castoreum

Beavers were hunted to extinction in Britain 400 years ago for their meat, furry water-resistant pelts and a substance they secrete called castoreum - used in food, medicine and perfume.

"They were hunted for predominantly their fur but also for the castoreum which is an internal gland that was used for medicinal purposes and, until very recently, in perfumes," said Robert Needham, restoration manager at Beaver Trust.

To harvest castoreum, trappers kill beavers and remove their castor glands, which are dried and crushed.

They then use alcohol to extract castoreum, similar to how vanilla is removed from the plant, Francl says.

For over 2,000 years, people have turned to castoreum to cure all sorts of maladies, including fevers, stomach issues, and mental illnesses.