Task 1: Key Concepts about Identifying Dietary Recall Variables and File Locations

NHANES dietary recall variables include data items that are related to food and nutrient intakes as reported on the 24-hour dietary recalls.  Some variables relate to the individual foods reported on the 24-hour recalls, including nutrient content and specifics about when and where the foods were eaten.  Other variables, such as the variables in the total nutrient intake file, represent the total or sum of the nutrients in all of the foods consumed by a participant on a particular day.  Both types of variables are available for the Day 1 and Day 2 dietary recall data.

These dietary recall variables, and information about the dietary recall variables, are stored within the Dietary component page of the “Questionnaires, Datasets and Related Documentation” section of the NHANES website for each two-year survey cycle.  The dietary recall data are contained in four separate data files:

• Individual Foods – Day 1
• Individual Foods – Day 2
• Total Nutrient Intakes – Day 1
• Total Nutrient Intakes – Day 2

The Individual Foods files provide a data record for each food reported by survey participants during their Day 1 and Day 2 dietary recalls. The variables contained in these files include food energy, nutrient values, gram weights, eating occasions, and related information, such as timing, source of foods, and location where eaten, for each food reported. Because most survey participants eat more than one food during a day, the Individual Foods Files contain multiple records per person for each recall day.  Consequently, these

The Total Nutrient Intakes files provide a summary of the dietary intake data for each 1-day recall period.  Variables representing total food energy and total intakes of dozens of nutrients are included.  Variable totals were derived by summing the nutrient amounts from all foods listed on a particular day in the Individual Foods File for a survey participant.  Because the daily nutrient intakes from all foods are summarized, the Total Nutrient Intake files contain only one record per person for each recall day.

IMPORTANT NOTE

For illustrations of this concept of multiple and single records per person, see the second task in Module 3: “NHANES Dietary Data Structure and Contents” of the Dietary Data Survey Orientation course.

 

As shown in the following lists, some variables are unique to particular dietary recall data files and other variables are common across the files.  For more detail on the variables, go to Information about Dietary Variables  .  Please note, however, that the most complete descriptions of these variables can be found in the Analytic Notes section of the Documentation (“Docs”) files. 

 

Variables in Individual Foods File Only

Food/individual component number

USDA food code

Modification code

Amount of food in grams

Food energy and nutrients contained in each amount of food consumed

Combination foods

Eating occasion

Food source

 

Variables in Total Nutrient Intakes File Only

Total food energy and nutrient intakes for the day

Self-reported comparison of recall day with typical diet

Water intake variables

Whether a person is on a special diet

 

Variables in both Individual Foods and Total Nutrient Intakes Files

Participant sequence number (SEQN)

Dietary recall status code

Dietary sample weights

Number of intake days

Breast-fed infant (either day)

Intake day of week

 

IMPORTANT NOTE

Dietary recall data are part of the Dietary component of NHANES 2003-2004.  Other variables necessary for your analysis may be located in other parts of the dataset.

 

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