Definition of Dietary

measurement of quantity of the individual foods consumed during one to several days OR pattern of food use

  • Levels of objectives
  • actual vs usual intake
  • group vs individual interpretation
  • Types of nutrients

Why measure diet?

  • Assessing and monitoring food and nutrient intake (also: estimating exposure to food additives and contaminants)
  •  Formulating and evaluating government health and agricultural policy
  • Conducting epidemiologic research, i.e. the relationships between diet and health
  • Commercial purposes, i.e. developing advertising campaigns or new food products


 Food Records: principle and uses

Two types:

  • Estimated Food Records
  • Weighed Food Records (Weighed Diet Record, WDR)

Principle and Uses:

  • Based on recording portion sizes of actual foods consumed by an individual, estimated using household measures or weighed using dietary scales.
  • Weighed Food Records ideal for scientific and controlled studies in particular when diet counseling or correlations of intake with biological parameters are involved.
  • Uses: research, multi-center epidemiological studies, for controlled metabolic studies.
  • Weighed food record respondents must be motivated, numerate and illiterate.

24-hour recalls: principles and uses

Two types: Single & Repeated

Principle and Uses:

  • assesses actual food intake of an individual during previous 24 hours period or preceding day.
  • the number of 24-h recalls requires to estimate the usual nutrient intake of individuals depends on day-to-day variation in food intake within one individual (i.e., within-subject variation. If more than one-day recall is required, nonconsecutive days should be selected.
  • 24hr recall data can be repeated during different seasons of the year to estimate the average food intake of individuals over a longer time period (i.e., usual food intake).

FFQ: principle and uses

Two types: Qualitative and Semi-Quantitative

Principle and Uses:

  • Assesses energy and/or nutrient intake by determining how frequently a person consumes a limited number of foods that are major sources of nutrients or of a particular dietary components in question during a specified time period (typically 6 months to 1 year)
  • Provide data on habitual intakes of selected nutrients, certain foods or food groups
  • Specific combination of food can be used as predictors for intakes of certain nutrients or non-nutrients, provided that the dietary intake components are concentrated in a relatively small number of foods or specific food groups, e.g. consumption of vitamin C are predicted from fresh fruits and fruit juice.
  • Often designed to gain information about specific aspects of diet, such as dietary fats or particular vitamins or minerals, and other aspects may be less well characterized
  • List of approximately =100  individual foods items or food groups that are important contributors to the specific nutrients of interest
  • Should feature simple, well-defined food and food categories, avoid use of open-ended questions
  • (Usually) self-administered; designed to be easy to complete by the study subjects
  • Often rely on assumptions regarding portion size; limited by the amount of detail that it is feasible to include in the questionnaire
  • It is possible for the questionnaires to be semi-quantitative where subjects are asked to estimate usual portion sizes
  • In epidemiology, FFQ are often filled in with reference to the previous year in order to ascertain usual food consumption patterns for that period.
  • The FFQ must be culture specific (Khonson, 2002)