Vitamin B12 is an essential vitamin found in animal protein. It is required to produce red blood cells. Vitamin B12 deficiency can lead to impaired red blood cell production and to a condition called anemia, which is characterized primarily by fatigue and pallor.
How B12 Gets into the Body
Vitamin B12 is a water-soluble member of the B vitamin complex that is found in animal products (for example, beef, liver and fish) and fortified breakfast cereals. It is absorbed in a two-step process. First, vitamin B12 binds intrinsic factor, a protein secreted by the stomach; second, the vitamin B12/intrinsic factor complex is absorbed in the small intestine.
Function of B12
Vitamin B12 is required for the process of DNA synthesis. Specifically, vitamin B12 is a co-factor for two enzymes: methionine synthase and L-methylmalonyl CoA mutase. Methionine synthase aids in the synthesis of methionine, which is incorporated into S-adenosyl methionine, or SAM. SAM donates a methyl group to uracil, which is a precursor of thymine, a DNA nucleotide.
Anemia
Anemia is caused by a deficiency of red blood cells, which are the cells of your body that carry oxygen from the atmosphere to your tissues. Symptoms of anemia include paleness; shortness of breath, particularly with exertion; fatigue; a rapid or irregular heartbeat; dizziness and chest pain. Anemia can be caused by many things, including poor iron intake, chronic disease, bone marrow failure and vitamin deficiency.
B12 and Anemia
Vitamin B12 deficiency can cause anemia because B12 is required to synthesize DNA for red blood cells. In the absence of vitamin B12, red blood cell production is impaired, and anemia results. You may be at risk of vitamin B12 deficiency is you have gastrointestinal problems that affect your ability to absorb B12, including (but not limited to) pernicious anemia (an autoimmune disease), Chrone's disease or a history of small bowel surgery. You may also be at risk if you consume low levels of animal protein--for example, if you eat a strict vegan diet without supplementing B12. However, B12 is stored for years in your liver, so it takes some time for vitamin levels to become low enough to cause disease.
Other Symptoms of B12 Deficiency
B12 deficiency is a serious concern not only because of anemia but because deficiency can cause serious neurological problems. The first symptoms of B12-mediated neurological problems are often tingling, numbness and loss of coordination.
Testing and Treatment
If you think you may be B12-deficient or have anemia, talk to your doctor. You can be tested for both with a blood smear or blood test. If you are B12 deficient, your doctor may prescribe B12 supplements or may request that you speak to a dietician.
