It is an especially common vitamer of the vitamin B12 family. It is the most famous vitamer of the family, because it is chemically the most air-stable, and it is the easiest to crystallize and therefore easiest to purify after it is produced by bacterial fermentation.
Vitamin B12 is necessary for the synthesis of red blood cells, the maintenance of the nervous system, and growth and development in children.
Deficiency can cause anemia. Vitamin B12 neuropathy, involving the degeneration of nerve fibres and irreversible neurological damage, can also occur.