Usual dietary intake is the long-term average daily intake of a nutrient or food. The concept of usual intake is important because dietary recommendations are intended to be met over time and diet-health hypotheses are based on dietary intakes over the long term. Consequently, it is the usual intake that is often of most interest to policy makers — when they want to know the proportion of the population at or below a certain level of intake — or to researchers — when they want to examine relationships between diet and health. However, until recently, sophisticated efforts to capture this concept have been limited at best.
Difficulties Posed By Intra-Individual Variation
A single day represents only a “snapshot in time” and does not represent a person’s long-term average daily intake. In fact, for many dietary