The discovery of vitamin B12 and the treatment of pernicious anemia with animal liver is attributed to American physician William Parry Murphy, who was born in Stoughton, Wisconsin, USA, in 1892, and received his M.D. degree from Harvard Medical School in 1922. He had explored various anemia pathologies and found that vitamin B12 and folic acid are both necessary substances for the maturation of red blood cells. Vitamin B12 has to be assisted by folic acid to prevent cancer. Vitamin B12 deficiency can cause folic acid . deficiency, and some people are deficient in both vitamins. Vitamin B12 and folic acid help the bone marrow to produce cells, and without vitamin B12, the body's production of cells slows down and eventually forms pernicious anemia.

In 1920, the American medical scientist George Whipple suggested that consuming animal liver is an effective way to treat anemia. He pointed out that one of the causes of anemia is the presence of toxic agents in the organism, destroying the hematopoietic function of the bone marrow, so that the generation of erythrocytes is insufficient to form a large reduction in the number of erythrocytes in the unit volume. While animal liver has a detoxifying effect, there is a certain substance in the liver that can stimulate the bone marrow to accelerate the production and formation of red blood cells. 1926, Murphy years acquaintance with Professor Minot, the two like-minded. They based on Whipple's theory,**** the same proposed the use of beef liver as the main food for the treatment of pernicious anemia, at the same time with beef liver to treat patients with hypohemoglobinemic anemia. Of the 45 patients who consumed beef liver, three-fourths (41 cases) had remarkable results, and some who had been ill for as long as 10 years were still able to survive after consuming beef liver. However, Murphy did not stop there. Because each patient, the daily need for cattle liver 300 to 600 grams, or even more, this approach is not easy to promote the application. He said, "As a doctor, how to make more patients with pernicious anemia to be treated and how to make them recover their health as soon as possible is my concern. Also, in order to achieve the goal, simplification and increased efficiency of treatment at a lower cost must be considered." Subsequently, he and Minot researched for more than three years at Brayham Hospital, analyzing the active ingredients of liver, figuring out the methods of extraction and isolation, and finally succeeding in obtaining a liver extract injection product. Clinical applications have proved that: every 100 grams of fresh liver extracted 3 ml of liver preparations, the efficacy of this product is 50 times the efficacy of oral fresh liver. In other words, 3 milliliters of injection extracted from 100 grams of fresh liver, after intramuscular injection, the efficacy is equivalent to 5000 grams of fresh liver taken orally. Now, with a 3-milliliter injection every 2 to 4 weeks, the number of granulocytes can be increased threefold within 6 to 8 hours after the injection. In addition, the activity of erythrocyte formation at the bone marrow is also increasing, abnormal cells in the blood are disappearing, and symptoms such as panic in patients with pernicious anemia are gradually disappearing. Clinical practice has proved that this drug is also suitable for a variety of diseases accompanied by a decrease in the number of granulocytes, such as pneumonia, acute infectious diseases, granulocyte deficiencies, and a number of post-surgical abnormalities of the blood phase of the disease. For this reason, in 1930, Murphy, together with Minott, received the Cameroon Prize of the University of Edinburgh; in 1934, in addition to winning the Brown Medal issued by the American Medical Association, but also shared the Nobel Prize in Physiology and Medicine in this year.