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Folate
Folate circulating in the blood. Serum folate reflects recent intake and can normalise within days of eating better, so red cell folate is sometimes measured instead when longer-term status matters. Folate and B12 are almost always interpreted together, because their deficiencies look alike on a blood count and treating one without the other can cause harm.
General information only — not a diagnosis, not treatment and not a substitute for your doctor. Reference ranges differ between laboratories, so the range printed on your own report is the one that counts, and only a clinician who knows your history can say what a result means for you. Never start, stop or change a medicine or supplement based on this page.
Usual adult reference range
The ranges below are typical adult reference intervals. Your own laboratory sets its own, printed next to your result, and that is the one to compare against.
| Group | SI units (nmol/L) | Conventional (µg/L (ng/mL)) |
|---|---|---|
| Commonly quoted adequate level | above 7 | above 3 |
| Commonly used deficiency threshold | below 7 | below 3 |
Source: Commonly used thresholds published by clinical laboratories; serum and red cell folate have different intervals and different meanings. · checked 2026-09-02
What a high result generally indicates
A high folate is generally not a concern in itself. It is usually supplementation or fortified food. The clinically important point is that folate supplementation can improve the blood count in B12 deficiency while the neurological damage continues, which is why B12 is checked alongside.
What a low result generally indicates
Low folate causes anaemia with large red cells, and in early pregnancy low folate status is associated with neural tube defects — which is why supplementation before conception and in the first trimester is standard public health advice. Causes include poor intake, alcohol, coeliac disease and some medicines.
These are general patterns, not a diagnosis. Many things cause a high or low result, and the same figure means different things in different people. What yours means is a question for the doctor who ordered the test.
What affects this result
- Recent diet — serum folate responds within days, so a single meal pattern can shift it.
- Alcohol lowers it.
- Coeliac disease and other malabsorption lower it.
- Methotrexate and some anti-epileptics interfere with folate metabolism.
- Pregnancy increases requirement substantially.
- Fortified flour and breakfast cereals raise it in countries that fortify.
Before the test
A fasting sample is sometimes requested because serum folate responds so quickly to a meal.
Any preparation instruction that comes with your test slip overrides this general note — follow the one your clinician or laboratory gave you.
The one thing to take from this page
The range above is a typical interval for orientation. Your own laboratory's range, printed beside your result, is the one that applies to you — and a result is only meaningful alongside your symptoms, your history, your medicines and your other tests. That reading is a clinician's job. This page cannot diagnose anything, cannot tell you to change a medicine or a supplement, and is not a substitute for the person who ordered your test.
Frequently asked questions
What is the normal range for folate?
A typical adult reference interval is 7 nmol/L or above, but laboratories differ — the range printed on your own report is the one to use. And a result inside or outside a range is only meaningful in context, which is your doctor's reading, not a web page's.
What does a high folate mean?
A high folate is generally not a concern in itself. It is usually supplementation or fortified food. The clinically important point is that folate supplementation can improve the blood count in B12 deficiency while the neurological damage continues, which is why B12 is checked alongside.
What does a low folate mean?
Low folate causes anaemia with large red cells, and in early pregnancy low folate status is associated with neural tube defects — which is why supplementation before conception and in the first trimester is standard public health advice. Causes include poor intake, alcohol, coeliac disease and some medicines.
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