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Vitamin B12

Vitamin B12 is also called cyanocobalmin, and is a cobalt-containing compound naturally blue in color. Of all vitamins, B12 is the most chemically complex, including cobalt, nitrogen groups, cyano groups, hydroxyls, methyls, and several others. It includes the only carbon-metal bond known in biology, the carbon-cobalt bond. B12 can’t be made by plants or animals; it is only made by bacteria and archaea.

Vitamin B12 is critical for certain types of enzyme-catalyzed reactions that, in humans, can extract energy from proteins and fats and catalyze the conversion of certain amino acids into others. Part of the processes it supports prevents anemia, so it is often used as a partner to iron supplementation. It is also one of the only treatments for cyanide poisoning; a large dose of vitamin B12 given intravenously can remove the cyanide that has bonded with red blood cells.

Signs of vitamin B12 deficiency may include demyelination (stripping of the outer layer of nerves) and nerve cell death, marked by numbness and tingling in extremities and sometimes an irregular gait. Elderly people who have a vitamin B12 deficiency may be clinically depressed. Intravenous administration and large oral doses of supplements are the normal means of treatment for vitamin B12 deficiency.

Nutritional sources for vitamin B12 include eggs, milk products, fortified breakfast cereal, and liver and shellfish. It is possible to overdose on vitamin B12; negative effects include cardiovascular, dermatologic, gastrointestinal, and hematological problems.

Web Resources On Vitamin B12

Dietary Supplement Fact Sheet: Vitamin B12
Vitamin B12 Deficiency

Book Resources On Vitamin B12

Dietary Reference Intakes for Thiamin, Roboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline by Institute of Medicine
Could It Be B12?: An Epidemic of Misdiagnoses by Sally M. Pacholok, Jeffrey J. Stuart

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