If the vagueness of the term “natural flavors” on ingredient lists has ever left you feeling uneasy, your gut may have been trying to tell you something. It turns out that one of the ingredients that can be grouped into this cryptic category is castoreum, which is basically a beaver’s anal secretion.
Beavers typically use castoreum to mark their territory. It is a yellow-ish liquid found in the beaver’s castor sac located in between the pelvis and base of the tail. Because of its location the gland often contains anal secretions and urine. Gross as it may be, it is nontoxic.
Due to the beaver’s healthy diet of leaves and bark, the secretion doesn’t stink. In fact, it is said to have a pleasant, musky aroma. It’s because of castoreum’s pleasing scent that it has been used as a flavoring in foods, mainly to enhance vanilla, raspberry or strawberry flavors. (It’s used in perfumes, too.)
Before you ban all vanilla-, strawberry- and raspberry-flavored products from your diet, you should know that castoreum is not a common ingredient in mass-produced foods. On average, only 292 pounds of the stuff is used in a year. But it is out there, and it does not have to be labeled.