Vitamin B12 information
Vitamin B12, vitamin B12 or vitamin B-12, also called cobalamin, is a water soluble vitamin with a key role in the normal functioning of the brain and nervous system, and for the formation of blood. It is one of the eight B vitamins. It is normally involved in the metabolism of every cell of the human body, especially affecting DNA synthesis and regulation, but also fatty acid synthesis and energy production. As the largest and most structurally complicated vitamin, it can be produced industrially only through bacterial fermentation-synthesis.
Vitamin B12 consists of a class of chemically-related compounds (vitamers), all of which have vitamin activity. It contains the biochemically rare element cobalt. Biosynthesis of the basic structure of the vitamin in nature is only accomplished by simple organisms such as some bacteria and algae, but conversion between different forms of the vitamin can be accomplished in the human body.
A common synthetic form of the vitamin, cyanocobalamin, does not occur in nature, but is used in many pharmaceuticals and supplements (such as those sold through this site), and as a food additive, because of its stability and lower cost. In the body it is converted to the physiological forms, methylcobalamin and adenosylcobalamin, leaving behind the cyanide, albeit in minimal concentration. More recently, hydroxocobalamin (a form produced by bacteria), methylcobalamin, and adenosylcobalamin can also be found in more expensive pharmacological products and food supplements. The usefulness of these is presently under debate.
Vitamin B12 was discovered from its relationship to the disease pernicious anemia, which is an autoimmune disease that destroys parietal cells in the stomach that secrete intrinsic factor. Intrinsic factor is crucial for the normal absorption of B12, so a lack of intrinsic factor, as seen in pernicious anemia, causes a vitamin B12 deficiency. Many other subtler kinds of vitamin B12 deficiency and their biochemical effects have since been investigated.
Vitamin B12 deficiency
Vitamin B12 deficiency can potentially cause severe and irreversible damage, especially to the brain and nervous system. At levels only slightly lower than normal, a range of symptoms such as fatigue, depression, and poor memory may be experienced. Read more about vitamin b12 deficiency here.
Vitamin B12 food sources
Vitamin B12 is found in foods that come from animals, including fish and shellfish, meat (especially liver), poultry, eggs, milk, and milk products. While lacto-ovo vegetarians usually get enough B12 through consuming dairy products, vegans will lack B12 unless they consume multivitamin supplements (as sold through this site) or B12-fortified foods. Examples of fortified foods include fortified breakfast cereals, fortified soy products, fortified energy bars, and fortified nutritional yeast. Read more about vitamin B12 food sources and supplements here.
Vitamin B12 recommended intake
The Dietary Reference Intake for an adult ranges from 2 to 3 µg (micrograms) per day.
Vitamin B12 is believed to be safe when used orally in amounts that do not exceed the recommended dietary allowance (RDA). The RDA for vitamin B12 in pregnant women is 2.6 µg per day and 2.8 µg during lactation periods. There is insufficient reliable information available about the safety of consuming greater amounts of vitamin B12 during pregnancy.
The Vegan Society, the Vegetarian Resource Group, and the Physicians Committee for Responsible Medicine, among others, recommend that vegans either consistently eat foods fortified with B12 or take a daily or weekly B12 supplement. Fortified breakfast cereals are a particularly valuable source of vitamin B12 for vegetarians and vegans. In addition, adults age 51 and older are recommended to consume B12 fortified food or supplements to meet the RDA, because they are a population at an increased risk of deficiency.
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