Vitamin B12

Smith, A. David, Warren, Martin J. ORCID: https://orcid.org/0000-0002-6028-6456 and Refsum, Helga (2018) Vitamin B12. In: New Research and Developments of Water-Soluble Vitamins. Advances in Food and Nutrition Research . Academic Press Inc., pp. 215-279.

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Abstract

The biosynthesis of B12, involving up to 30 different enzyme-mediated steps, only occurs in bacteria. Thus, most eukaryotes require an external source of B12, and yet the vitamin appears to have only two functions in eukaryotes: as a cofactor for the enzymes methionine synthase and methylmalonylCoA mutase. These two functions are crucial for normal health in humans, and in particular, the formation of methionine is essential for providing methyl groups for over 100 methylation processes. Interference with the methionine synthase reaction not only depletes the body of methyl groups but also leads to the accumulation of homocysteine, a risk factor for many diseases. The syndrome pernicious anemia, characterized by lack of intrinsic factor, leads to a severe, sometimes fatal form of B12 deficiency. However, there is no sharp cutoff for B12 deficiency; rather, there is a continuous inverse relationship between serum B12 and a variety of undesirable outcomes, including neural tube defects, stroke, and dementia. The brain is particularly vulnerable; in children, inadequate B12 stunts brain and intellectual development. Suboptimal B12 status (serum B12 < 300 pmol/L) is very common, occurring in 30%–60% of the population, in particular in pregnant women and in less-developed countries. Thus, many tens of millions of people in the world may suffer harm from having a poor B12 status. Public health steps are urgently needed to correct this inadequacy.

Item Type: Book Section
Additional Information: Publisher Copyright: © 2018 Elsevier Inc.
Uncontrolled Keywords: brain,children,cobalamin,cognition,elderly,homocysteine,memory,methylmalonic acid,pregnancy,food science,medicine(all),sdg 3 - good health and well-being ,/dk/atira/pure/subjectarea/asjc/1100/1106
Faculty \ School: Faculty of Science
Related URLs:
Depositing User: LivePure Connector
Date Deposited: 20 Sep 2022 14:30
Last Modified: 27 Sep 2022 23:50
URI: https://ueaeprints.uea.ac.uk/id/eprint/88473
DOI: 10.1016/bs.afnr.2017.11.005

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