vitamin B12

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vi·ta·min B12

generic descriptor for compounds exhibiting the biologic activity of cyanocobalamin; the antianemia factor of liver extract that contains cobalt, a cyano group, and corrin in a cobamide structure. Several substances with similar formulas and with the characteristic hematinic action have been isolated and designated: B12a, hydroxocobalamin; B12b, aquacobalamin; B12c, nitritocobalamin; B12r, cob(II)alamin; B12s, cob(I)alamin; B12III, factors A and V1a (cobyric acid) and pseudovitamin B12. Vitamins B12a and B12b are known to be tautomeric compounds; B12b has been obtained from cultures of Streptomyces aureofaciens; B12c has been obtained from cultures of Streptomyces griseus and is distinguishable from B12 by differences in its absorption spectrum. The physiologically active vitamin B12 coenzymes are methylcobalamin and deoxyadenosinecobalamin. A deficiency of vitamin B12 is often associated with certain methylmalonic acidurias.

vitamin B12

vitamin B12

A water-soluble vitamin of animal origin required for DNA synthesis. It is a glycoprotein produced and secreted by the gastric parietal cells, and is absorbed from the GI tract bound to intrinsic factor; the body stores up to one years’ worth of vitamin B12 in the liver, kidneys and heart. Rapid cell turnover (e.g., growth spurts in children, malignancy) require increased amounts of vitamin B12. Vegans, who ingest no protein of animal origin, are at risk for vitamin B12 deficiency.

Increased by
Chronic myeloid leukaemia, chronic obstructive pulmonary disease, congestive heart failure, liver disease, obesity, polycythemia vera, renal failure.
 
Decreased by
Atrophic gastritis, drugs (antibiotics, anticonvulsants, antimalarials, antituberculous agents, chemotherapy, contraceptives, diuretics, oral hypoglycemics, sedatives), inflammatory bowel disease (e.g., Crohn’s disease, ulcerative colitis), intrinsic factor deficiency (causing megaloblastic anaemia), malabsorption, malnutrition, parasites (e.g., Diphyllobotrium latum), veganism.

vitamin B12

Cyanocobalamin, extrinsic factor, methylcobalamin Clinical nutrition A water-soluble vitamin of animal origin, required for DNA synthesis; absorbed from the GI tract bound to intrinsic factor; it is a glycoprotein produced and secreted by the gastic parietal cells; the body stores up to one yr's worth of vitamin B12 in the liver, kidneys, heart; rapid cell turnover–eg, growth spurts in children, CA require ↑ amounts of vitamin B12. ↑CML, COPD, CHF, liver disease, obesity, polycythemia vera, renal failure. ↓Atrophic gastritis, drugs–antibiotics, anticonvulsants, antimalarials, antituberculous agents, chemotherapy, contraceptives, diuretics, oral hypoglycemics, sedatives; IBD–eg, Crohn's disease, ulcerative colitis; intrinsic factor deficiency–causing megaloblastic anemia, malabsorption, malnutrition, parasites–eg, Diphyllobotrium latum, veganism. Note: A strict vegetarian diet's victim ingests no proteins of animal origin, including meat, fish and dairy products; all vegans are at risk for vitamin B12 deficiency; in addition, vegan adolescents may not meet energy requirements during the growth spurt and may become deficient in vitamin B6 and riboflavin; the high-fiber diet may chelate calcium, zinc and iron, and ↓ absorption of essential cations and trace minerals See Intrinsic factor, Pareve, Vegan, Vegetariansim; Cf Lacto-ovo vegetarian.

vi·ta·min B12

(vī'tă-min)
Generic descriptor for compounds exhibiting the biologic activity of cyanocobalamin. The physiologically active vitamin B12 coenzymes are methylcobalamin and deoxyadenosinecobalamine. A deficiency of vitamin B12 causes megaloblastic anemia with or without peripheral neuropathy, and is often associated with certain methylmalonic acidurias.

cobalamin, cyanocobalamin

or

vitamin B12

one of the B-COMPLEX of water-soluble vitamins, containing cobalt and required for red blood cell formation. A deficiency of B12 can lead to pernicious anaemia especially amongst old people. The vitamin is synthesized by bacteria in the gut rather than being obtained from the diet, and is required in very tiny amounts. The richest food source is raw liver.
vitamin B12 group of compounds all showing cyanocobalamine-like activity

vitamin B,

n a water-soluble vitamin found in animal foods such as meat, eggs, and dairy. Has been used for deficiencies (often found in vegetarians, particularly vegans) or lower levels from colchicine, metformin, phenformin, AZT, and nitrous oxide and to treat pernicious anemia and bursitis of the shoulder. No known precautions. Also called
cyanocobalamin, hydrocobalamin, or
methylcobalamin.

vi·ta·min B12

(vī'tă-min)
Generic descriptor for compounds exhibiting biologic activity of cyanocobalamin.

Patient discussion about vitamin B12

Q. Can a food rich in vitamin B12 will help for his depression or vitamin B12 pills are always required? Hi all…..having one question related to my friends depression and its relation to vitamin B12, as a medicine given to him by his Doctor. Can a food rich in vitamin B12 will help for his depression or vitamin B12 pills are always required?

A. Yes low level of vitamin B12 is associated with depression. You can complete its deficiency by having good diet which will cover the B12 requirements. What happens that depressed people tend to eat less of healthy food and which reduces the B12. So, it again reduces the capacity to fight against the depression.

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