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As part of our efforts to keep all patients and staff safe, we are no longer accepting walk-ins.

Please call or book online to be seen.

Vitamin B12 & Folate

Tests for anaemia & autoimmune disease

B12 and folate are necessary for the formation of red blood cells (RBCs), as well as tissue and cell repair. B12 is essential for proper nerve function, and can be a marker of behavioral changes in the elderly.

B12 & Anaemia

Low levels of B12 and folate (sometimes called B9) can lead to a type of anaemia where the body produces abnormally large red blood cells (RBCs), which are then unable to do their job of carrying oxygen around the body.

This is different from iron deficiency anaemia, but both include symptoms of extreme tiredness, pins and needles (feeling that a limb has “fallen asleep”, also known as paraesthesia), mouth ulcers, vision problems, muscle weakness, depression, and impaired cognitive function.

B12 & Iron

B12 also activates an enzyme in the body that helps it to absorb and use folate, which is why low intake of B12 can lead to lower iron levels in the blood, even if you are consuming a good amount of iron.


In addition to different kinds of anaemia, B12 and folate deficiencies can be caused by:

  • diet (particularly vegan diets)
  • conditions affecting the intestines or stomach (such as Crohn’s disease or poor gut absorption)
  • certain medications (like PPIs)
  • long-term health conditions that damage your body’s ability to maintain its levels of certain nutrients

What to do next

Please give us a call or use our online booking system to make your appointment for testing. You will be able to specify whether you want to see a doctor to discuss your symptoms and help you interpret and treat the results, or whether you prefer to have the test on its own and take the results to your existing GP.

  • 02073231023Harley St Area
  • 02071010355City of London


Preparing for test

Please arrive for this test well-hydrated, to make the testing process easier.

During the test

This test is a blood test. The doctor or nurse inserts a needle into a vein, usually on the inner arm near your elbow. They will draw a small amount of blood. You may feel a brief pricking or scratching sensation.

Type of sample taken:



We will email you the results as soon as they arrive from the laboratory. The interpretation of the results is not included in the test price. If you would like to have the test results explained to you by one of our experienced doctors, please book for a consultation as well.


Is it possible to overdose on Vitamin B12 and folate supplements?

Both of these vitamins are water soluble, which means the body will get rid of any excess amounts through the urine. Your doctor may recommend that you test for both before taking supplements, however, as taking folic acid can mask low levels of B12.

What causes B12 and folate deficiency?

There are a number of possible conditions that can cause you to become deficient in these vitamins, including pernicious anemia (an absorption issue), a lack of dietary vitamins, taking certain medications, and old age. Both deficiencies are more common after 75 years of age.

What are some natural sources of B12?

B12 is naturally found in animal products, such as fish, red meat, poultry, milk, cheese, and eggs. It is also sometimes added to some products (“fortified”). Organ meats such as liver have the highest levels of B12.


Vitamin B12 & Folate

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