Vitamin B12 is essential for healthy red blood and nerve cells and is also necessary for the formation of DNA. According to the Mayo Clinic, vitamin B12 deficiency is rare due to the fact that your body can store several years' worth of vitamin B12. However, deficiency can occur due to a number of factors.
According to the National Institutes of Health Medline Plus website, symptoms of vitamin B12 deficiency include loss of balance, weakness, tingling or numbness in the legs and arms and anemia. Other symptoms include nausea/vomiting, constipation, diarrhea, gas and bloating, heartburn, loss of appetite, weight loss and an enlarged liver. A beefy red, smooth tongue is another sign of deficiency. Severe deficiency can lead to nerve damage, depression, dementia, confusion and memory loss.
Pernicious anemia occurs when the body lacks enough vitamin B12 to make enough healthy red blood cells. During digestion, vitamin B12 is released from protein you get from the food you eat. It then combines with a substance called intrinsic factor, or IF, before it is absorbed into your bloodstream. Pernicious anemia is caused by insufficient IF. Symptoms include fatigue; dizziness when standing up; headaches; shortness of breath; chest pain; and pale skin, gums and nail beds. Left untreated, pernicious anemia can lead to heart murmurs or arrhythmias, enlarged heart or heart failure.
Medical disorders that impair vitamin B12 absorption can cause deficiency, such as Crohn's or celiac disease. Some antibiotics and seizure and diabetic medications can affect vitamin B12 absorption in the small intestine, as can removal of all or part of the small intestine. A tapeworm infection can also cause a deficiency because the tapeworm feeds on the vitamin B12.
A diet lacking in foods rich in vitamin B12 can lead to a deficiency. According to the National Heart, Lung and Blood institute, vegetarians who exclude dairy or animal products are at a higher risk for vitamin B12 deficiency, as are breastfed infants whose mothers are vegetarians. Fish, poultry, meat, eggs and dairy product are your best sources of vitamin B12. Vegetarians may need to take supplements to ensure they get enough vitamin B12 in their diets.
Diagnosing vitamin B12 deficiency involves a physical examination and a series of blood tests to check your complete blood count or CBC; vitamin B12 levels; methylmalonic acid, MMA, and homocysteine levels; and intrinsic factor and parietal cell antibodies. Your doctor may also perform bone marrow tests.
Treatment of vitamin B12 deficiency involves replenishing vitamin B12 via pills or injections. Shots are given every week or every day until vitamin B12 levels are restored, after which time you may get one shot per month. A person with pernicious anemia may require shots for the rest of his life.