Table of Contents

Locator Record

Title: Dietary Interview (DRXDOC_E )
Contact Number: 1-866-441-NCHS
Years of Content: 2007 - 2008
First Published: July, 2010
Revised: August, 2010
Access Constraints: None
Use Constraints: None
Geographic Coverage: National
Subject:Dietary interview component provides detailed dietary intake information from NHANES participants.
Record Source: NHANES 2007 - 2008
Survey Methodology: NHANES 2007 - 2008 is a stratified multistage probability sample of the civilian non-institutionalized population of the U.S.
Medium: NHANES Web site; SAS transport files

Component Description

The objective of the dietary interview component is to obtain detailed dietary intake information from NHANES participants. The dietary intake data are used to estimate the types and amounts of foods and beverages (including all types of water) consumed during the 24-hour period prior to the interview (midnight to midnight), and to estimate intakes of energy, nutrients, and other food components from those foods and beverages. Following the dietary recall, participants are asked questions on salt use, whether the person’s overall intake on the previous day was much more than usual, usual or much less than usual, and whether the respondent is on any type of special diet. Questions on frequency of fish and shellfish consumed during the past 30 days were asked of survey participants 1 year or older, with the use of proxies or adult assistants for young children (see the MEC In-Person Dietary Interviewers Procedures Manual for more information on proxy interview).

The dietary interview component, called What We Eat in America (WWEIA), is conducted as a partnership between the U.S. Department of Agriculture (USDA) and the U.S. Department of Health and Human Services (DHHS). Under this partnership, DHHS’ National Center for Health Statistics (NCHS) is responsible for the sample design and data collection and USDA’s Food Surveys Research Group (FSRG) is responsible for the dietary data collection methodology, maintenance of the databases used to code and process the data, and data review and processing.

All NHANES examinees are eligible for two 24-hour dietary recall interviews. The first dietary recall interview is collected in-person in the Mobile Examination Center (MEC) and the second interview is collected by telephone 3 to 10 days later.

As in previous years, two types of dietary intake data are available for the 2007-2008 survey cycle - Individual Foods files and Total Nutrient Intakes files. Starting with the 2007-2008 data release, data documentation will be published only in HTML format. The document in its new format contains the same information as it has in previous years.

What’s New with the 2007-2008 WWEIA Release:

Vitamin D has been added to the list of nutrients. The vitamin D values in this dataset reflect the sum of ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3) content of foods reported by survey participants. The contribution of another form of vitamin D, 25-hydroxycholecalciferol, which may be present in certain foods, was not included because adequate data from validated methods for this form of vitamin D were not available. Caution should be used when comparing these data to earlier reported vitamin D intakes by various investigators, since some differences may be attributed to discrepancies in analytical methods and food sampling.

A variable has been added in each of the four files (DR1DBIH for day 1 files and DR2DBIH for day 2 files) to indicate the number of days between the intake day and the day of family questionnaire administered in the household. NHANES has collected information on the receipt of food stamps, including the last benefit received date as part of the family interview. Previous research has indicated that there is a monthly cycle in food consumption behavior for different levels of benefits. These new variables will be critical in understanding dietary behavior of food stamp recipients over the month.

In 2007-2008, a new sample design was implemented. All Hispanics were oversampled, not just Mexican Americans. In addition, for each of the race/ethnicity domains, the 12-15 and 16-19 year age domains were combined and the 40-59 year age minority domains were split into 10 year age domains 40-49 and 50-59. This has led to an increase in the number of participants aged 40+ and a decrease in 12-19 year olds from previous cycles. Lastly, pregnant women were no longer oversampled. Based on these changes, unweighted frequencies of certain variables may differ slightly in this survey cycle compared to earlier survey cycles. Refer to the NHANES 2007–2008 Public Data General Release File Documentation (http://www.cdc.gov/nchs/nhanes/nhanes2007-2008/generaldoc_e.htm) on the NHANES website for more detail.

NHANES has been collecting data on study participants’ use of dietary supplements in the past 30 days, during the Dietary Supplements Section (DSQ) in the household interview. In 2007-2008, additional information on supplement and antacid use for the previous 24 hours was collected to provide data of the same timeframe as the food and beverage intake. This will allow researchers to improve the total nutrient intake estimations as well as examine associations by nutrient source such as from foods versus supplements.

With a similar protocol, the 24-hour dietary supplement interview was collected following the 24-hour dietary recall. All NHANES examinees responding to the dietary recall interview were eligible for the dietary supplement and antacid use questions. Information was obtained on all vitamins, minerals, herbals and other dietary supplements that were consumed during a 24-hour time period (midnight to midnight), including the name and the amount of dietary supplement taken.

The 24-hour dietary supplement data are released in separate files available on the NHANES website. They can be linked to the dietary files by the respondent sequence number (SEQN). For more information on the data, refer to the documentation accompanying the 24-hour dietary supplement datasets.

Further details about these and other changes for 2007-2008 are provided within this document. Appendix 1 provides a summary of changes among the 3 latest cycles of data collection.

Dietary Interview Data Files: Four data files were produced from the information collected in the dietary interview: two Individual Foods files and two Total Nutrient Intake files. Each file includes one day of intake data. The number “1” or “2” in the file name identifies the day (and mode) of the interview: 1 = first day (in-person), 2 = second day (phone). File names are the following:

File Names for Dietary Interview Data:
File Day 1 Day 2
Individual Foods File DR1IFF_E DR2IFF_E
Total Nutrient Intakes File DR1TOT_E DR2TOT_E

The nutrient amounts in these files reflect only nutrients obtained from foods, beverages, and water including tap and bottled water. They do not include nutrients obtained from dietary supplements, antacids, or medications.

Individual Foods Files (DR1IFF_E and DR2IFF_E): Detailed information about the types and amounts of individual foods reported by each participant, as well as amounts of nutrients from each food are included in the Individual Foods files. The names for both Day 1 and Day 2 variables are listed in Appendix 2.

