of accurate and convenient tools, expanding on the availability and use of sophisticated hand-held calculators and computers and easy Internet access to a spectrum of data and software. Communicate tenth and educate nutrition professionals. For full implementation and use of the DRIB, communication
IMPLICATIONS AND RECOMMENDATIONS 153 strategies are neecleci to effectively educate nutrition professionals on how the DRI recommendations can be practically and effectively applied. The DRIs are more complex than past efforts (NRC, 1989; Health Canada, 1990b) and draw more and more from the realms of the basic sciences and mathematics. There is a neeci to formally examine how to best integrate this information into the education of nutrition professionals. Assess application of the DR]s for food and supplement labeling. The DRIs provide upciateci nutrient intake recommendations with scientific justification and extensive documentation. For some nutri- ents (e.g., folate and vitamin Bit), the neeci to evaluate appropriate labeling information in both the United States and Canada is recog- nizeci to convey the recommendation for synthetic sources. Devel- oping and testing a labeling format that conveys the meaning and use of the Tolerable Upper Intake Level may be especially helpful to consumers. Develop and evaluate food guides for group planning. Planning for groups to have a low prevalence of inacloquate clietary intakes involves methods different from those used in plan- ning for a low risk of clietary inacloquacy for inclivicluals. However, in both cases, the emphasis should be on food sources of nutrients. In the United States fooci-baseci menu planning guides have long been part of specifications for professionals to use in planning the food offered in various nutrition programs such as the National School Lunch Program. Convenient-to-use, fooci-baseci guidelines for menu planning for specific groups should be developed to assist professionals in planning for a low group prevalence of inadequate or excessive intakes. As with the pilot testing of group planning methodologies already mentioned, such guides will neeci to be eval- uated. RESEARCH TO IMPROVE ESTIMATES OF NUTRIENT REQUIREMENTS Even for nutrients for which an Estimated Average Requirement (EAR) is available, requirement data on which the EAR is based are typically scarce and usually only for adults. Such EARs and Recom- mencleci Dietary Allowances (RDAs) are often baseci on just a few experiments or studies with very small sample sizes, and therefore
154 DIETARY REFERENCE INTAKES considerable uncertainty exists about the true meclian and stanciarci deviation of the distribution of requirements within a group. Given the importance of meclian and distribution of requirements in both assessment and planning, aciclitional carefully conclucteci research is neecleci in this area to accomplish the tasks cliscusseci below. Improve existing estimates of the EAR and RDA. -r r- - ----- -- - ------------m - - -I - There is neeci to both improve the database of controlled experi- mental studies relevant to the EAR, as well as to broaclen the approach to estimating requirements. Congruence of evidence should be expected from different sources, including population baseci and clinical investigations as well as experimental and factorial approaches, before being truly confident in an EAR. Provide better information on requirements so it becomes possible to establish an EAR (and thus an RDAJ for nutrients that currently have Adequate Intakes (AlsJ. Research that allows replacement of the AIs with EARs for age groups older than infants will allow for aciclitional applications. As cliscusseci in earlier chapters, EARs present more possibilities for assessing incliviclual and group prevalence of inacloquacy and espe- cially for planning for low group prevalence of inacloquacy. Improve estimates of the distribution of requirements so that the appropriate method for assessing the prevalence of inadequacy for groups can be determined (cutpoint method versus probability approachJ. Research in this area is also neecleci to enable more accurate appli- cations of the Dietary Reference Intakes to specific inclivicluals and populations. Adjustment factors for considerations such as body size, physical activity, and intakes of energy and other nutrients may be appropriate but are often unknown. Studies to evaluate nutrient requirements or adverse effects should provide individual data where possible to allow estimation of their distributions. Identify factors that can alter the upper intake levels that can be tolerated biologically. Establishment of Tolerable Upper Intake Levels (ULs) provides an opportunity to evaluate the risk of adverse effects for inclivicluals
IMPLICATIONS AND RECOMMENDATIONS 155 and populations and is an extremely important step forward in assessing nutrient intakes. Research to allow ULs to be set for all nutrients should be undertaken in carefully controlled settings. In aciclition, information on the distribution of adverse effects via close- response ciata (e.g., risk curves) would allow greatly expancleci appli- cations of the UL, particularly for population groups. More infor- mation is neecleci on ways to identify and conceptualize the risk of exceecling the UL.