Using DRIs for dietary assessment.

Nutrient standards such as the Dietary Reference Intakes (DRIs) may be used to assess diets of both individuals and of population groups. The goal is to estimate the probability of dietary adequacy (or inadequacy) for an individual and the prevalence of dietary adequacy for a group. The DRI that is needed to estimate the probability of dietary adequacy is the estimated average requirement for a nutrient (EAR), as well as an estimate of the standard deviation of the requirement. The probability of adequacy for an individual should be based on usual long-term intake, because the DRIs apply to a person's usual intake, rather than to intake on only a few days. Due to day-to-day variation in intakes, it is usually necessary to record or observe a person's intake for a large number of days. For population groups, the prevalence of adequacy can be calculated as the average of each person's probability of adequacy, and should correspond to the proportion of the population with nutrient intakes exceeding nutrient needs. A short-cut method to estimating the prevalence of adequacy simply calculates the proportion of intakes that are above the EAR. It is not necessary to have usual long-term intake for each person in the group, but a statistical procedure must be used to remove the effect of day-to-day variation from the intake distribution before the prevalence of adequacy within a group is estimated. With the new DRIs, a more informative assessment of both individual and group intakes is possible.