The assessment of diet is often a difficult task: accurate evaluation of a person's diet is dependent on that person's ability to give a precise account of their food intake; yet the act of recording a person's intake can easily influence what the person eats during that time, and people tend to have difficulty remembering what they have eaten. Moreover, the limitations of computerized nutrient databases renders it impossible to calculate precise nutrient values in certain foods: these databases may not contain new food items and do not account for loss of nutrients through cooking, or geographic differences in soil nutrients where vegetables are grown. Nevertheless, a methodology does exists that can obtain adequate estimates of dietary intake. These estimates can then be used to describe intakes of populations and examine relationships between dietary intakes and disease.
This section will discuss: dietary assessment of the nation, a household, and an individual; computerized dietary assessment; nutrition monitoring activities; and recommended intakes of nutrients.