by Erin Byers

Created on: February 14, 2009

The world of vitamins seems to be a complex alphabet comprised of strange letter and number combinations. In a sense, it is a complex alphabet. Vitamin B12, one of the eight B vitamins (yes, eight), is a water-soluble vitamin that aids in metabolism and in the formation of red blood cells and DNA. It also plays an important role in maintaining the health of the myelin sheath (the insulation that surrounds nerve cells). So, what does all this mean?

Deficiencies of vitamin B12 are rare because of the nature of the vitamin. B12 is a water-soluble vitamin; however, it is different than most other water soluble vitamins. Most water-soluble vitamins are not stored in the body. Instead, whatever is not absorbed through digestion is excreted through urine and feces. This is why we must consume water-soluble vitamins daily. However, vitamin B12 is stored in the body (mainly in the liver) for several years. Although deficiencies in vitamin B12 are not common, certain people are at great risk for developing this type of deficiency.

Elderly patients are at most risk for developing B12 deficiency. This is due to various causes, the most common being poor diet and malabsorption. Gastric atrophy, the main cause behind malabsorption, is also due to various reasons. Contributing factors include: long term use of certain medications (antacids, metformin, and antibiotics), H. pylori bacteria, and alcoholism. Vitamin B12 deficiency is also thought to play a role in Alzheimer's and dementia.

Another group at risk is vegans. Since vitamin B12 is found naturally in meat, dairy and egg products, strict vegans will need to find alternative sources of B12. Most plant and soy products lack B12. Options for vegans include dietary supplement (pill or liquid) and fortified foods. Food products include fortified soy milk, soy meat products, certain yeasts, and fortified cereals.

The human body absorbs vitamin B12 in the ileum, which is located in the small intestine. In order for absorption to take place, vitamin B12 must bind to a glycoprotein called intrinsic factor. Some people lack intrinsic factor for one of two reasons. Most commonly, this is due to an autoimmune disorder in which the body attacks the stomach's parietal cells which make intrinsic factor. The other, less common reason is a rare congenital disorder in which the child is born unable to produce enough intrinsic factor. A lack of intrinsic factor leads to pernicious anemia. Pernicious anemia is caused by the body's inability to absorb vitamin B12 resulting in a lack of red blood cell formation.

Other people who may be at risk include persons diagnosed with Crohn's disease, individuals with chronic pancreatitis, and those who have had gastric bypass surgery. Sometimes vitamin B12 deficiency presents in a milder manner with some of the following symptoms.

Numbness and tingling in the extremities

Dulled mental function

Depression

Constant tiredness/weakness

The recommended intake for vitamin B12 is 2.4-3.0 micrograms daily. Pregnant and lactating females need between 2.6 and 2.8 micrograms per day. As long as one eats a balanced diet, obtaining the recommended intake should be quite easy. The following table shows just how easy it is to meet the required intake. These values are estimated and should just be used as a guide.

A little knowledge is all you need to decipher the complex language of vitamins. Just remember to keep the following in mind. Although vitamins seem natural and harmless, it is possible that they could react in a negative manner with certain medications. You should never begin taking vitamins or supplements without first consulting your healthcare provider.

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