Vitamin B12 Deficiency Causes and Symptoms

Vitamin B12 is necessary for red blood cell formation and has other important functions in the body. A deficiency of B12 can have serious consequences.

Role of Vitamin B12 in the Body

Vitamin B12 is a necessary cofactor for two important enzymes. One enzyme, methionine synthase, is involved in the synthesis of the amino acid methionine, which is required for DNA and RNA metabolism. The other enzyme, L-methylmalonyl-CoA mutase, is necessary for the production of hemoglobin, a critical component of red blood cells.

Causes of B12 Deficiency

Vitamin B12 deficiency is more common in older adults, affecting 10-15% of people over 60 years of age. Aside from simply not getting enough vitamin B12 in the diet, certain medical conditions inhibit B12 uptake.

Pernicious anemia is an autoimmune disease that prevents vitamin B12 from being properly absorbed by the gastrointestinal tract. Another cause of B12 deficiency is food-bound vitamin B12 malabsorption, a condition in which the uptake of protein-bound B12 in foods is impaired due to decreased production of stomach acid. Other conditions that interfere with the absorption of vitamin B12 by the intestines, such as Crohn's disease, celiac disease or surgery to remove part of the small intestine can also lead to vitamin B12 deficiency.

B12 Deficiency Symptoms

Vitamin B12 deficiency causes a low red blood cell count, which is the basis of many of the symptoms, such as:

• Fatigue or lack of energy
• Shortness of breath
• Dizziness or lightheadedness
• Paleness
• Heart palpitations
• Chest pain

Vitamin B12 deficiency can also lead to damage of the nervous system. While the mechanism is not clear, a B12 deficiency appears to cause damage to the myelin sheath that covers nerves. If the B12 deficiency exists for a prolonged period of time, these neurological symptoms may be irreversible. Some neurological symptoms caused by B12 deficiency include:

• Poor memory
• Numbness or tingling in arms and legs
• Difficulty walking
• Disorientation
• Dementia

In addition, vitamin B12 deficiency sometimes causes further symptoms whose origin is unclear, but may be related to inflammation of the stomach. Some of these symptoms include:

• Constipation
• Loss of appetite
• Nausea
• Weight loss
• Sore tongue

How to Get Enough Vitamin B12

The Recommended Daily Allowance of Vitamin B12 is 2.4 mcg per day, which should easily be met by a normal diet. Foods rich in vitamin B12 include meat, fish and shellfish, poultry, eggs and milk. Since B12 is only found in foods derived from animals and is not present in plants or yeast, vegans may be at higher risk of deficiency and should take B12 supplements. Some nutritionists recommend that individuals over the age of 50 should take B12 supplements because the rate of food-bound vitamin B12 malabsorption increases with age.

Sources:

http://lpi.oregonstate.edu/infocenter/vitamins/vitaminB12/

http://www.wrongdiagnosis.com/v/vitamin_b12_deficiency/intro.htm