Vitamin B12 or B9 (folate) deficiency anaemia happens when you have a shortage of either of these vitamins. The body responds by producing abnormally large red blood cells that do not function properly.
Red blood cells carry oxygen around the body using a substance called haemoglobin.
Anaemia means you either have:
- fewer red blood cells than normal
- a low amount of haemoglobin in each red blood cell
Symptoms of vitamin B12 or folate deficiency
Vitamin B12 and folate perform many important functions in the body. This includes keeping the nervous system healthy.
A deficiency in either of these vitamins can cause a wide range of problems, such as:
- extreme tiredness
- a lack of energy
- pins and needles (paraesthesia)
- a sore and red tongue
- mouth ulcers
- muscle weakness
- disturbed vision
- psychological problems, including depression and confusion
- problems with memory, understanding and judgement
Some of these problems can also happen if you have a deficiency in vitamin B12 or folate and do not have anaemia.
Non-urgent advice: Contact your GP if:
- you think you may have a vitamin B12 or folate deficiency
You can usually be diagnosed by a blood test.
It's important to start treatment as soon as possible. This is because some problems caused by the condition cannot be reversed.
Causes of a deficiency
A deficiency is more common in older people.
It affects around:
- 1 in 10 people age 75 or over
- 1 in 20 people age 65 to 74
Several other causes can lead to a vitamin B12 or folate deficiency.
Pernicious anaemia
Pernicious anaemia is where your immune system attacks healthy cells in your tummy. This prevents your body from absorbing vitamin B12 from the food you eat. It's the most common cause of vitamin B12 deficiency.
Diet
A lack of B12 or folate in your diet can cause a deficiency.
This is not common, but can happen if you:
- have a vegan diet
- follow a fad diet
- have a generally poor diet for a long time
Medicine
Certain medicines can affect how much of these vitamins your body absorbs. These include anticonvulsants and proton pump inhibitors (PPIs).
Coeliac disease
Coeliac disease is a condition where your immune system attacks your own tissues when you eat gluten. This can also lead to B12 deficiency anaemia.
Treating deficiency anaemia
Most cases can be treated with injections or tablets to replace the missing vitamins.
Vitamin B12
Vitamin B12 supplements are normally given by injection at first.
After that you'll either need B12 tablets between meals or regular injections. This depends on whether your deficiency is related to your diet.
You may need supplements for the rest of your life.
Folate
Folic acid tablets are used to restore folate levels. You usually need to take these for 4 months.
Improving your diet
In some cases, improving your diet can help treat the condition and stop it from returning.
Vitamin B12 is found in:
- meat and fish
- eggs
- dairy products
- yeast extract
- fortified foods
Sources of folate include green vegetables such as:
- broccoli
- brussel sprouts
- peas
Complications
Vitamin B12 or folate deficiency can lead to complications. But this is not common.
Complications include:
- problems with the nervous system
- temporary infertility
- heart conditions
- pregnancy complications and birth defects
- risk of developing heart failure
Complications are more likely if you have a deficiency in the vitamin for some time. Some will improve with the right treatment. Others can be permanent, such as problems with the nervous system.
Content supplied by the NHS and adapted for Ireland by the HSE
