William Bosworth Castle, in 1926, ate minced raw beef every morning, regurgitated it an hour later, and then fed it to his patients suffering from pernicious anaemia. Castle was testing his theory that there was an intrinsic factor produced in a normal stomach that hugely increased the uptake of the extrinsic factor (now identified as vitamin B12), lack of which leads to pernicious anaemia. Beef is a good source of B12, but patients did not respond with beef alone. Castle reasoned they lacked production of intrinsic factor and he could provide it from his own stomach. While Castle was not the recipient of this treatment, his story is included in "Who Goes First?: The Story of Self-experimentation in Medicine" and is considered a self-experimenter by the author.