Did you know that human urine contains traces of saltpetre? In days of yore, urine was collected and the saltpetre extracted to cure meats such as bacon.
And no, I'm taking the proverbial
. 'Tis true.
Nowadays you're probably better off eating bacon and other meats which haven't been preserved with saltpetre. Common salt (which is used for most home-cured bacon) does just as good a job of preservation although it allows the meat to turn slightly greyish. Saltpetre leaves a lovely meaty red colour but it carries an avoidable cancer risk.
Apologies to Rik for discussing salted meats!