The Individual Foods files include, for each interview day, one record for each food consumed by a survey participant. Each food record is sequentially numbered and contains the information listed below:

Beginning with the 2005-2006 WWEIA and continued in 2007-2008 WWEIA, the consumption of all types of water (including tap and bottled water, plain and carbonated, sweetened and unsweetened water) has been collected during the 24-hour recall. As a result, each report of water intake throughout the day was collected and coded as a separate food item. These water intake items now appear in the Individual Foods file with food codes designating the type of water. As with other foods, a variable is present to indicate if the water was consumed at home or away. For bottled waters, a variable is present indicating where the water was obtained. For tap water, the variables DR1TWS and DR2TWS in the Total Nutrient Intake files indicate the main source of tap water drunk by the participant. In 2003-2004, only sweetened bottled waters were collected during the 24-hour recall and included in the Individual Foods file. Information on daily intake of non-sweetened waters (total plain water, total tap water and the source of tap water, total bottled water, and plain carbonated water) were collected after the 24-hour dietary recall and included in the Total Nutrient Intake file for 2003-2004. Starting in 2005-2006, summary water variables that are compatible with previous data cycles are included in the Total Nutrient Intake files with the exception of plain carbonated water. These water totals (DR1_320Z, DR2_320Z, DR1_330Z, DR2_330Z, DR1BWATZ and DR2BWATZ) represent total water consumed as a beverage by itself. Therefore, they do not include the moisture content of foods and beverages (such as watermelon, coffee, lettuce) that are available for each food reported in the Individual Foods files.

Two supporting files are also included with the Individual Foods files: the Food Code Description file (DRXFCD_E) and the Modification Code Description file (DRXMCD_E). The DRXFCD_E file includes complete descriptions (up to 200 characters) associated with each USDA food code identified in the Individual Foods files. The DRXMCD_E file includes descriptions (up to 200 characters) associated with each modification code identified in the Individual Foods files. Modification codes represent adjustments to predefined recipe ingredients that reflect more closely the food as described by the respondent. Appendix 4 provides SAS code examples that may be used to link the food code or the modification code description to the Individual Foods file.

Total Nutrient Intakes Files (DR1TOT_E and DR2TOT_E): For each participant, daily total energy and nutrient intakes from foods and beverages and whether the amount of food consumed was usual, much more than usual, or much less than usual are included in the Total Nutrient Intakes files. The Day 1 file also includes information on salt use in cooking and at the table; whether the participant is currently on any kind of diet to lose weight or for other health-related reason and, if so, the type of diet; and for participants 1 year or older, information on frequency of fish and shellfish consumption. The names for both Day 1 and Day 2 variables are listed in Appendix 5.

The Total Nutrient Intakes files provide a summary record of total nutrient intakes for each individual. Each total intake record contains the following information:

Eligible Sample

All NHANES examinees are eligible for the dietary interview component. However, only examinees one year or older are eligible for the frequency of fish and shellfish consumption questions following the 24-hour recall.

Protocol and Procedure

The examination protocol and data collection methods are fully documented in the NHANES dietary interviewers procedures manuals (In-person interview: http://www.cdc.gov/nchs/data/nhanes/nhanes_07_08/manual_dietarymec.pdf; phone follow-up interview: http://www.cdc.gov/nchs/data/nhanes/nhanes_07_08/manual_dietarypfu.pdf).

Interviews were conducted for survey participants less than six years of age with a proxy who was generally the person most knowledgeable about the survey participant’s intake. With children ages 6 to 11, the interviews were conducted with the child and the assistance of an adult familiar with the child’s intake. Dietary interviews were conducted in English and Spanish. Translators were used to conduct interviews in other languages.

The in-person interview was conducted in a private room in the NHANES mobile examination center (MEC). A set of measuring guides (various glasses, bowls, mugs, drink boxes and bottles, household spoons, measuring cups and spoons, a ruler, thickness sticks, bean bags, and circles) was available in the MEC dietary interview room for the participant to use for reporting amounts of foods (NHANES Measuring Guides for the Dietary Recall Interview: http://www.cdc.gov/nchs/nhanes/measuring_guides_dri/measuringguides.htm). Upon completion of the in-person interview, participants were given measuring cups, spoons, a ruler, and a food model booklet, which contained two-dimensional drawings of the various measuring guides available in the MEC, to use for reporting food amounts during the telephone interview. Telephone dietary interviews were collected 3 to 10 days following the MEC dietary interview but not on the same day of the week as the MEC interview. Any participant who did not have a telephone was given a toll-free number to call so that the recall could be conducted.

What We Eat in America data were collected using USDA's dietary data collection instrument, (the Automated Multiple Pass Method (AMPM) (http://www.ars.usda.gov/ba/bhnrc/fsrg). The AMPM was designed to provide an efficient and accurate means of collecting intakes for large-scale national surveys. The AMPM is a fully computerized recall method that uses a 5-step interview outlined below:

  1. Quick List - Participant recalls all foods and beverages consumed the day before the interview (midnight to midnight).
  2. Forgotten Foods - Participant is asked about consumption of foods commonly forgotten during the Quick List step.
  3. Time and Occasion - Time and eating occasion are collected for each food.
  4. Detail Cycle - For each food, a detailed description, amount eaten, and additions to the food are collected. Eating occasions and times between eating occasions are reviewed to elicit forgotten foods.
  5. Final Probe - Additional foods not remembered earlier are collected.

The AMPM includes an extensive compilation of standardized food-specific questions and possible response options. Routing of questions is based on previous responses. The AMPM is updated yearly to reflect the changing food supply and to address research needs from the data user community. Additional information about the AMPM is provided in Raper et al. (Raper et al., 2004).

The AMPM was validated in a large study and shown to be an effective method for collecting accurate group energy intake of adults. Completed in 2004, this extensive research project included 524 healthy, weight-stable volunteers, aged 30-69 years. The accuracy of the AMPM was evaluated by comparing reported energy intake (EI) to total energy expenditure (TEE) using the doubly labeled water technique (Moshfegh et al., 2008). Among the findings were that EI compared to TEE was under-reported by 11% overall, by less than 3% for normal weight subjects with body mass index (BMI) <25 and 16% for overweight subjects with BMI ≥ 25.

Additional studies provide evidence that the AMPM accurately measures group energy intake. Blanton (Blanton et al., 2006) reported that EI was not significantly different from TEE for a sample of 20 adult females. Rumpler and colleagues found that mean EIs were accurately reported for a sample of 12 adult males (Rumpler et al., 2008).

