Vitamin B 12 deficiency anemia, also known as pernicious anemia, is a condition in which the body does not make enough healthy red blood cells due to lack of vitamin B 12. Red blood cells contain a protein called hemoglobin, which gives blood its red color. More importantly, hemoglobin helps the blood store and transport oxygen from the lungs to other parts of the body.

Individuals with vitamin B12 deficiency anemia have low oxygen in their blood. As a result, they often feel tired as their bodies cannot make enough energy. In severe cases of vitamin B12 deficiency anemia, the insufficient oxygen in the blood can cause serious and sometimes fatal damage to the heart and other important organs in the body.

As the name suggests, this type of anemia results from vitamin B12 deficiency. Causes of vitamin B12 deficiency,on the other hand, include low dietary intake and absorption disorder. An absorption disorder may result from reduced stomach acid, lack of intrinsic factor, or diseases that impair absorption of nutrients in the small intestine.

So, who is most at risk and why? Adults aged 50 and older are at INCREASED risk of developing vitamin B12 deficiency, primarily because of reduced stomach acid. Vitamin B 12 found in foods is bound to protein, and stomach acid (like hydrochloric acid) is needed to separate it. Reduced stomach acid decreases the body's ability to release the vitamin from protein. An estimated 30% of older adults have vitamin B12 absorption disorder. For this reason, the Food and Nutrition Board of the Institute of Medicine recommends that older adults should meet their vitamin B12 daily requirement mainly from fortified food or supplements like multivitamins and B complex.

People who lack or produce low levels of intrinsic factor are also at increased risk of vitamin B12 deficiency. Intrinsic factor is a class of protein produced by the cells found in the lining of the stomach. After vitamin B12 has been separated from protein, it must bind to intrinsic factor before the body can absorb it. Without this protein, vitamin B12 cannot be absorbed into the blood stream; instead, it is excreted in stool. Lack of intrinsic factor may be caused by autoimmune reaction in which abnormal antibodies, produced by a person's own overactive immune system, attack and destroy the protein.

Furthermore, individuals with inflammatory bowel disease like Crohn's disease can develop vitamin B12 deficiency. Crohn's disease causes inflammation of the digestive system, especially the lower part of the small intestine (or ileum) where vitamin B12 is absorbed. Certain surgeries that result in the removal of the ileum also increase the risk of vitamin B12 deficiency.

Vegans are another high risk group for vitamin B12 deficiency. Consumption of strict vegetarian diet substantially reduces the amount of vitamin B12 a person can get from food. This is because plant foods are very low in vitamin B12 and over time may cause deficiency and anemia.

The good news, however, is that anemia due to vitamin B12 deficiency is treatable. Patients with the disease receive vitamin B12 deficiency treatment designed to restore the blood level of the vitamin to normal. For example, patients with neurologic symptoms of vitamin B12 deficiency are given vitamin B12 injection daily or weekly for weeks until the level of vitamin B12 returns to normal. Then, injections are given once a month. Those with advanced vitamin B12 deficiency, especially older adults, may receive treatment for the rest of their lives. Patients with mild deficiency are treated with vitamin B12 pills or spray until normal levels of the vitamin is restored.

Vitamin B12 deficiency anemia is a serious medical condition that reduces the amount of oxygen in the blood. People with the disease always feel tired because their body cannot make enough energy. It is caused by low levels of vitamin B12 in the body. Certain groups in the population are more susceptible to the disease than others, and these groups include adults 50 years and older, people with inflammatory bowel disease and overactive immune system, and strict vegetarians. Doctors treat the disease with vitamin B12 injection or pills.