Science Fair Project Encyclopedia
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.
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  and 2002 .
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, soy-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.
Vitamin B12 is a popular substance for use in diluting (or cutting) methamphetamine.
- Vitamin B12 information
- Sources of Vitamin B12 in a raw food diet
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