For additional information about the dietary interview component and related survey protocols, please go to the Survey Operations Manual, Consent Documents, Brochures site at:
http://www.cdc.gov/nchs/nhanes/nhanes2007-2008/current_nhanes_07_08.htm

Quality Assurance & Quality Control

All dietary interviewers were required to complete an intensive one-week training course and to conduct supervised practice interviews before working independently in the field. Retraining sessions were conducted annually to reinforce the proper protocols and technique.

Interviewers were monitored throughout the data collection period. Monitoring consisted of the following:

Data Processing and Editing

Interview data files were sent electronically from the field and were imported into Survey Net, a computer-assisted food coding and data management system developed by USDA (Raper et al., 2004).

USDA's Food and Nutrient Database for Dietary Studies, 4.1 (FNDDS 4.1), was used for processing the 2007-2008 intakes (http://www.ars.usda.gov/ba/bhnrc/fsrg). The FNDDS includes comprehensive information that can be used to code individual foods and portion sizes reported by participants and also includes nutrient values for calculating nutrient intakes. The underlying nutrient values for FNDDS 4.1 were based on values in the USDA National Nutrient Database for Standard Reference, release 22, produced by USDA’s Nutrient Data Lab (http://www.ars.usda.gov/nutrientdata). FNDDS values are updated for every 2-year WWEIA, NHANES release cycle. FNDDS 4.1 corresponds with WWEIA 2007-2008. Additional information about the FNDDS and related tools is available on the Food Surveys Research Group website (Raper et al., 2004; Anand et al., 2006; Bodner-Montville et al, 2006; Ahuja et al., 2008).

Coders were required to pass a certification test after the initial training. They were routinely monitored to ensure the quality and completeness of their work. Approximately 10 percent of the coder's work was randomly selected to be independently coded by another coder. Results from the two codings were compared and adjudicated, if necessary.

After intake data were coded, various types of reviews were conducted to ensure the quality of the data. An overview of quality assurance procedures conducted during the data processing stage is available in Anand, et al. (Anand et al., 2006). Examples of reviews include the following:

During data processing, the following edits were made to ensure the logical consistency and analytic usefulness of the data:

Analytic Notes

Each Individual Foods file (Day 1 and Day 2) is comprised of food records. For most survey participants, there are multiple records in each file. For each Total Nutrient Intakes file (Day 1 and Day 2) there is one record for each participant. These files can be linked with other NHANES files by the respondent sequence number (SEQN).

Variable names: For data collected on both Day 1 and Day 2, variable names are differentiated by having the number "1" or "2" in the third position of the variable name to identify the collection day. For example, the USDA food code variable (in the Individual Foods File), which identifies the food reported by the participant, is named DR1IFDCD in the Day 1 file and DR2IFDCD in the Day 2 file. Appendices 2 and 5 list the Day 1 and Day 2 variable names for the Individual Foods file and the Total Nutrient Intakes file, respectively.

Names for the following variables are the same for both days in the Individual Foods file and the Total Nutrient Intakes file: 

Variables with the Same Name for Both Days in the Dietary Interview Files
Day 1 and Day 2 variable name Label
SEQN Respondent sequence number
WTDRD1 Dietary day one sample weight
WTDR2D Dietary two-day sample weight
DRABF Breast-fed infant (either day)
DRDINT Number of days of intake

Number of days of intake: Because two days of data are included in the 2007-2008 release, a variable has been included to indicate the number of days of intake available for each participant. The variable name is DRDINT. For 2007-2008, 9,255 respondents provided complete dietary intakes for Day 1 and of those providing the Day 1 data, 7,838 provided complete dietary intakes for Day 2.

Dietary recall status code: A status code (DR1DRSTZ or DR2DRSTZ) is used in both the Individual Foods and Total Nutrient Intake files to indicate the quality and completeness of a survey participant's response to the dietary recall section. The codes are the following: 

1 = Reliable and met the minimum criteria

2 = Not reliable or did not meet the minimum criteria

3 [Code 3 is not included in the current datasets. It was only used for data from the 1999-2000 survey cycle.]

4 = Reported consuming breast milk

5 = Not done

Although there are four possible values, only codes 1 and 4 appear in the Individual Foods file. In addition to the status code described above, the variable DR1_300 and DR2_300 in the Total Nutrients file, denotes the participant's assessment of whether the amount of food he/she consumed on the recall day was usual, much more than usual, or much less than usual.

Participants who reported consuming only water, no food or other beverages: Beginning in 2005-2006, information on all waters were collected during the 24-hour recall and reported in the Individual Foods file, including tap water and bottled water. Therefore, records are now included in the Individual Foods file for participants who consumed only water. There are 5 such individuals in the 2007-2008 datasets, all in the Day 2 data. Their dietary recall status variable for the day is coded as "1" (complete and reliable) in the Total Nutrients file and the total number of foods is coded based on how many times water was reported. There are 5 nutrients for the tap water and plain bottled water codes that have values greater than zero - calcium, magnesium, sodium, zinc, and copper. Individuals with just water intake and no food intake will have zero energy intake for the day. Depending on the type of analysis, these individuals may need to be excluded from the analysis.

Participants who reported consuming no water, food or other beverages: In addition to the survey respondents consuming just water, there are 2 intakes (1 intake in Day 1 and 1 intake in Day 2) with no water, food or other beverage records for the day. These records are not included in the Individual Foods File for these intakes. However, their dietary recall status is coded as complete and reliable and their records will have zero values for all nutrients in the Total Nutrients file.

Number of days between the intake day and the day of family interview: A variable has been added in each of the four files (DR1DBIH for day 1 files and DR2DBIH for day 2 files) to indicate the number of days between the intake day and the day that the family questionnaire was administered in the household. A positive value in DR1BHIH or DR2BHIH indicates the family interview occurred prior to the day the intake was recalled for. In the survey, most of the family interviews were done before the participant came to the MEC and received the dietary interview. A value of “0” in DR1BHIH or DR2BHIH indicates the family interview occurred on the same date the intake was recalled for. A negative value (i.e., DR1BHIH<0 or DR2BHIH<0) means that the family interview occurred after the day the intake recalled for.

