The eight vitamins that belong the B-complex group are all important in helping your body convert carbohydrate nutrients into glucose, which travels throughout your body and helps fuel all your cells. One of these, vitamin B-12, is especially important for a healthy nervous system and for the production of many types of new cells. Consuming insufficient amounts of vitamin B-12, also called cobalamin, can cause early symptoms that may be subtle and difficult to recognize, but could eventually lead to serious problems.
Early Warning Signs
The recommended dietary allowance for vitamin B-12 is 2.4 micrograms daily for adult men and women, according to the Office of Dietary Supplements. A deficiency is rare in healthy young people, but isn't uncommon for older people with poor diets. Some individuals with a mild deficiency might have no obvious symptoms, but because vitamin B-12 is essential for the production of new red blood cells, mild anemia may occur with a low intake of this vitamin. Early symptoms of anemia might include a general sense of tiredness, or fatigue. A mild-to-moderate B-12 deficiency could also cause some shortness of breath, a feeling of nervousness and possibly diarrhea.
As the Problem Progresses
If a vitamin B-12 deficiency isn't corrected, you might experience numbness or tingling in your hands or feet, problems with balance, some confusion or memory problems, all due to nerve damage. Some people with an autoimmune disease called pernicious anemia may become B-12-deficient even if they consume enough of the vitamin because stomach damage interferes with production of acid and a compound called intrinsic factor, both produced in the stomach and needed for absorption of the vitamin from food. In these people, a severe anemia called megaloblastic anemia and serious neurological problems may develop, causing symptoms that can include muscle weakness, weight loss and increased heart rate.
Identifying the Risk
Because the early symptoms of vitamin B-12 deficiency can be subtle, it's important to be aware of factors that can raise your risk of the problem. Vitamin B-12 is only provided by animal-based foods, such as meat, poultry, fish and, to a lesser extent, dairy products. Because of this, your risk of deficiency increases if you follow a vegetarian or vegan diet. People with Crohn's disease, a pancreatic condition, or an eating disorder, or those who have gastric bypass surgery, can have problems absorbing enough vitamin B-12, even if it's available contained in their diets. Older adults, especially those with a stomach condition called atrophic gastritis, are also at increased risk of B-12 deficiency because of problems absorbing the vitamin.
Supplementing the Vitamin
Vitamin B-12 supplements are widely available. It's also found in most over-the-counter multi-vitamin preparations. The vitamin is available as a prescription medication in an injectable form that's given under a doctor's care as well. Vitamin B-12 can interact with several medications, including certain antibiotics, drugs used to treat stomach conditions and some diabetes medications. Although no toxicity is associated with vitamin B-12 supplements, discuss taking them with your doctor, who can best advise you about their potential benefit for your situation.