Vitamin B12 is a nutrient that helps keep the body's nerve and blood cells healthy. It helps prevent a type of anemia called megaloblastic anemia that makes people tired and weak. Vitamin B12 helps make DNA, the genetic material in all cells.
The body absorbs Vitamin B12 from food in 2 steps:
First, hydrochloric acid in the stomach separates vitamin B12 from the protein to which vitamin B12 is attached in food. After this, vitamin B12 combines with a protein made by the stomach called intrinsic factor and is absorbed by the body. Some people have pernicious anemia, a condition where they cannot make intrinsic factor. As a result, they have trouble absorbing vitamin B12 from all foods and dietary supplements.
Vitamin B12 is found naturally in a wide variety of animal foods and is added to some fortified foods.
Plant foods have no vitamin B12 unless they are fortified.
You can get recommended amounts of Vitamin B12 by eating a variety of foods including the following:
Most people get enough vitamin B12 from the foods they eat. But some people have trouble absorbing vitamin B12 from food. As a result, vitamin B12 deficiency affects between 1.5% and 15% of the public.
Certain groups may not get enough Vitamin B12 or have trouble absorbing it:
Vitamin B12 Deficiency causes constipation, weakness, tiredness ,weight loss, loss of appetite, and megaloblastic anemia. Numbness and tingling in the hands and feet due to nerve problem, can also occur. Other symptoms of vitamin B12 deficiency include problems with balance,confusion, depression, dementia, poor memory, and soreness of the mouth or tongue. Vitamin B12 deficiency can damage the nervous system even in people who don't have anemia, so it is important to treat a deficiency as soon as possible.
In infants, signs of a vitamin B12 deficiency include failure to thrive, problems with movement, delays in reaching the typical developmental milestones, and megaloblastic anemia.
Large amounts of folic acid can hide a vitamin B12 deficiency by correcting megaloblastic anemia, a hallmark of vitamin B12 deficiency.
But folic acid does not correct the progressive damage to the nervous system that vitamin B12 deficiency also causes. For this reason, healthy adults should not get more than 1,000 mcg of folic acid a day.
Vitamin B12 can interact or interfere with medicines that you take, and in some cases, medicines can lower vitamin B12 levels in the body.
Vitamin B12 has not been shown to cause any harm.
25 April 2011