What is folate?
Folic acid is the name of the B vitamin in tablets and fortified food; folate is the natural form in green leafy vegetables, legumes, whole grains, fruit and liver. The word comes from folium, leaf. In your body it is a helper in making the building blocks of DNA and in converting homocysteine, and with that indispensable for every cell that divides. The cells that divide fastest, in your bone marrow, the wall of your gut and a growing embryo, notice a deficiency first. Your body does not make folate itself and stores only a few months' supply, in the liver. The number in your blood therefore follows what you ate in recent weeks, and it responds quickly: a meal with a lot of vegetables or a supplement shortly before the draw lifts it straight away. With a deficiency the red blood cells become too large and too few, an anaemia recognisable by a high MCV, and homocysteine rises. Your report prints folate in nmol/L. Normal is roughly 12.2 to 38.5 nmol/L, where the labs overlap; below 10 nmol/L the World Health Organization speaks of a deficiency. Above the band nothing is wrong, because a surplus leaves the body through the urine.
Why is folate relevant?
Folate is the vitamin that runs out first in anyone who eats few vegetables, drinks a lot or eats one-sidedly, and the deficiency shows in the blood count: large red blood cells, a rising RDW and eventually anaemia with tiredness. Homocysteine rises with it, and that is one of the reasons a deficiency is linked to cardiovascular disease. The second reason is pregnancy. In the first weeks, when the neural tube of the embryo closes, often before a woman knows she is pregnant, enough folate greatly reduces the chance of spina bifida and other birth defects. That is why the advice is to take 400 micrograms every day from the moment you want to become pregnant up to and including the tenth week, beside what you eat. The honest limitation is that the number in the blood is a snapshot of recent days, not of the store in your cells. A vegetable-rich meal or a tablet the morning before can mask a deficiency. And folate and vitamin B12 work together: a lot of folate can hide the anaemia of a B12 deficiency while the nerve damage continues, so always read the two together.
Folate reference ranges
What counts beside the number:
- Your vitamin B12, because the two work together and a lot of folate can hide a B12 deficiency
- Your MCV and RDW, because large red blood cells with a high spread are the picture of a deficiency
- Your haemoglobin, because that says whether there is already anaemia
- Whether you took a supplement or ate a lot of vegetables the morning of the draw, because that lifts the number straight away
- How much alcohol you drink and whether you are pregnant or breastfeeding, because those use up the store
- Your homocysteine, because that reflects the store in your cells more honestly than the number in the blood
The band differs more here than for most values, especially at the bottom: the lower limit runs apart by more than a factor of two between the labs. Where they overlap, 12.2 to 38.5 nmol/L, everyone agrees, and below 10 nmol/L there is a deficiency according to the World Health Organization. The number responds strongly to what you ate in the days before, so preferably have blood drawn before breakfast and before your supplement of that day, and always read folate together with vitamin B12. Above the band nothing is wrong.
What Dutch labs actually use
The lower limit runs from 5 at Star-shl to 12.2 at Unilabs, more than a factor of two, and the upper limit from 38.5 at Certe to 78.1 at Unilabs. Someone with 10 nmol/L is too low at Unilabs and normal at the other three, while the World Health Organization limit Clinical Diagnostics names sits exactly below that.
12.2 – 38.5nmol/L
Between 5 and 12.2 and between 38.5 and 78.1 it depends on the lab, because each sets its limits on its own method and population. Above 78.1 every lab calls it abnormal.
every lab calls 12.2 – 38.5 nmol/L normal. Between 5 and 12.2 and between 38.5 and 78.1 it depends on the lab.
Every age, per lab
| Laboratory | Group | Reference range |
|---|---|---|
| Unilabs(Saltro, Medlon, SHO, Atalmedial)2026 | Adults | 12.2–78.1 nmol/L |
| Star-shl2026 | Adults | 5–61 nmol/L |
| Certe2026 | From 18 yrs | 7.3–38.5 nmol/L |
| Clinical Diagnostics2026 | Adults | 7–45 nmol/L |
| Deficient (WHO) | < 10 nmol/LDecision limit |
Each band as the lab publishes it, retrieved in 2026, unless marked otherwise.
Folate high or low: what it means
A low folate means too little came in or too much was used in recent weeks. Usually it is the first and rarely the last: too few vegetables, legumes and whole grains in the diet, the most common reason in anyone who eats one-sidedly or mainly processed food; a pregnancy or breastfeeding, in which the embryo and the child use a lot; alcohol, which inhibits absorption and drains the store in the liver; medication, such as methotrexate, some epilepsy medicines and the pill; and a bowel disease such as coeliac disease or Crohn's disease, in which the gut does not absorb it. A high folate is harmless and almost always comes from supplements or fortified food, such as breakfast cereals and some breads; a surplus leaves the body through the urine. The one thing to watch: a lot of folate with a B12 deficiency hides the anaemia while the nerve damage continues, so with a high value from supplements have your B12 measured too. What you do about it: eat green leafy vegetables, broccoli, legumes, whole grains and fruit daily, and cook vegetables briefly, because folate is lost in cooking water. Drink less alcohol. If you want to become pregnant, take 400 micrograms a day from the moment you stop contraception up to and including the tenth week. With a deficiency a tablet brings the number up in a few weeks; the red blood cells need three to four months to recover. Always have vitamin B12 measured as well before you replenish folate. Folate belongs beside vitamin B12, because the two work together and a lot of folate can hide a B12 deficiency, beside MCV and RDW, which rise with a deficiency, beside haemoglobin, which says whether there is already anaemia, and beside homocysteine, which reflects the store in your cells more honestly than the number in the blood.
