FoodData Central (Formerly USDA National Nutrient Database for Standard Reference)

Created and maintained by the US Department of Agriculture this 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. Contains data on 6,220 food items and up to 117 food components. The database is downloadable via the USDA web site; files required to search the databases are also available for download.