Several data sources were used to create a profile of each food in the database. The primary sources of data and key adjustments to the data are listed below.
Serving Sizes and Nutrients
Common serving sizes were selected for each food from the following USDA, Agricultural Research Service (ARS) databases:
- USDA Food and Nutrient Database for Dietary Studies, 5.0
- USDA National Nutrient Database for Standard Reference, 24
Serving sizes were standardized across all forms of a food to allow comparison of all nutrient and price values.
Nutrient values were obtained from the USDA, ARS databases listed above for most foods. For foods without nutrient values in the USDA, ARS databases, average nutrient values were calculated for the top three selling foods using nutrient data available from the following proprietary database:
Access to the Gladson Nutrition Database was made available through an agreement with the U.S. Department of Agriculture, Economic Research Service (ERS).
Food groups were obtained from the following USDA, ARS database:
The FPED data corresponds to the total foods and beverages reported as consumed in What We Eat in America dietary intake portion of the National Nutrition Health and Examination Survey, 2009-2010. Not all foods on the website have food group data available from the USDA databases.
For most foods, prices were obtained from the USDA, CNPP Food Prices Database, 2009. Earlier versions of the CNPP Food Prices Database are available here:
The initial version of the Food Value Analysis data used the 2003-2004 version of the Food Prices Database, adjusted for inflation. In November 2015, the prices were updated using the 2009 version of the Food Prices Database (obtained directly from USDA).
For a few foods (10 items total), prices were not available in the USDA, CNPP Food Prices Database, and therefore average prices were calculated using the following proprietary database:
All food prices were adjusted to 2011 values using the Consumer Price Index for food at home obtained from the U.S. Bureau of Labor Statistics.
Access to the Nielsen Homescan data was made available through an agreement with the U.S. Department of Agriculture, Economic Research Service (ERS).
Food Preparation Time
Food preparation times for home recipes were obtained and averaged from the following sources:
- Betty Crocker Cookbook: 1500 Recipes for the Way You Cook Today
- Better Homes and Gardens New Cookbook, 15th Edition
- FoodNetwork.com's "Recipes and Cooking"
For foods prepared from packaged foods, we obtained preparation times from package instructions. For foods without preparation times from recipes or packages, we prepared the foods and recorded the time required for preparation.
Food Safety Concerns
Food safety concerns were determined and assigned based primarily on information posted at the following locations:
Shelf-life estimates were obtained from the following Cooperative Extension publications:
- Colorado State University Cooperative Extension (Kendall, 2012)
- Texas Agricultural Extension Service (Van Laaneen, 2011)
- Virginia Cooperative Extension (Boyer, 2009)
For packaged foods, we calculated the length of time until the use-by or sell-by date.