Vitamin B12, or cobalamin, is the only vitamin that contains an essential mineral cobalt.  It is also unique in that it is required in much smaller amounts 3 to 4 mcg; however, levels of up to 1 mg are often used therapeutically.  It is essential for the metabolism of the nerve tissue and necessary for the health of the entire nervous system.

The body stores vitamin B12, so deficiencies may take several years to develop.  The highest concentrations of B12 are found in the liver, heart, kidney, pancreas, brain, testes, blood and bone marrow all active metabolic tissues.

Vitamin B12 is found in significant amounts in the animal proten foods.  Primary food sources include most fish (specially the oily ones), crabs and oysters, eggs, milk products and meat.  Three to 4 mcg of vitamin B12 is needed in most adults to prevent deficiency, but 10 to 20 mcg daily is a good insurance level.  Vitamin B12 can also be consumed through oral supplementation, most widely found as cyanocobalamin.  Hydroxycobalamin is a form of B12 used in injections which are recommended in cases of B12 malabsorption.

Perhaps because of the small amount necessary to maintain recommended vitamin B12 levels, the Framingham Nutrition Studies reported that approximately 94 percent of men and 83% of women meet the RDI guidelines the highest percentage of all nutrients.

The classic B12 deficiency disease is pernicious anemia, which is often accompanied by weight loss, weakness, pale skin and psychological disturbances.  This type of anemia occurs frequently in alcoholics, the elderly and strict vegetarians.  There have been no known toxic effects from megadoses of vitamin B12.

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