Also found in: Dictionary, Thesaurus, Medical, Wikipedia.


see coenzymecoenzyme
, any one of a group of relatively small organic molecules required for the catalytic function of certain enzymes. A coenzyme may either be attached by covalent bonds to a particular enzyme or exist freely in solution, but in either case it participates intimately in
..... Click the link for more information.
; vitaminvitamin,
group of organic substances that are required in the diet of humans and animals for normal growth, maintenance of life, and normal reproduction. Vitamins act as catalysts; very often either the vitamins themselves are coenzymes, or they form integral parts of coenzymes.
..... Click the link for more information.



(or Vitamin B12), C63H88CoN14O14P, a cobalt-corrin complex in which the cobalt atom is bonded to a cyano group, a nucleotide residue, and four reduced pyrrole rings; molecular weight, 1355.40. Cyanocobalamin is a dark-red crystalline compound, which is soluble in water and polar organic solvents. It was first isolated in crystalline form from cattle liver. Its structure was established by A. Todd and D. Crowfoot Hodgkin and their co-workers.

The primary sources of cyanocobalamin in nature are microorganisms; cyanocobalamin is synthesized by several bacteria, by actinomycetes, and by blue-green algae. It occurs in almost all animal tissues. It is not encountered, as a rule, in the tissues of higher plants (legume tubers are an exception). In ruminants, it is synthesized in sufficient amounts by the microflora of the intestine and the rumen. In man and several higher animals, such as birds and hogs, its synthesis by intestinal microflora is insufficient, and thus the vitamin must be obtained from food. The daily requirement for humans is about 5 μg. The major sources of the vitamin are liver, kidneys, fish meal, and milk.

In the form of its coenzymes methylcobalamin and deoxyadenosylcobalamin, cyanocobalamin participates in the enzymic reactions involved in hematopoiesis and facilitates normal liver function and nerve fiber regeneration. It is produced by microbiological synthesis using propionic-acid bacteria for the fermentation process.

Vitamin B12 is used for the treatment of pernicious anemia and other anemias, as well as of diseases of the central and peripheral nervous systems and the liver. It is prescribed in solutions for intramuscular injections. (See alsoVITAMINS; ANEMIA; and COBALAMINS.)


Smith, L. Vitamin B12. Moscow, 1962. (Translated from English.)
Friedrich, W. Vitamin B12 und Verwandte Corrinoide, 3rd ed. Stuttgart, 1975.



vitamin B12
References in periodicals archive ?
Oral cyanocobalamin supplementation in older people with vitamin [B.
Whereas treatment with hydroxocobalamin or cyanocobalamin would increase the concentration of both biologically active forms of vitamin B12, treatment with methylcobalamin may not increase the concentration of adenosylcobalamin.
Outcomes: The effectiveness of oral cyanocobalamin treatment was evaluated by measuring hematologic and neurologic improvement, as well as changes in serum concentrations of cobalamin, MMA, and homocysteine.
12] (methylcobalamin, hydroxycobalamin, and adenosylcobalamin) into the stable cyanocobalamin form.
It is available in a cherry flavored, all natural, proprietary cyanocobalamin (vitamin B12) sub-lingual lozenge that is taken twice daily to regulate allergy sufferers' response to both indoor and outdoor allergens with daily and year round usage.
Contract awarded for order 78, code 10853, cyanocobalamin, pyridoxine hydrochloride, sodium diclofenac, thiamine mononitrate
Recently the FDA posted on their website that cyanocobalamin b12 was in short supply due to manufacturers not being able to keep up with demand as well as a delay in shipping.
5 mg per day), pyridoxine (50 mg per day), and cyanocobalamin (1 mg per day) or placebo.
3 mg Cyanocobalamin (Vitamin B12) mega-dose sub-lingual lozenge, has essentially no risks or adverse side effects to the general population including sedation and drowsiness found in many allergy medications currently available.
It is a rich source of GLA (gamma linolenic acid) and is an excellent source of cyanocobalamin (an analogue of vitamin B12), which is especially important in vegetarian diets.
Allergy patients in the Pacific Northwest were given 15 mcg cyanocobalamin IM for 15 days (n=27) or placebo (n=34).