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Folate, also known as vitamin B9, is an essential nutrient acquired from the diet that has important roles in the formation of red blood cells and DNA synthesis. Low levels can indicate deficiency and may cause anaemia.
Written by Leanne Edermaniger
April 30, 2024
Reviewed by:
Dr Thom PhillipsFolate is the natural form of vitamin B9, a water-soluble vitamin that is important for the development of DNA, protein metabolism, and many other bodily functions. Folate naturally occurs in some foods and is also widely available in supplement form.
B vitamins are essential for the maintenance of good health and wellbeing. They influence energy levels, metabolism, and brain function. Vitamin B9 specifically:
The healthy range for folate levels depends on several factors. For example, the reference ranges can be different depending on the laboratory and the techniques they use to determine folate levels.
According to the National Institute for Health and Care Excellence (NICE), folate reference ranges are as follows:
Folate deficiency indicated | < 3 micrograms/L (µg/L) | < 7 nanomoles/L (nmol/L) |
Suggestive folate deficiency | 3 – 4.5 µg/L | 7 – 10 nmol/L[5] |
Normal range | > 4 µg/L | > 9 nmol/L |
Elevated folate levels | > 20 µg/L | > 45.3 nmol/L[6] |
At Forth, our data shows that 57% of men and 43% of women have healthy folate levels.
Vitamin B9, folate, and vitamin B12 work closely together to help make red blood cells, synthesise DNA to build healthy cells, and support immune function.
Here’s a short breakdown of how vitamin B9 and B12 interact:
If you are deficient in either of these vitamins, then it can cause anaemia, so it is important to check your folate and vitamin B12 levels to find out the cause of any symptoms you may be experiencing.
Folate is a water-soluble vitamin which means the human body is unable to store it, so it must be acquired through our diet to keep our cells functioning normally. Generally, if you take in too much of a water-soluble vitamin, the excess will be excreted out through your urine.
Too little, however, can lead to folate deficiency.
There is some research which suggests that cancer patients are at an increased risk of developing folate deficiency. A cohort study published in 2018 found that 6.8% of hospitalised cancer patients were folate deficient[8].
There is also some research which suggests that folate deficiency can increase your risk of certain cancers, such as colorectal cancer[9].
If you are concerned about your risk of cancer, The TruCheck™ Early Multi-Cancer Screening test can check for the existence of circulating tumour cells in the blood. The test screens for more than 70 types of cancer and has been validated on over 40,000 people.
There are several things you can do to help increase your folate levels, including:
High folate levels can be caused by taking high doses of folic acid supplements or increased consumption of fortified foods. This causes a build-up of unmetabolised folic acid or UMFA in the blood[10]. However, this accumulation doesn’t occur when you eat foods that are naturally rich in folate.
However, high folate levels may pose some risks. For example, masking a vitamin B12 deficiency[11].
If you are not pregnant or trying for a baby, the best way to ensure you’re getting enough folate is to eat a healthy, balanced diet that incorporates folate-rich food sources. Because your body is unable to store folate, you must get it from your diet every day to keep your levels topped up.
Folate is found in:
Bananas are a rich source of folate containing approximately 24 mcg per serving[13].
Eggs can be a good source of folate, vitamin D and protein. One large egg can contain up to 22 µg of folate[14].
Milk and cheese can be good sources of folate, particularly mould cheeses, fermented milk drinks, and cottage cheese[15].
If your folate levels are low, you might consider taking a folic acid supplement or your doctor might prescribe them to you.
Folic acid is the man-made or synthetic form of folate found in vitamin supplements and fortified foods[16].
Most people will get all the folate they need from their diet, but folic acid supplements are recommended for women who are planning to get pregnant or who fall pregnant.
The NHS recommends that women should start taking a folic acid supplement as soon as they start trying for a baby. Ideally, that should be 3 months before conception and up until the 12th week of pregnancy. Folic acid supplementation should help the baby’s brain and spine develop normally and prevent neural tube defects.
The recommended dose is 400 mcg per day, but your doctor may advise taking an increased dose if you are at a greater risk of having a baby with a neural tube defect[17].
Folic acid supplements may not be suitable for everyone and you should discuss with your doctor if you have:
Based in the UK, Leanne specialises in writing about health, medicine, nutrition, and fitness.
She has over 5 years of experience in writing about health and lifestyle and has a BSc (hons) Biomedical Science and an MSc Science, Communication and Society.
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Duthie, S.J. et al. (2002) ‘Impact of folate deficiency on DNA stability’, The Journal of Nutrition, 132(8). doi:10.1093/jn/132.8.2444s.
Homocysteine lowering with folic acid and B vitamins in vascular disease’ (2006) New England Journal of Medicine, 354(15), pp. 1567–1577. doi:10.1056/nejmoa060900.
Epstein-Peterson, Z.D. et al. (2018) ‘Folate testing and deficiency in hospitalized cancer patients’, Blood, 132(Supplement 1), pp. 5814–5814. doi:10.1182/blood-2018-99-117073.
Kowalska, M., & Cichosz, G. (2014). Produkty mleczarskie jako źródło folianów [Dairy products as source of folates]. Polski merkuriusz lekarski : organ Polskiego Towarzystwa Lekarskiego, 36(214), 287–290.
Thom works in NHS general practice and has a decade of experience working in both male and female elite sport. He has a background in exercise physiology and has published research into fatigue biomarkers.
Dr Thom Phillips
Head of Clinical Services