The human body requires the water-soluble vitamin B12 for the proper formation of red blood cells, neurological functioning and the synthesis of DNA. The recommended daily allowances for vitamin B12 are 2.4 mcg per day for both adult males and females, 2.6 mcg per day for pregnant females and 2.8 mcg per day for breastfeeding females, according to the Office of Dietary Supplements. Over time, deficiencies in this important vitamin can lead to a circulatory system disorder called anemia.
Vitamin B12 Absorption
In order to understand how B12 deficiency anemia develops, it is important to understand how vitamin B12 is absorbed in the body. When foods containing vitamin B12 are ingested, hydrochloric acid and an enzyme called protease break down the food and trigger the release of the vitamin in the stomach. Vitamin B12 must then combine with a protein called intrinsic factor, which is secreted by special cells called parietal cells in the stomach. Vitamin B12 is carried by intrinsic factor to the small intestine where it is absorbed and deposited into the bloodstream.
About Anemia
Anemia is a condition characterized by a lack of healthy red blood cells in the body. A deficiency of vitamin B12 causes a type of anemia called megaloblastic anemia. This type of anemia is characterized by larger than normal red blood cells that cannot properly bind oxygen and deliver it to the body tissues. Pernicious anemia is a subtype of megaloblastic anemia that occurs as a result of a B12 deficiency due to a lack of intrinsic factor in the body. Without intrinsic factor, vitamin B12 cannot be absorbed, regardless of how much is available in the body.
Causes of Anemia
There are a number of reasons why a person might not have intrinsic factor available in the body. A lack of intrinsic factor can be due to gene defects that are acquired at birth, autoimmune diseases that attack the stomach cells that produce intrinsic factor or a weakened stomach lining, according to Medline Plus.
Anemia that is not caused by a lack of intrinsic factor may develop as a result of lack of vitamin B12 in the diet, chronic alcoholism, digestive diseases, certain surgeries that affect the small intestine or prolonged used of antacids.
Symptoms
Mild anemia does not usually cause any symptoms. As the anemia worsens, those with the B12 deficiency may experience diarrhea or constipation, fatigue, weakness, loss of appetite, shortness of breath, difficulty concentrating and bleeding gums. Over time, anemia caused by a vitamin B12 deficiency can lead to nerve damage. Neurological symptoms of anemia include confusion, depression, loss of balance and tingling and numbness in the extremities, according to Medline Plus.
Treatment
Vitamin B12 deficiency anemia can be successfully treated with the supplementation of B12. Most cases require long-term or lifetime supplementation. Vitamin B12 is often given as injections, but may also be administered orally in some cases.
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