A Brief History of Castoreum, the Beaver Butt Secretion Used as Flavoring

In September 2013, popular blogger “The Food Babe” released a video proclaiming that beavers “flavor a ton of foods at the grocery store with their little butthole!” Since then, the internet has been crowded with alarmist posts saying that beaver’s butts are used to flavor everything from soft drinks to vanilla ice cream. The culprit behind this scare is a flavorant called castoreum—but what exactly is it, and is it worth all the fuss?

What is castoreum?

Castoreum is a substance secreted by male and female Alaskan, Canadian, and Siberian beavers from pouchlike sacs located near the base of their tails (castor is the word for beaver in Latin). Beavers can’t see or hear very well, but they have a great sense of smell—and as a result of their castoreum glands, they also smell great. They use their castoreum in part to mark their territory, secreting it on top of mounds of dirt they construct on the edges of their home turf. (The castoreum squirting out is apparently so loud, you can hear it if you’re standing nearby.) Beavers also use the fatty, waxy secretion to waterproof their fur.

An odorous combination of vanilla and raspberry with floral hints, castoreum carries information about a beaver’s health and helps to make distinctions between family members and outsiders. Beavers are so interested in the smell that historically, fur trappers would bait traps with castoreum.

Castoreum History

When castoreum is fresh, it’s a fluid that ranges in color from yellow and milky to grey and sticky, depending on the type of beaver and its gender. In a live animal, this fluid is milked and dried to a solid for perfume making. In a dead animal, the entire castoreum gland is removed and, traditionally, preserved by smoking it over a wood fire.

For much of its history, castoreum was used as a medicine. Roman women inhaled the fumes of castoreum burned in lamps because they believed it would induce abortions (it didn’t). Hildegard von Bingen, a 12th-century Benedictine abbess, mystic, and scholar, wrote that powdered beaver “testicles” drunk in wine would reduce a fever (the castoreum gland, when dried, is easily mistaken for testes). Castoreum has also been used to treat headaches, which makes sense given that it contains salicylic acid, the main ingredient in aspirin.

The colonization of America led into an increase in the availability of beaver pelts, which were used to make fine hats all over Europe, and to a resurgence of interest in castoreum as medicine. Sold in drugstores and pharmacies, it was recommended for earaches, toothaches, colic, gout, inducing sleep, preventing sleep, and general strengthening of the brain. It was also in the 19th century that the substance began to be used in the perfume industry as a fixative—an ingredient that makes other scents smell better and last longer.

By the end of the 19th century, the demand for pelts and castoreum was so great that North American beavers were on the edges of extinction. In 1894, a representative of the Hudson Bay Company, a major beaver pelt and castoreum trading firm, said: “The beaver’s days are numbered. He cannot coexist with civilization.”

Is castoreum still being used today?

According to The Oxford Companion to Sugar and Sweets, castoreum was first used as a food additive in the early 20th century, but is now rarely, if ever, used in the mass-produced flavor industry. Nevertheless, the FDA considers it a “natural flavor,” since it is derived from a natural source, and can be used to add fruity strawberry or raspberry notes, or as substitute for vanilla (the compounds come from the beaver’s diet of bark and leaves). One of the few places it’s reliably found is the Swedish schnapps BVR HJT.

Beavers are generally no longer hunted for their pelts or castoreum; to acquire the sticky stuff, humans must anesthetize beavers and milk the castoreum gland. The process was described as “pretty gross” by Joanne Crawford, a wildlife ecologist at Southern Illinois University who is no stranger to beaver butts; she noted that the goo has a consistency somewhat like molasses. Due to the inconvenience and expense of harvesting castoreum from live beavers, the substance is now seldom used. According to Fenaroli’s Handbook of Flavor Ingredients, the annual industry consumption is very low—around 300 pounds—whereas the consumption of natural vanillin is over 2.6 million pounds annually. When castoreum is used, it’s far more likely to be in the profitable fragrance industry rather than in the foods we eat.

“In the flavor industry, you need tons and tons of material to work with,” flavor chemist Gary Reineccius told NPR’s The Salt. “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.”

So while it’s hard to know what foods or fragrances contain castoreum, there is very little of it out there. It may be worth saving your alarm for another topic—or simply sparing a thought for the beaver.

A version of this story ran in 2017; it has been updated for 202