Vitamin B12

Symptoms of vitamin B12 or folate deficiency:

Vitamin B12 and Folate perform several important functions in the body, including keeping the nervous system healthy. A deficiency in either of these vitamins can cause a wide range of problems, including:

  • extreme tiredness
  • a lack of energy
  • pins and needles (paraesthesia)
  • a sore and red tongue
  • mouth ulcers
  • muscle weakness
  • disturbed vision
  • psychological problems, which may include depression and confusion 
  • problems with memory, understanding and judgement

Some of these problems can also occur if you have a deficiency in vitamin B12 or folate, but don’t have anaemia.

Causes of a vitamin B12 or folate deficiency

There are a number of problems that can lead to a vitamin B12 deficiency, including:

  • a lack of these vitamins in your diet – this is uncommon but can occur if you have a vegan diet, follow a fad diet or have a generally poor diet for a long time
  • medication – certain medications, including anticonvulsants and proton pump inhibitors (PPIs), can affect how much of these vitamins your body absorbs 
  • pernicious anaemia – where your immune system attacks healthy cells in your stomach, preventing your body from absorbing vitamin B12 from the food you eat; this is the most common cause of vitamin B12 deficiency in the UK

Vitamin B12 deficiency is common in older people, affecting around 1 in 10 people aged 75 or over, and 1 in 20 people aged 65 to 74.

Conditions affecting the intestines

Some conditions that affect your intestines can also stop you from absorbing the necessary amount of vitamin B12.

For example, Crohn’s disease (a long-term condition that causes inflammation of the lining of the digestive system) can sometimes mean your body doesn’t get enough vitamin B12.

Medication

Some types of medicine can lead to a reduction in the amount of vitamin B12 in your body.

For example, proton pump inhibitors (PPIs) – a medication sometimes used to treat indigestion – can make a vitamin B12 deficiency worse. PPIs inhibit the production of stomach acid, which is needed to release vitamin B12 from the food you eat.

Your GP will be aware of medicines that can affect your vitamin B12 levels and will monitor you if necessary.

Functional vitamin B12 deficiency

Some people can experience problems related to a vitamin B12 deficiency, despite appearing to have normal levels of vitamin B12 in their blood.

This can occur due to a problem known as functional vitamin B12 deficiency – where there’s a problem with the proteins that help transport vitamin B12 between cells. This results in neurological complications involving the spinal cord.

Diet

Some people can develop a vitamin B12 deficiency as a result of not getting enough vitamin B12 from their diet.

A diet that includes meat, fish and dairy products usually provides enough vitamin B12, but people who don’t regularly eat these foods – such as those following a vegan diet or who have a generally very poor diet – can become deficient.

Stores of vitamin B12 in the body can last around two to four years without being replenished, so it can take a long time for any problems to develop after a dietary change.

Conditions affecting the stomach

Some stomach conditions or stomach operations can prevent the absorption of enough vitamin B12.

For example, a gastrectomy (a surgical procedure where part of your stomach is removed) increases your risk of developing a vitamin B12 deficiency.

Pernicious anaemia

Pernicious anaemia is the most common cause of vitamin B12 deficiency in the UK.

Vitamin B12 or B9 (commonly called folate) deficiency anaemia occurs when a lack of vitamin B12 or folate (Folic Acid) causes the body to produce abnormally large red blood cells that can not function properly. Red blood cells carry oxygen around the body using a substance called haemoglobin.

Anaemia is the general term for having either fewer red blood cells than normal or having an abnormally low amount of haemoglobin in each red blood cell.

Pernicious anaemia is an autoimmune condition that affects your stomach. An autoimmune condition means your immune system (the body’s natural defence system that protects against illness and infection) attacks your body’s healthy cells.

In your stomach, vitamin B12 is combined with a protein called intrinsic factor. This mix of vitamin B12 and intrinsic factor is then absorbed into the body in part of the gut called the distal ileum.

Pernicious anaemia causes your immune system to attack the cells in your stomach that produce the intrinsic factor, which means your body is unable to absorb vitamin B12.

The exact cause of pernicious anaemia is unknown, but the condition is more common in women around 60 years of age, people with a family history of the condition and those with another autoimmune condition, such as Addison’s disease or vitiligo.

Complications of vitamin B12 or folate deficiency anaemia

Although it’s uncommon, vitamin B12 or folate deficiency (with or without anaemia) can lead to complications, particularly if you’ve been deficient in vitamin B12 or folate for some time.

Potential complications can include:

  • problems with the nervous system
  • temporary infertility
  • heart conditions
  • pregnancy complications and birth defects

Adults with severe anaemia are also at risk of developing heart failure.

Some complications improve with appropriate treatment, but others – such as problems with the nervous system – can be permanent. 

When to see your GP

See your GP if you think you may have a vitamin B12 or folate deficiency. These conditions can often be diagnosed based on your symptoms and the results of a blood test.

It’s important for vitamin B12 or folate deficiency anaemia to be diagnosed and treated as soon as possible because, although many of the symptoms improve with treatment, some problems caused by the condition can be irreversible.