Download the full ascii version of the USDA Nutrient Database, available from
http://www.ars.usda.gov/nutrientdata or from http://nut.sourceforge.net, and unzip it in some directory.
Then, run "update-nut" to create or upgrade the NUT code in the SQLite database that runs the application
in the same directory as the USDA Nutrient Database. If upgrading, you have to be in the same directory
as the "nut.db" file. After this step, "update-nut" is not required for anything. Updating the NUT code
with "update-nut" is independent of updating the USDA database, although it is certainly possible that
the USDA could change the format of their tables, so that a later version of "update-nut" would be
required in order to read their tables or display new nutrients. The main idea is that your personal
data is permanent, even though the application code and USDA tables can change as necessary.