Upon further research, I can indeed confirm that castoreum is recognized a legitimate food additive by the Food and Drug Administration of American. However, Snopes insists that, while it is perfectly safe to use, its modern practical usage in vanilla flavoring is not particularly common:
The use of castoreum in common food products today is exceedingly rare, in large part because collecting the substance is difficult (and therefore expensive).
According to Fernelli's Handbook of Flavor Ingredients, total annual national consumption of castoreum, castoreum extract, and castoreum liquid combined is only about 292 pounds, which works out to an average of less than a millionth of a pound per person in the U.S. Compare that figure with the approximately 20 million pounds of vanilla naturally harvested from real vanilla beans every year.
In a survey of 5 major vanilla flavoring manufacturers by the Vegetarian Resource Group, none of them claimed to currently use castoreum. But it is true that it has historically been used—and is in fact still fairly common in the perfume industry.
In the course of my frantic no-fucking-way googling about this bit of knowledge, I also discovered something else: that castoreum is also used as a homeopathic remedy for anxiety, insomnia, and menstrual cramps. Granted, even WebMD acknowledges that there is very little data to support the effectiveness of beaver butt juice in treating in these conditions.
And so, if you are suffering from anxiety, and the thought of the drinking the anal secretions of a beaver somehow does not exacerbate your anxiousness, you might want to try some castoreum. Maybe.
Does Your Food Contain Beaver Anal Secretions? [David Mikkelson / Snopes]
Beaver Butts Emit Goo Used for Vanilla Flavoring [Mollie Bloudoff-Indelicato / National Geographic]
Where does vanilla flavouring come from? Beaver castoreum explained – and why we use it in cakes and icing [Rhona Shennan / Edinburgh News]
Image: Public Domain via National Park Services