What is B12 deficiency?

Vitamin B12 (cobalamin) is an essential vitamin that your body needs for everyday good health and day-to-day living.

Being deficient in Vitamin B12 can effect your body, your mind and your appetite for life.

So why is vitamin B12 so important?

Vitamin B12, along with Vitamin B9 (folate), helps your body produce red blood cells and is vital for keeping both your nervous system and immune system healthy. It is crucial for the construction of your DNA.

Where do I find vitamin B12?

This essential, complex vitamin is only found naturally in animal products (meat, poultry, fish, shellfish, dairy, and eggs), but starts as cobalt in soil. Vitamin B12 is also found in fortified vegetarian foods and in B12 supplements. However, please note that seaweed, spirulina and other plant foods contain B12 analogues (cobamides). This means that although these are very similar chemically, they are not recognised by the body and therefore cannot be used. These analogues can interfere with absorption of true vitamin B12 and disrupt B12 metabolism.

Why is vitamin B12 deficiency so damaging?

When the body does not have enough Vitamin B12 (a deficiency), the fatty tissue that surrounds your nerves (myelin) becomes damaged and can lead to brain damage, spinal cord damage, peripheral nerve damage and eye nerve damage. Vitamin B12 deficiency is a progressive neurological disorder and can result in symptoms ranging from severe anaemia requiring blood transfusions, to serious psychiatric conditions and potential misdiagnosis.

How is vitamin B12 absorbed?

Vitamin B12 deficiency is a particular problem for sufferers who cannot absorb B12 from food, even though their diet includes animal products or fortified vegetarian foods. Chemically, B12 must follow a complex pathway within the body for proper absorption. If your body has problems absorbing Vitamin B12 deficiency then follows. When this is the case, Vitamin B12 deficiency can only be effectively treated by injections of B12 (Hydroxocobalamin in the UK) and NOT oral supplementation.

There are many causes for vitamin B12 deficiency and pernicious anaemia is just one of them. If you’d like to look more in depth at this pathway, you can read further about the enterohepatic circulation here. 

Symptoms of vitamin B12 deficiency

The effects of Vitamin B12 deficiency can be far-reaching and long lasting which is why an early diagnosis and treatment are essential to stop permanent damage. It affects all body systems, both sexes and all ages, and symptoms can present in a number of surprising ways. Symptoms can also take years to develop. Symptoms of B12 deficiency can vary from mild to severely debilitating, and can be potentially life-threatening if left untreated and undiagnosed. You can read about the symptoms of Vitamin B12 deficiency here.

Body systems affected by B12 deficiency

  • Neurological
  • Haematological
  • Immunological
  • Vascular
  • Gastrointestinal
  • Musculoskeletal
  • Genitourinary

A quick note on oral vitamin B12 supplements

Oral Vitamin B12 (cyanocobalamin) tablets will raise B12 serum levels but will not repair nerve damage in those who cannot absorb B12 from food. This Cochrane review found evidence on oral B12 verses B12 injections to be of low quality. Oral B12 should only be prescribed when the deficiency is caused by a proven dietary lack of B12. (Note: This is not to be confused with injectable cyanocobalamin which can and does heal nerves and is most commonly used in Canada and America – please see B12 treatment).

Common problems that patients face…

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