Vitamin B12 was discovered simultaneously by two research teams, one in the United States and one in England. It was the culmination of an intensive worldwide search for a compound that could effectively treat pernicious anemia.
B12 and Liver
During the 1930s, researchers around the world began trying to isolate the active ingredient in liver that contained its curative properties. The "antipernicious anemia factor" was believed to be a B vitamin. It was even given the name B12 long before it was isolated.
Testing was surprisingly slow. Patients were fed extracts of liver rather than the liver itself, but for some reason researchers could not measure the amount of vitamin B12 these liver extracts contained. They could only guess at the extracts' potency by measuring red blood cell growth in each patient's blood.
For years, Karl Folkers, an American chemist at a prominent pharmaceutical company, had been directing a research team that was working on the problem. In 1948, the group finally came up with a solution. They found they could measure the vitamin indirectly by measuring the growth rate of certain bacteria that needed vitamin B12 to grow. This system speeded the purification process of the vitamin enormously.
The New Vitamin
The new vitamin was a large and complicated molecule roughly four times the size of a penicillin molecule. The molecule was so complex that its structure could only be worked out through the aid of advanced technology. In 1956 English physicist Dorothy Hodgkin (1910-) completed the mapping of B12′s chemical structure by using x-ray crystallography. She received the 1964 Nobel Prize in chemistry for her work. Vitamin B12 was finally synthesized by Robert Burns Woodward (1917-1979) in 1971, after a ten-year effort.
Pernicious anemia is a blood disorder in which red blood cells fail to develop normally. The steady decline of red blood corpuscles eventually leads to death. The disease was first described completely in 1849 by English physician Thomas Addison (1793-1860). Addison noted the typical symptoms included increasing weakness and pallor of the patient. This was accompanied by obesity (weight gain) rather than weight loss.
Until the 1920s, this pernicious anemia was always fatal. Then two physicians named George Richards Minot (1885-1950) and William Perry Murphy became inspired by George Whipple's (1878-1976) studies. The Whipple studies showed that beef liver could improve the formation of red corpuscles in anemic dogs. To test Whipple's findings, Minot and Perry began feeding their patients large amounts of beef liver. In 1926, the researchers were able to announce that a daily diet of about a half a pound of liver could control the disease. For their work, Minot, Murphy, and Whipple shared the 1934 Nobel Prize in medicine.
The isolation and synthesis of B12 removed pernicious anemia from the list of deadly medical problems. B12 was the last vitamin to be discovered. Work on the vitamin served to round out the remarkable half-century of vitamin research that began in the 1890s with Dutch physician Christiaan Eijkman (1858-1930).