Vitamin B12. Shortage of this vitamin causes anaemia.

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This woman’s accent in this clip is a little hard to understand, but it does summarise the main points about Vitamin B12, otherwise known as cobalamin.

What vitamin B12 does in the body.

  • It works closely with folate to form and maintain DNA and RNA.
  • It maintains the integrity of the nervous system.
  • It helps the body uptake and use fat from the diet – we really, really do need fat in our diet.
  • It helps the body’s energy production.

What are the symptoms of deficiency?

  • Decreased blood cell count.
  • Pale skin.
  • Tired all the time.
  • Short of breath.
  • Palpitations.
  • Nerve problems – tingling, numbness in the hands or feet
  • Poor balance
  • Brain problems – irritability, depression, memory loss, dementia, Alzheimers disease.
  • Anorexia and weight loss.
  • Age related hearing loss.
  • Pernicious anaemia.

Principal reasons for developing deficiency.

  • Vegetarian/vegan diet.
  • Loss of gastric parietal cells (the cells in the stomach wall that produce the stomach’s digestive juices).
  • Some pharmaceuticals – eg proton pump inhibitors, nitrous oxide anesthesia
  • Genetic disorders such as sickle cell disease and the MTHFR gene.
  • Tapeworm.
  • Poor stomach function: not enough HCl so stomach not acid enough allowing for bacterial overgrowth in the stomach.
  • Getting old – the stomach slowly atrophies and can no longer process B12.


Oh dear.  It is complex.  The simplest reason is that the best dietary sources of B12 are liver, red meat, fish, especially oily fish.  So if a vegetarian or vegan, the dietary intake of B12 is poor;  eggs and dairy are not such good sources as the animal or fish sources and vegetables do not give any B12.

The second slightly more complex reason is lack of stomach acid and atrophic gastritis.  The best dietary sources of B12 are found in animal/fish meat and in this form, B12 enters the body bound to the protein.  After a good chewing, the food goes down into the stomach where it should get bathed in a strong acid bath, broken from its protein carrier, attached to a different protein carrier and then shunted into the small intestine where it combines with stuff called intrinsic factor.  Intrinsic factor is pumped out by the same cells of the stomach that produce HCl, stomach acid.  B12 is then carried on through the small intestine until it reaches specific receptors which allow it to be absorbed into the bloodstream.  As we age, our stomach wall starts to atrophy and produce less HCl and intrinsic factor.  Without these, we cannot absorb the B12.  The onset of this atrophy is quite young – about 40 years old and progresses with the passing years.  Sometimes children do not produce HCl, so they too will have low B12 levels.  Also, some have a genetic condition, for example sickle cell disease, which means they cannot produce any intrinsic factor, so cannot absorb vitamin B12.  These people need regular B12 injections to stay alive and active.

The third, complex, reason is a gene called the MTHFR gene. It is a dominant gene, apparently stemming from the Romans.  The classic symptom is asparagus pee – those of us with the gene will be able to smell a strong smell from our wee after eating asparagus.  And no, not everybody can smell it.  This gene means that the body can no longer perform an important cellular function called methylation.  Why is this complex?  Well, here is what should happen in the body to keep the brain, liver and body organs ticking along nicely.1

To accomplish this conversion from methionine to either SAMe or Glutathione, we need to have good levels of all the following nutrients : B2, B6, B12, folate, zinc, magnesium, sulphur and finally TMG.  TMG is trimethlyglycine which we make in the body from choline – the best dietary source of which is egg yolks. The simplest thing that goes wrong is if we are lacking in any of the above nutrients, we cannot convert homocysteine to glutathione or SAMe.

Apart from this, what else can go wrong?  Well the liver can have an abnormal enzyme – this is the genetic part – that means it cannot use either B12 or folate to convert homocysteine to SAMe or glutathione OR the process using sulphur, called transulphuration, cannot occur. 2  With any of these 3 liver abnormalities, we end up with raised homocysteine levels.  Homocysteine is a poison to the body which causes many diseases, including hardening of the arteries, so heart attacks and strokes; cancers; thyroid problems; dementia.  Putting it another way, in the book The H Factor, by Patrick Holford and Dr James Braly, they list over 100 medical conditions linked to high homocysteine.


If low B 12 levels are suspected, it is worth trying to get a blood test to confirm this.  It is also possible to test homocysteine levels, but this may be a struggle here in the UK.  If we have a major B12 deficiency, then it is best to take a series of B12 injections.  Apart from that, the supplement of use will contain at least cyanocobalamine and intrinsic factor.  Even better, the supplement will also contain folate as L-5-methyl-tetrahydrofolate, riboflavin, vitamin B6, zinc glycinate, TMG and choline.

All the B vitamins are water soluble.  The blog about folate gave importance to taking folate in the L-5 version just mentioned as this version is not linked to nerve damage due to build up in the body.  Lack of B12 is linked to permanent nerve damage, of course.  Supplementation, although frowned on in the UK, can make a huge difference to our health.  But we cannot just nip down the local supermarket and pick it up from the shelves.  Care has to be taken.




  1. Adapted from The H Factor by Patrick Holford and Dr James Braly. []
  2. Kilmer S McCully,  The Homocysteine Revolution []

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