Vitamin B-12 (Cyanocobalamin, Corrinoids)
Howerde E. Sauberlich in Laboratory Tests for the Assessment of Nutritional Status, 2018
Cyanocobalamin is the commercially available form of vitamin B-12. This form is stable and readily converted in the body to metabolically active vitamin B-12. Microorganisms are the source of all vitamin B-12 in nature. Hence, all plants and plant food are devoid of vitamin B-12 unless contaminated by microorganisms. In Zimbabwe, vitamin B-12 deficiency is the primary cause of megaloblastic anemia. Vegetarian diets have long been recognized to be deficient in vitamin B-12. Serum methylmalonic acid concentrations are elevated with a deficiency of vitamin B-12, but not by a folate deficiency. In the United States, blacks also had significantly higher serum vitamin B-12 concentrations than whites. Vitamin B-12 evaluations may be assisted by neutrophil hypersegmentation measurements, deoxyuridine suppression tests, or formiminoglutamic acid excretion levels. Measurements of both serum vitamin B-12 and holotranscobalamin II would provide the most useful information for the assessment of vitamin B-12 status.
Nutritional and Dietary Supplementation during Pregnancy
“Bert” Bertis Britt Little in Drugs and Pregnancy, 2022
A balanced “nonfad” diet should provide pregnant women with an adequate complement of nutrients during pregnancy. A balanced diet should provide necessary nutrients during pregnancy, except for iron, which is routinely prescribed. Vitamin A is an essential nutrient, and the recommended supplement of vitamin A is usually consumed. Niacin is a B complex vitamin that is metabolized to niacinamide, the active form of B 3 , in humans. Niacin is naturally present in a wide variety of foods. Pantothenate is an essential cofactor in metabolism of carbohydrates, proteins, and fats. It contributes to the composition of coenzyme A. Pyridoxine, another essential nutrient, is an enzyme cofactor. Dietary pyridoxine requirements are increased among pregnant women. Vitamin B12, cyanocobalamin, is an essential nutrient. Megadose cyanocobalamin is used to treat pernicious anemia. Folic acid, a water-soluble vitamin B complex, is an essential nutrient. It is a coenzyme, and has been shown to be extremely important in normal embryonic development, the neural tube complex in particular.
Cobalt in Vitamin B
Pabitra Krishna Bhattacharya, Prakash B. Samnani in Metal Ions in Biochemistry, 2020
Structure of vitamin B 12 , its formation, characterization, model systems and roles of vitamin B 12 in biological systems are described in detail. Vitamin B 12 is a tetraaza macrocyclic (corrin) ligand complex of Co(III). Cobalt in the complex is hexa-coordinated, four planar positions being occupied by pyrrole ring nitrogens; fifth coordination site is occupied by benzimidazole, bound to the corrin ring, and sixth position by water molecule or other ligands. When the sixth position is occupied by cyanide, the complex is called cyanocobalamin, which is water-soluble, red-coloured complex. Structure of the complex has been established by X-ray crystallographic studies. This chapter also discusses the formation of vitamin B 12 coenzyme from vitamin B 12 and mechanism of alkylation reaction. Stability of the complex in terms of π electron delocalisation and redox changes is also explained. Various roles of vitamin B 12 including alkylation of organic compounds and metals, generation of methane, isomerase activity, deamination reaction and reduction reactions have all been described along with chemical equations. Various oxidation states that are taken up by cobalt in these reactions have been shown. Role of vitamin B 12 in the synthesis of blood cells in bone marrow has also been discussed.
Fallacies of clinical studies on folic acid hazards in subjects with a low vitamin B
Published in Critical Reviews in Toxicology, 2020
Jan D. van Gool, Herbert Hirche, Hildegard Lax, Luc De Schaepdrijver
A 2016 plea for revision of the 1 mg/day upper level of folic acid intake prompted us to comprehensively review the 1945–2017 literature on folic acid hazards in subjects with low cyanocobalamin. The concept of folic acid treatment ‘masking’ the anemia in undiagnosed cyanocobalamin deficiency, thereby delaying the diagnosis of neuropathy, does not account for the dissociation between the deficiency’s hematologic and neurologic manifestations. Possible risks of this concept were addressed by 1963–1971 FDA rulings, classifying all folic acid preparations as prescription-only drugs, delivering ≤1 mg daily. The neuropathy in folic acid trials for ‘pernicious anemia’ is due to the singular use of folic acid–neuropathy improved or disappeared with replacement of folic acid by liver extract or cyanocobalamin. The hypothesis that cognitive impairment in ‘subclinical’ cyanocobalamin deficiency is folate-mediated is untenable. Of 6 papers specifically investigating this, none could prove that increased cognitive impairment was related to high folate intake. This review fully supports the safety of the 1 mg/day upper level for folic acid intake.
Toxicity induced by multiple high doses of vitamin B
Published in Clinical Toxicology, 2020
Jessica Morales-Gutierrez, Sebastián Díaz-Cortés, María A. Montoya-Giraldo, Andres F. Zuluaga
Context: The clinical consequences of excess vitamin B12 induced by multiple oral doses of cyanocobalamin are not well-known. Case details: A young woman was treated with multiple daily doses of 1 mg of cyanocobalamin for severe pernicious anemia. After a total dose of 12 mg, she developed acne, palpitations, anxiety, akathisia, facial ruddiness, headache, and insomnia. She improved two weeks after stopping the drug. There were no sequelae nor complications. Discussion: Although these symptoms of cobalamin toxicity were unexpected and unusual, the case reminds us that the administration of any drug is not entirely safe.
Improvement berry color skin profile by exogenous cyanocobalamin treatment of ‘Crimson seedless’ grapevines
Published in Egyptian Journal of Basic and Applied Sciences, 2017
The experiment was conducted to study the effect of cyanocobalamin (B12) treatments (0, 3, 6, and 9 mM B12) on Vitis vinifera L. ‘Crimson seedless’ which conducted during two seasons 2014 and 2015. The study aims to regenerate berry color during growth and preserve it during shelf-life at room temperature for four days. The results showed that B12 treatments were significantly effective in reducing weight loss. Berry shatter, rachis browning index, while it preserved another quality parameter high such as berry firmness, separation force, total phenol content (TPC), total sugar content (TSC), total anthocyanin content (TAC), B-Carotene, ascorbic acid (AA) and color hue angle during shelf-life for four days. The previous results were significantly observed with B12 at 9 mM compared to control and other B12 concentrations. However, total solid content (SSC%), titratable acidity (TA%), and SSC/TA ratio were significantly affected by B12 at 9 mM up to end the shelf-life period. In contrast, the lowest values of total chlorophyll (Chlab) content during shelf-life compared with other B12 concentrations. Therefore, cyanocobalamin (B12) is an effective vitamin for improving or generating berry color at harvest time and maintaining cluster quality of ‘Crimson seedless’ grapes during shelf-life (marketing).
Related Knowledge Centers
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