Vitamin B12 : Uses, Deficiency and Adverse effects

Today we will know about Vitamin B12 -- also Known as Cobalamin – is a water soluble Vitamin.  Vitamin B12 mainly used in the normal functioning of brain and nervous system and formation of blood.

Vitamin B12 doesn’t produce naturally by any plant, animal or fungi. Vitamin B12 is produced only by bacterial synthesis. Many foods are natural source of Vitamin B12 but Vitamin B12 present in these plants is because of bacterial symbiosis.

A common semi-synthetic form of the vitamin, cyanocobalamin, does not occur in nature, but is produced from bacterial hydroxocobalamin and then used in many pharmaceuticals and supplements, and as a food additive, because of its stability and lower production cost. In the body it is converted to the human physiological forms methylcobalamin and 5'-deoxyadenosylcobalamin, leaving behind the cyanide, albeit in minimal concentration. More recently, hydroxocobalamin, methylcobalamin, and adenosylcobalamin can be found in more expensive pharmacological products and food supplements. The extra utility of these is currently debated. ^{http://en.wikipedia.org/wiki/Vitamin_B12}

Vitamin B₁₂ was discovered from its relationship to disease pernicious anemia, which is an autoimmune disease in which parietal cells of the stomach responsible for secreting intrinsic factor are destroyed; the same cells are responsible for secreting acid in the stomach. Intrinsic factor is crucial for the normal absorption of B₁₂, so a lack of intrinsic factor, as seen in pernicious anemia, causes a vitamin B₁₂ deficiency. Many other subtler kinds of vitamin B₁₂ deficiency and their biochemical effects have since been elucidated. ^{http://en.wikipedia.org/wiki/Vitamin_B12}

Medical uses:

Vitamin B₁₂ is used to treat vitamin B₁₂ deficiency, cyanide poisoning, and hereditary deficiency of transcobalamin II. It is given as part of the Schilling test for detecting pernicious anemia.

For cyanide poisoning, a large amount of hydroxocobalamin may be given intravenously and sometimes in combination with sodium thiosulfate. The mechanism of action is straightforward: the hydroxycobalamin hydroxide ligand is displaced by the toxic cyanide ion, and the resulting harmless B₁₂ complex is excreted in urine. In the United States, the Food and Drug Administration approved (in 2006) the use of hydroxocobalamin for acute treatment of cyanide poisoning.

High vitamin B₁₂ level in elderly individuals may protect against brain atrophy or shrinkage associated with Alzheimer's disease and impaired cognitive function. ^{http://en.wikipedia.org/wiki/Vitamin_B12}

Deficiency:

Vitamin B₁₂ deficiency can potentially cause severe and irreversible damage, especially to the brain and nervous system. At levels only slightly lower than normal, a range of symptoms such as fatigue, depression, and poor memory may be experienced.

Vitamin B₁₂ deficiency can also cause symptoms of mania and psychosis.

Imerslund-Gräsbeck syndrome is a rare disease where there is selective malabsorption of cobalamine with proteinuria caused due to defect in ileal receptor.  ^{http://en.wikipedia.org/wiki/Vitamin_B12}

Adverse effects:

·         Vitamin B₁₂ has extremely low toxicity, and even taking enormous doses does not appear to be harmful to healthy individuals.

·         Hematologic.

·         Peripheral vascular thrombosis has been reported.

·         Leber's disease.

^{http://en.wikipedia.org/wiki/Vitamin_B12}

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