Blood test

Low vitamin B9 (folic acid) level in the blood

Blood test
Low vitamin B9 (folic acid) level in the blood
Last update: 13/05/2022

What is low vitamin B9 level in the blood called?

  • Vitamin B9 low

What is the normal level of vitamin B9 in the blood?

If you need to know which are the vitamin B9 reference ranges or you require more information about vitamin B9 in a blood test, you can visit normal vitamin B9 in a blood test.

What does a low vitamin B9 level in the blood mean?

Vitamin B9 is also called folic acid or folate. Vitamin B9 is essential for the correct production of RBCs (Red Blood Cells) and the deficiency of vitamin B9 may lead to anemia.

Deficiency of vitamin B9 is related to megaloblastic anemia, a type of anemia where RBCs are very large.

The most common causes of vitamin B9 (folic acid) low in the blood can be classified as:

Vitamin B9 blood values are usually given in ng/ml but sometimes you can see these values in nmol/l following the International System of Units (SI). In case your values are in nmol/l you can convert them using this tool:


A low vitamin B9 level in the blood means:

  • Mild vitamin B9 decrease (2-3 ng/ml in adults):

    Vitamin B12 level in the blood is below the normal range and it is advisable to monitor the values in future blood tests. It is important to know the vitamin B12 level in the blood. If the vitamin B12 level is also low, it is a sign of a real vitamin B9 (folic acid) deficiency.

    Several drugs that include antibiotics, anticonvulsants or oral contraceptives may reduce the vitamin B9 level in the blood. If you are taking such medication, it is recommended to ask your doctor about possible interactions.

  • Severe vitamin B9 decrease (< 2 ng/ml in adults):

    Vitamin B9 values are very low and you should visit your doctor because it is usually related to a megaloblastic anemia.

    You may experience glossitis (inflammation of the tongue) or mouth ulcers. In addition, you may feel the common symptoms of anemia like fatigue or irritability.

    You should ask your doctor for the proper treatment.

Which factors can reduce the vitamin B9 level in the blood?

Some particular health situations or drugs may reduce your vitamin B9 (folic acid) level in the blood:

Which diseases can reduce your vitamin B9 level in the blood?

The following diseases can explain a vitamin B9 (folic acid) blood level lower than normal:

What can I do to increase the vitamin B9 level in the blood?

The possible causes of vitamin B9 deficiency should be studied to know how to increase the level.

If the cause is related to a nutritional deficit, you must increase the intake of green leafy vegetables and fruit. There are also folic acid supplements available that your doctor may prescribe.

Another possibility is related to a vitamin B12 deficiency. In this case, you should increase the intake of meat (rich in vitamin B12) or take vitamin B12 supplements.

Where can I find more information about vitamin B9 level in the blood?

You can visit our pages about:

Which values are considered a low vitamin B9 level in the blood?

The following values are considered to be above the normal range:

IMPORTANT: These levels are expressed in ng/ml. They are an example of a healthy adult of about 45 years old with no known disease and not taking any medication. The ranges can be different depending on the laboratory or on your personal circumstances.

Vitamin B9 (Folic Acid)
Mild decrease
2.9 ng/ml2.8 ng/ml2.7 ng/ml2.6 ng/ml2.5 ng/ml2.4 ng/ml2.3 ng/ml2.2 ng/ml
2.1 ng/ml2 ng/ml      
Severe decrease
1.9 ng/ml1.8 ng/ml1.7 ng/ml1.6 ng/ml1.5 ng/ml1.4 ng/ml1.3 ng/ml1.2 ng/ml
1.1 ng/ml1 ng/ml0.9 ng/ml0.8 ng/ml0.7 ng/ml0.6 ng/ml0.5 ng/ml0.4 ng/ml
0.3 ng/ml0.2 ng/ml0.1 ng/ml0 ng/ml    
Medically reviewed by our Medical staff on 13/05/2022


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