martes, 3 de mayo de 2011

vitamin B12

What high-vitamin B12 foods can do for you:
  • support production of red blood cells and prevent anemia
  • allow nerve cells to develop properly
  • help your cells metabolize protein, carbohydrate, and fat
What events can indicate a need for more high-vitamin B12 foods?
  • red or sore tongue
  • tingling or numbness in feet
  • nervousness
  • heart palpitations
  • depression
  • memory problems
What is vitamin B12?
Vitamin B12 is one of the most controversial members of the vitamin family collectively referred to as the "B-complex" vitamins. Although the full chemical structure of B12 was not identified until the 1960s, two Nobel Prizes have already been awarded for research involving this vitamin. The first of these Nobel Prizes, awarded in 1934, involved the discovery that a food (liver, a very rich source of B12) could be used to treat a particular type of anemia (inability of the bloodstream to carry oxygen) called pernicious anemia. The second came thirty years later when chemists figured out the exact structure of this important vitamin.
Vitamin B12 is unusual with respect to its origins. While most vitamins can be made by a wide variety of plants and specific animals, no plant or animal has been shown capable of producing B12, and the exclusive source of this vitamin appears to be tiny microorganisms like bacteria, yeasts, molds, and algae.
Like most vitamins, B12 can occur in a variety of forms and can take on a variety of names. Names for B12 include: cobrynamide, cobinamide, cobamide, cobalamin, hydroxcobalamin, aquocobalamin, nitrotocobalamin, and cyanocobalamin. Each of these designations contains a form of the word "cobalt," since cobalt is the mineral found in the center of the vitamin.
B-12 is also unusual in that it is dependent upon a second substance, called intrinsic factor, to make its way from the "GI" tract (gastrointestinal tract--the stomach and intestines) into the rest of the body. Without intrinsic factor, which is a unique protein made in the stomach, vitamin B12 cannot gain access to the rest of the body where it is needed.
What is the function of vitamin B12?
Forming red blood cells
Perhaps the most well-known function of B12 involves its role in the development of red blood cells. As red blood cells mature, they require information provided by molecules of DNA. (DNA, or deoxyribose nucleic acid, is the substance in the nucleus of our cells which contains genetic information.) Without B12, synthesis of DNA becomes defective, and so does the information needed for red blood cell formation. The cells become oversized and poorly shaped, and begin to function ineffectively, a condition called pernicious anemia. More often than not, pernicious anemia isn't caused by a lack of B12 itself, but by a lack of intrinsic factor -- the stomach-made protein required for the absorption of B12.
Developing nerve cells
A second major function of B12, less clearly understood than the first, involves its participation in the development of nerve cells. A coating which encloses the nerves -- called the myelin sheath -- forms less successfully whenever B12 is deficient. Although the vitamin plays an indirect role in this process, supplementation of B12 has been shown to be effective in relieving pain and other symptoms in a variety of nervous system disorders.
Other roles for vitamin B12
Protein -- the component of food required for growth and repair of cells -- depends upon B12 for proper cycling through the body. Many of protein's key components, called amino acids, become unavailable for use in the absence of B12. Since one of the steps in carbohydrate and fat processing requires B12 for its completion, insufficiency of the vitamin can also affect the movement of carbohydrates and fats through the body.
What are deficiency symptoms for vitamin B12?
Although B12 is not the only nutrient deficiency that can contribute to occurrence of the following symptoms, B12 deficiency should be considered as a possible underlying factor whenever any of the symptoms listed below are present.
Symptoms potentially associated with vitamin B12 deficiency:

dandruffnervousness
decreased blood clottingnumbness in feet
decreased reflexespaleness
depressionred tongue
difficulty swallowingsore tongue
fatiguetingling in feet
heart palpitationsweakness
memory problemsweak pulse
menstrual problems

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