Dear Dr. B: What is the importance of vitamin B12? What are the causes of its deficiency?
Answer: Our body needs vitamin B12 to make blood cells. It is also important for normal function of nerve cells in the brain and the peripheral nerves.
Vitamin B12 deficiency frequently occurs in elderly people although it may also be present in the young, particularly women. It is estimated that 30 per cent of the adults older than 50 may have vitamin B12 deficiency.
Lack of vitamin B12 causes anemia and causes damage to the spinal cord and the peripheral nerves. The symptoms of these conditions may be obvious or quite subtle. Screening for B12 deficiency (by way of a blood test) is recommended in the following groups of people:
-all elderly patients who are malnourished
-all patients in institutions and psychiatric hospitals
-all patients who have blood disorders, neurological or psychiatric problems.
Vitamin B12 is an important vitamin that we usually get from our food. It is mainly found in meat and dairy products.
There are various reasons why a person is low in vitamin B12. There may not be enough of it in our diet. Especially vegetarians who do not eat meat or dairy products are at risk for vitamin B12 deficiency. But the vegetarians can get enough of it from legumes.
Quiet often the cause of B12 deficiency is not poor diet but problems with absorption in the gastro-intestinal tract.
The vitamin is absorbed through the last part of our small intestine. It can be absorbed after a protein called intrinsic factor attaches to it. Intrinsic factor is made in our stomach and attaches to vitamin B12 only if there is enough acid in the stomach.
But there are many individuals who take medication to reduce acid in the stomach in cases like gastritis, gastro-esophageal reflux disease or bacterial infection (H. pylori). These individuals are at risk of vitamin B12 deficiency if they are on these medications on a long term basis.
Pernicious anaemia is a fairly common condition in which the stomach does not have enough acid and does not make intrinsic factor normally. Absorption of vitamin B12 is also impaired in individuals who have had intestinal illness or intestinal surgery, which makes it hard for the intestines to absorb vitamin B12.
Vitamin B12 is also known as cobalamin was first isolated in 1948 and was immediately shown to be effective in the treatment of pernicious anaemia. The liver contains most of the body’s B12 (about 1.5 mg), followed by the kidneys, heart, spleen, and brain. The Recommended Dietary Allowance (RDA) for vitamin B12 is 2.4 micrograms/day for persons aged 14 to 70 years. The average diet contains about 5 micrograms daily.
Treatment of vitamin B12 deficiency is by B12 injections on a regular basis for the rest of persons life.
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