Vitamin B12 Deficiency: Symptoms and Causes

The brain and nervous system depend on a chemical called cobalamin, or vitamin B12, for essential metabolic processes. Deficiency can result in neurologic symptoms, however, deficiency is rare in the modern diet. Typically, it occurs in vegans or those with a disorder called pernicious anemia.

Function and Sources

B12 plays a role in metabolism of all cells in the body, but is essential especially for the brain, neurological system, and red blood cells. Its natural source is from animal foods, like meat and eggs, who ultimately get it from algae and yeast. Iron rich foods like liver are especially high in B12. Its absorption method is complex in the human body, which leaves several "links in the chain" by which deficiency can occur.

Symptoms of Deficiency

Symptoms of slightly below normal deficiencies include depression, fatigue, and memory problems. Keep in mind that these symptoms are too non-specific to diagnose a lack of B12 alone, as they can mimic other problems. In more extreme deficiencies, like those resulting from pernicious anemia can result in more extreme symptoms, such as psychotic episodes, lack of coordination, and problems with reflexes.

Causes of Deficiency

Deficiencies serious enough to cause problems are not common in the Western world (although several studies have found below normal levels in almost half the US population). When they do occur, they most commonly happen for two reasons: an autoimmune disease called pernicious anemia that destroys the body's ability to absorb B12, or strict vegan diets that do not supplement with B12.

Pernicious anemia is a disease that causes the body to attack it's own gastric system, which is necessary for B12 to be absorbed. It is treatable with B12 supplements or injections. If left untreated for a long period of time, it can lead to permanent neurological damage.

Vegan diets are lacking in the necessary animal foods that provide vitamin B12, and deficiency can occur if supplementation is not provided. B12 can be supplemented through oral pills, but there are non-animal food sources as well, such as fortified yeast and fortified soy milk. Deficiency is more common in children on vegan diets, as they require a high dose of the vitamin and their bodies cannot store it for long periods of time like adults can.

While symptoms are too non-specific to diagnose directly, if you have any of the symptoms described above and you fall into one of the two groups (pernicious anemia or strict vegan diets), you may want to see a doctor to figure out if you have below normal levels of B12 and whether supplementation can help.