apparent adequacy of an individual's intake to maintain the state of nutriture used to define a requirement. However, DRIs can neither provide precise quantitative assessments of the adequacy of diets of individuals nor be used to exactly assess nutritional status. Diet software programs based on the DRIs cannot do so either.
Assessing dietary adequacy by comparing an individual's intake and requirement for a nutrient is problematic for two reasons: first, the individual's requirement for a given nutrient must be known, and second, the individual's usual intake of the nutrient must be known. As described in Chapter 1, requirement is defined as the lowest continuing intake level of a nutrient that will maintain a defined level of nutriture in an individual for a given criterion of nutritional adequacy. Usual intake is defined as the individual's average intake over a long period of time. As is evident from these definitions, determining an individual's exact requirement would involve a controlled clinical setting in which the individual would be fed graded levels of a particular nutrient over a period of time, while undergoing numerous physiological and biochemical measurements. Determining usual intake requires a prohibitively large number of accurate diet records or recalls assessed using accurate food composition information (see Chapter 8 for further discussion of the importance of accurate intake and food composition data). Because neither type of information is usually available, it is simply not possible to exactly determine whether an individual's diet meets his or her individual requirement.
For some nutrients, however, it is possible to approximately assess whether an individual's nutrient intake meets his or her requirement. The remainder of this chapter and Appendix B provide specific guidance to help professionals assess individual dietary intake data relative to the DRIs. To do so, it is necessary to obtain information on an individual's usual intake, choose the appropriate reference standard, and then interpret the intake data.
Whenever possible, the assessment of apparent dietary adequacy should consider biological parameters such as anthropometry (e.g., weight for height), biochemical indices (e.g., serum albumin, blood urea nitrogen, creatinine, retinol binding protein, hemoglobin), diagnoses (e.g., renal disease, malabsorption), clinical status, and other factors as well as diet. Dietary adequacy should be assessed and diet plans formulated based on the totality of the evidence, not on dietary intake data alone.