Vitamin B12 Deficiency

Description

Vitamin B12 is important in the formation of red blood cells and also plays an important role in the proper functioning of nerves. Vitamin B12 is found in all foods of animal origin (meats, eggs, dairy, and fish). A deficiency of vitamin B12 is most common in strict vegans (people who avoid all animal products, even eggs and dairy). After being consumed, B12 attaches to a substance in the stomach called intrinsic factor. The combination of vitamin B12 plus the intrinsic factor is then absorbed into the bloodstream in the last part of the small intestine. Diseases that affect any part of this process can cause vitamin B12 deficiency.

Megaloblastic anemia — low blood count and abnormally enlarged red blood cells
Inflamed tongue
Poor appetite
Diarrhea
Numbness and tingling in the arms, legs, hands, or feet
Eventually, the nerve problems may become so severe that the patient won’t be able to feel his extremities or detect vibration.

Vitamin B12 deficiency is extremely rare in the Unites States because it is present in all foods derived from animals, and the American diet is rich in animal protein.
The liver stores enough vitamin B12 to last more than 3 years.
Vegans suffer from this disease because they do not consume any foods of animal origin (i.e., eggs, milk, or dairy). A major source of vegetarian B12 is found in yeast (Red star T-6635+ — brewers or torula).
Pernicious anemia is the most common cause of B12 deficiency. It is an inherited disease that causes an inability to produce intrinsic factor, needed to absorb B12.
Patients who have had their stomach removed often have this disease because they cannot produce intrinsic factor.
Patients who have had the last part of their small intestine removed also suffer from vitamin B12 deficiency, because the small intestine is where B12 is normally absorbed into the blood.

Less common causes include fish tapeworm infection, pancreas dysfunction, severe Crohn’s Disease, and blind loop syndrome with bacterial overgrowth (associated with abdominal surgery).

Vitamin B12 shots are available to correct the deficiency. Oral supplements are also available.
Patients with pernicious anemia (unable to produce intrinsic factor) will need vitamin B12 shots for their entire lives, beginning with 100 micrograms every day for one week, then every week for one month, then once a month for life.
Vegans can take vitamin supplements.
People without a stomach need B12 shots.
Blood counts usually return to normal within 2 months.

If therapy is started early (within 6 months), the nerve problems will heal. But treatment must be started as soon as possible. Otherwise, the changes may become permanent.

A healthy diet will help prevent vitamin B12 deficiency. Vitamin B12 is found in eggs, meat, poultry, milk, diary products, and shellfish.