What Is USDA FoodData Central? Where Our Food Data Comes From

Food composition data has to come from somewhere. For the pages under /nutrition, it comes from USDA FoodData Central, run by the U.S. Department of Agriculture. It is a public-domain database that records how much of each nutrient a food contains, with the release behind each record.

FoodData Central is called FDC for short, and every food in it has an FDC id: a number that points to exactly one record. That id is how our pages stay checkable. Each food page links its FDC record, so you can open the source and compare.

The datasets we read

FDC is several datasets under one roof, and the difference matters. We read three. Foundation Foods is the newer dataset. SR Legacy is the long-running national reference table, final since April 2018. FNDDS, the Food and Nutrient Database for Dietary Studies, covers mixed dishes as people eat them, such as a casserole or a sandwich. We prefer SR Legacy or Foundation, and use FNDDS for prepared dishes.

Of the 461 foods on the site, 403 come from SR Legacy, 2 from Foundation Foods and 56 from FNDDS. A fourth dataset, Branded Foods, holds manufacturer label data. We deliberately do not use it for the food pages.

From record to page

A script reads the downloaded USDA files and writes one data file per food. Nothing is typed by hand, and running it again on the same files gives the same output. For each food a person chooses one FDC id that matches the state the page means: a page that says "cooked" uses the cooked record. The id is a choice, but the values under it are USDA's.

USDA reports every nutrient per 100 grams of edible food, and that is what we store without adjusting. A nutrient USDA did not report is kept as missing, never as zero. The steps are written out on how we calculate.

Worked example

Take almonds. The page uses FDC id 170567, which USDA describes as "Nuts, almonds", and reads 579 kcal per 100 grams from that record. Anything else on the page, such as a handful in grams or an ounce, is a straight proportion of those per-100-gram values, so the page and the underlying record cannot disagree. The same figures feed the protein list and derived values like net carbs.

What FoodData Central does not tell you

A database record describes a typical sample of a food, not the one on your plate. Brands, ripeness, growing conditions and cooking all move the true value, which is why packaged foods are better read from their own label. The values are also a snapshot: USDA updates records, and each of our pages states the date it was retrieved.

When you photograph or describe a meal in the app, the numbers are estimates matched against USDA candidates, and the app shows them to you to check. This page is general information about a data source, not nutrition advice, and our full list of outside sources is on sources.