Vitamin B-12 deficiency is a blood and neurological disorder caused by a lack of Vitamin B-12 in the blood. The vitamin is required to create red blood cells and to regulate nerve function. As a result, patients with a deficiency of the vitamin start suffering from the symptoms of anemia, and start suffering neurological problems. If the problem is untreated, the neurological damage can be permanent.
There are several causes for the deficiency:
Diet - both vegans and omnivores can develop Vitamin B-12 deficiency when they have little or no B-12 in their diet. B-12 is stored in the liver and the body can store several years supply, so the symptoms may not come on quickly. Meat, particularly organ meats such as liver, contain ample supplies of the vitamins and omnivores rarely develop the disorder. Treatment is oral B-12 supplements.
Pernicious Anemia - In some patients, there is a lack of an enzyme that breaks down B-12 from food and allows it to travel from the digestive tract to the bloodstream. As such, patients cannot get B-12 from their diet. In such cases, B-12 must be injected intravenously on a regular basis.
Tapeworm - In rare cases, B-12 can be absorbed by tapeworms, leaving none for the use of the patient.