Herbs in alphabetical order
Vitamin B12 ( Cobalamin )
Also known as cyanocobalamin and B12 cobalamin is the
largest molecule of all the vitamins. It is unique in that it is the
only vitamin to contain a metal, cobalt. Because of its
complexity, cobalamin was not synthesized until 1972.
Like folic acid, cobalamin is an essential participant in
nucleic
acid synthesis. Cobalamin is also essential to the metabolism of
folate, and is essential to the structure and function of the
nervous system.
Cobalamin absorption from the gastrointestinal tract is
almost nonexistent unless another substance, called the intrinsic
factor, is also present. Intrinsic factor is a glycoprotein which is
secreted by a normal, healthy stomach. If the intrinsic factor is
not present, very large doses of cobalamin (more than .025 mg.)
will be only partially absorbed. Other proteins are necessary for
transport of the vitamin in the
blood and uptake by the cells.
These proteins are called transcobalamines.
The cause of cobalamin deficiency (pernicious
anemia) is
usually the lack of intrinsic factor, not dietary lack of the
vitamin. People with pernicious anemia have been found to
excrete large amounts of the vitamin when it is given them,
indicating that it is not being absorbed.
Animals can synthesize cobalamin (or rather, the
bacteria in
their gastrointestinal tract can synthesize it), utilizing dietary
cobalt. Humans cannot do this, however, and must rely on a
dietary source. The only cobalt the human body uses is that
which enters via cobalamin.
The symptoms of pernicious anemia include weakness, sore and
inflamed tongue, numbness and tingling in the extremities,
pallor, weak pulse, stiffness, drowsiness, irritability,
depression,
and diarrhea.
Pernicious anemia, however, does not always result from a
deficiency of cobalamin, not even severe deficiencies. A
marginal deficiency could be expected to produce lesser versions of the
above symptoms. And any person who suffers such symptoms on
a day-to-day basis should first of all suspect some form of
nutritional deficit.
However, other symptoms, ranging from mental problems to
increased susceptibility to infections, can result. Certain organs
or organ systems may be more susceptible to shortfalls in the
supply of nutrients, from person to person. Two people with the
same diet may suffer totally different symptoms. And a third
person might appear perfectly healthy.
Cobalamin appears to play a role in mental health independent
of the dementia associated with pernicious anemia. Some people
apparently have nervous systems which need more cobalamin to
stay healthy. A severe deficiency can land them in the mental
hospital, while a marginal deficiency may be just enough to
make them very hard to get along with.
A cobalamin deficiency impairs the activity of the
immune
system, primarily by inhibiting the leukocytes (the white and
clear blood cells). Phagocytosis, the devouring of invading
organisms by the leukocytes, was reduced to slightly more than
one-third of normal. Bacterial killing was decreased, too.
Supplementation with the vitamin reversed these effects.
Where is it found ?
Organ meats are the best sources of cobalamin; muscle meats
and fish supply it in moderate amounts, milk in somewhat
smaller amounts. There are some vegetable sources: sea
vegetables (seaweed such as wakame and kombu) and fermented
soybeans (tempeh). Nutritional yeast can be grown on a
cobalamin-fortified base, and the resultant yeast will provide cobalamin.
Some yeasts are fortified with synthetic cobalamin, too.
Cobalamin is sensitive to light, acids, and alkalies. It is
normally not destroyed in cooking; however, overheating may
destroy it.
Cobalamin is available in supplements ranging from a few
micrograms up to a milligram (1000 micrograms).
Who is likely to be deficient ?
Vegans (vegetarians who also avoid dairy and eggs)
frequently become deficient, though the process may
take many years. People with malabsorption
conditions may suffer from vitamin B12 deficiency.
Individuals suffering from pernicious anemia require
high-dose supplements of vitamin B12. Older people
with urinary incontinence and
hearing loss have been
reported to be at increased risk of B12 deficiency.
How much to take
The RDA for cobalamin ranges from.5 micrograms (.0003 mg.)
for infants to four micrograms (.004 mg.) for pregnant women.
For adults, the RDA is three micrograms. These ranges are much
lower than the doses used therapeutically. If a deficiency is based
on dietary lack, improving the diet or supplementation will
correct it. However, many deficiencies appear to be from a
metabolic defect or a lack of intrinsic factor. In such cases, the
intrinsic factor must be taken with any supplement, or the
vitamin must be injected in order to bypass faulty absorption.
People who have such a metabolic defect usually require one or
the other of these treatments for life.
Side effects
Vitamin B12 supplements are not associated with side
effects.
If a person is deficient in vitamin B12 and takes
1,000 mcg of folic acid per day or more, the
folic acid can improve anemia caused by the B12
deficiency, but not affect neurological symptoms. This is not a toxicity but rather a partial solution to one of the
problems caused by B12 deficiency. The other problems
caused by a lack of vitamin B12 (mostly neurological) do
not improve with folic acid supplements.
Vitamin B12 deficiencies often occur without anemia
(even in people who don't take folic acid supplements).
Some doctors do not know that the absence of anemia
does not rule out a B12 deficiency. If this confusion
delays diagnosis of a vitamin B12 deficiency, the patient
could be injured, sometimes permanently. This
problem is rare and should not happen with doctors
knowledgeable in this area using correct testing procedures.
Anyone supplementing more than 1,000 mcg per
day of folic acid needs to be initially evaluated by a
doctor of natural medicine to avoid this potential
problem.
Water - soluble vitamins are: Fat-soluble vitamins are:
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