Task 2: Key Concepts About Dietary Recall Data Files

Beginning in 2002, two 24-hour recalls were requested from all NHANES examinees.  All Day 1 interviews were conducted at the Mobile Examination Center using an in-person mode of interview. The Day 2 recalls were collected approximately three to ten days after the examination using a telephone mode of interview.

The main data are captured in four files, found on the 2003-2004 Dietary Files page. (Note that additional data, derived from these main files, can be found on the USDA Web site. See “Module 4: Resources for Dietary Data Analysis” for more information.)

 

NHANES 24-Hour Recall Interview Data Files
Data File File Name Data Contained in the Data File
Dietary Interview (Individual Foods – First Day) DR1IFF_C
  • Detailed description about foods reported (i.e. type, form, brand name, amount consumed)
  • Amounts of nutrients from each food
Dietary Interview (Individual Foods – Second Day) DR2IFF_C
  • Detailed description about foods reported (i.e. type, form, brand name, amount consumed)
  • Amounts of nutrients from each food
Total Nutrient Intakes (First Day) DR1TOT_C
  • Total energy and nutrient intakes from foods on recall day
  • Total amount of water consumed on recall day
  • Recall day's consumption amount compared to typical diet
  • Information on added salt (frequency and type)
  • Whether on a special diet and type of diet
  • Frequency of fish and shellfish consumed (past 30 days)
Total Nutrient Intakes (Second Day) DR2TOT_C
  • Daily total energy and nutrient intakes from foods
  • Daily amount of water consumed on recall day
  • Recall day's consumption amount compared to typical diet

 

Be aware that the first two files, relating to individual foods, contain multiple records per person.  The second two files, relating to total nutrient intake, contain a single record per person.  This difference is illustrated below.  These files can be linked by sequence number (SEQN), the variable that identifies individual NHANES participants, and the observations are indexed by line number.

Also be aware that the individual foods files contains records only for participants with complete intakes that were considered to be reliable (DR1DRSTZ=1), with the exception of those individuals who reported no food on a day even though their intakes were considered complete because they were fasting. The total nutrient intakes files, on the other hand, have records for all persons with complete intakes, including the fasters, but also have records for those with incomplete/unreliable intakes and those who did not participate in the dietary recall interview at all. Therefore, individuals with incomplete/unreliable intakes have no records in the individual foods file; however, they do have a record in the associated total nutrient file but the total nutrient variables contain missing values.

 

Example from Individual Foods Files of Multiple Food Records Per Person

screenshot of individual foods files of multiple records per person

 

Notice that in this illustration of a partial food record printout, the participant associated with SEQN 27530 reported consuming 2 foods (denoted by the food codes), which gives this participant two records for each variable in the dietary recall file (e.g., the calories from food and calcium from food shown here). The participant associated with SEQN 30888 reported consuming 25 foods, which gives this participant 25 records for each variable in the dietary recall file.

 

Example from Total Nutrient Intakes Files of One Record Per Person

screenshot of total nutrient intakes files of one record per person

 

Notice that in this illustration of a partial nutrient record printout, each SEQN is associated with one record for each of the variables in the table.  That is because each record represents a total derived from summing individual records.  This is in contrast to the previous table in which SEQN was associated with more than one record per variable, depending on the number of foods that the participant reported consuming.

 

info iconIMPORTANT NOTE

The Dietary Files page has links to each of these data files as well as to the documentation and the procedures used to collect the data.


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