What Is Folate in a Blood Test?

In a blood test, you may have noticed your blood being tested for folate levels. Folate is an essential nutrient required by the body to aid in the production of healthy red blood cells (RBC). A folate deficiency can have some serious short- and long-term effects and is something your healthcare provider may test for if you are displaying certain symptoms. The role of folate in the body, the risks of a folate deficiency and what you can do to treat it are discussed here.  

What is folic acid or folate?

Folate and folic acid are different forms of vitamin B9. Folate is the naturally occurring form of vitamin B9 and is an essential nutrient required by our bodies, whereas folic acid is a synthetic form of folate. There is often confusion surrounding these two terms as folate and folic acid are sometimes used interchangeably. 

Dietary folate is converted to the biologically active form of vitamin B9, known as levomefolic acid or 5-methyltetrahydrofolate (5-MTHF), in your digestive system before entering the bloodstream.1

Folic acid, also known as pteroylmonoglutamic acid, is used as a B9 supplement and added to fortified foods. Although a relatively safe supplement, research has shown that unmetabolized folic acid has been associated with some serious health problems. The process of converting folic acid into the active 5-MTHF compound is slower and more inefficient than seen with folate. Therefore, unmetabolized folic acid is often detected in people's bloodstream.2 Adverse health effects suggested to be caused by unmetabolized folic acid in the body include an increased cancer risk;3 however, this evidence is inconclusive and needs further investigation.4

Folate levels are often seen in a blood test in conjunction with B12. This is because taking a folic acid supplement can sometimes improve your symptoms to an extent where an underlying B12 deficiency is masked. If a B12 deficiency goes undiagnosed and untreated, it can lead to serious effects on the nervous system. 

Where do our bodies get folate?

Folate is acquired from our diet and is found in small amounts in a variety of different foods. Some good sources of folate include:

  • leafy green vegetables, such as kale and spinach.

- broccoli

- Brussel sprouts

  • chickpeas and kidney beans
  • liver
  • peas
  • avocado 

There are also some foods fortified with folic acid, such as breakfast cereals and sometimes flour and bread. 

Adults require 200mg of folate each day. There are no long-term stores of folate in the body, unlike vitamin B12, so it is important to consume folate-rich foods frequently. For most people, consuming enough folate should be easily achieved by eating a balanced diet, including a variety of different foods. 

Why is folate important?

Folate helps the body to form healthy and functioning RBC, and a lack of folate can lead to the development of folate deficiency anaemia. This occurs when a lack of folate causes the body to produce oversized RBC that are unable to function properly. RBC are responsible for carrying oxygen around the body; therefore, folate deficiency anaemia can result in impaired oxygen transportation in the bloodstream.

A folate deficiency can occur for a number of reasons. Most often it is as a result of a poor diet with a lack of dietary folate. In some cases, folate deficiency may be caused by:

  • Malabsorption: Where your body is unable to absorb folate as effectively as it should, this is often caused by an underlying digestive system problem, such as coeliac disease.
  • Excessive peeing: Folate levels can drop through frequent urination. This can be the result of an underlying health condition such as congestive heart failure, acute liver damage or long-term dialysis
  • Medication: Certain drugs can affect the amount of folate in your body, and even make folate more difficult to absorb. These include some anticonvulsants, methotrexate and colestyramine. Your doctor will be aware of this when prescribing these medications and may monitor your folate levels if necessary. 
  • Other causes: Other causes like pregnancy, cancer, infections or certain blood disorders may require more folate than normal and you may show symptoms of a folate deficiency if you cannot meet your body's demands. 

What are the effects of folate deficiency?

Folate deficiency can cause a wide range of symptoms, including:

  • extreme fatigue and a lack of energy
  • a sore and red tongue
  • mouth ulcers
  • pins and needles
  • weakness of the muscles
  • vision problems
  • impaired memory, understanding and judgement abilities
  • psychological problems, which may include confusion and depression

During pregnancy, a folate deficiency has been linked to the development of neural tube defects, such as spina bifida, in babies.5 To help prevent this, if you are pregnant or trying to get pregnant, it is advised by the Department of Health and Social Care that you should take a folic acid supplement. The recommended amount of folic acid supplement is 400µg everyday until you are 12 weeks pregnant. In certain cases, some women have an increased risk of their pregnancy being affected by neural tube defects, so a higher dose of folic acid supplement is recommended (5mg daily until 12 weeks pregnant). Your healthcare provider will be able to advise if you're at an increased risk of having an affected pregnancy.

Furthermore, severe folate deficiency can result in someone developing folate deficiency anaemia.

Folate deficiency anaemia

Anaemia developed from a folate deficiency results in blood being unable to carry sufficient amounts of oxygen throughout the body to different organs and tissues.

Additional symptoms experienced by people with folate deficiency anaemia may include:

  • reduced sense of taste
  • depression
  • numbness and tingling in your hands and feet
  • muscle weakness
  • diarrhoea
  • irritability 
  • general anaemic symptoms include fatigue, irregular heartbeats, breathlessness, shortness of breath, cold extremities, pale or yellowish skin.


