04/09/2017 07:13 BST | Updated 04/09/2017 07:13 BST

What Is B12 And Are You Getting Enough?

B12 is a vitamin that your body can't make but needs for making red blood cells and DNA, as well as lots of other functions. The amount you need depends on your age, your diet, which medications you take and any medical conditions you may have.

A lack of vitamin B12 in the diet can cause red blood cells to become abnormally large and unable to function properly. Red blood cells carry oxygen around the body using haemoglobin, and if these cells are unable to work correctly then the body will suffer from symptoms of anaemia.


Vitamin B12 performs several important functions in the body; if levels are low, this can cause:

• Extreme tiredness, shortness of breath or heart palpitations

• Lack of energy / feeling faint

• Pins and needles

• Sore, smooth and red tongue (glossitis)

• Mouth ulcers

• Muscle weakness

• Disturbed vision/ headaches

• Depression or behavioural changes

• Confusion

• Problems with memory and understanding

• Pale skin or a yellow tinged skin

• Loss of appetite/weight loss/ constipation

These symptoms normally develop gradually and may not be noticed at first. If you're experiencing any of these issues, it's important for you to see your GP but many of the symptoms can improve quickly with treatment.


There are a variety of causes of a B12 deficiency, including:

Pernicious anaemia, preventing you from absorbing B12 in your stomach

• A lack of B12 in the diet (especially if vegan or on a fad diet)

• Medications such as anti-convulsants ad proton pump inhibitors which affect how much B12 you can absorb

• Surgery that has removed part of your stomach and gut

• Heavy drinking

• Immune system disorders such as Crohn's, Lupus or Grave's disease

Pernicious aneamia is an autoimmune condition where the immune system attacks the healthy cells of the stomach that produce intrinsic factor. Intrinsic factor combines with B12 in order for B12 to be absorbed in the distal ileum, a part of the gut. Without the cells that produce intrinsic factor, B12 cannot be absorbed for the body to use it. Pernicious anaemia is more common in women in their 60s, people with a family history of pernicious anaemia and people with another autoimmune disease.

Some stomach conditions can also cause problems in absorbing B12. Surgical procedures where parts of the stomach or intestine are removed may mean that the areas that absorb B12 may be missing. Conditions such as Crohn's, a long term disease that causes inflammation of the lining of the digestive system can also stop you from absorbing enough B12.

Long term B12 deficiencies can rarely cause more serious complications such as:

• Problems with the nervous system

• Temporary infertility

• Heart conditions

• Complications in pregnancy

• Birth defects


The diagnosis of B12 deficiency is done by your GP taking your medical history and doing some blood tests. Your blood will be checked to determine whether you have a lower level of haemoglobin than normal; whether your red blood cells are larger than normal; the level of B12 in your blood.

Whilst you may have a suitable level of B12 in your blood, it may not be of the active form that you can use. You may then have further tests done to determine the cause of your deficiency, especially to check if you have developed pernicious anaemia.


The treatment of B12 deficiency is with injections of B12 every other day for two weeks or until your symptoms have stopped improved. After this initial treatment, further treatment will depend on the cause of the lack of B12. If the deficiency is related to your diet, you may be given tablets to take between meals. Depending on how difficult it is for you to get B12 in your diet, you may be on these tablets for life. If the deficiency is due to a condition such as pernicious anaemia or Crohn's, you may have to remain on B12 injections once a month for life.

B12 deficiencies are common in older people, with 1 in 10 over 75s suffering from a B12 deficiency and 1 in 20 for aged 65 to 75. Improving your diet can help to treat the condition and prevent it from occurring again. Adding foods like meat, fish, eggs, dairy products and specially fortified foods can help to raise B12 levels.

Dr Seth Rankin is founder of London Doctors Clinic