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Saturday, July 6, 2013

Vitamin B12

Cyanocobalamin, Cobalamin (Vitamin B12)
Vitamin B12, also called cyanocobalamin or cobalamin, is one of eight water-soluble B vitamins. Vitamin B12 is the only vitamin containing metal ion (trivalent cobalt). This is the reason called cobalamin. Vitamin B12 is a bright red crystalline compound because of its cobalt content. It is needed in many body processes; in the manufacture and the maintenance of red blood cells, the synthesis of DNA, the stimulate of nerve cells, the growth promotion and energy releasise, the proper functioning of folic acid,. The form of cyanocobalamin os used in most supplements as it is readily converted to 5-deoxyadenosyl , the form of vitamin B12 with coenzyme activity.
Vitamin B12 is mostly absorbed in the terminal ileum. The production of intrinsic factor in the stomach is vital to absorption of this vitamin. Megaloblastic anemia can result from inadequate intake of vitamin B12, inadequate production of intrinsic factor (pernicious anemia), disorders of the terminal ileum resulting in malabsorption, or by competition for available B12 (such as fish tapeworms or bacteria present in the blind loop syndrome). Neurological signs of B12 deficiency, which can occur without accompanying hematologic abnormalities, include demyelination and irreversible nerve cell death. Symptoms include numbness or tingling of the extremities and an ataxic gait.
Cyanocobalamin is considered the most potent vitamin and is one of the last true vitamins that has been classified. The vitamin was discovered through studies of pernicious anemia, a condition that begins with a megaloblastic anemia and leads to an irreversible degeneration of the central nervous system. Scientists found that this condition could be reversed by feeding afflicted patients large amounts of raw liver. The active material in the liver was later found to be vitamin B-12, but it is present only in very small concentrations, so many years passed before enough was isolated for serious investigations. Cyanocobalamin is a very unusual biochemical that contains a tetrapyrrole ring system, called a corrin ring, that is chemically very similar to the porphyrin ring system of the heme compounds. Contained within the corrin ring, at the coordination point, is a cobalt ion that is associated with a cyanide ion and a dimethylbenzimidazole nucleotide. Vitamin B-12 functions to provide a methyl group that is used in the synthesis of a number of products during biochemical reactions. Clinically, cyanocobalamin works to promote normal growth and development, helps with certain types of nerve damage, and treats pernicious anemia. This vitamin is not available from plant sources (vegetarians beware!), but animal sources include beef, liver, blue cheese, eggs, fish, milk, and milk products. Symptoms associated with a deficiency of vitamin B-12 are primarily those of pernicious anemia.
Vitamin B12 is an especially important vitamin for maintaining healthy nerve cells and it aids in the production of DNA and RNA, the body's genetic material. Vitamin B12 also works closely together with vitamin B9 (folate) to regulate the formation of red blood cells and to help iron function better in the body. The synthesis of S-adenosylmethionine (SAMe), a compound involved in immune function and mood, depends on the participation of folate and vitamin B12. Similar to other B complex vitamins, cobalamine is considered an "anti-stress" vitamin because it is believed to enhance the activity of the immune system and improve the body's ability to withstand stressful conditions. Vitamins B12, B6, and B9 (folate) work closely together to control blood levels of the amino acid homocysteine. Elevated levels of this substance appear to be linked with heart disease and, possibly, depression and Alzheimer's disease.
Deficiencies of vitamin B12 are usually caused by a lack of intrinsic factor, a substance that allows the body to absorb vitamin B12 from the digestive system. Such a deficiency can cause a range of symptoms including fatigue, shortness of breath, diarrhea, nervousness, numbness or tingling sensation in the fingers and toes., People with the blood disorder pernicious anemia do not produce sufficient intrinsic factor and must take high doses of vitamin B12 to maintain their health. Similarly, people who have had stomach surgery (for example, for a severe ulcer) are at risk for vitamin B12 deficiency and pernicious anemia. They require lifetime B12 injections after the surgery.
Cyanocobalamin appears as dark red crystals or as an amorphous or crystalline red powder. It is very hygroscopic in the anhydrous form, and sparingly soluble in water (1:80). It is stable to autoclaving for short periods at 121° C. The vitamin B12 coenzymes are very unstable in light. The chemical name is 5,6-dimethyl-benzimidazolyl cyanocobamide; the molecular formula is C63H88CON14O14P. The cobalt content is 4.34%. The molecular weight is 1355.39.

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