NCS Dietary Assessment Literature Review
Definitions and Abbreviations
Definitions of and abbreviations for dietary assessment methods and reference methods discussed in this report.(5,6)
| Food Record (FR) |
Food records are used to record food intake at the time of consumption, over a number of days that are not necessarily sequential. Most studies ask respondents to enter the information on hard copy form, although tape-recording, bar-coding, and electronic weighing also have been used to collect descriptive and quantity information. Weighed FR: The respondent weighs on a small scale all food and beverages consumed. Estimated FR: The respondent estimates all food consumed using household measures or portion size estimating aides. |
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| Diet History (DH) | Diet History questionnaires are a retrospective assessment method ascertaining a respondent's "usual" food intake by collecting descriptive detail and amount information about each food. DHs may include questions on meal patterns, lists of common foods and groups of generic food. DH questionnaires are typically administered by a trained interviewer either in-person or by telephone, but also can be self-reported. |
| 24-Hour Recall (24HR) | The 24HR is a retrospective assessment method in which an interviewer prompts a respondent to recall and describe all foods and beverages consumed in the preceding 24 hours or the preceding day. The interview may be conducted in-person or by telephone and may be paper and pencil or computer assisted. Portion size estimating aides assist the respondent to recall amounts consumed. The methodology for conducting the 24HR has evolved during the last two decades. Among the methods reported are: 3-pass method, 5-pass method, U.S. Department of Agriculture protocol, University of Minnesota protocol, Bogalusa Heart Study protocol. |
| Food Frequency Questionnaire (FFQ) |
The food frequency questionnaire is a retrospective method asking respondents to report their usual frequency of consumption of each food from a list of foods for a specific period (several months or a year). Food lists vary by the purpose of the study and study population. Frequency of consumption categories also vary by questionnaire but usually include per day, week, or month. Semi quantitative FFQ: In this type of FFQ, portion size information is collected; portion sizes are specified as standardized portions or choice (range of portions). Non-quantitative FFQ: Portion size information not collected. NCI Health Habits and History Questionnaire (HHHQ): Semi-quantitative FFQ developed at the National Cancer Institute under the direction of Gladys Block. Harvard FFQ (HFFQ): FFQ developed at Harvard University by Walter Willett and colleagues. Portion size information is included as part of the food item rather than as a separate listing. NCI Diet History Questionnaire (DHQ): Semi-quantitative FFQ, using an embedded question approach, developed at the NCI under the direction of Amy Subar and Fran Thompson (7,8). |
| Propensity Questionnaire | Comprehensive FFQ-type questionnaire designed to supplement other dietary assessment method. Information on portion size information is not collected. May provide information on infrequently consumed foods (9). |
| Direct Observation (DO) | Intakes are watched and recorded by trained observers. |
| Doubly Labeled Water Method (DLW) for total energy expenditure (TEE) | The DLW method is used to measure energy expenditure in free-living subjects. This method involves the administration of water containing enriched quantities of the stable isotopes deuterium (2H) and oxygen-18 (18O). The label of "doubly" labeled comes from the fact that both the hydrogen and oxygen are labeled. The oxygen-18 is eliminated from the body in the form of carbon dioxide (C18O2) and water (H218O), and the deuterium is eliminated in water (2H2O). The difference in elimination rate between these two isotopes is a measure of carbon dioxide production. Carbon dioxide production can then be used to calculate energy expenditure by use of standard equations for indirect calorimetry (3). The DLW method has been shown to be accurate to 1%, with within-subject precision of 5 to 8% (10). Because the method is expensive and analysis requires specialized, expensive equipment, it cannot be considered routine. However, the method is widely available and is being applied to dietary assessment validations with sample sizes ranging from 20 to 500 (10). |
| Test Method (TM) | Dietary assessment method being validated. |
| Reference Method (RM) | Method against which the TM is being compared and validated. |