What Is Vitamin B12 Deficiency? What Causes Vitamin B12 Deficiency?

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Main Category: Blood / Hematology
Also Included In: Nutrition / Diet;  Immune System / Vaccines
Article Date: 02 Dec 2009 - 9:00 PDT

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Vitamin B12 is crucial for the proper formation of red blood cells, as well as the health of nerve tissue. Vitamin B12 deficiency, or B12 deficiency, if left untreated can result in anemia, as well as irreversible nerve and brain damage.

A lack of vitamin B12 in the blood can lead to a blood disorder called pernicious anemia. Those with the disorder are unable to produce enough of a protein substance - IF (intrinsic factor) - in their stomach that allows their body to absorb vitamin B12. Vitamin B12 is injected straight into the patient's blood, therefore bypassing the stomach which is unable to absorb it properly.

Apart from creating red blood cells and keeping our nervous system healthy, we also need vitamin B12 in order to be able to absorb folic acid. Vitamin B12 also helps to release energy.

According to Medilexicon's medical dictionary:

Vitamin B12 is a "generic descriptor for compounds exhibiting the biologic activity of cyanocobalamin; the antianemia factor of liver extract that contains cobalt, a cyano group, and corrin in a cobamide structure. Several substances with similar formulas and with the characteristic hematinic action have been isolated and designated: B12a, hydroxocobalamin; B12b, aquacobalamin; B12c, nitritocobalamin; B12r, cob(II)alamin; B12s, cob(I)alamin; B12III, factors A and V1a (cobyric acid) and pseudovitamin B12. Vitamins B12a and B12b are known to be tautomeric compounds; B12b has been obtained from cultures of Streptomyces aureofaciens; B12c has been obtained from cultures of Streptomyces griseus and is distinguishable from B12 by differences in its absorption spectrum. The physiologically active vitamin B12 coenzymes are methylcobalamin and deoxyadenosinecobalamin. A deficiency of vitamin B12 is often associated with certain methylmalonic acidurias."

What are the signs and symptoms of vitamin B12 deficiency?

A symptom is something the patient feels and reports, while a sign is something other people, such as the doctor detect. For example, pain may be a symptom while a rash may be a sign.

Vitamin deficiencies tend to develop gradually and slowly; sometimes over a period of several years. At first, signs and symptoms may be subtle - but as time goes by they become more noticeable.

Our cells need vitamin B12 in order to multiply properly. We produce millions of red blood cells every minute. A vitamin B12 deficiency affects the production of red blood cells. Subsequently, the red blood cell count drops and the patient develops anemia. The most common symptoms of anemia are:

• Fatigue (tiredness)
• Panting (shortness of breath)
• Palpitations (disagreeable sensations of irregular and/or heavy beating of the heart)

B12 deficiency anemia may also be caused by a lack of intrinsic factor - pernicious anemia. The patient's digestive system cannot absorb B12 properly. Signs and symptoms of pernicious anemia may include:

• Fatigue
• Shortness of breath
• Palpitations

Anemia may also have the following signs and symptoms:

• A sore mouth and/or tongue
• Weight loss
• Pale or yellowish skin
• Diarrhea (sporadic)
• Menstrual problems
• Higher susceptibility to infections

If the deficiency continues untreated the patient may have the following neurological signs and symptoms:

• Tingling or numbness of the fingers
• Tingling or numbness of the toes
• General muscle weakness
• Difficulty walking properly (staggering)
• Irritability
• Confusion
• Forgetfulness
• Tender calves

What are the causes of vitamin B12 deficiency?

• Causes of pernicious anemia - pernicious anemia is caused by an autoimmune disease; the person's own immune system attacks good parts of the body, as if they were bacteria or viruses.
  
  
  The immune system of patients with pernicious anemia creates antibodies which attack the lining of the stomach, damaging cells that produce intrinsic factor. Intrinsic factor is a substance that is secreted by the gastric mucous membrane (lining of the stomach) and is vital for the absorption of vitamin B12 in the intestines. If the production of intrinsic factor is undermined, vitamin B12 cannot be absorbed into the body properly.


• Bowel problem - patients with Crohn's disease, as well as people who have had their bowels surgically shortened, may have problems absorbing vitamin B12 into their bloodstream. Short bowel syndrome is a term used for people who have had their bowel shortened (half or more of their small intestine removed). Patients with short bowel syndrome typically experience diarrhea, cramping and heartburn. It is not uncommon for individuals to become malnourished because what is left of the small intestine cannot absorb adequate quantities of vitamins, water and other nutrients.


• Vegan diet - some people who follow a vegan diet may suffer from B12 deficiency if they do not eat fortified foods, or some types of yeast.

How is B12 deficiency diagnosed?

A GP (general practitioner, primary care physician) will interview the patient and carry out a physical examination, looking out for such signs as an accelerated pulse and pale/yellowish skin.

• Blood test - to determine whether the red blood cell count is low. The appearance of the red blood cells is also checked, because they may have an unusual shape. A blood test can also determine what the level of B12 is.
  
  The GP may also want to check the patient's blood intrinsic factor antibody levels, in order to determine whether the person has pernicious anemia.


• Bone marrow biopsy - the aim here is to rule out other possible causes of red cell abnormalities or anemia.

What are the treatment options for B12 deficiency?

Hydroxocobalamin injections - this is a form of B12. It is injected into a muscle every two to four days. After about six injections the patient should have a good store of B12.

In the majority of cases the patient will notice significant improvements in symptoms soon after receiving injections.

Annual blood tests are common, to monitor the success of treatment.

Most patients require booster injections of B12 every three months for the rest of their lives.

Prevention of B12 deficiency

• Vegans and some vegetarians - vegetarians who do not eat eggs, as well as vegans should make sure their B12 intake is adequate. There are various breakfast cereals which are fortified with vitamin B12. Some brands of nutritional yeast are also good sources of B12. Some types of soy milk are fortified with B12.


• People who eat meat and/or fish - a balanced diet containing fish, meat and dairy foods should have enough B12 for human requirements.

There is no way to prevent pernicious anemia caused by an autoimmune condition.

Written by Christian Nordqvist
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

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