Food source: The source of each food (where it was obtained, e.g., from a store, fast food restaurant, cafeteria) is included with the 2007-2008 release as it was for 2005-2006. The variable names are DR1FS and DR2FS and are located in the Individual Foods file. The code descriptions for this variable are:

Code Description for Source of Food Variable
Code Description
1 Store
2 Restaurant with waiter/waitress
3 Restaurant fast food/pizza
4 Bar/tavern/lounge
5 Restaurant, no additional information
6 Cafeteria not at school
7 Cafeteria at school
8 Child care center
9 Family/adult day care center
10 Soup kitchen/shelter/food pantry facility
11 Meals on Wheels
12 Community food program – other
13 Community program, no additional information
14 Vending machine
15 Common coffee pot or snack tray
16 From someone else/gift
17 Mail order purchase
18 Residential dining facility
19 Grown or caught by you or someone you know
20 Fish caught by you or someone you know
24 Sport, recreation, or entertainment
25 Street vendor, vending truck
26 Fundraiser sales
91 Other, specify

Eating occasion: The variables DR1_030Z and DR2_030Z are located in the Individual Foods file. The code descriptions for the eating occasion variables are shown in the table below. 

Code Description for Eating Occasion Variable
Code Description
1 Breakfast
2 Lunch
3 Dinner
4 Supper
5 Brunch
6 Snack
7 Beverage/Drink
8 Feeding-infant only
9 Extended consumption
10 Desayuno
11 Almuerzo
12 Comida
13 Merienda
14 Cena
15 Entre comida
16 Botana
17 Bocadillo
18 Tentempie
19 Bebida
91 Other

Eating occasion is designated by the respondent. During the interview, a list of eating occasion names is available to the respondent for reference. However, eating occasion names are not defined for the respondent and the interpretation may differ from one person to another.

Combination foods: Foods that are eaten in combination with other foods, such as cereal with milk, are identified by a combination food type (DR1CCMTX) and a combination food number (DR1CCMNM). They are located in the Individual Foods file. About half of the foods reported in 2007-2008 were consumed in combination with other foods. The code descriptions for this variable are the following:

Code Description for Type of Combination Food Variable
Code Description
0 Non-combination food
1 Beverage w/ additions
2 Cereal w/ additions
3 Bread/baked prod w/ additions
4 Salad
5 Sandwiches
6 Soup
7 Frozen meals
8 Ice cream/frozen yogurt w/ additions
9 Dried beans and vegetable w/ additions
10 Fruit w/ additions
11 Tortilla products
12 Meat, poultry, fish
13 Lunchables®
14 Chips w/ additions
90 Other mixtures

Special diet: Information on whether the participant is currently on any kind of diet to lose weight or for other health-related reason and, if so, the type of diet, is included. The variable DRQSDIET identifies whether a participant is on a special diet. The variables DRQSDT1 through DRQSDT10 and DRQSDT91 identify the type of diet(s) that the participant is following. These variables can be found in the Total Nutrient Intakes file.

Note: A participant could report more than one type of diet, and all the responses were recorded. In 2003-2004 and 2005-2006, the variable DRQSDT1 denotes the type of diet the participant followed specifically for weight loss purposes, including a variety of low calorie diets, low carbohydrate diets, and/or high protein diets. In 2007-2008, 2 new variables have been added to allow participants to report "low carbohydrate diet (DRQSDT9)" and "high protein diet (DRQSDT10)" individually. The variable "DRQSDT1" is now used to denote a weight loss or low calorie diet.

Sample weights for dietary intake data: The NHANES participants were selected on the basis of a national probability design. In order to increase the number of participants for specific demographic groups, a multi-stage, unequal probability of selection design was implemented. All Hispanics were oversampled, not just Mexican Americans. In addition, for each of the race/ethnicity domains, the 12-15 and 16-19 year age domains were combined and the 40-59 year age minority domains were split into 10 year age domains 40-49 and 50-59. This has led to an increase in the number of participants aged 40+ and a decrease in 12-19 year olds from previous cycles. Lastly, pregnant women were no longer oversampled.

Sample weights are constructed that encompass the unequal probabilities of selection, as well as adjustments for non-participation by selected sample persons. In order to produce national, representative estimates, the appropriate sample weights must be used.

For the 2007-2008 NHANES, there were 12,943 persons selected; of these 9,762 were considered respondents to the MEC examination and data collection. However, 9,255 of the MEC respondents provided complete dietary intakes for Day 1. Furthermore, of those providing the Day 1 data, 7,838 provided complete dietary intakes for Day 2.

Most analyses of NHANES data use data collected in the MEC and the variable WTMEC2YR should be used for the sample weights. However, for the WWEIA dietary data, different sample weights are recommended for analysis. Although attempts are made to schedule MEC exams uniformly throughout the week, proportionally more exams occur on weekend days than on weekdays. Because food intake can vary by day of the week, use of the MEC weights would disproportionately represent intakes on weekends.

A set of weights WTDRD1 is provided that should be used when an analysis uses the Day 1 dietary recall data (either alone or when Day 1 nutrient data are used in conjunction with MEC data). The set of weights WTDRD1 is applicable to the 9,255 respondents with Day 1 data. Day 1 weights were constructed by taking the MEC sample weights (WTMEC2YR) and further adjusting for (a) the additional non-response and (b) the differential allocation by day of the week for the dietary intake data collection. These Day 1 weights are more variable than the MEC weights, and the sample size is smaller, so estimated standard errors using Day 1 data and Day 1 weights are larger than standard errors for similar estimates based on MEC weights.

When analysis is based on both days of dietary intake, only 7,838 sample persons have valid data. The NHANES protocol requires an attempt to collect the second day of dietary data at least 3 days after the first day, but the actual number of days between the two interviews is variable. A set of adjusted weights, WTDR2D, is to be used only when analysis uses both Day 1 and Day 2 dietary data. This two-day weight was constructed for the 7,838 respondents by taking the Day 1 weights (WTDRD1) and further adjusting for (a) the additional non-response for the second recall and (b) for the proportion of weekend-weekday combinations of Day 1 and Day 2 recalls.

