FoOdS In ViTaMiN B-12(CoBaLaMiN)

Vitamin B12 (cobalamin) is an important water-soluble vitamin.

In contrast to other water-soluble vitamins it is not excreted quickly in the urine, but rather accumulates and is stored in the liver, kidney and other body tissues. As a result, a vitamin B12 deficiency may not manifest itself until after 5 or 6 years of a diet supplying inadequate amounts.

Vitamin B12 functions as a methyl donor and works with folic acid in the synthesis of DNA and red blood cells and is vitally important in maintaining the health of the insulation sheath (myelin sheath) that surrounds nerve cells.

The classical vitamin B12 deficiency disease is pernicious anaemia, a serious disease characterized by large, immature red blood cells. It is now clear though, that a vitamin B12 deficiency can have serious consequences long before anaemia is evident. The normal blood level of vitamin B12 ranges between 200 and 600 picogram/milliliter (148-443 picomol/liter).

A deficiency often manifests itself first in the development of neurological dysfunction that is almost indistinguishable from senile dementia and Alzheimer's disease.

There is little question that many patients exhibiting symptoms of Alzheimer's actually suffer from a vitamin B12 deficiency.

Their symptoms are totally reversible through effective supplementation. A low level of vitamin B12 has also been associated with asthma, depression, AIDS, multiple sclerosis, tinnitus, diabetic neuropathy and low sperm counts. Clearly, it is very important to maintain adequate body stores of this crucial vitamin.


The amount of vitamin B12 actually needed by the body is very small, probably only about 2 micrograms or 2 millionth of a gram/day. Unfortunately, vitamin B12 is not absorbed very well so much larger amounts need to be supplied through the diet or supplementation.

The richest dietary sources of vitamin B12 are liver, especially lamb's liver, and kidneys. Eggs, cheese and some species of fish also supply small amounts, but vegetables and fruits are very poor sources.

Several surveys have shown that most strict, long-term vegetarians are vitamin B12 deficient.

Many elderly people are also deficient because their production of the intrinsic factor needed to absorb the vitamin from the small intestine decline rapidly with age.

Fortunately, oral supplementation with vitamin B12 is safe, efficient and inexpensive. Most multi-vitamin pills contain 100-200 microgram of the cyanocobalamin form of B-12. This must be converted to methylcobalamin or adenosylcobalamin before it can be used by the body. The actual absorption of B12 is also a problem with supplements. Swallowing 500 micrograms of cyanocobalamin can result in absorption of as little as 1.8 microgram so most multivitamins do not provide an adequate daily intake. The best approach is to dissolve a sublingual tablet of methylcobalamin (1000 micrograms) under the tongue every day. That will be sufficient to maintain adequate body stores. However, if a deficiency is actually present then 2000 microgram/day for one month is recommended followed by 1000 microgram/day. Some physicians still maintain that monthly injections of vitamin B12 is required to maintain adequate levels in the elderly and in patients with a diagnosed deficiency. There is however, no scientific evidence supporting the notion that injections are more effective than sublingual supplementation.