Furthermore, large day-to-day variations in intake, which are exhibited by almost all individuals, mean that it often takes a prohibitively large number of days of intake measurement to approximate usual intake (Basiotis et al., 1987; IOM, 2000). As a result, caution is indicated when interpreting nutrient assessments based on self-reported dietary data covering only a few days of intake. Data on nutrient intakes should be interpreted in combination with information on typical food usage patterns to determine if the recorded intakes are representative of an individual’s usual intake.
Finally, because there is considerable variation in intakes both within and between individuals, as well as variation associated in estimating requirements, other factors must be evaluated in conjunction with the diet. The appropriate DRIs should be used in conjunction with other data in assessing the adequacy of the diet of a specific individual. The nutritional status of an individual can be definitively determined only by a combination of dietary, anthropometric, physiological, and biochemical data.
As is discussed in each chapter covering a specific nutrient, there were insufficient data to establish an Estimated Average Requirement (EAR) and therefore a Recommended Dietary Allowance (RDA) for the nutrients discussed in this report. Nevertheless, because these categories of DRIs exist for other nutrients, their use in the assessment of individuals will be described briefly.
The EAR is defined as estimating the median of the distribution of requirements for a specific life stage and gender group, but it is not possible to know where an individual’s requirement falls within this distribution without further anthropometric, physiological, or biochemical measures. Thus from dietary data alone, it is only possible to estimate the likelihood of nutrient adequacy or inadequacy. The EAR is an amount that would meet the needs as defined for a chosen criterion of adequacy for half the individuals in the group to which the EAR is applied. The RDA is the amount that would meet the needs of almost all members of the group.
For practical purposes, many users of the DRIs may find it useful to consider that when observed intakes are below the EAR, they very likely need to be improved (because the probability of adequacy is 50 percent or less), and those between the EAR and the RDA probably need to be improved (because the probability of adequacy is less than 97 to 98 percent). Only if intakes have been