Note that all sample weights are person-level weights and each set of dietary weights should sum to the same population control total as the MEC weights (WTMEC2YR). In addition, the MEC weights (WTMEC2YR) are appropriate for use in the analysis of the fish and shellfish consumption data (i.e., variables DRD340, DRD350A-K, DRD350AQ-JQ DRD360, DRD370A-V, and DRD370AQ-UQ) located in the Day 1 Total Nutrient Intake File (DR1TOT_E), if no other dietary data are included in the analysis. Additional explanation of sample weights and appropriate uses are included in the NHANES Analytic Guidelines (http://www.cdc.gov/nchs/nhanes/nhanes2003-2004/analytical_guidelines.htm). Please also refer to the on-line NHANES Tutorial (http://www.cdc.gov/nchs/tutorials) for further details on other analytic issues.

References

Appendix 1. Changes between WWEIA 2003-2004, WWEIA 2005-2006 and WWEIA 2007-2008

Item WWEIA 2003-2004 WWEIA 2005-2006 WWEIA 2007-2008
Number of days of intake data released on each respondent 2 days 2 days 2 days
Nutrients included Food energy and 62 nutrients/food components. "Added vitamin E" and "Added vitamin B12" were added. Food energy and 63 nutrients/food components. Total choline added. Food energy and 64 nutrients/food components. Vitamin D added.
Food source (Where food obtained) Collected and released. Codes for 23 food sources. Collected and released. Codes for 24 food sources; added “fundraiser sales”. Same as 2005-2006
Combination food types Codes for 15 combination types; added “chips with additions”. Same as 2003-2004 Same as 2003-2004
Eating occasion names (10 english, 10 spanish) 20 codes; 3 existing codes modified and 2 new codes. Same as 2003-2004 Same as 2003-2004
Special diet variables Collected and released. Same as 2003-2004 Collected and released; 2 new codes: Low carbohydrate diet and High protein diet.
Water consumed (does not include the moisture content of foods) Total amount of non-sweetened water collected after the 24-hour recall and reported in the Total Nutrient Intake files. Minerals in tap water and plain bottled water not included. All waters, including tap water and bottled water, were collected during the 24-hour recall and reported in the Individual Foods file, complete with food codes, gram weights and nutrient values. Summary water variables compatible with previous data cycles are included in the Total Nutrient Intake files with the exception of plain carbonated water. Same as 2005-2006
Number of intakes that include only water consumption for the day 3 intakes (1 intake in Day 1 and 2 intakes in Day 2 data), no records in Individual Foods file. 3 intakes (1 intake in Day 1 and 2 intakes in Day 2 data), records are included in Individual Foods file. 5 intakes (all in Day 2 data), records are included in Individual Foods file.
Number of intakes that include no water or food consumption for the day No such intake reported. No such intake reported. 2 intakes (1 intake in Day 1 and 1 intake in Day 2) with no food or water records for the day. Records are not included in the Individual Foods File for these intakes.
Eligible sample for questions on fish/ shellfish consumptions in the past 30 days Children 1-5 years and women 16-49 years of age. All examinees one year or older. Same as 2005-2006
Number of days between the intake day and the day of family interview Not calculated Not calculated Calculated and released; 2 new continuous variables calculated for both Day 1 and Day 2

 

Appendix 2. Variables in the Individual Foods Files (DR1IFF_E and DR2IFF_E) by Position

Day1 Name Day2 Name Variable Label
SEQN SEQN Respondent sequence number
WTDRD1 WTDRD1 Dietary day one sample weight
WTDR2D WTDR2D Dietary two-day sample weight
DR1ILINE DR2ILINE Food/Individual component number
DR1DRSTZ DR2DRSTZ Dietary recall status
DR1EXMER DR2EXMER Interviewer ID code
DRABF DRABF Breast-fed infant (either day)
DRDINT DRDINT Number of days of intake
DR1DBIH DR2DBIH # of days b/w intake and HH interview
DR1DAY DR2DAY Intake day of the week
DR1LANG DR2LANG Language respondent used mostly
DR1CCMNM DR2CCMNM Combination food number
DR1CCMTX DR2CCMTX Combination food type
DR1_020 DR2_020 Time of eating occasion (HH:MM)
DR1_030Z DR2_030Z Name of eating occasion
DR1FS DR2FS Source of food
DR1_040Z DR2_040Z Did you eat this meal at home?
DR1IFDCD DR2IFDCD USDA food code
DR1MC DR2MC Modification code
DR1IGRMS DR2IGRMS Grams
DR1IKCAL DR2IKCAL Energy (kcal)
DR1IPROT DR2IPROT Protein (gm)
DR1ICARB DR2ICARB Carbohydrate (gm)
DR1ISUGR DR2ISUGR Total sugars (gm)
DR1IFIBE DR2IFIBE Dietary fiber (gm)
DR1ITFAT DR2ITFAT Total fat (gm)
DR1ISFAT DR2ISFAT Total saturated fatty acids (gm)
DR1IMFAT DR2IMFAT Total monounsaturated fatty acids (gm)
DR1IPFAT DR2IPFAT Total polyunsaturated fatty acids (gm)
DR1ICHOL DR2ICHOL Cholesterol (mg)
DR1IATOC DR2IATOC Vitamin E as alpha-tocopherol (mg)
DR1IATOA DR2IATOA Added alpha-tocopherol (Vitamin E) (mg)
DR1IRET DR2IRET Retinol (mcg)
DR1IVARA DR2IVARA Vitamin A, RAE (mcg)
DR1IACAR DR2IACAR Alpha-carotene (mcg)
DR1IBCAR DR2IBCAR Beta-carotene (mcg)
DR1ICRYP DR2ICRYP Beta-cryptoxanthin (mcg)
DR1ILYCO DR2ILYCO Lycopene (mcg)
DR1ILZ DR2ILZ Lutein + zeaxanthin (mcg)
DR1IVB1 DR2IVB1 Thiamin (Vitamin B1) (mg)
DR1IVB2 DR2IVB2 Riboflavin (Vitamin B2) (mg)
DR1INIAC DR2INIAC Niacin (mg)
DR1IVB6 DR2IVB6 Vitamin B6 (mg)
DR1IFOLA DR2IFOLA Total Folate (mcg)
DR1IFA DR2IFA Folic acid (mcg)
DR1IFF DR2IFF Food folate (mcg)
DR1IFDFE DR2IFDFE Folate, DFE (mcg)
DR1ICHL DR2ICHL Total choline (mg)
DR1IVB12 DR2IVB12 Vitamin B12 (mcg)
DR1IB12A DR2IB12A Added vitamin B12 (mcg)
DR1IVC DR2IVC Vitamin C (mg)
DR1IVD DR2IVD Vitamin D (D2 + D3) (mcg)
DR1IVK DR2IVK Vitamin K (mcg)
DR1ICALC DR2ICALC Calcium (mg)
DR1IPHOS DR2IPHOS Phosphorus (mg)
DR1IMAGN DR2IMAGN Magnesium (mg)
DR1IIRON DR2IIRON Iron (mg)
DR1IZINC DR2IZINC Zinc (mg)
DR1ICOPP DR2ICOPP Copper (mg)
DR1ISODI DR2ISODI Sodium (mg)
DR1IPOTA DR2IPOTA Potassium (mg)
DR1ISELE DR2ISELE Selenium (mcg)
DR1ICAFF DR2ICAFF Caffeine (mg)
DR1ITHEO DR2ITHEO Theobromine (mg)
DR1IALCO DR2IALCO Alcohol (gm)
DR1IMOIS DR2IMOIS Moisture (gm)
DR1IS040 DR2IS040 SFA 4:0 (Butanoic) (gm)
DR1IS060 DR2IS060 SFA 6:0 (Hexanoic) (gm)
DR1IS080 DR2IS080 SFA 8:0 (Octanoic) (gm)
DR1IS100 DR2IS100 SFA 10:0 (Decanoic) (gm)
DR1IS120 DR2IS120 SFA 12:0 (Dodecanoic) (gm)
DR1IS140 DR2IS140 SFA 14:0 (Tetradecanoic) (gm)
DR1IS160 DR2IS160 SFA 16:0 (Hexadecanoic) (gm)
DR1IS180 DR2IS180 SFA 18:0 (Octadecanoic) (gm)
DR1IM161 DR2IM161 MFA 16:1 (Hexadecenoic) (gm)
DR1IM181 DR2IM181 MFA 18:1 (Octadecenoic) (gm)
DR1IM201 DR2IM201 MFA 20:1 (Eicosenoic) (gm)
DR1IM221 DR2IM221 MFA 22:1 (Docosenoic) (gm)
DR1IP182 DR2IP182 PFA 18:2 (Octadecadienoic) (gm)
DR1IP183 DR2IP183 PFA 18:3 (Octadecatrienoic) (gm)
DR1IP184 DR2IP184 PFA 18:4 (Octadecatetraenoic) (gm)
DR1IP204 DR2IP204 PFA 20:4 (Eicosatetraenoic) (gm)
DR1IP205 DR2IP205 PFA 20:5 (Eicosapentaenoic) (gm)
DR1IP225 DR2IP225 PFA 22:5 (Docosapentaenoic) (gm)
DR1IP226 DR2IP226 PFA 22:6 (Docosahexaenoic) (gm)

