Dietary Reference Intakes: The Essential Guide to Nutrient Requirements (2006)

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Chapter: Introduction to the Dietary Reference Intakes

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Suggested Citation:"Introduction to the Dietary Reference Intakes." Institute of Medicine. 2006. Dietary Reference Intakes: The Essential Guide to Nutrient Requirements. Washington, DC: The National Academies Press. doi: 10.17226/11537.

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PART I: INTRODUCTION TO THE DIETARY REFERENCE INTAKES 5 INTRODUCTION TO THE DIETARY REFERENCE INTAKES I n 1941, the National Research Council issued its first set of Recommended Dietary Allowances (RDAs) for vitamins, minerals, protein, and energy. De- veloped initially by the forerunner of the Food and Nutrition Board of the Institute of Medicine, the recommendations were intended to serve as a guide for good nutrition and as a âyardstickâ by which to measure progress toward that goal. Since then, RDAs have served as the basis for almost all federal and state food and nutrition programs and policies. By 1989, they had been revised nine times and expanded from a coverage of 8 original nutrients to 27 nutrients. In 1938, the Canadian Council on Nutrition prepared the first dietary standard designed specifically for use in Canada. The Dietary Standard for Canada was revised in 1950, 1963, 1975, and 1983 and published by Health Canada and its predecessors. The 1983 revision was renamed Recommended Nutrient Intakes (RNIs) for Canadians. In the late 1980s, it was decided to incorporate considerations of the prevention of chronic diseases as well as nutritional defi- ciencies into the revision of the RNIs. In 1990, Nutrition Recommendations: The Report of the Scientific Review Committee was published. The report contained updated RNIs and recommendations on the selection of a dietary pattern that would supply all essential nutrients, while reducing risk of chronic diseases. Both RDA and RNI values have been widely used for planning diets, as- sessing the adequacy of diets in individuals and populations, providing nutri- tion education and guidance, and as a standard for nutrition labeling and forti- fication. However, the former RDAs and RNIs were not always well suited for these applications and the need for new values was recognized. Also of note, the RNIs and RDAs differed from each other in their definition, revision and publication dates, and how their data have been interpreted by both U.S. and Canadian scientific committees. Beginning in 1994, the Food and Nutrition Board, with support from the U.S. and Canadian governments and others, set out to develop and implement a new paradigm to establish recommended nutrient intakes that replaced and

DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 6 expanded upon the RDAs and RNIs. Reflecting updated scientific and statistical understandings, this decade-long review resulted in the development of the family of reference values collectively known as the Dietary Reference Intakes (DRIs). In contrast to the creation of the RDAs and RNIs, which involved estab- lishing single values for each nutrient, adjusted for age, sex, and physiological condition, the DRIs feature four reference values, only one of which, the RDA, is familiar to the broad nutrition community (although the method by which it is derived has changed). The DRIs are a common set of reference values for Canada and the United States and are based on scientifically grounded relation- ships between nutrient intakes and indicators of adequacy, as well as the pre- vention of chronic diseases, in apparently healthy populations. The development of the DRIs publication series (see Box 1 for a list of publications in the series) was undertaken by the standing Committee on the Scientific Evaluation of Dietary Reference Intakes, two standing subcommittees (the Subcommittee on Upper Reference Levels of Nutrients and the Subcom- mittee on Uses and Interpretation of Dietary Reference Intakes), and a series of expert panels. Each of the panels was responsible for reviewing the require- ments for a specific group of nutrients. Totaling nearly 5,000 pages, these reports summarize what is known about how nutrients function in the human body; the selection of indicators of ad- equacy on which to determine nutrient requirements; the factors that may af- fect how nutrients are utilized and therefore affect requirements; and how nu- trients may be related to the prevention of chronic disease across all age groups. They also provide specific guidance on how to use the appropriate values to assess and plan the diets of groups and individuals. A NEW APPROACH TO NUTRIENT REFERENCE VALUES Collectively referred to as the Dietary Reference Intakes, the DRIs include four nutrient-based reference values that are used to assess and plan the diets of healthy people. The reference values include the Estimated Average Require- ment (EAR), the Recommended Dietary Allowance (RDA), the Adequate Intake (AI), and the Tolerable Upper Intake Level (UL). (Brief definitions of the DRI categories are provided in Box 2.) Developed for vitamins, minerals, macronu- trients, and energy, these reference values replace and expand upon the previ- ous nutrient reference values for the United States and Canada. New to the nutrition world, the DRIs represent a significant paradigm shift in the way di- etary reference values are established and used by practitioners, educators, and researchers. Unlike the RDAs and RNIs (prior to 1990), which focused prima- rily on reducing the incidence of diseases of deficiency, the DRI values are also

