Fungi, plants, and animals can't produce it. Only some bacteria and archaea have the enzymes needed for its synthesis.
Plants that are source of vitamin B12 get it from bacterial symbiosis.
Industrial production requires a bacterial fermentation-synthesis.
Synthetic vitamin B12 is a form that has been produced using such a process.
All vitamin B12 vitamers show pharmacological activity.
Cobalt
Vitamin B12 contains cobalt, which is a rare element.
The tetra-pyrrole ring containg the cobalt is a called the corrin ring.
Bacterial hydroxocobalamin
Bacteria produces hydroxocobalamin.
Conversion of hydroxocobalamin into other forms occurs in the human body.
Cyanocobalamin
Cyanocobalamin is produced by modifying bacterial hydroxocobalamin.
Cyanocobalamin is mareketed instead of hydroxocobalamin because of superior stability.
In the body, cyanocobalamin is converted to methylcobalamin and 5'-deoxyadenosylcobalamin.
Conversion of cyanocobalamin to methylcobalamin and 5'-deoxyadenosylcobalamin leave a cyanide ion.
Cyanide ions are bad for the human body, but less cyanide is produced than cyanide that comes from food.
20 µg of cyanide is produced per 1,000 µg of cyanocobalamin.
The other vitamers (hydroxocabalamin, methylcobalamin, and adenosylcobalamin) are cyanide-free.
Superiority of the cyanid-free vitamers to cyanocobalamin is "debatable"
Pernicious anemia and other causes of vitamin B12 deficiency
Pernicious anemia is an autoimmune disease in which parietal cells of the stomach are destroyed.
Without such cells, some (intrinsic factor)(?) and and digestive acids are not produced.
(Intrinsic factor)(?) is crucial for the normal absorption of vitamin B12.
Lack of that (Intrinsic factor)(?) causes vitamin B12 deficiency.
There are other subtler kinds of vitamin B12 deficiency whose effects have been elucidated.
Pseudovitamin-B12
Pseudovitamin-B12 vitamer analogues that are biologically inactive in humans
They are found to be present alongside active vitamers in humans, in many food sources and possibly in supplements and fortified foods.
They are found to predominate in most cyanobacteria and in some algae.
Examples include Spirulina and dried Asakusa-nori (Porphyra tenera).
Medical uses
Vitamin B12 is used to treat vitamin B12 deficiency
Vitamin B12 is used to treat cyanide poisoning
Hydroxocobalamin, possibly with sodium thiosulfate, induce cyanide ions to take the place of the hydroxide ligand
This leads to the harmless cyanocobalamin which is then excreted in urine
That treatment was FDA-approved in 2006
This is the reverse of the usual process of converting cyancobolamin into hydroxocobalamin.
This shows that conversion from cyancobolamin to hydroxocobalamin or from hydroxocobalamin to cyancobolamin is a statistical process in the body
Lots of hydroxocobalamin + lots of cyanide => some cyanocobolamin and some less cyanide
Lots of cyanocobolamin => some more cyanide and some hydroxocobalamin
Some conditions may influence one way of the reaction or the other.
Vitamin B12 is used to hereditary deficiency of transcobalamin II
Vitamin B12 is given as part of the Shilling test for detecting pernicious anemia.
High vitamin B12 levels in elderly individuals may protect against
brain atrophy
shrinkage associated with Alzheimer's disease
impaired cognitive function
Facts from Hydroxycobalamin article Information
Color
Most Vitamin B12 vitamers have an intense red color
Conversion
In humans, hydroxycobalamin is rapidly converted to usable coenzyme forms of Vitamin B12
Uses
vitamin B12 deficiency
cyanide poisoning
scavenger of nitric oxide
DNA synthesis
cobalamins are essential cofactors required for DNA synthesis
DNA synthesis occurs notably in bone marrow and myeloid cells
reactions
mitochondrial methylmalonyl-CoA mutase conversion of methylmalonic acid to succinate
links lipid and carbohydrate metabolism
activation of methionine synthase
rate-limiting step in the synthesis of methionine from homocysteine and 5-methyltetrahydrofolate
WHO
Hydroxycobalamin (or cobalamins as a group) is on the WHO Model List of Essential Medicines
Deficiency
Vitamin B12 defiency can be treated by intramuscular injection of either hydroxycobalamin or cyanocobalamin
Cyanocobalamin is traditionally prescribed in the United States.
