Castoreum is a natural flavoring used in vanilla and strawberry-flavored foods. However, it’s not from a lab or a unique plant. It’s an excretion from beavers’ anal castor sacs, historically used in medicines, soaps, and foods. Despite this, you won’t see “castoreum” on ingredient lists; it’s grouped under “natural flavorings.”

The FDA deems castoreum safe, citing “a long historical use…resulting in no reports of human adverse reactions.” Yet, it’s costly and prevents products from being certified kosher. Flavor chemist Gary Reineccius notes, “It’s not like you can grow fields of beavers to harvest. There aren’t very many of them.”

Michelle Francl, a chemist, reassures that due to high costs, beaver excretion is rarely used in foods. It’s more common in niche products like bäversnaps, a Swedish liquor, where it’s proudly advertised.

Historically, castoreum treated stomach upsets, fevers, and mental illnesses. It was also added to soaps, lotions, and even cigarettes. Its discovery during the fur trade almost led to the beaver’s extinction in North America and Eurasia.

Beavers use sac excretion to mark territories and identify family members. It also makes their tails and fur more water-resistant.

Thanks to their diet, castoreum has a sweet-smelling vanilla aroma. However, flavor chemists ensure that food companies prefer other substitutes, making castoreum’s presence in everyday foods unlikely.