24 Facts About Vitamin B12


Vitamin B12, known as cobalamin, is a water-soluble vitamin involved in metabolism.

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Vitamin B12 is the most chemically complex of all vitamins, and for humans, the only vitamin that must be sourced from animal-derived foods or from supplements.

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Foods containing vitamin B12 include meat, clams, liver, fish, poultry, eggs, and dairy products.

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Vitamin B12 was discovered as a result of pernicious anemia, an autoimmune disorder in which the blood has a lower than normal number of red blood cells, due to a deficiency in vitamin B12.

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Vitamin B12 is a coordination complex of cobalt, which occupies the center of a corrin ligand and is further bound to a benzimidazole ligand and adenosyl group.

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Pseudovitamin B12 is the majority corrinoid in spirulina, an algal health food sometimes erroneously claimed as having this vitamin activity.

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Vitamin B12 deficiency is most commonly caused by malabsorption, but can result from low intake, immune gastritis, low presence of binding proteins, or use of certain medications.

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Children diagnosed with low serum Vitamin B12 can be treated with intramuscular injections, then transitioned to an oral dietary supplement.

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Severe vitamin B12 deficiency is corrected with frequent intramuscular injections of large doses of the vitamin, followed by maintenance doses of injections or oral dosing at longer intervals.

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Vitamin B12 supplements are available as single or multivitamin tablets.

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Vitamin B12 is produced in nature by certain bacteria, and archaea.

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Animal-derived food sources with a high concentration of vitamin B12 include liver and other organ meats from lamb, veal, beef, and turkey; shellfish and crab meat.

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Natural plant and algae sources of vitamin B12 include fermented plant foods such as tempeh and seaweed-derived foods such as nori and laver.

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Vitamin B12 is included in multivitamin pills; in some countries grain-based foods such as bread and pasta are fortified with B12.

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Deficiency does not develop if dietary intake of vitamin B12 is adequate or prophylactic B12 supplementation is given.

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Vitamin B12 is the most chemically complex of all the vitamins.

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The structure of Vitamin B12 is based on a corrin ring, which is similar to the porphyrin ring found in heme.

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Protein-bound vitamin B12 must be released from the proteins by the action of digestive proteases in both the stomach and small intestine.

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The next binding protein for Vitamin B12 is intrinsic factor, a protein synthesized by gastric parietal cells that is secreted in response to histamine, gastrin and pentagastrin, as well as the presence of food.

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Absorption of food vitamin B12 thus requires an intact and functioning stomach, exocrine pancreas, intrinsic factor, and small bowel.

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Vitamin B12 is derived from a tetrapyrrolic structural framework created by the enzymes deaminase and cosynthetase which transform aminolevulinic acid via porphobilinogen and hydroxymethylbilane to uroporphyrinogen III.

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Industrial production of Vitamin B12 is achieved through fermentation of selected microorganisms.

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Complete laboratory synthesis of Vitamin B12 was achieved by Robert Burns Woodward and Albert Eschenmoser in 1972.

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Industrial production of vitamin B12 is achieved through fermentation of selected microorganisms.

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