PART I: INTRODUCTION TO THE DIETARY REFERENCE INTAKES 7 BOX 1 The DRI Publications Nutrient-specific reports: â¢ DRIs for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride (1997) â¢ DRIs for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline (1998) â¢ DRIs for Vitamin C, Vitamin E, Selenium, and Carotenoids (2000) â¢ DRIs for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc (2001) â¢ DRIs for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (2002/2005) â¢ DRIs for Water, Potassium, Sodium, Chloride, and Sulfate (2005) Reports that explain appropriate uses: â¢ DRIs: Applications in Dietary Assessment (2000) â¢ DRIs: Applications in Dietary Planning (2003) Related or derivative reports: â¢ DRIs: Proposed Definition and Plan for Review of Dietary Antioxidants and Related Compounds (1998) â¢ DRIs: A Risk Assessment Model for Establishing Upper Intake Levels for Nutrients (1998) â¢ DRIs: Proposed Definition of Dietary Fiber (2001) â¢ DRIs: Guiding Principles for Nutrition Labeling and Fortification (2003), prepared as a separate activity http://www.nap.edu/catalog/dri intended to help individuals optimize their health, prevent disease, and avoid consuming too much of a nutrient. Specifically, the DRIs differ from the former RDAs and RNIs in several key ways: â¢ When available, data on a nutrientâs safety and role in health are consid- ered in the formulation of a recommendation, taking into account the potential reduction in the risk of chronic degenerative disease or devel- opmental abnormality, rather than just the absence of signs of deficiency.

DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 8 BOX 2 DRI Definitions Estimated Average Requirement (EAR): The average daily nutrient intake level that is estimated to meet the requirements of half of the healthy individuals in a particular life stage and gender group.a Recommended Dietary Allowance (RDA): The average daily dietary nutrient intake level that is sufficient to meet the nutrient requirements of nearly all (97â98 percent) healthy individuals in a particular life stage and gender group. Adequate Intake (AI): The recommended average daily intake level based on ob- served or experimentally determined approximations or estimates of nutrient intake by a group (or groups) of apparently healthy people that are assumed to be adequate; used when an RDA cannot be determined. Tolerable Upper Intake Level (UL): The highest average daily nutrient intake level that is likely to pose no risk of adverse health effects to almost all individuals in the general population. As intake increases above the UL, the potential risk of adverse effects may increase. a In the case of energy, an Estimated Energy Requirement (EER) is provided. The EER is the average dietary energy intake that is predicted to maintain energy balance in a healthy adult of a defined age, gender, weight, height, and level of physical activity consistent with good health. In children and pregnant and lactating women, the EER is taken to include the needs associated with the deposition of tissues or the secretion of milk at rates consistent with good health. â¢ The concepts of probability and risk explicitly underpin the deter- mination of the DRIs and inform their application in assessment and planning. â¢ Greater emphasis is placed on the distribution of nutrient requirements within a population, rather than on a single value (like the former RDAs and RNIs). â¢ Where data exist, upper levels of intake have been established regarding the risk of adverse health effects. â¢ Compounds found naturally in foods that may not meet the traditional concept of a nutrient, but have a potential risk or possible benefit to health, are reviewed and, if sufficient data exist, reference intakes are established.

