Updated April 30, 2017
Vitamin B12, also called “cobalamin,” is one of the eight water-soluble vitamins that play a key role in the metabolism of every cell in the human body, and is especially important in the normal functioning of the brain and nervous system, and the formation of red blood cells.
Only bacteria have the enzymes needed for the synthesis of various forms of Vitamin B12. No fungi, plants, or animals can make vitamin B12. However, animal tissues significantly store vitamin B12, which is made from bacteria that they have consumed. This is the reason that meat, poultry, eggs, fish, and dairy foods are recommended sources of B12 in people’s diets. Those of us who follow a vegan diet (no animal foods) are often told we must eat animal foods or risk developing deficiency of this essential vitamin.
Fortunately, we live in a world naturally populated with trillions of B12-producing bacteria. Plus our mouth and large intestine are very large reservoirs of B12-synthesizing bacteria. The various sources of bacteria in our environments supply sufficient amounts for most people, and as a result, actual cases of vitamin B12 deficiency disease due to lack of sufficient oral intake are very rare.