Britain's new £5 note contains animal fat, the Bank of England confirmed on Twitter.
In reply to a user who asked if the substance is used, the central bank said that there is "a trace of tallow in the polymer pellets used in the base substrate of the polymer £5 notes."
Tallow is the fat that surrounds a cow's organs and is often used in soaps and candles.
Vegetarians and vegans reacted furiously to the news that animal fat is used in the note, which is the first to be made of polymer and has been touted as Britain's most advanced ever.
Twitter user Steffi Rox asked "what consideration was given to vegans & their human rights," while another user said the news gives a whole new meaning to the term "blood money."
When asked by Business Insider if they have any plans to change the way they produce the notes, a spokesperson for the Bank of England said they have no further comment.
At the time of publishing this article, 5,000 people had signed a petition on Change.org calling on the Bank of England to stop using the substance.
The bank note, which became available to the public in September, marks the end of 320 years of the use of cotton paper in Britain's bank notes. It has been introduced to increase the durability of the notes, as they are now waterproof, harder to tear, and harder to counterfeit.
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