PART I: INTRODUCTION TO THE DIETARY REFERENCE INTAKES 9 As discussed earlier, the previous RDAs and RNIs were originally only intended to plan nutritional adequacy for groups. But because previous RDAs and RNIs were the only values available to health professionals, they were also used to assess and plan the diets of individuals and to make judgments about excess intakes for both individuals and groups. However, they were not ideally suited for these purposes. To prevent further misapplication, the expansion to the DRI framework included methodologies for appropriate uses of the nutrient values with individuals and groups. The four primary uses of the DRIs are to assess the intakes of individuals, assess the intakes of population groups, plan diets for individuals, and plan diets for groups. Some of the dietary planning activities that are most relevant to DRI use include dietary guidance, institutional food planning, military food and nutrition planning, planning for food-assistance programs, food labeling, food fortification, developing new or modified food products, and food-safety assurance. THE DRI CATEGORIES Most nutrients have a set of DRIs. Often, a nutrient has an Estimated Average Requirement (EAR) from which the Recommended Dietary Allowance (RDA) is mathematically derived. When an EAR for a nutrient cannot be determined (thus precluding the setting of an RDA), then an Adequate Intake (AI) is often developed. Many nutrients also have a Tolerable Upper Intake Level (UL). The values for the EAR and AI are defined by using specific criteria for nutrient adequacy and answer the question âadequate for what?â. For example, values for vitamin C were set based on the amount of vitamin C that would nearly saturate leukocytes without leading to excessive urinary loss, rather than the level necessary to prevent scurvy. The UL is defined by using a specific indicator of excess, if one is available. Where data were available, the chosen criteria have been identified in each nutrient chapter. In some cases, various intake levels can produce a range of benefits. For example, one criterion, or indicator, of adequacy may be the most appropriate one to use when determining an individualâs risk of becoming deficient in the nutrient, while another criterion of adequacy may be more applicable to reduc- ing oneâs risk of chronic diseases or conditions, such as certain neurodegenerative diseases, cardiovascular disease, cancer, diabetes mellitus, or age-related macu- lar degeneration. It is also important to note that each reference value refers to average daily nutrient intake. Some deviation around this average value is expected over a number of days. In fact, it is the average mean intake over this time frame that

DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 10 serves as the nutritionally important reference value. In most cases, the amounts derived from day-to-day intake may vary substantially without ill effect. Estimated Average Requirement The Estimated Average Requirement (EAR) is the average daily nutrient intake level that is estimated to meet the nutrient needs of half of the healthy individu- als in a life stage or gender group. Although the term âaverageâ is used, the EAR actually represents an estimated median requirement. As such, the EAR ex- ceeds the needs of half of the group and falls short of the needs of the other half. The EAR is the primary reference point for assessing the adequacy of esti- mated nutrient intakes of groups and is a tool for planning intakes for groups. It is also the basis for calculating the RDA. Although it can also be used to exam- ine the probability that usual intake is inadequate for individuals (in conjunc- tion with information on the variability of requirements), it is not meant to be used as a goal for daily intake by individuals. In the case of energy, an estimated energy requirement called the Estimated Energy Requirement (EER) is provided. Recommended Dietary Allowance The Recommended Dietary Allowance (RDA) is an estimate of the daily average dietary intake that meets the nutrient needs of nearly all (97â98 percent) healthy members of a particular life stage and gender group. The RDA thus exceeds the requirements of nearly all members of the group. It can be used as a guide for daily intake by individuals, and because it falls above the requirements of most people, intakes below the RDA cannot be assessed as being inadequate. Usual intake at the RDA should have a low probability of inadequacy. If an EAR cannot be set due to data limitations, no RDA will be calculated. For nutrients that have a statistically normal requirement distribution, the RDA is set by adding two standard deviations (SD) to the EAR. Thus, RDA = EAR + 2SD For nutrients with skewed requirement distributions (most notably, iron in menstruating women) the RDA is set between the 97th and 98th percentile of the requirement distribution. (See Part I, âApplying the Dietary Reference In- takesâ for more information on calculating RDAs when nutrient requirements are skewed.) Adequate Intake If sufficient or adequate scientific evidence is not available to establish an EAR and thus an RDA, an AI is usually derived for the nutrient instead. An AI is

