Anemia
The first deficiency symptom that was discovered was anemia characterized by enlarged blood corpuscles, so-called megaloblastic anemia.The anemia is easy to cure with vitamin B12.Far more serious is the damage to the nervous system that may occur due to deficiency.
Early and even fairly pronounced deficiency does not always cause distinct or specific symptoms. Common early symptoms are tiredness or a decreased mental work capacity, decreased concentration and decreased memory, irritability and depression; also sleep disturbances may occur.
Neurological signs of B12 deficiency, which can occur without anemia, include sensory disturbances due to damage to peripheral nerves caused by demyelination and irreversible nerve cell death. Symptoms include numbness, tingling of the extremities, disturbed coordination and, if not treated in time, an ataxic gait, a syndrome known as subacute combined degeneration of spinal cord.
Recent studies have devalued a possible connection between B12 deficiency and Alzheimer's dementia, and such a correlation is unlikely as of June 2007.
Vitamin B12 and Depression
Studies showing a relationship between clinical depression levels and deficient B12 blood levels in elderly people are documented in the clinical literature.Bipolar disease appears to genetically co-segregate with the hereditary B12-deficiency disorder pernicious anemia.
Causes of deficiency
B12 is mostly absorbed in the terminal ileum, the lower part of the small intestine. Hydrochloric acid is also necessary for enabling the uptake.Vitamin B12 deficiency can result from inadequate intake of B12, disorders of the terminal ileum resulting in malabsorption, or by competition for available B12 (such as fish tapeworms or bacteria present) or due to disturbed bacterial flora after antibiotics treatment.
The popular stomach acid reducing drugs such as proton pump inhibitors (e.g. Losex, Nexium, Prevacid, Pariet and others), can decrease B12 absorption to a large extent.
The diabetes medication, metformin may interfere with B12 dietary absorption.
Helicobacter Pylori
Another common cause of B12 deficiency is Helicobacter (Pylori) infection which is a major cause of gastritis. The risk for B12 deficiency in this condition is enhanced by the fact that gastritis is treated with proton pump inhibitors that greatly decrease B12 absorption.B12 Deficiency
Recent research indicates that B12 deficiency is far more widespread than formerly believed. A large study in the US found that 39 percent had low levels of B12.B12 deficiency is even more common in the elderly. This is because B12 absorption decreases greatly in the presence of atrophic gastritis, which is common in elderly.
B12 and Vegetarians
B12 deficiency is common among vegetarians. In vegans the risk is very high because virtually none of their natural food sources contain B12 (fortunately many use B12 supplements nowadays). One American study found blood levels below normal in 92 % of vegans, 64 % of lactovegetarians, 47 % of lacto-ovovegetarians.Treatment of B12 deficiency
Traditionally, treatment for B12 deficiency was through intramuscular injections of cyanocobalamin. However, allergy against B12 may sometimes be triggered by injections.It has been appreciated since the 1960s that deficiency can sometimes be treated with oral B12 supplements when given in sufficient doses.
