Methods Used to Develop the Tool and Nutrient/Food Group Database
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The list of foods, beverages, supplements, and portion sizes in the DHQ III are based on analyses of combined data from 24-hour recalls reported in the 2007-08, 2009-10, and 2011-12, 2013-14 National Health and Nutrition Examination Surveys (NHANES).
The NHANES foods and beverages reported on 24-hour dietary recalls were placed into cognitively and nutritionally similar food groups and analyzed for their contribution to nutrient intakes to determine the list of foods and beverages to be included in the questionnaire. Those food groups selected for inclusion in DHQ III include many different individual foods recorded on recalls that are subsumed by the line items. For example, for the line item, "lasagna, stuffed shells, stuffed manicotti, ravioli, or tortellini," the NHANES recall data were analyzed to provide a mean nutrient or food group value, for each portion size and both genders, based on distributions of all reported intakes of the various individual food codes comprising the food group lasagna, stuffed shells, etc., reported on 24-hour recalls in NHANES. This produced a single nutrient or food group value by portion size and gender for each food on the DHQ III.
Nutrient values were not computed separately by age group because our research showed that separate nutrient values by age group did not improve estimates.
The DHQ III nutrient and food group values were derived from the following nutrient and food group databases:
- USDA's Food and Nutrient Databases for Dietary Studies (FNDDS) (2007-08, 2009-10, and 2011-12, 2013-14)
- USDA's Food Pattern Equivalents Databases (FPED) (2007-08, 2009-10, and 2011-12, 2013-14)
- University of Minnesota’s Nutrient Database for Research (NDSR) (2017)
The nutrient database [CSV - 2.30 MB] for DHQ III relies primarily on USDA’s Food and Nutrient Database for Dietary Studies (FNDDS). It has been enhanced, however, with nutrients that are unavailable in FNDDS using the Nutrition Data System for Research (NDSR) database. To add nutrient values from NDSR, USDA FNDDS food codes were matched to NDSR food codes and nutrients were derived using methods identical to methods used to obtain FNDDS nutrients. It is recommended that researchers use the same nutrient database when looking at nutrients and their subgroups. For example, soluble and insoluble fiber are subgroups of dietary fiber found in the NDSR but not the FNDDS database. Therefore, in researching these subgroups, researchers should use the total dietary fiber variable derived from NDSR, even though a total dietary fiber variable derived from the USDA database is included in the DHQ III output files.
In the DHQ III nutrient database, nutrients derived from NDSR vs. USDA, FNDDS are clearly indicated by the terms “USDA” or “NDSR” in the variable names. NDSR nutrients were first added in May 2019. Researchers with DHQ III data collected prior to this date can rerun their data to obtain data files that include NDSR nutrients.