Vitamin B12 Vitamin B12, scientifically known as cobalamin, has specific chemical structure and characteristics which qualify as a water-soluble vitamin. However, unlike the other water-soluble vitamins it is not disgorged quickly in the urine, but accumulates in the liver, kidney and other body tissues. Therefore, only after 5 or 6 years of B12 insufficient diet the vitamin deficiency can be adequately distinguished. Vitamin B12 serves as a methyl donor and cooperates with folic acid in processes known as the DNA and red blood cells syntheses. Thus, vitamin is crucially important in maintaining the health of the insulation sheath, known as myelin sheath that surrounds nerve cells. The most common vitamin B12 deficiency disease is considered to be pernicious anemia, a disease characterized by large but immature red blood cells.
However, according to contemporary medical studies, a vitamin B12 deficiency can have serious consequences long before anemia becomes evident. Numerous medical sources indicate that the normal blood level of vitamin B12 varies between 200 and 600 picogram per milliliter. Vitamin B12 is considered to be a coenzyme, which means that it is needed for enzymes to change one molecule into another. The structure of Vitamin B12 is complex. One part of its texture is represented with the corrin nucleus, which contains an atom of cobalt. The corrin has strong similarity with the heme of hemoglobin, which contains an atom of iron.
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My name is Rafael, the Red Blood Cell, doctors call me erythrocyte and born in the bone marrow. My shape is bi-concave disk. Also do not possess a nucleus. I am one of trillions of red blood cells that live inside and travel through your body. I deliver oxygen to all the organs and tissues and transport wastes as carbon dioxide out of your body. Oxygen helps keep the body running and healthy. I ...
The combination of corrin and other atoms constitute the cobalatamin part of Vitamin B12. There are only two known cobalatamins that act as coenzymes in the human body, namely methylcobalamin and adenosylcobalamin. Interestingly, the human body is capable to convert some of other cobalamins into one of mentioned active types. The amount of vitamin B12 actually required by the body is very small, and constitutes only about 2 micrograms or 2 millionth of a gram per day. However, comparing to other vitamins and minerals, vitamin B12 is not absorbed very well by the organism and thus more volumes of vitamin should be supplied through the diet or supplementation. Medical science considers microorganisms, primarily bacteria, to be the only organisms to produce Vitamin B12.
Bacteria live in soil, water and the digestive tracts of animals, however, normally Vitamin B12 is attached to animals protein either for transport or storage. Therefore, when people consume animal foods, the B12 becomes protein-bound. However, when the protein-B12 complex reaches the stomach, the latter secretes acids and enzymes that separate the B12 from the protein. Subsequently, another protein, R-protein known as cobalophilin, transcobalamin I1 or haptocorrin, holds the B12 and delivers it through the stomach into the small intestine. R-protein can be found in many fluids throughout the human body, in particular saliva and stomach secretions. Simultaneously, along with Vitamin B12 R-protein pick up any corrinoid. In addition to B12, R-protein can pick up any corrinoid (Scalabrino, 109).
The stomach cells manufacture a protein called intrinsic factor, known also as IF, which also travels to the small intestine. When the corrinoid-R-protein complex reaches the small intestine, the corrinoid is detached from the R-protein by enzymes made by the pancreas (Groff, 71).
Once corrinoids are liberated, only the cobalamins are attached to intrinsic factor. Intrinsic factor then delivers the cobalamins to the last section of the small intestine, called the ileum. The cells bordering the ileum include receptors for the cobalamin-IF complex. The latter secures the cobalamin from bacterial and digestive enzyme degradation (Messina, 47).
The Essay on Nutrition: Fat, Proteins, And Carbohydrates
Many Americans can tell you what components make up their food. Looking at a nutrition facts label, they can tell you the content of fat, carbohydrate, and protein in the foods they eat. Many participate in low carbohydrate dieting, one of the most popular diets around. Others have opted for the United States Department of Agriculture’s low fat diet, but neither understands the chemistry of ...
The IF-receptor also ensures the process during which cobalamins are given the priority for absorption over non-cobalamin corrinoids. Moreover, B12 passive diffusion accounts for 1-3% of vitamin absorbed through usual food sources (Groff, 76).
Through passive diffusion process some inactive B12 analogues are likely to be absorbed. Various medicine evidences indicate that in supplements B12 is not confined to protein and thus, it is not necessary for stomach digestive enzymes to be separated from a protein. Enzymes are needed to dissolve B12 tablets, especially if not chewed. However, taken in large doses, unbound Vitamin B12 is able to overcome IF defects due to absorption through passive diffusion process.
In addition, some preliminary evidence asserts that unbound to protein B12 combined with absorption enhancer can be immediately imbibed through membranes under the tongue at significantly higher rates than those during passive diffusion in digestive tract. The richest dietary sources of vitamin B12 are considered to be liver, and kidneys. In addition, eggs, cheese and deep water species of fish can also supply relatively small amounts. Simultaneously, vegetables and fruits constitute very poor source of Vitamin B12. Thus, several surveys indicate that most strict, long-term vegetarians become vitamin B12 deficient. In addition, elderly people are recognized as Vitamin B12 deficient because their production of the IF required to absorb the vitamin from the small intestine decreases drastically with age. Contemporary physicians consider oral supplementation with Vitamin B12 to be safe and efficient. The majority of multi-vitamin tablets contains 100-200 microgram of cyanocobalamin form of B12, which subsequently should be converted to methylcobalamin in order to be used by the body. To avoid already mentioned problem of Vitamin B12 absorption, the best option is to dissolve a tablet of methylcobalamin under the tongue (Elia, 1721).
Some medical practitioners assert that monthly injections of B12 are mandatory in order to maintain sufficient vitamin levels in old people and patients with a diagnosed deficiency. Simultaneously, there is no scientific evidence supporting the allegation that injections are more efficient than sublingual supplementation. Vitamin B12 deficiency often reveals itself first in the development of neurological dysfunction, which is highly difficult to distinguish from senile dementia and Alzheimers disease. Some medical studies indicate that many patients showing symptoms of Alzheimers disease actually suffer from a vitamin B12 deficiency. Avitaminosis of B12 is associated with asthma, depression, tinnitus, multiple sclerosis, AIDS, diabetic neuropathy as well as low sperm counts. It is inevitable fact that in order to have healthy and full organisms, individuals should maintain adequate body stored of this important vitamin. Bibliography Scalabrino G.
The Essay on Diffusion and Osmosis Shown In Solutions
This lab, title Diffusion and Osmosis, was centered around the diffusion across a cellular membrane and how exactly materials move and diffuse in concentrations. Both diffusion and osmosis are forms of movement that are part of passive transport dealing with cell membranes. Diffusion is where the solutes move from an area of high concentration to a low concentration. Water goes through the cell ...
Subacute combined degeneration one century later. The neurotrophic action of cobalamin (vitamin B12) revisited. Boston Books, 1999 Groff J, Gropper S. Advanced Nutrition and Human Metabolism, 3rd ed. Wadsworth: 2000 Messina M, Messina V. The Dietitian’s Guide to Vegetarian Diets.
Gaithersburg, MD: Aspen Publishers, Inc., 1996 Elia, M. Oral or parenteral therapy for B12 deficiency. The Lancet, Vol. 352, November 28, 1998, pp. 1721-22.