PART I: INTRODUCTION TO THE DIETARY REFERENCE INTAKES 11 Acceptable Macronutrient Distribution Ranges (AMDR) A growing body of evidence indicates that an imbalance in macro- nutrients (e.g., low or high percent of energy), particularly with certain fatty acids and relative amounts of fat and carbohydrates, can increase risk of several chronic diseases. Based on this evidence, Acceptable Macronutrient Distribution Ranges (AMDRs) have been estimated for in- dividuals. An AMDR is the range of intakes of an energy source that is associated with a reduced risk of chronic disease, yet can provide ad- equate amounts of essential nutrients. The AMDR is expressed as a percentage of total energy intake. A key feature of each AMDR is that it has a lower and upper boundary. For example, the AMDR for carbohydrates ranges from 45 to 65 percent of total energy intake. Intakes that fall below or above this range increase the potential for an elevated risk of chronic diseases. Intakes outside of the range also raise the risk of inadequate consumption of essential nutri- ents. The AMDRs are discussed in more detail in Part II, âMacronutrients, Healthful Diets, and Physical Activity.â based on fewer data and incorporates more judgment than is used in establish- ing an EAR and subsequently the RDA. The setting of an AI usually indicates that more research is needed to determine, with some degree of confidence, the mean and distribution of requirements for that specific nutrient. The AI is a recommended average daily nutrient intake level based on ob- served or experimentally determined approximations or estimates of nutrient intake by a group (or groups) of apparently healthy people who are assumed to be maintaining an adequate nutritional state. Examples of adequate nutritional states include normal growth, maintenance of normal levels of nutrients in plasma, and other aspects of nutritional well-being or general health. The AI is expected to meet or exceed the needs of most individuals in a specific life stage and gender group. When an RDA is not available for a nutri- ent (because an EAR could not be developed), the AI can be used as the guide for an individualâs intake. However, the AI has very limited uses in assessments of any type. Tolerable Upper Intake Level The Tolerable Upper Intake Level (UL) is the highest average daily nutrient intake level likely to pose no risk of adverse health effects for nearly all people

DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 12 EAR 1.0 1.0 RDA UL Risk of Adverse Effects Risk of Inadequacy 0.5 0.5 0.0 0.0 Observed Level of Intake FIGURE 1 Relationship between Dietary Reference Intakes. This figure shows that the Estimated Average Requirement (EAR) is the intake at which the risk of inadequacy is 0.5 (50 percent) to an individual. The Recommended Dietary Allowance (RDA) is the intake at which the risk of inadequacy is very smallâonly 0.02 to 0.03 (2 to 3 percent). The Adequate Intake (AI) does not bear a consistent relationship to the EAR or the RDA because it is set without the estimate of the requirement. At intakes between the RDA and the Tolerable Upper Intake Level (UL), the risks of inadequacy and of excess are both close to zero. At intakes above the UL, the risk of adverse effects may increase. in a particular group. As intake increases above the UL, the potential risk for adverse effects increases. The need for setting a UL grew out of two major trends: increased fortification of foods with nutrients and the use of dietary supple- ments by more people and in larger doses. The UL is not a recommended level of intake, but rather the highest intake level that can be tolerated without the possibility of causing ill effects. The value applies to chronic daily use and is usually based on the total intake of a nutrient from food, water, and supplements if adverse effects have been associated with total intake. However, if adverse effects have been associated with intake from supplements or food fortificants alone, the UL is based on the nutrient intake from one or both of these sources only, rather than on total intake. For some nutrients, not enough data were available to set a UL. However, this does not mean that consuming excess amounts poses no risks. Instead, it indicates a need for caution in consuming large amounts. See Figure 1 for a visual relationship between the DRIs. PARAMETERS USED IN DEVELOPING DRIS The DRIs presented in this publication apply to the healthy general population. In addition, DRI values are assigned to life stage groups that correspond to

PART I: INTRODUCTION TO THE DIETARY REFERENCE INTAKES 13 various periods of the human lifespan. Reference heights and weights for life stage and gender groups were used for extrapolations performed on the basis of body weight or size. They also indicate the extent to which intake adjustments might be made for individuals or population groups that significantly deviate from typical heights and weights. Applicable Populations An important principle underlying the DRIs is that they are standards for ap- parently healthy people and are not meant to be applied to those with acute or chronic disease or for the repletion of nutrient levels in previously deficient individuals. Meeting the recommended intakes for the nutrients would not nec- essarily provide enough for individuals who are already malnourished, nor would they be adequate for certain disease states marked by increase nutrient require- ments. Although the RDA or AI may serve as the basis for specialized guidance, qualified medical and nutrition personnel should make the needed adjustments for individuals with specific needs. Life Stage Groups Where data were available, DRIs were divided into 12 life stage groups and also by gender. The life stage groups were chosen by considering variations in the requirements of all of the nutrients under review. If data were too limited to distinguish different nutrient requirements by life stage or gender groups, the analysis was then presented for a larger grouping. INFANCY Infancy covers the first 12 months of life and is divided into two 6-month intervals. The first 6-month interval was not subdivided because intake is rela- tively constant during this time. That is, as infants grow, they ingest more food; however, on a body-weight basis their intake remains the same. During the second 6 months of life, growth rate slows. As a result, total daily nutrient needs on a body-weight basis may be less than those during the first 6 months of life. The average intake by full-term infants born to healthy, well-nourished mothers and exclusively fed human milk has been adopted as the primary basis for deriving the AI for most nutrients during the first 6 months of life. The only exception to this criterion is vitamin D, which occurs in low concentrations in human milk. In general, special consideration was not given to possible variations in physiological need during the first month after birth or to the intake variations that result from differences in milk volume and nutrient concentration during

DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 14 early lactation. Specific recommended intakes to meet the needs of formula-fed infants have not been set. â¢ First 6 months (Ages 0 through 6 months): The AI for a nutrient for infants in this age group was calculated using two measures, the average concentration of the nutrient from 2 through 6 months of lactation and an estimated average volume of human milk intake of 0.78 L/day. The AI represents the product of these two measures. Infants are expected to consume increasing volumes of human milk as they grow. â¢ Second 6 months (Ages 7 through 12 months): During this time, in- fants experience slowed growth and gradual weaning to a mixed diet of human milk and solid foods. There is no evidence for markedly differ- ent nutrient needs, except for some nutrients such as iron and zinc, which have relatively high requirements. An EAR and RDA for iron and zinc have been derived for this age group. The AIs (again, with the ex- ception of vitamin D) are based on the sum of the average amount of the nutrient provided by 0.6 L/day of human milk and the average amount of the nutrient provided by the usual intakes of complementary wean- ing foods consumed by infants at this age. TODDLERS: AGES 1 THROUGH 3 YEARS Toddlers experience greater velocity of growth in height compared to 4- and 5- year-olds, and this distinction provides the biological basis for establishing sepa- rate recommended intakes for this age group. Data on which to base DRIs for toddlers are sparse, and in many cases, DRIs were derived by extrapolating data taken from the studies of infants or adults (see Appendix C). EARLY CHILDHOOD: AGES 4 THROUGH 8 YEARS Children aged 4 through 8 or 9 years (the latter depending on puberty onset in each gender) undergo major changes in velocity of growth and endocrine sta- tus. For many nutrients, a reasonable amount of data was available on nutrient intake and various criteria for adequacy to serve as the basis for the EARs/RDAs and AIs for this group. For nutrients that lack data on the requirements of children, EARs and RDAs for children are based on extrapolations from adult values. PUBERTY/ADOLESCENCE: AGES 9 THROUGH 13 YEARS, AND 14 THROUGH 18 YEARS The adolescent years were divided into two categories because growth occurs in some children as late as age 20 years. For some nutrients, different EARs/

PART I: INTRODUCTION TO THE DIETARY REFERENCE INTAKES 15 RDAs and AIs were derived for girls and boys. Several indicators support the biological appropriateness of creating two adolescent age groups and gender groups: â¢ Age 10 years as the mean age of onset of breast development for white females in the United States; this is a physical marker for the beginning of increased estrogen secretion (in African American girls, onset is about a year earlier, for unknown reasons). â¢ The female growth spurt begins before the onset of breast development, thereby supporting the grouping of 9 through 13 years. â¢ The mean age of onset of testicular development in males is 10.5 through 11 years. â¢ The male growth spurt begins 2 years after the start of testicular devel- opment, thereby supporting the grouping of 14 through 18 years. YOUNG ADULTHOOD AND MIDDLE AGE: AGES 19 THROUGH 30 YEARS, AND 31 THROUGH 50 YEARS Adulthood was divided into two age groups to account for the possible value of achieving optimal genetic potential for peak bone mass with the consumption of higher nutrient intakes during early adulthood rather than later in life. More- over, mean energy expenditure decreases from ages 19 through 50 years, and nutrient needs related to energy metabolism may also decrease. ADULTHOOD AND OLDER ADULTS: AGES 51 THROUGH 70 YEARS, AND OVER 70 YEARS The age period of 51 through 70 years spans active work years for most adults. After age 70, people of the same age increasingly display different levels of physiological functioning and physical activity. Age-related declines in nutrient absorption and kidney function also may occur. PREGNANCY AND LACTATION Nutrient recommendations are set for these life stages because of the many unique changes in physiology and nutrition needs that occur during pregnancy and lactation. In setting EARs/RDAs and AIs, consideration was given to the following factors: â¢ The needs of the fetus during pregnancy and the production of milk during lactation

DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 16 â¢ Adaptations to increased nutrient demand, such as increased absorp- tion and greater conservation of many nutrients â¢ Net loss of nutrients due to physiological mechanisms, regardless of intake, such as seen with calcium in lactation Due to the last two factors, for some nutrients there may not be a basis for setting EAR/RDA or AI values for pregnant or lactating women that differ from the values set for other women of comparable age. Reference Heights and Weights Reference heights and weights for life stage and gender groups are useful when more specificity about body size and nutrient requirements is needed than that provided by life stage categories. For example, while an EAR may be developed for 4- to 8-year-olds, it could be assumed that a 4-year-old girl small for her age might require less than the EAR for her age group. Conversely, an 8-year-old boy who is big for his age might require more than the EAR for his age group. However, based on the model for establishing RDAs, the RDA (and AI) should meet the needs of both. There are other reasons for using reference heights and weights in deter- mining requirements. Data regarding nutrient requirements that are reported on a body-weight basis (such as with protein) necessitate the use of reference heights and weights to transform the data for comparison purposes. Or, fre- quently, the only available data are those regarding adult requirements. In these situations, extrapolating the data on the basis of body weight or size is a pos- sible option to arrive at values for other age groups. Thus, when data are not available, the EARs or ULs for children or pregnant women may be established by extrapolating from adult values on the basis of body weight or, depending on the nutrient, on the basis of relative energy expenditure. The reference heights and weights used in the more recent DRI reports are shown in Table 1. Earlier reports used slightly different reference heights and weights. (For more information on previous reference heights and weights see Appendix B of the report titled Dietary Reference Intakes for Energy, Carbohy- drate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids, 2002/2005.) The new charts include reference heights and weights that are more representa- tive of U.S. and Canadian populations.

PART I: INTRODUCTION TO THE DIETARY REFERENCE INTAKES 17 TABLE 1 Reference Heights and Weights for Children and Adults Median Body Median Reference Mass Indexa Weight,b Reference (kg/m2) Height,a cm (in) Gender Age kg (lb) Males/females 2â6 mo â 62 (24) 6 (13) 7â12 mo â 71 (28) 9 (20) 1â3 y â 86 (34) 12 (27) 4â8 y 15.3 115 (45) 20 (44) Males 9â13 y 17.2 144 (57) 36 (79) 14â18 y 20.5 174 (68) 61 (134) 19â30 yc 22.5 177 (70) 70 (154) Females 9â13 y 17.4 144 (57) 37 (81) 14â18 y 20.4 163 (64) 54 (119) 19â30 yc 21.5 163 (64) 57 (126) a Taken from data on male and female median body mass index and height-for-age data from the Centers for Disease Control and Prevention (CDC)/National Center for Health Statistics (NCHS) Growth Charts. b Calculated from CDC/NCHS Growth Charts; median body mass index and median height for ages 4 through 19 years. c Since there is no evidence that weight should change as adults age, if activity is maintained, the reference weights for adults aged 19 through 30 years are applied to all adult age groups. SUMMARY The Dietary Reference Intakes (DRIs) replace and expand upon the previous revisions of the RDAs and RNIs and represent a new approach to setting nutri- ent values by greatly extending the scope and application of previous nutrient standards. DRIs are a family of quantitative estimates of nutrient intakes intended for use in assessing and planning diets for healthy people. The DRI concept goes beyond the goal of former RDAs and RNIs of ensuring healthy diets, quantify- ing the relationship between a nutrient and the risk of disease, including chronic disease that results from either inadequate or excess intake. The next chapter, âApplying the Dietary Reference Intakes,â provides help- ful guidelines and methods on how to accurately apply the DRI values when assessing and planning the diets of both individuals and groups.

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