Dietary Supplement Fact Sheet: Vitamin B12
What is vitamin B12?
Vitamin B12 helps maintain healthy nerve cells and red blood cells [1-4]. It is also needed to help make DNA, the genetic material in all cells. Vitamin B12 is also called cobalamin because it contains the metal cobalt [1-4].
Vitamin B12 is bound to the protein in food. Hydrochloric acid in the stomach releases vitamin B12 from proteins in foods during digestion. Once released, vitamin B12 combines with a substance called intrinsic factor (IF). This complex can then be absorbed by the intestinal tract.
What foods provide vitamin B12?
Vitamin B12 is naturally found in foods that come from animals, including fish, meat, poultry, eggs, milk, and milk products. Fortified breakfast cereals are a particularly valuable source of vitamin B12 for vegetarians [5-7]. Table 1 lists a variety of food sources of vitamin B12.
When is a deficiency of vitamin B12 likely to occur?
Results of two national surveys, the National Health and Nutrition Examination Survey (NHANES III-1988-94)  and the Continuing Survey of Food Intakes by Individuals (CSFII 1994-96) found that most children and adults in the United States (US) consume recommended amounts of vitamin B12 [6-8]. A deficiency may still occur as a result of an inability to absorb vitamin B12 from food and in strict vegetarians who do not consume any foods that come from animals . As a general rule, most individuals who develop a vitamin B12 deficiency have an underlying stomach or intestinal disorder that limits the absorption of vitamin B12 . Sometimes the only symptom of these intestinal disorders is subtly reduced cognitive function resulting from early vitamin B12 deficiency. Anemia and dementia follow later [1,11].
Signs, symptoms, and health problems associated with vitamin B12 deficiency:
Characteristic signs, symptoms, and health problems associated with vitamin B12 deficiency include anemia, fatigue, weakness, constipation, loss of appetite, and weight loss [1,3,12].
Deficiency also can lead to neurological changes such as numbness and tingling in the hands and feet [7,13].
Additional symptoms of vitamin B12 deficiency are difficulty in maintaining balance, depression, confusion, dementia, poor memory, and soreness of the mouth or tongue .
Signs of vitamin B12 deficiency in infancy include failure to thrive, movement disorders, delayed development, and megaloblastic anemia .
So there it is- the meat vitamin. Low carbers have this in abundance. Well, I guess most people have enough- almost of all us eat meat or animal products. And good thing we do! I've also seen research on a link between depression and B12 and folate deficiency. I'll post that one as well.