Outside of the United States, hydroxocobalamin is preferred
Hydroxocobalamin is considered the “drug of choice” for vitamin B12 deficiency by the Martindale Extra Pharmacopoeia and the WHO Model List of Essential Drugs.
Hydroxocobalamin has a longer retention in the body
Hydroxocobalamin requires less-frequent IM injections for restoring vitamin B12 serum levels
IM administration of hydroxocobalamin is the preferred treatment for
pediatric patients with intrinsic cobalamin metabolic diseases
vitamin B12-deficient patients with tobacco amblyopia due to cyanide poisoning
patients with pernicious anemia who have optic neuropathy
Levels
Defiency is recognized when serum levels are less than 200 pg/ml
Daily IM injections of hydroxocobalamin up to 1 mg per day are then prescribed
if neurological symptoms persist, injections up to weekly or biweekly are recommended for six months
then monthly IM injections are considered sufficient
after clinical improvement is confirmed, maintenance supplementation will generally be needed for life
Properties
Hydroxocobalamin acetate
odorless
dark-red
orthorhombic needles
injection formulations
clear
dark-red
distribution coefficient: 1.133 × 10-5
pKa : 7.65
Causes of deficiency
Dietary deficiency
Malabsorption
damage to the stomach where intrinsic factor is secreted
damage to the ileum where intrinsic factor facilitates vitamin B12 absorption
tropical sprue and nontropical sprue
Inadequate secretion of intrinsic factor
lesions that destroy the gastric mucosa
ingestion of corrosives
extensive tumors
conditions associated with gastric atrophy
multiple sclerosis
endocrine disorders
iron deficiency
subtotal gastrectomy
Structural lesions
regional ileitis
ileal reactions
malignancies
Competition for vitamin B12 by intestinal parasites or bacteria
Diphyllobothrium latum
blind loop syndrome
Inadequate use of vitamin B12, which may occur if antimetabolites for the vitamin are employed in the treatment of neoplasia
Little story Information
Characters:
Cobalamin : any of the B12 vitamers
Haptocorrin, aka. cobalophilin, transcobalamin-1, TC-1, transcobalamin I, TCN1, R-factor, R-protein
Fungi, plants, and animals can't produce it. Only some bacteria and archaea have the enzymes needed for its synthesis.
Plants that are source of vitamin B12 get it from bacterial symbiosis.
Industrial production requires a bacterial fermentation-synthesis.
Synthetic vitamin B12 is a form that has been produced using such a process.
All vitamin B12 vitamers show pharmacological activity.
Cobalt
Vitamin B12 contains cobalt, which is a rare element.
The tetra-pyrrole ring containg the cobalt is a called the corrin ring.
Bacterial hydroxocobalamin
Bacteria produces hydroxocobalamin.
Conversion of hydroxocobalamin into other forms occurs in the human body.
Cyanocobalamin
Cyanocobalamin is produced by modifying bacterial hydroxocobalamin.
Cyanocobalamin is mareketed instead of hydroxocobalamin because of superior stability.
In the body, cyanocobalamin is converted to methylcobalamin and 5'-deoxyadenosylcobalamin.
Conversion of cyanocobalamin to methylcobalamin and 5'-deoxyadenosylcobalamin leave a cyanide ion.
Cyanide ions are bad for the human body, but less cyanide is produced than cyanide that comes from food.
20 µg of cyanide is produced per 1,000 µg of cyanocobalamin.
The other vitamers (hydroxocabalamin, methylcobalamin, and adenosylcobalamin) are cyanide-free.
Superiority of the cyanid-free vitamers to cyanocobalamin is "debatable"
Pernicious anemia and other causes of vitamin B12 deficiency
Pernicious anemia is an autoimmune disease in which parietal cells of the stomach are destroyed.
Without such cells, some (intrinsic factor)(?) and and digestive acids are not produced.
(Intrinsic factor)(?) is crucial for the normal absorption of vitamin B12.
Lack of that (Intrinsic factor)(?) causes vitamin B12 deficiency.
There are other subtler kinds of vitamin B12 deficiency whose effects have been elucidated.
Pseudovitamin-B12
Pseudovitamin-B12 vitamer analogues that are biologically inactive in humans
They are found to be present alongside active vitamers in humans, in many food sources and possibly in supplements and fortified foods.
They are found to predominate in most cyanobacteria and in some algae.