 

Appendix 3. List of Nutrients/Food Components (Unit)

Energy and Macronutrients

Food energy (kcal)
Protein (gm)
Carbohydrate (gm)
Fat, total (gm)
Alcohol (gm)

Sugars, total (gm)
Dietary fiber, total (gm)
Water (moisture) (gm)*

Saturated fatty acids, total (gm)
Monounsaturated fatty acids, total (gm)
Polyunsaturated fatty acids, total (gm)
Cholesterol (mg)

Individual fatty acids:
    4:0 (gm)
    6:0 (gm)
    8:0 (gm)
    10:0 (gm)
    12:0 (gm)
    14:0 (gm)
    16:0 (gm)
    18:0 (gm)
    16:1 (gm)
    18:1 (gm)
    20:1 (gm)
    22:1 (gm)
    18:2 (gm)
    18:3 (gm)
    18:4 (gm)
    20:4 (gm)
    20:5 n-3 (gm)
    22:5 n-3 (gm)
    22:6 n-3 (gm)

Vitamins, Minerals, and Other Components

Vitamin A as retinol activity equivalents (mcg)
Retinol (mcg)
Carotenoids:
    Carotene, alpha (mcg)
    Carotene, beta (mcg)
    Cryptoxanthin, beta (mcg)
    Lycopene (mcg)
    Lutein + zeaxanthin (mcg)
Vitamin E as alpha-tocopherol (mg)
    Added vitamin E as alpha-tocopherol (mg)
Vitamin D (D2 + D3) (mcg)
Vitamin K as phylloquinone (mcg)
Vitamin C (mg)
Thiamin (mg)
Riboflavin (mg)
Niacin (mg)
Vitamin B-6 (mg)
Folate, total (mcg)
    Folate as dietary folate equivalents (mcg)
    Folic acid (mcg)
    Food folate (mcg)
Choline, total (mg)
Vitamin B-12 (mcg)
    Added vitamin B-12 (mcg)

Calcium (mg)
Iron (mg)
Magnesium (mg)
Phosphorus (mg)
Potassium (mg)
Sodium (mg)
Zinc (mg)
Copper (mg)
Selenium (mcg)
Caffeine (mg)
Theobromine (mg)
__________________________________________________________________________

  * Value reflects moisture present in all foods, beverages, and water consumed as a beverage (variables DR1IMOIS, DR2IMOIS, DR1TMOIS, DR2TMOIS)

 

Appendix 4. Adding Food Code Descriptions or Modification Code Descriptions to Your Files

Two technical support files are included with the Individual Foods files: the Food Code Description file (DRXFCD_E) and the Modification Code Description file (DRXMCD_E).

The DRXFCD_E file includes abbreviated descriptions (up to 60 characters) and complete descriptions (up to 200 characters) associated with each USDA food code identified in the Individual Foods files. The DRXMCD_E file includes descriptions associated with each modification code identified in the Individual Foods files.

The Food Code Description file (DRXFCD_E) contains two variables:

DRDIFDCD a numeric value corresponding to DR1IFDCD in the file DR1IFF_E or DR2IFDCD in the file DR2IFF_E.

DRXFCLD a long description (up to 200 characters) of the food code.

