known about the relative sizes of nutrient versus energy underreporting.
Various techniques may be used to encourage accurate reporting. Because many studies of dietary intake rely on subjects' memory of food, food ingredients, and portion sizes, dietary survey instruments often specify the use of memory probes and cues to improve accuracy (Domel, 1997). Those with poor memory, such as some elderly adults and young children, are not good candidates for dietary intake interviews (Van Staveren et al., 1994; Young, 1981).
Some retrospective diet studies depend on the individual's long-term recall of past food intake and rely on memory that is more generic than that for recent intake. Complete food lists and probes using specific circumstances of life are helpful in these studies (Dwyer and Coleman, 1997; Kuhnlein, 1992; Smith et al., 1991a). The interview atmosphere should be kept neutral so that respondents do not feel they must report (or not report) items because of their social desirability (Hebert et al., 1997).
When dietary intakes are assessed for individuals with strong cultural or ethnic identities, it is useful to employ interviewers from the same background who speak the language of the interviewees and can knowledgeably guide dietary information exchange about the food, its ingredients, and portion sizes. Food composition databases used should contain the appropriate culture-specific food items. Respondents must be literate if written survey instruments are used (Hankin and Wilkens, 1994; Kuhnlein et al., 1996; Teufel, 1997).
To minimize portion size as a source of error, various kinds of food models, portion-size models, and household measures have been used to assist the respondent (Burk and Pao, 1976; Guthrie, 1984; Haraldsdottir et al., 1994; Thompson et al., 1987; Tsubono et al., 1997). Training the interviewer in use of portion-size models improves accuracy of reporting (Bolland et al., 1990).
Supplement use needs to be determined, and quantified, to obtain accurate estimates of the prevalence of inadequate nutrient intakes for a group. Otherwise, the prevalence of inadequacy will be overestimated, as will the probability of inadequacy for an individual. However, the proportion of individuals with intakes above the