The USDA National Nutrient Database for Standard Reference (SR) is the major source of food composition data in the United States. It provides the foundation for most food composition databases in the public and private sectors. As information is updated, new versions of the database are released. This version, Release 20 (SR20), contains data on 7,519 food items and up to 140 food components. It replaces SR19 issued in August 2006. SR20 includes composition data for all the food groups and nutrients published in the 21 volumes of AAgriculture Handbook 8@ (U.S. Department of Agriculture 1976B92), and its four supplements (U.S. Department of Agriculture 1990B93), which superseded the 1963 edition (Watt and Merrill, 1963). Since 1992, updated data have been published electronically on the USDA Nutrient Data Laboratory (NDL) website. SR20 supersedes all previous releases, including the printed versions, in the event of any differences.
With the first release of data from the new Nutrient Databank System (NDBS) in July 2001, formats were changed and fields added to improve the descriptive information for food items and the statistical information about the nutrient values. While data in previous releases have been moved to the new NDBS, they may not have been updated through the complete system. Therefore, many of these new fields contain data only for those items that have been processed through the new NDBS and it will take a number of years before they are populated for most food items in the database.
Data have been compiled from published and unpublished sources. Published sources include the scientific and technical literature. Unpublished data include those obtained from the food industry, other government agencies, and research conducted under contracts initiated by USDA Agricultural Research Service (ARS). These analyses are currently conducted under the National Food and Nutrient Analysis Program (NFNAP), in cooperation with the National Cancer Institute and 16 other offices and institutes of the National Institutes of Health (Pehrsson et al., 2000). Data from the food industry represents the nutrient content of a specific food or food product at the time the data is sent to NDL. The values may change due to reformulations or other processing changes by individual companies between the time that SR is released and the next update of the database. Values in the database may be based on the results of laboratory analyses or calculated by using appropriate algorithms, factors, or recipes, as indicated by the source code in the Nutrient Data file. Not every food item contains a complete nutrient profile.