The Modification Code Description file (DRXMCD_E) contains two variables:

DRDMC a numeric value corresponding to DR1MC in the file DR1IFF_E or DR2MC in the file DR2IFF_E.

DRMCD a description (up to 200 characters) of the modification code.

The following SQL code is an example of appending the modifications code description (here called DR1MCD) to one of the Individual Foods files. This code is for SAS® Proc SQL. Other SQL implementations may be different. This same technique may be used for the Food Code Description file as well.

        proc sql; 
          create table dr1iff_e_plus as 
          select a.*, b.drxmcd as dr1mcd 
          from nhanes.dr1iff_e a 
          left join 
          nhanes.drxmcd_e b 
          on a.dr1mc = b.drxmc 
          order by seqn, dr1iline; 
        quit;

SAS® users may wish to use Proc Format to assign labels to the food codes or to the modification codes. The following example assigns a permanent format to the food code based on the short description. It is assumed that the user has stored the Individual Foods files and the Food Code Description file in a library called NHANES and wishes to store the formats there as well.

       options fmtsearch = (NHANES);

       data DRXFMT; 
         set NHANES.DRXFCD_E; 
         retain FMTNAME 'DRIFDCD'; 
         rename DRDIFDCD = start; 
         rename DRXFCSD  = value; 
         drop DRXFCLD; 
       run;

       proc format cntlin = DRXFMT 
         library = NHANES; 
       run;

       proc datasets lib = NHANES; 
         modify DR1IFFC; 
         format DR1IFDCD DRDIFDCD.; 
         modify DR2IFFC; 
         format DR2IFDCD DRDIFDCD.; 
       quit;

__________________________________________________________________________

  SAS® is a registered trademark of SAS Institute, Inc.

 

