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PROMOTES Energy Production Utilization of the Carbohydrates, Fats and Proteins Availability of Building Blocks Body Needs Accurate Production of DNA Normal Cell Replication Nervous System Function Red Blood Cell Production Normal Homocysteine Levels
PROTECTS AGAINST Anemia Cardiovascular Disease Alzheimer's Disease
The action of vitamin B12 is complimented by some of the other members of the B complex family.
Folic Acid works in a synergistic way with B12 to boost the activity associated with red blood cell production as well as the effect on homocysteine levels in the blood stream.
People with active lives that have frequent increases in stress levels need B complex vitamin supplementation (all the B vitamins). That includes approximately 500 micrograms of B 12.
Overview Vitamin B12 was isolated in 1948 from an extract of liver. It was shown to correct and used to treat pernicious anemia from that time on. Interestingly it's structure was not fully understood until 1955.
The name cobalamin reflects the fact that vitamin B12 contains the heavy metal cobalt. The presence of cobalt in the molecule gives it a rich red color.
Vitamin B12, like all the other B vitamins, is water soluble. A protein called intrinsic factor which is found in gastric secretions predominated by hydrochloric acid is what binds to the vitamin B12 in the stomach and down into the intestinal tract. This facilitates its being absorbed into the body for use. Less than 1% of the vitamin B12 eaten in food or supplements can be absorbed without intrinsic factor being present in the gastrointestinal tract.
Even though vitamin B12 is water soluble, it can be stored in large amounts in the body predominantly in the liver. This is very unlike the other B and B like vitamins. Acquired deficiency develops over a longer period of time and usually presents in a more insidious manner.
Vitamin B12 activity is exhibited in several cobalamin compounds. Cyanocobalamin is the most stable and active form of the vitamin. It contains a cyanide cluster which is negligible. It is therefore the most commonly used pharmaceutical supplementation of vitamin B12 parenterally, frequently called the vitamin "B12 shot."
Deficiency Symptoms Vitamin B12 deficiency most frequently manifests as anemia. The symptoms of anemia, including fatigue, pale skin, feeling cold, breathlessness and palpitations, are usually the first seen. A macrocytic anemia, the anemia of abnormally large red blood cells (RBCs), develops because of impaired DNA synthesis without the same level of impairment of the RNA which leads to a build up of cytoplasmic components in a slower than normal dividing cell, thus the larger, ill functioning RBCs. The decreased functioning of the RBCs results in decreased oxygen carrying capacity.
Vegetarians are at risk for B12 deficiency. Some attempt to get B12 from sea vegetables such as nori and wakame, but these and their related species do not have the B12 analogue that is metabolically active in humans. It is best for vegetarians to supplement B12.
Many of the antibiotics deplete vitamin B12.
See DRUG DEPLETION TABLE for specific drug information.
Boiling can deplete vitamin B12.
Animal protein products are the natural source of this vitamin as B12 is synthesized by micro organisms in the digestive tract of animals.
These animal sources include: -Eggs -Fish -Meat -Milk and Milk Products -Poultry -Organ meats are the best source.
It does not occur naturally in fruits, grains, legumes or vegetables. Brewers or nutritional yeast does provide it in small quantities.
Primarily breads and cereals; also orange juice and soymilk.
Vitamin B12 in the form of cobalamin coenzymes plays a central role in the replication of the genetic code thus making it an essential growth factor for all of the cells of the body. These coenzymes are necessary for the progression of RNA to DNA. Vitamin B12 **demetholates** methylfolate in the generation of tetrahydrofolate in the synthesis of DNA.
Vitamin B12 is involved in various aspects of all macronutrient (protein, fat and carbohydrate) metabolism primarily through the methyl group transfer. This is also a step in the synthesis of methionine and in folic acid metabolism.
Vitamin B12 is required for the synthesis of myelin which is the insulating cover around certain types of nerves that allows for high speed, instantaneous transport of neuro impulses. In this way it plays a major role in the overall functioning of the nervous system.
Vitamin B12 is needed for the maturation of red blood cells.
Relatively large amounts of vitamin B12 are stored in the liver. Since vitamin B12 must be separated from proteins by the digestive tract, individuals with atrophic gastritis or bacterial overgrowths that produce an inflammation of the lining of the stomach and interfere with the normal secretion of acids necessary for this process are at higher risk for low levels. Dietary supplements and fortified foods are more accessible forms for these folks. Approximately 10 - 30% of persons over 50 have varying levels of deficiency and supplementation can correct this where dietary changes are not possible.
Elevated homocysteine levels in the blood is now recognized as one of the most critical independent risk factors to the development of cardiovascular disease which causes heart attacks and strokes. Homocysteine, a toxic intermediate metabolite of the amino acid methionine, can directly damage the blood vessel inner lining called the endothelium. These damaged areas scar which leads to a decrease in the flexibility of the arteries, a process called athrosclerosis. Vitamin B12 is one of the nutrients that is felt to lower circulating plasma homocysteine levels and keep it from accumulating to higher then normal levels in the blood. Studies are underway to determine how much vitamin B12 in combination with what other substances is most efficacious in bringing down elevated homocysteine levels.
Recommended Dietary Allowance: The RDA -recommended dietary allowance- for vitamin B12 is listed below. The currently established minimal recommended daily requirement for vitamin B12 is 6 micrograms (mcg). Intramuscular injections are the most effective route of administration for supplementation. Since oral supplements are not readily absorbed, between 100 to 2000 mcg per day is the range of recommended doses. A frequently seen standard dose for supplementation and correction of pernicious anemia is 1000 mcg (1 gram) per day by mouth.
RDA/AI* (Adequate Intake)
AGE (YRS) AMOUNT in micrograms (mcg) / day
Infants 0.0-0.5: 0.4 - 0.5* 0.5-1.0: 0.4 - 0.5*
Children 1-3: 0.9 - 1.2 4-8: 0.9 - 1.2
Males 9-13: 1.8 14-18: 2.4 19-30: 2.4 31-50: 2.4 51-70: 2.4 71+: 2.4
Females 9-13: 1.8 14-18: 2.4 19-30: 2.4 31-50: 2.4 51-70: 2.4 71+: 2.4
Pregnant: 2.6
Lactating: 2.8
There are no known symptoms of toxicity for vitamin B12. This holds true when doses 1000 times higher than the RDA are taken. |