Cobalamin or vitamin B₁₂ is a chemical compound that is also known as cyanocobalamine. It is needed for nerve cells and red blood cells, and to make DNA. It is an organometallic compound with a trivalent cobalt ion bound inside a corrin ring. Its chemical structure was determined by Dorothy Crowfoot Hodgkin.

History as a treatment for anemia

Vitamin B₁₂ deficiency is the cause of several forms of anemia. The treatment for this disease was first devised by William Murphy who bled dogs to make them anemic and then fed them various substances to see what (if anything) would make them healthy again. He discovered that ingesting large amounts of liver seemed to cure the disease. George Minot and George Whipple then set about to chemically isolate the curative substance and ultimately were able to isolate vitamin B₁₂ from the liver. For this, all three shared the 1934 Nobel Prize in Medicine.

Deprivation

Vitamin B₁₂ is mostly absorbed in the terminal ileum. The production of intrinsic factor in the stomach is vital to absorption of this vitamin. Megaloblastic anemia can result from inadequate intake of vitamin B₁₂, inadequate production of intrinsic factor (pernicious anemia), disorders of the terminal ileum resulting in malabsorption, or by competition for available B₁₂ (such as fish tapeworms or bacteria present in blind loop syndrome). Neurological signs of B₁₂ deficiency, which can occur without accompanying hematologic abnormalities, include demyelination and irreversible nerve cell death. Symptoms include numbness or tingling of the extremities and an ataxic gait.

The American Psychiatric Association's American Journal of Psychiatry has published studies showing a relationship between depression levels and deficient vitamin B₁₂ blood levels in elderly people in 2000 [1] (http://ajp.psychiatryonline.org/cgi/content/abstract/157/5/715) and 2002 [2] (http://ajp.psychiatryonline.org/cgi/content/abstract/159/12/2099).

Sources

In nature, B₁₂ is solely produced by bacteria found in animals (including humans), so that dirt could actually be considered a natural source of B₁₂. While vegetarians usually get enough B₁₂ through dairy products or eggs, it can sometimes be lacking in those following vegan diet who do not make an effort to find B₁₂ enriched foodstuffs, like enriched cereals, soya based products or yeast extract. Claimed sources of B12 that have been shown through direct studies of vegans to be inadequate include spirulina (an algae), nori (a seaweed), barley grass, and human gut bacteria. Several studies of vegans on raw food diets show that raw food offers no special protection against B12 deficiency either.

Other uses

Vitamin B₁₂ is a popular substance for use in diluting (or cutting) methamphetamine.

External links

• http://ods.od.nih.gov/factsheets/cc/vitb12.html
• Vitamin B12 information (http://www.talkwellness.org/vitaminb12.html)
• Sources of Vitamin B12 in a raw food diet (http://www.1st-in-raw-food-diet.com/vitamin-b12.html)
• http://www.vegansociety.com/html/food/nutrition/b12/