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.

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.

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.

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.

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).

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