It is important to book an appointment to visit the healthcare provider if you think you may have the symptoms of a folate deficiency. A folate deficiency can often be diagnosed based on your symptoms and the results of a blood test. If folate deficiency anaemia remains undiagnosed and untreated, some problems caused by the condition can be irreversible, so it is important to obtain a diagnosis as soon as possible. 

Folate deficiency can often be easily treated with folic acid tablets to supplement low folate levels, and they usually only need to be taken for around 4 months. It is also recommended that you take steps to improve your diet and introduce more folate-rich foods, to prevent the deficiency from returning after finishing your course of supplements. 

Alternatives to folic acid supplements, such as Metafolin, contain the active 5-MTHF compound and are suggested to be an effective and safe alternative to folic acid.6

If your blood test indicates a folate deficiency, your doctor may also refer you for further tests or treatments to identify the cause of your deficiency. This may include:

  • Your doctor may refer you to a specialist dietitian if they suspect your folate deficiency is caused by a poor diet, and they will create a personalised eating plan to increase the amount of folate in your diet. 
  • If it is suspected that you are not maintaining good folate levels as a result of absorption problems in your digestive system, you may be referred to a gastroenterologist.
  • If you have folate deficiency anaemia, you will likely be referred to a haematologist who specialises in treating blood conditions. 

To ensure treatment is working, you may need to have further blood tests to monitor your folate levels. 

Complications of folate deficiency

Folate deficiency, although uncommon, can lead to some severe complications, particularly if you have long-time folate deficiency. Some potential complications seen in people with long-term folate deficiencies include nervous system problems, temporary infertility, pregnancy complications and heart conditions. Some of these complications improve with treatment; however others, such as nervous system complications, are likely to have permanent effects. Severe anaemia also increases your risk of developing heart failure.7


In conclusion, folate is an essential form of vitamin B9 that your body uses to produce healthy RBC. Without a sufficient level of folate in your diet, you may put yourself at risk of developing some uncomfortable side effects and possibly even more serious conditions such as folate deficiency anaemia. The longer a folate deficiency goes untreated, the greater the chance of permanent damage being caused. Therefore, it is important that you must visit your healthcare provider as soon as possible if you think you may have a folate deficiency.


  1. Alpers DH. Absorption and blood/cellular transport of folate and cobalamin: Pharmacokinetic and physiological considerations. Biochimie [Internet]. 2016 [cited 2022 Oct 21]; 126:52–6. Available from: https://linkinghub.elsevier.com/retrieve/pii/S0300908415003533.
  2. Wright AJA, Dainty JR, Finglas PM. Folic acid metabolism in human subjects revisited: potential implications for proposed mandatory folic acid fortification in the UK. BJN [Internet]. 2007 [cited 2022 Oct 21]; 98(04). Available from: http://www.journals.cambridge.org/abstract_S0007114507777140.
  3. Oliai Araghi S, Kiefte-de Jong JC, Dijk SC van, Swart KMA, Laarhoven HW van, Schoor NM van, et al. Folic Acid and Vitamin B12 Supplementation and the Risk of Cancer: Long-term Follow-up of the B Vitamins for the Prevention of Osteoporotic Fractures (B-PROOF) Trial. Cancer Epidemiology, Biomarkers & Prevention [Internet]. 2019 [cited 2022 Oct 21]; 28(2):275–82. Available from: https://aacrjournals.org/cebp/article/28/2/275/71897/Folic-Acid-and-Vitamin-B12-Supplementation-and-the.
  4. Qin T, Du M, Du H, Shu Y, Wang M, Zhu L. Folic acid supplements and colorectal cancer risk: meta-analysis of randomized controlled trials. Sci Rep [Internet]. 2015 [cited 2022 Oct 21]; 5(1):12044. Available from: http://www.nature.com/articles/srep12044.
  5. Imbard A, Benoist J-F, Blom H. Neural Tube Defects, Folic Acid and Methylation. IJERPH [Internet]. 2013 [cited 2022 Oct 21]; 10(9):4352–89. Available from: http://www.mdpi.com/1660-4601/10/9/4352.
  6. Pietrzik K, Bailey L, Shane B. Folic Acid and L-5-Methyltetrahydrofolate: Comparison of Clinical Pharmacokinetics and Pharmacodynamics. Clinical Pharmacokinetics [Internet]. 2010 [cited 2022 Oct 21]; 49(8):535–48. Available from: http://link.springer.com/10.2165/11532990-000000000-00000.
  7. Agarwal A, Shah. Anemia associated with chronic heart failure: current concepts. CIA [Internet]. 2013 [cited 2022 Oct 21]; 111. Available from: http://www.dovepress.com/anemia-associated-with-chronic-heart-failure-current-concepts-peer-reviewed-article-CIA.
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Alys Schirmer

Bachelor of Science - BSc, Biomedical sciences, University of Bristol

Alys is an experienced Article Writer and Editor.

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