A possible vitamin B12 (cyanocobalamine,
cobalamine, hydroxycobalamine) deficiency is
without doubt an important issue in connection
with the health of vegetarians and vegans. For
vegans though, it's recommended without
hesitation, to use vitamin B12 supplements.
What does vitamin B12 do?
Vitamin B12 is a water soluble vitamin which
plays a key role in many different processes
in our body. B12 is essential for a normal digestion
and absorption of nutrients, for a good carbohydrates-
and fat metabolism and for the synthesis of new
protein. Also, vitamin B12 plays a role in other
processes, like sleep- and eating disorders,
mental functioning, immunity, emotional balance,
the reproduction and for the development in children.
How do you get vitamin B12?
Micro-organisms, mainly bacteria, are the only
organisms that we know of, that can produce B12.
Our alimentary canal is accommodated by an estimation
of four- to five-hundred different kinds of bacteria.
Among them are the vitamin B12 generating bacteria.
It is assumed that bacteria in our intestines
make a variable amount of biological active (usable)
forms of vitamin B12. However, these vitamin B12 generating bacteria are only found in the
last part of the intestinal canal, not high enough
to be absorbed. B12 in green products? Some others have suggested that active B12 could
be found in certain seaweeds, yet, there hasn't
been a conclusive outcome of research on this
claim. Studies that have been carried out with
the most reliable test methods, showed that most
seaweeds that were thought to contain B12, in
fact contained the inactive, analogue version
of B12. Also tempe, miso and other fermented
nutrients are no sources of active B12 , unless
this vitamin is added. From the present day knowledge we have to conclude
that (not enriched) vegetables cannot supply
us with vitamin B12.
Absorption of B12
Besides the intake of B12 via the food, the absorption is
also of vital importance. For a sufficient absorption
of this vitamin enough calcium, folium acid and
the so called "intrinsic
factor" (a protein secreted by stomach cells,
necessary for the intake of B12 in the small intestine)
is acquired. However, it doesn't stop here.
Other nutrients have to be present in the ideal proportion
within the body. This is to ensure that the vitamin B12 that's been absorbed then gets transported
to the tissues and that the vitamin can be effective
in the many enzymatic functions for which it
is acquired. A variable food pattern is necessary
to get all the sufficient nutrients.
What happens in case of a shortage of vitamin B12 ?
In case of a low intake of B12 there is less
secreted and the absorption gets increased. Through
this mechanism a shortage of this vitamin can
sometimes be delayed for twenty or thirty years.
That's how it can happen that vegans who
do not use supplements can live for some years
without experiencing any of the symptoms.
People with psychological problems, with eating-
or sleeping-disorders, alcoholics and elderly
run a chance of suffering from a B12 -shortage.
Because it plays a role in many enzymatic processes
in our body, it is difficult to list all the
symptoms of B12 shortage.
Vitamin B 12 deficiency may give rise to in general:
extreme fatigue, digestive problems, low appetite
and nausea. More specific symptoms are haematological
(anaemia), neurological (paresthesias, neuropathy)
and psychiatric manifestations (impaired memory,
irritability and depression).
B12 has functions very similar with folium-acid
and the shortage of one or both can cause the
same symptoms. A massive amount of folium-acid
in the food-intake can disguise a B12 shortage.
Testing the B12 The test which determines the amount of MMA
(methylmalonic Acid or methylmalonate) in the
blood or urine is considered reliable enough
to determine whether one has a sufficient amount
of active B12. Most physicians though still use B12 tests for bloodserum (sB12), but this test
is not accurate enough to determine which part
of the B12 is active and which part inactive.
Supplements in practice
It's advisable for vegans to eat foods
which are enriched with vitamin B12 , or to regularly
take supplements to keep the B12 at a descent
level. Cyanocobalamine is the most represented
form in vitamin-tablets, while hydroxycobalamine
is used in B12 injections. Tablets and capsules
are available at pharmacists and reform shops.
They often contain gelatine. The following required
daily intake should be sufficient for vegans.
1,5 - 2,5 µg, twice a day, from B12 enriched food
10 - 100 µg, once a day, from a supplement
Higher dosages then 1000 µg are of no
beneficial use, as they won't be absorbed.
You can safely break a 1000 µg tablet
into four pieces. Supplements which contain only B12 are believed to be the most efficient. Besides,
you can use products which are enriched with B12 , for example soja-products and breakfast-cereals
(check the package).