Vitamin B12 or B9 (commonly called folate) deficiency anaemia occurs when a lack of vitamin B12 or folate causes the body to produce abnormally large red blood cells that can't 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.
There are several different types of anaemia, and each one has a different cause. For example, iron deficiency anaemia, which occurs when the body doesn't contain enough iron.
SYMPTOMS►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.
There are a number of problems that can lead to a vitamin B12 or folate deficiency, including:
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.
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.
Both vitamin B12 deficiency and folate deficiency are more common in older people, affecting around 1 in 10 people aged 75 or over, and 1 in 20 people aged 65 to 74.
To diagnose anemia, your doctor will likely ask you about your medical history, perform a physical exam, and order blood tests.
You can help by providing detailed answers about your symptoms, family medical history, diet, medications you take, alcohol intake, and ethnic background. Your doctor will look for symptoms of anemia and other physical clues that might point to a cause.
There are basically three different causes of anemia: blood loss, decreased or faulty red blood cell production, or destruction of red blood cells.
Blood tests will not only confirm the diagnosis of anemia, but also help point to the underlying condition. Tests might include:
- Complete blood count (CBC), which determines the number, size, volume, and hemoglobin content of red blood cells
- Blood iron level and your serum ferritin level, the best indicators of your body's total iron stores
- Levels of vitamin B12 and folate, vitamins necessary for red blood cell production
- Special blood tests to detect rare causes of anemia, such as an immune attack on your red blood cells, red blood cell fragility, and defects of enzymes, hemoglobin, and clotting
- Reticulocyte count, bilirubin, and other blood and urine tests to determine how quickly your blood cells are being made or if you have a hemolytic anemia, where your red blood cells have a shortened life span
Only in rare cases will a doctor need to remove a sample of bone marrow to determine the cause of your anemia.
Most cases of vitamin B12 and folate deficiency can be easily treated with injections or tablets to replace the missing vitamins.
Vitamin B12 supplements are usually given by injection at first. Then, depending on whether your B12 deficiency is related to your diet, you'll either require B12 tablets between meals or regular injections. These treatments may be needed for the rest of your life.
Folic acid tablets are used to restore folate levels. These usually need to be taken for four months.
In some cases, improving your diet can help treat the condition and prevent it recurring. Vitamin B12 is found in meat, fish, eggs, dairy products, yeast extract (such as Marmite) and specially fortified foods. The best sources of folate include green vegetables such as broccoli, Brussels sprouts and peas.
COMPLICATIONS► 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.