Castoreum is a natural flavoring that can be used in vanilla or strawberry-flavored foods. But it’s not a lab-made creation, neither is it a unique-sounding plant.

It’s the name of an excretion from the anal castor sacs of beavers. This substance has been used for centuries in medicines and soaps in addition to food. But you won’t find “castoreum” listed as an ingredient in ice cream or strawberry syrup. It’s often grouped under the term “natural flavorings.”

Using Beaver Sac Excretion as a Vanilla Flavoring

However, there’s no need to stress about how much castoreum you may have unknowingly consumed. It’s deemed safe by the FDA, which claimed, “a long historical use of castoreum extract as a flavoring and fragrance ingredient has resulted in no reports of human adverse reactions.” But companies avoid it for several reasons.

For one, it prevents their products from being certified kosher. And even more importantly, it’s costly to use beaver sac excretion. “In the flavor industry, you need tons and tons of material to work with,” says flavor chemist Gary Reineccius, from the University of Minnesota.

“It’s not like you can grow fields of beavers to harvest. There aren’t very many of them. So it ends up being a very expensive product — and not very popular with food companies.”

“Proud to be Castoreum”

Similarly, Michelle Francl, a chemist at Bryn Mawr College, assures people that there’s no chance that beaver excretion of any kind is snuck into foods because of the high costs. Especially when compared to plants like vanilla orchids, which can be grown and harvested on a massive scale.

However, people may use castoreum in niche products like bäversnaps, a Swedish liquor. In those cases, the unique ingredient is proudly advertised. The substance is harvested by trapping and killing beavers before removing their castor glands, which are dried and ground up. Alcohol extracts castoreum, a method similar to how vanilla extract is taken from plants.