As information is updated, new versions of the database are released. This version, Release 28 (SR28), contains data on 8,789 food items and up to 150 food components. It replaces SR27, initially issued in August 2014 and revised in May 2015.
Updated data have been published electronically on the USDA Nutrient Data Laboratory (NDL) website since 1992. SR28 includes composition data for all the food groups and nutrients published in the 21 volumes of “Agriculture Handbook 8” (US Department of Agriculture 1976-92), and its four supplements (US Department of Agriculture 1990-93), which superseded the 1963 edition (Watt and Merrill, 1963). SR28 supersedes all previous releases, including the printed versions, in the event of any differences. In July 2001, when NDL converted to a new version of its Nutrient Databank System (NDBS), 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 all food items in the database.
As part of this upgrade and in various modifications to the NDBS performed since then, various checks have been built into the system to ensure data integrity and quality control. Additional checks are performed after the SR files have been disseminated from the NDBS. These checks include making sure that, to the extent possible, all fields are complete.
Another check is to make sure that various calculations are completed and correct, such as calculating carbohydrate by difference; calculating energy by multiplying protein, fat and carbohydrate by the appropriate factors; and calculating vitamin A from individual carotenoids. Other checks include making sure that values for related nutrients are complete. For example, if there are individual fatty acids, there should also be values for total saturated fatty acids, total monounsaturated fatty acids, and total polyunsaturated fatty acids. With some adaptation, the procedures described in FAO/INFOODS Guidelines for Checking Food Composition Data prior to the Publication of a User Table / Database (FAO/INFOODS, 2012) and Ahuja and Perloff (2008) have been used. Nutrient values are also compared from release to release to make sure any changes in the values can be explained. Reasons for these changes include new data generated by the National Food and Nutrient Analysis Program (NFNAP) analyses or provided by manufacturers, reformulations by the manufacturer, better food sampling, and changes in weighting based on market share data. Quality control procedures associated with the analytical data are described in the discussion of NFNAP under Notes on Foods.