Examples include Spirulina and dried Asakusa-nori (Porphyra tenera).
Medical uses
Vitamin B12 is used to treat vitamin B12 deficiency
Vitamin B12 is used to treat cyanide poisoning
Hydroxocobalamin, possibly with sodium thiosulfate, induce cyanide ions to take the place of the hydroxide ligand
This leads to the harmless cyanocobalamin which is then excreted in urine
That treatment was FDA-approved in 2006
This is the reverse of the usual process of converting cyancobolamin into hydroxocobalamin.
This shows that conversion from cyancobolamin to hydroxocobalamin or from hydroxocobalamin to cyancobolamin is a statistical process in the body
Lots of hydroxocobalamin + lots of cyanide => some cyanocobolamin and some less cyanide
Lots of cyanocobolamin => some more cyanide and some hydroxocobalamin
Some conditions may influence one way of the reaction or the other.
Vitamin B12 is used to hereditary deficiency of transcobalamin II
Vitamin B12 is given as part of the Shilling test for detecting pernicious anemia.
High vitamin B12 levels in elderly individuals may protect against
brain atrophy
shrinkage associated with Alzheimer's disease
impaired cognitive function
Facts from Hydroxycobalamin article Information
Color
Most Vitamin B12 vitamers have an intense red color
Conversion
In humans, hydroxycobalamin is rapidly converted to usable coenzyme forms of Vitamin B12
Uses
vitamin B12 deficiency
cyanide poisoning
scavenger of nitric oxide
DNA synthesis
cobalamins are essential cofactors required for DNA synthesis
DNA synthesis occurs notably in bone marrow and myeloid cells
reactions
mitochondrial methylmalonyl-CoA mutase conversion of methylmalonic acid to succinate
links lipid and carbohydrate metabolism
activation of methionine synthase
rate-limiting step in the synthesis of methionine from homocysteine and 5-methyltetrahydrofolate
WHO
Hydroxycobalamin (or cobalamins as a group) is on the WHO Model List of Essential Medicines
Deficiency
Vitamin B12 defiency can be treated by intramuscular injection of either hydroxycobalamin or cyanocobalamin
Cyanocobalamin is traditionally prescribed in the United States.
Outside of the United States, hydroxocobalamin is preferred
Hydroxocobalamin is considered the “drug of choice” for vitamin B12 deficiency by the Martindale Extra Pharmacopoeia and the WHO Model List of Essential Drugs.
Hydroxocobalamin has a longer retention in the body
Hydroxocobalamin requires less-frequent IM injections for restoring vitamin B12 serum levels
IM administration of hydroxocobalamin is the preferred treatment for
pediatric patients with intrinsic cobalamin metabolic diseases
vitamin B12-deficient patients with tobacco amblyopia due to cyanide poisoning
patients with pernicious anemia who have optic neuropathy
Levels
Defiency is recognized when serum levels are less than 200 pg/ml
Daily IM injections of hydroxocobalamin up to 1 mg per day are then prescribed
if neurological symptoms persist, injections up to weekly or biweekly are recommended for six months
then monthly IM injections are considered sufficient
after clinical improvement is confirmed, maintenance supplementation will generally be needed for life
Properties
Hydroxocobalamin acetate
odorless
dark-red
orthorhombic needles
injection formulations
clear
dark-red
distribution coefficient: 1.133 × 10-5
pKa : 7.65
Causes of deficiency
Dietary deficiency
Malabsorption
damage to the stomach where intrinsic factor is secreted
damage to the ileum where intrinsic factor facilitates vitamin B12 absorption
tropical sprue and nontropical sprue
Inadequate secretion of intrinsic factor
lesions that destroy the gastric mucosa
ingestion of corrosives
extensive tumors
conditions associated with gastric atrophy
multiple sclerosis
endocrine disorders
iron deficiency
subtotal gastrectomy
Structural lesions
regional ileitis
ileal reactions
malignancies
Competition for vitamin B12 by intestinal parasites or bacteria
Diphyllobothrium latum
blind loop syndrome
Inadequate use of vitamin B12, which may occur if antimetabolites for the vitamin are employed in the treatment of neoplasia
Little story Information
Characters:
Cobalamin : any of the B12 vitamers
Haptocorrin, aka. cobalophilin, transcobalamin-1, TC-1, transcobalamin I, TCN1, R-factor, R-protein