What lowers it
Too little taken in or too much used, usually through the diet.
| Cause | How often |
|---|---|
| Too few vegetablesGreen leafy vegetables, legumes and whole grains are the source; anyone who eats one-sidedly or mainly processed food drains the store in a few months | Often |
| Pregnancy and breastfeedingThe embryo and the child use a lot, and precisely for that reason 400 micrograms a day is the advice from wanting a child up to and including the tenth week | Often |
| AlcoholInhibits absorption in the gut and drains the store in the liver; anyone who drinks daily often sits low | Often |
| MedicationMethotrexate, some epilepsy medicines and the pill inhibit absorption or use | Sometimes |
| Bowel diseaseCoeliac disease and Crohn's disease make the gut absorb less, even with a good diet | Sometimes |
What raises it
Harmless: a surplus leaves the body through the urine.
| Cause | How often |
|---|---|
| SupplementsA multivitamin or folic acid tablet lifts the number straight away, certainly if you took it the morning of the draw | Often |
| Fortified foodBreakfast cereals and some breads contain added folic acid, and a meal with them shortly before the draw raises the value | Sometimes |
How does a folate blood test work?
- Referral
- Not needed. You can have folate measured yourself, and it is in most panels for anaemia and tiredness.
- Fasting
- Advisable. A meal with a lot of vegetables or a supplement shortly before the draw lifts the value straight away and can mask a deficiency.
- When
- In the morning, before breakfast and before your supplement of that day. When wanting a child, before you start taking it, to know where you stand.
- The draw
- One tube of blood from a vein in your arm. Request vitamin B12 and a blood count with it, because a deficiency of the one looks like a deficiency of the other and the approach differs.
- Repeating
- Three to four months after replenishing a deficiency, because that is how long the red blood cells need to recover. Compare with the band on your own report, because the lower limit differs by more than a factor of two between the labs.
- Which test
- Folate is in the Iron & fatigue test (€99) and in .
- Where to draw
- You can draw at 250+ locations near you, no referral needed. See the locations
Frequently asked questions
What is folate?
The B vitamin your cells need to make new DNA and divide, also known as folic acid or vitamin B11. It is in green leafy vegetables, legumes, whole grains, fruit and liver. Your body does not make it itself and holds a store of only a few months, so the number follows what you ate in recent weeks. A deficiency shows first in the cells that divide fastest: those of your blood, your gut and a growing embryo.
What is a normal folate value?
Roughly 12.2 to 38.5 nmol/L, where the labs overlap; the lower limit differs by more than a factor of two between the labs, so compare with the band on your own report. Below 10 nmol/L there is a deficiency. Above the band nothing is wrong, because a surplus leaves the body through the urine.
What does a low folate value mean?
That too little came in or too much was used in recent weeks: too few vegetables, legumes and whole grains, a pregnancy or breastfeeding, or alcohol, which inhibits absorption and drains the store in the liver. Sometimes it comes from medication or a bowel disease. The bone marrow then makes red blood cells that are too large and too few, and homocysteine rises. Always have vitamin B12 measured as well, because a deficiency of the one looks like a deficiency of the other.
What does a high folate value mean?
Almost always that you use a supplement or fortified food, and that is harmless: a surplus leaves the body through the urine. The one thing to watch is your vitamin B12, because a lot of folate can hide the anaemia of a B12 deficiency while the nerve damage continues.
What do I do about a deficiency?
Eat green leafy vegetables, broccoli, legumes, whole grains and fruit daily, and cook vegetables briefly, because folate is lost in cooking water. Drink less alcohol. A tablet brings the number up in a few weeks; the red blood cells need three to four months to recover. Have your vitamin B12 measured first, because replenishing folate with a B12 deficiency hides the anaemia without protecting the nerves.
Which folate value do I aim for when wanting to become pregnant?
More important than a number is taking it: 400 micrograms a day from the moment you stop contraception up to and including the tenth week of pregnancy, beside what you eat. The neural tube of the embryo closes in the first weeks, often before you know you are pregnant, and enough folate greatly reduces the chance of spina bifida. A measurement beforehand shows where you stand; if you are within the band, the supplement is still the rule.
When is a folate deficiency worrying?
When haemoglobin is already falling and the red blood cells are large, because then there is anaemia, and always in a pregnancy or when wanting a child. Also when the deficiency returns despite a good diet, because then the gut may not be absorbing it and a test for coeliac disease belongs with it.
Do I need to fast?
Advisable. A meal with a lot of vegetables, fortified breakfast cereals or a supplement shortly before the draw lifts the value straight away and can mask a deficiency. Have blood drawn before breakfast and take your supplement only afterwards.
Which tests include folate?
Folate is in the Iron & fatigue test (€99, also as an add-on for €15), in the True vitamin B12 test (€119, also as an add-on for €69), in the comprehensive test (€229) and in .
Related biomarkers
Read on
Sources
- 1.Unilabs, test catalogue (Dutch): folate. 2026. bepalingenklapper.nl
- 2.Star-shl, test catalogue (Dutch): folate. 2026. star-shl.nl
- 3.Certe, test catalogue (Dutch): folate. 2026. bepalingenwijzer.certe.nl
- 4.Clinical Diagnostics, lab guide (Dutch): folate. 2026. clinicaldiagnostics.nl
- 5.LESA Laboratory diagnostics (Dutch primary-care laboratory agreement). 2026. richtlijnen.nhg.org
Educational information only, not medical advice. Consult a healthcare professional for clinical decisions.
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