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Dietary Assessment of Individuals

24-Hour Recall

For this method, a dietitian or a trained interviewer asks an individual to recall all foods

consumed in the past 24 hours. The interviewer prompts the individual for information

on brand names, portion sizes, recipe ingredients, cooking methods, condiments, and

beverages. If the interview is conducted in person, food models and household

measuring instruments may be used to increase the accuracy of portion sizes. The

interviewer must be highly trained to capture detailed information and to conduct the

interview in a non-judgmental manner. People are often reluctant to divulge poor

dietary habits, especially if the interviewer exhibits any reaction to what the person is

saying. Those who consume high quantities of foods often underreport their intake;

individuals with low intakes often exaggerate their reports.

The 24-hour recall method is more appropriate for assessing the intake of large

populations than of individuals. Usual intake of an individual cannot be captured by a

one-day recall. If applying the method to a large population, the sample population

should be representative of the population that is being studied and interviews should

take place on different days of the week in order to reflect both weekday and weekend

eating patterns.

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Food Records

In this method of assessment, individuals are asked to record food intake over a

specified period of time. They are instructed to record details such as brand names,

portion sizes, recipe ingredients, cooking methods, condiments, and beverages. The

individual may be given measuring instruments or food models if possible to ensure

accurate reporting of portion sizes. It is best to review the food record afterwards as

well, and query the individual for details that are omitted. Food records may be

collected for any length of time but are usually collected for three to seven days. It is

recommended to include weekend days in the recording period.

Weighed-Food Records

In compiling these records, the subject is instructed to weigh all recipe ingredients and

foods consumed. The same details required of food records are recorded. The weighed-

food record is the most accurate record of individual food intake, though it does require

the subject to be motivated and able to weigh and record accurately.

Dietary History

The dietary history method of assessment is used to evaluate usual intake in an

individual over a long period. The subject is asked questions about his or her usual

eating patterns. Test administrators may ask such questions as "What do you usually eat

first in the day?" or "How often do you eat [certain food]?" This method may also

include a 24-hour recall and/or food record to supplement the information obtained.

Note that the dietary history is rather labor intensive and the information obtained is

more qualitative than quantitative.

Food Frequency Questionnaire

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A food frequency questionnaire (FFQ) is used to determine the frequency of

consumption of certain foods. It contains a list of foods and a series of frequencies such

as "daily," "three times a week," "monthly," etc. Respondents check off the frequency in

which they eat each food on the supplied list. The food frequency provides qualitative

data on types and frequency of foods or food groups. A semi-quantitative food

frequency questionnaire provides a ranking classification of individuals into low,

medium, and high intakes of specific nutrients and is used to examine associations

between nutrients and disease. The questionnaire must contain enough foods that are

good sources of the nutrient of interest in order to discriminate between low and high

consumers. The FFQ can examine current diet or diet in the recent or remote past.

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Figure 3.2: Example of Food Frequency Questionnaire