In old times, this leavening agent existed through animal origin. However, now you can get them in vegetarian as well as non-vegetarian options. It is also prepared by using calcium carbonate and ammonium sulfate. As a result, vegans, as well as vegetarians, can use it for baking several products.
While you are making a purchase, it is vital to see the red or green mark on the packet of raising agent 503. If there is a red mark, it means it is derived from animal sources, and green mark refers to it being vegetarian.