Vitamin B12 belongs to a group of vitamins called water-soluble vitamins. The vitamin helps red blood cells form, protects nerve cells and allows DNA synthesis. A vitamin B12 deficiency develops when there is not enough B12 available in the body. Pernicious anemia is a condition in which the body has a decreased number of red blood cells due to a vitamin B12 deficiency.
Physiology
When you eat foods that contain vitamin B12, the body breaks the foods down, separating the vitamin. Vitamin B12 then binds to a protein in the stomach, called intrinsic factor, which is produced by the parietal cells in the stomach. When vitamin B12 is bound to intrinsic factor, it can be successfully carried into the small intestine where it gets absorbed by the body.
Causes
The most common cause of pernicious anemia is a lack of intrinsic factor. A lack of intrinsic factor can develop as a result of an autoimmune condition or surgical removal of all of part of the stomach.
Pernicious anemia may also develop because the small intestine cannot properly absorb vitamin B12. This malabsorption may be the result of bacterial overgrowth in the intestine, digestive diseases, infection, certain medications or surgical removal of all or part of the small intestine.
Less commonly, pernicious anemia can develop due to a diet that is lacking in vitamin B12. This is most common in strict vegetarians or vegans because animal foods are the richest sources of vitamin B12.
Symptoms
Initially, pernicious anemia causes fatigue, dizziness, shortness of breath, headache, chest pain and coldness in the hands and feet. The lack of red blood cells can also cause your gums, skin and nail beds to turn pale. As pernicious anemia develops, it can result in damage to the nerves, which is characterized by tingling and numbness in the hands and feet, muscle weakness, loss of balance and difficulty walking. Pernicious anemia also affects the digestive tract, causing nausea, vomiting, heartburn, abdominal pain, gas, bloating, constipation, diarrhea, weight loss and lack of appetite, according to the National Heart, Lung and Blood Institute.
Treatment
The goal of treatment for pernicious anemia is to replace the missing vitamin B12 in the body. For mild pernicious anemia, oral supplementation of vitamin B12 is usually sufficient. Those with severe pernicious anemia may require regular intravenous injections of the vitamin. If a cause of pernicious anemia can be identified, it is also important to seek treatment for the cause in order to prevent pernicious anemia from developing again.
Prevention
There is no way to prevent pernicious anemia that develops from a lack of intrinsic factor. For those that produce intrinsic factor, pernicious anemia can be prevented by increasing dietary intake of vitamin B12. The best sources of vitamin B12 include meat, fish, shellfish, eggs, dairy products and fortified cereals. Supplements that contain vitamin B12 are also available, but you should discuss any supplementation with your health care provider.
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