24-hour Dietary Recall (24HR) At a Glance

Purpose

To obtain detailed information about all foods and beverages consumed on a given day.

Description

A 24-hour dietary recall (24HR) is a structured interview intended to capture detailed information about all foods and beverages (and possibly, [glossary term:] dietary supplements) consumed by the respondent in the past 24 hours, most commonly, from midnight to midnight the previous day. A key feature of the 24HR is that, when appropriate, the respondent is asked for more detailed information than first reported. For example, a respondent reporting chicken for dinner or a sandwich for lunch would be asked about the preparation method and type of bread. This open-ended response structure is designed to prompt respondents to provide a comprehensive and detailed report of all foods and beverages consumed.

In addition to other detailed descriptors, such as time of day and source of food, portion size of each food and beverage is captured. Food models, pictures, and other visual aids may be used to help respondents judge and report portion size and may improve [glossary term:] accuracy.

Dietary recalls typically ask about foods and beverages first, before questions on dietary supplements.

A 24HR usually requires 20 to 60 minutes to complete.

Standardized automated interviewing systems that include multiple passes, such as the USDA's Automated Multiple-Pass Method, have been developed to facilitate complete recalls. These systems include nearly complete automated coding that is supplemented by manual coding for reported foods or beverages not in the database.

24HRs are typically administered by a trained interviewer, but automated self-administered tools, such as the National Cancer Institute's Automated Self-Administered 24-Hour Dietary Assessment Tool (ASA24), also are available.

Utility of Data

• 24HR data can be used to assess total dietary intake and/or particular aspects of the diet:
  • The 24HR yields detailed information on foods and beverages consumed on a given day. The total amount of each specific food and beverage consumed is captured.
  • Similar types of food and beverage items reported, such as soups or sugar-sweetened beverages, can be grouped. Totals for each group can then be summed.
  • If data are linked to a nutrient composition database, nutrient intake from foods and beverages can be determined (Learn More about Food Composition Databases for 24-hour Dietary Recalls and Food Records). However, [glossary term:] total nutrient intake cannot be ascertained unless dietary supplement intake data also are collected (Learn More about Dietary Supplements and Estimating Total Nutrient Intakes).
  • If data are linked to a database that translates foods and beverages into food group equivalents, such as the Food Patterns Equivalents Database, foods and beverages reported can be disaggregated into their component ingredients, which can then be converted to equivalent amounts of relevant guidance-based food groups (For more information, read a factsheet on FPED products and associated data files or its application to dietary analysis.). This provides information about the consumption of food groups of particular interest, such as total intake of fruits, vegetables, or added sugars.
  • If information such as names of eating occasions, timing and locations of meals and snacks, sources of food and beverages, and other activities such as TV and computer use during meals is collected, the 24HR can yield contextual information, such as meal and snack patterns, consumption of foods and beverage from home and away from home, and activities during meals.
• 24HRs can be used to describe a population's intake (e.g., the [glossary term:] cross-sectional study [glossary term:] What We Eat in America/National Health and Nutrition Examination Survey) (see Choosing an Approach for Dietary Assessment).
  • [glossary term:] Mean usual intakes can be estimated with a single administration.
  • Collecting a recall for at least two non-consecutive days allows application of statistical techniques to estimate [glossary term:] usual dietary intake distributions for a group (for example, to answer research questions such as the proportion above or below some threshold) (Learn More about Usual Dietary Intake).
• 24HRs can be used to examine relationships between diet and health or other variables, in which diet is the [glossary term:] independent variable (see Choosing an Approach for Dietary Assessment).
  • Sometimes, they are used as a [glossary term:] reference instrument to [glossary term:] validate or [glossary term:] calibrate estimates when another less detailed assessment instrument, such as a food frequency questionnaire (FFQ), is used as the [glossary term:] main dietary assessment instrument.
  • With the advent of self-administered automated 24HRs, 24HRs potentially can be used as a main dietary assessment instrument with or without an FFQ for diet-health studies, including in large [glossary term:] prospective studies.
  • The number and timing of the 24HRs needed depends on the objectives.
• 24HRs can be used to examine relationships between some factor and diet, in which diet is the dependent variable (see Choosing an Approach for Dietary Assessment).

• 24HRs can be used to evaluate the effectiveness of an [glossary term:] intervention study to change diet. The potential for [glossary term:] differential response bias due to the possibility that the intervention group and control group may report their diets differently, especially following an intervention should be considered. However, while this type of [glossary term:] bias is a concern for all self-report instruments, it may be less problematic with 24HRs than with other instruments (see Choosing an Approach for Dietary Assessment).
  • The number and timing of the 24HRs needed depends on the intervention design and the objectives.

Limitations of Data

• The requirements of completing a 24HR may limit participation in some groups, leading to potential [glossary term:] selection bias.
• Because a single administration of a 24HR is unable to account for [glossary term:] day-to-day variation, two or more non-consecutive recalls are required to estimate usual dietary intake distributions. Multiple administrations are also recommended when 24HRs are used to examine diet and health or other variables.

Salient Features Compared to Other Self-Report Instruments Methods

For an at-a-glance comparison of the major features of self-report instruments for assessing diet, including the 24HR, see the Comparing Dietary Assessment Instruments table.

• Captures current short-term diet (in contrast to FFQ and screener).
• Typically interviewer-administered (in contrast to FFQ, food record, and screener), but automated self-administered 24HRs are available and becoming more widely used.
• Relies on [glossary term:] specific memory (in contrast to FFQ and screener, which rely on [glossary term:] generic memory, and food record, which does not rely on memory).
• If recalls are unannounced, they are not affected by [glossary term:] reactivity (in contrast to food record) (Learn More about Reactivity).
• Its major type of [glossary term:] measurement error is [glossary term:] random versus [glossary term:] systematic (in contrast to FFQ and screener) (see Key Concepts about Measurement Error).