Appendix 5. DR1TOT_E and DR2TOT_E Variables by Position

Day1 Name Day2 Name Variable Label
SEQN SEQN Respondent sequence number
WTDRD1 WTDRD1 Dietary day one sample weight
WTDR2D WTDR2D Dietary two-day sample weight
DR1DRSTZ DR2DRSTZ Dietary recall status
DR1EXMER DR2EXMER Interviewer ID code
DRABF DRABF Breast-fed infant (either day)
DRDINT DRDINT Number of days of intake
DR1DBIH DR2DBIH # of days b/w intake and HH interview
DR1DAY DR2DAY Intake day of the week
DR1LANG DR2LANG Language respondent used mostly
DR1MNRSP DR2MNRSP Main respondent for this interview
DR1HELPD DR2HELPD Helped in responding for this interview
DBQ095Z N/A Type of table salt used
DBD100 N/A How often add salt to food at table
DRQSPREP N/A Salt used in preparation?
DRQSDIET N/A On special diet?
DRQSDT1 N/A Weight loss/Low calorie diet
DRQSDT2 N/A Low fat/Low cholesterol diet
DRQSDT3 N/A Low salt/Low sodium diet
DRQSDT4 N/A Sugar free/Low sugar diet
DRQSDT5 N/A Low fiber diet
DRQSDT6 N/A High fiber diet
DRQSDT7 N/A Diabetic diet
DRQSDT8 N/A Weight gain/Muscle building diet
DRQSDT9 N/A Low carbohydrate diet
DRQSDT10 N/A High protein diet
DRQSDT91 N/A Other special diet
DR1TNUMF DR2TNUMF Number of foods reported
DR1TKCAL DR2TKCAL Energy (kcal)
DR1TPROT DR2TPROT Protein (gm)
DR1TCARB DR2TCARB Carbohydrate (gm)
DR1TSUGR DR2TSUGR Total sugars (gm)
DR1TFIBE DR2TFIBE Dietary fiber (gm)
DR1TTFAT DR2TTFAT Total fat (gm)
DR1TSFAT DR2TSFAT Total saturated fatty acids (gm)
DR1TMFAT DR2TMFAT Total monounsaturated fatty acids (gm)
DR1TPFAT DR2TPFAT Total polyunsaturated fatty acids (gm)
DR1TCHOL DR2TCHOL Cholesterol (mg)
DR1TATOC DR2TATOC Vitamin E as alpha-tocopherol (mg)
DR1TATOA DR2TATOA Added alpha-tocopherol (Vitamin E) (mg)
DR1TRET DR2TRET Retinol (mcg)
DR1TVARA DR2TVARA Vitamin A, RAE (mcg)
DR1TACAR DR2TACAR Alpha-carotene (mcg)
DR1TBCAR DR2TBCAR Beta-carotene (mcg)
DR1TCRYP DR2TCRYP Beta-cryptoxanthin (mcg)
DR1TLYCO DR2TLYCO Lycopene (mcg)
DR1TLZ DR2TLZ Lutein + zeaxanthin (mcg)
DR1TVB1 DR2TVB1 Thiamin (Vitamin B1) (mg)
DR1TVB2 DR2TVB2 Riboflavin (Vitamin B2) (mg)
DR1TNIAC DR2TNIAC Niacin (mg)
DR1TVB6 DR2TVB6 Vitamin B6 (mg)
DR1TFOLA DR2TFOLA Total Folate (mcg)
DR1TFA DR2TFA Folic acid (mcg)
DR1TFF DR2TFF Food folate (mcg)
DR1TFDFE DR2TFDFE Folate, DFE (mcg)
DR1TCHL DR2TCHL Total choline (mg)
DR1TVB12 DR2TVB12 Vitamin B12 (mcg)
DR1TB12A DR2TB12A Added vitamin B12 (mcg)
DR1TVC DR2TVC Vitamin C (mg)
DR1TVD DR2TVD Vitamin D (D2 + D3) (mcg)
DR1TVK DR2TVK Vitamin K (mcg)
DR1TCALC DR2TCALC Calcium (mg)
DR1TPHOS DR2TPHOS Phosphorus (mg)
DR1TMAGN DR2TMAGN Magnesium (mg)
DR1TIRON DR2TIRON Iron (mg)
DR1TZINC DR2TZINC Zinc (mg)
DR1TCOPP DR2TCOPP Copper (mg)
DR1TSODI DR2TSODI Sodium (mg)
DR1TPOTA DR2TPOTA Potassium (mg)
DR1TSELE DR2TSELE Selenium (mcg)
DR1TCAFF DR2TCAFF Caffeine (mg)
DR1TTHEO DR2TTHEO Theobromine (mg)
DR1TALCO DR2TALCO Alcohol (gm)
DR1TMOIS DR2TMOIS Moisture (gm)
DR1TS040 DR2TS040 SFA 4:0 (Butanoic) (gm)
DR1TS060 DR2TS060 SFA 6:0 (Hexanoic) (gm)
DR1TS080 DR2TS080 SFA 8:0 (Octanoic) (gm)
DR1TS100 DR2TS100 SFA 10:0 (Decanoic) (gm)
DR1TS120 DR2TS120 SFA 12:0 (Dodecanoic) (gm)
DR1TS140 DR2TS140 SFA 14:0 (Tetradecanoic) (gm)
DR1TS160 DR2TS160 SFA 16:0 (Hexadecanoic) (gm)
DR1TS180 DR2TS180 SFA 18:0 (Octadecanoic) (gm)
DR1TM161 DR2TM161 MFA 16:1 (Hexadecenoic) (gm)
DR1TM181 DR2TM181 MFA 18:1 (Octadecenoic) (gm)
DR1TM201 DR2TM201 MFA 20:1 (Eicosenoic) (gm)
DR1TM221 DR2TM221 MFA 22:1 (Docosenoic) (gm)
DR1TP182 DR2TP182 PFA 18:2 (Octadecadienoic) (gm)
DR1TP183 DR2TP183 PFA 18:3 (Octadecatrienoic) (gm)
DR1TP184 DR2TP184 PFA 18:4 (Octadecatetraenoic) (gm)
DR1TP204 DR2TP204 PFA 20:4 (Eicosatetraenoic) (gm)
DR1TP205 DR2TP205 PFA 20:5 (Eicosapentaenoic) (gm)
DR1TP225 DR2TP225 PFA 22:5 (Docosapentaenoic) (gm)
DR1TP226 DR2TP226 PFA 22:6 (Docosahexaenoic) (gm)
DR1_300 DR2_300 Compare food consumed yesterday to usual
DR1_320Z DR2_320Z Total plain water drank yesterday (gm)
DR1_330Z DR2_330Z Total tap water drank yesterday (gm)
DR1BWATZ DR2BWATZ Total bottled water drank yesterday (gm)
DR1TWS DR2TWS Tap water source
DRD340 N/A Shellfish eaten during past 30 days
DRD350A N/A Clams eaten during past 30 days
DRD350AQ N/A # of times clams eaten in past 30 days
DRD350B N/A Crabs eaten during past 30 days
DRD350BQ N/A # of times crabs eaten in past 30 days
DRD350C N/A Crayfish eaten during past 30 days
DRD350CQ N/A # of times crayfish eaten past 30 days
DRD350D N/A Lobsters eaten during past 30 days
DRD350DQ N/A # of times lobsters eaten past 30 days
DRD350E N/A Mussels eaten during past 30 days
DRD350EQ N/A # of times mussels eaten in past 30 days
DRD350F N/A Oysters eaten during past 30 days
DRD350FQ N/A # of times oysters eaten in past 30 days
DRD350G N/A Scallops eaten during past 30 days
DRD350GQ N/A # of times scallops eaten past 30 days
DRD350H N/A Shrimp eaten during past 30 days
DRD350HQ N/A # of times shrimp eaten in past 30 days
DRD350I N/A Other shellfish eaten past 30 days
DRD350IQ N/A # of times other shellfish eaten
DRD350J N/A Other unknown shellfish eaten past 30 d
DRD350JQ N/A # of times other unknown shellfish eaten
DRD350K N/A Refused on shellfish eaten past 30 days
DRD360 N/A Fish eaten during past 30 days
DRD370A N/A Breaded fish products eaten past 30 days
DRD370AQ N/A # of times breaded fish products eaten
DRD370B N/A Tuna eaten during past 30 days
DRD370BQ N/A # of times tuna eaten in past 30 days
DRD370C N/A Bass eaten during past 30 days
DRD370CQ N/A # of times bass eaten in past 30 days
DRD370D N/A Catfish eaten during past 30 days
DRD370DQ N/A # of times catfish eaten in past 30 days
DRD370E N/A Cod eaten during past 30 days
DRD370EQ N/A # of times cod eaten in past 30 days
DRD370F N/A Flatfish eaten during past 30 days
DRD370FQ N/A # of times flatfish eaten past 30 days
DRD370G N/A Haddock eaten during past 30 days
DRD370GQ N/A # of times haddock eaten in past 30 days
DRD370H N/A Mackerel eaten during past 30 days
DRD370HQ N/A # of times mackerel eaten past 30 days
DRD370I N/A Perch eaten during past 30 days
DRD370IQ N/A # of times perch eaten in past 30 days
DRD370J N/A Pike eaten during past 30 days
DRD370JQ N/A # of times pike eaten in past 30 days
DRD370K N/A Pollock eaten during past 30 days
DRD370KQ N/A # of times pollock eaten in past 30 days
DRD370L N/A Porgy eaten during past 30 days
DRD370LQ N/A # of times porgy eaten in past 30 days
DRD370M N/A Salmon eaten during past 30 days
DRD370MQ N/A # of times salmon eaten in past 30 days
DRD370N N/A Sardines eaten during past 30 days
DRD370NQ N/A # of times sardines eaten past 30 days
DRD370O N/A Sea bass eaten during past 30 days
DRD370OQ N/A # of times sea bass eaten past 30 days
DRD370P N/A Shark eaten during past 30 days
DRD370PQ N/A # of times shark eaten in past 30 days
DRD370Q N/A Swordfish eaten during past 30 days
DRD370QQ N/A # of times swordfish eaten past 30 days
DRD370R N/A Trout eaten during past 30 days
DRD370RQ N/A # of times trout eaten in past 30 days
DRD370S N/A Walleye eaten during past 30 days
DRD370SQ N/A # of times walleye eaten in past 30 days
DRD370T N/A Other fish eaten during past 30 days
DRD370TQ N/A # of times other fish eaten past 30 days
DRD370U N/A Other unknown fish eaten in past 30 days
DRD370UQ N/A # of times other unknown fish eaten
DRD370V N/A Refused on fish eaten past 30 days