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Cyanocobalamin (sye-AN-oh-koh-BAL-uh-min) is more commonly known as vitamin B12. At least three active forms of the vitamin are known. They include hydroxocobalamin and nitrocobalamin, in addition to cyanocobalamin, all with slightly different molecular structures. Cyanocobalamin occurs as dark red crystals or a red powder that is odorless and tasteless. When heated, the compound darkens above 200°C (392°F), but does not melt when heated further.



Cobalamin; vitamin B12




Carbon, hydrogen, cobalt, nitrogen, oxygen, phosphorus


Heterocyclic ring (organic)




1355.36 g/mol


Undetermined; greater than 300°C (575°F)


Not applicable


Soluble in water in alcohol; insoluble in acetone, ether, and chloroform

Cyanocobalamin is required for the synthesis of DNA in cells and for the proper functioning of red blood cells and nerves. A deficiency of vitamin B12 in the diet results in a condition known as pernicious anemia, a condition in which red blood cells are smaller in size, number, and hemoglobin content than normal red blood cells. These defects result in general weakness, nervous disorders, gastrointestinal disturbances, and, eventually and inevitably, death.

The earliest research on pernicious anemia dates to the 1920s when American physician George Hoyt Whipple (1878–1976) found that anemia in dogs could be cured by feeding them beef liver. Inspired by this work, American physicians William Murphy (1892–1987) and George Minot(1885–1950) discovered that feeding pernicious anemia patients beef liver cured the disease. These discoveries led to the suspicion that one of the B vitamins present in liver was responsible for the cure of pernicious anemia. Scientists even invented a name for the missing vitamin, vitamin B12, long before it was actually discovered. The problem, unknown to researchers at the time, was that vitamin B12 was such a complex molecule that its isolation and identification was a significant challenge.

In 1948, American chemist Karl Folkers (1906–1997) and his research team discovered that they could measure amounts of the vitamin by measuring the growth rate of bacteria that grew on vitamin B12. Soon the team learned how to purify the vitamin, which formed small red crystals that many scientists consider quite beautiful. It still took many years for scientists to determine exactly how the enormous molecule was structured. In 1956, however, the British chemist Dorothy Hodgkin (1910–1994) determined its chemical structure, allowing her American colleague Robert Burns Woodward (1917–1979) to actually synthesize the compound, an accomplishment of enormous complexity that took fifteen years to complete.

Interesting Facts

  • Cyanocobalamin gets its name because it contains the metal cobalt.
  • For a period of time, the only cure available for pernicious anemia was for patients to eat about a pound of liver every day. Since many patients disliked that diet, they were very happy when synthetic vitamin B12 supplements became available.


Vitamin B12 is made naturally by bacteria that live in the intestines of all animals, including humans, as well as in soil. It binds to protein in food. Plants do not synthesize vitamin B12. Manufacturers who make vitamin B12 supplements use bacteria to grow the vitamin by a process similar to that which occurs naturally. Good food sources of vitamin B12 include animal foods, such as fish, meat, poultry, eggs, milk, cheese, and yogurt; as well as fortified cereals. People who do not eat animal products should be sure to select foods fortified with artificially produced vitamin B12, because the synthetic vitamin is produced by a natural process that does not involve the destruction of animals or the consumption of animal products.


Cyanocobalamin is essential to human health. The body cannot make properly functioning red blood cells, white blood cells, or platelets without it. It is also essential for the production of DNA and nerve cells. People whose diet is deficient in cyanocobalamin are likely to develop pernicious anemia. The symptoms of this disorder include fatigue, weakness, numbness, blurred vision, poor memory, confusion, hallucinations, personality changes, a smooth shiny tongue, stiffness, diarrhea, poor appetite, slow growth in children, and reduced sensitivity to pain and pressure.

Words to Know

Deoxyribonucleic acid, a material with a cell that carries its genetic information and is capable of reproducing itself.
A compound whose molecules contain at least one ring in which some element other than carbon is also present.
A chemical reaction in which some desired chemical product is made from simple beginning chemicals, or reactants.


Brody, Tom. Nutritional Biochemistry. San Diego: Academic Press,1998.

"Dietary Supplement Fact Sheet: Vitamin B12." National Institutes of Health, Office of Dietary Supplements. (accessed on October 6, 2005).

"Nascobal Gel." Nastech Pharmaceutical Company. (accessed on October 6, 2005).

Opt, Robert C., and David J. Brown. "Vitamin B12 Deficiency." American Academy of Family Physicians. March 1, 2003. Also available online at (accessed on October 6, 2005).

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cy·a·no·co·bal·a·min / ˌsīənōˌkōˈbaləmin; sīˌanō-/ • n. a vitamin found in foods of animal origin such as liver, fish, and eggs, a deficiency of which can cause pernicious anemia. Also called vitamin B12.

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cyanocobalamin (vitamin B12) (sy-ă-noh-koh-bal-ă-min) n. see vitamin B.

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cyanocobalamin See vitamin B complex.

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cyanocobalamin See vitamin B12.