MTHFR, Folate and Methylfolate: What You Need to Know
MTHFR is one of the most talked-about genes in nutrition. Here is what it does, how common variants affect the way your body uses folate, and why the active form, methylfolate, comes up so often. Explained simply, and without the hype.
Methylfolate (L-5-MTHF) is the active form of folate your body uses.
- MTHFR is a gene that gives instructions for an enzyme which helps convert folate and folic acid into methylfolate, the active form your body uses.
- Common MTHFR variants (such as C677T) can make that enzyme work less efficiently. Carrying one is very common and is not, by itself, a diagnosis.
- Methylfolate (L-5-MTHF) is already active, so it does not depend on that conversion step.
- Folate works closely with vitamins B6 and B12, including in normal homocysteine metabolism.
- This is general education, not medical advice. Testing and pregnancy decisions should involve a healthcare professional.
What is MTHFR?
MTHFR stands for methylenetetrahydrofolate reductase. It is both a gene and the enzyme that gene makes. The enzyme's job is to help convert folate from food and folic acid from supplements into methylfolate, the active form the body uses in a process called methylation.
Everyone has the MTHFR gene, and everyone needs the enzyme it produces. It has become a popular topic online mainly because of small, common differences in the gene, called variants, that can change how well the enzyme works.1
Understanding MTHFR really comes down to one idea: how your body turns folate into its usable, active form.
What does the MTHFR enzyme do?
The MTHFR enzyme carries out a key step in the folate cycle: it produces 5-MTHF (methylfolate), the active form of folate. Methylfolate then supplies the methyl groups used in methylation, the process behind many everyday functions, including how the body handles a substance called homocysteine.
Folate and vitamin B12 are the two nutrients most central to keeping this cycle running.23 When the cycle works smoothly, methyl groups are passed around as needed. The MTHFR enzyme is one of the gatekeepers that keeps active folate flowing into it.
What are MTHFR variants like C677T?
MTHFR variants are common, natural differences in the gene. The best known, C677T, can reduce how efficiently the enzyme works, particularly in people who inherit two copies. Carrying a variant is very common, and on its own it is normal rather than a medical problem.
Two variants come up most often, usually written as C677T and A1298C. Around half of people carry at least one copy, which has only a small, intermediate effect on the enzyme, and inheriting a variant is a normal part of human variation.1 The more reduced form, where someone inherits two copies of C677T, is less common, around 1 in 10 people in Western populations, and is linked to lower enzyme activity. That is partly why the topic gets so much attention.
Carrying an MTHFR variant is not a diagnosis and does not mean something is wrong with you. It is simply information about one step in how your body uses folate.
Because carrying a variant is so common, it makes sense that people look for folate in a form that does not rely on that conversion step. That is where methylfolate comes in.
Folic acid, folate and methylfolate: what's the difference?
Folate is the natural form found in foods. Folic acid is a stable, synthetic form used in supplements and fortified foods, which the body has to convert. Methylfolate (L-5-MTHF) is the active end form the body actually uses. They are all "vitamin B9", but in different states.
| Form | What it is | Where you find it |
|---|---|---|
| Folate | The natural form of vitamin B9 | Leafy greens, legumes, liver |
| Folic acid | A stable, synthetic form the body converts | Supplements, fortified cereals and flour |
| Methylfolate (L-5-MTHF) | The active form the body uses directly | Higher-quality supplements; made in the body from the forms above |
Scroll the table sideways on mobile to see all columns.
Folic acid is widely used because it is stable and inexpensive, and for most people the body converts it perfectly well.2 Methylfolate skips the need for that conversion, because it is already the finished, active form.
Why methylfolate is used in supplements
Methylfolate is used because it is already the active form, so it does not depend on the MTHFR conversion step. This appeals to people who may convert folic acid less efficiently, and it means the folate is ready for the body to use straight away.
To be balanced: for most people, folic acid is effective and very well studied, and it remains the form used in official fortification and public-health programmes.2 The case for methylfolate is not that folic acid "does not work", but that the active form removes a step, which is reassuring for those who suspect their conversion is less efficient.
This is the same logic behind a methylated B complex, which pairs methylfolate with other active B vitamins.
How MTHFR links to B12, B6 and homocysteine
Folate does not work alone. Vitamins B12 and B6 work alongside it, and together folate, B6 and B12 contribute to normal homocysteine metabolism. This is why active-form supplements usually combine methylfolate with methylcobalamin (B12) and P5P (B6).
Homocysteine is a substance the body produces and then processes using folate, B6 and B12. Keeping that teamwork supplied is one reason these three nutrients are so often grouped together.3
Should you get tested for MTHFR?
MTHFR testing is a clinical decision, not something to act on alone. Health services do not routinely test for it in healthy people, and a result on its own does not tell you to start or stop any particular supplement. If you are considering testing, speak to your GP or a registered professional.
Direct-to-consumer genetic tests can report MTHFR status, but the result is easy to misread, and carrying a common variant is, as above, very common and usually not a cause for concern on its own.1
If you are pregnant or planning a pregnancy, folate is genuinely important, but the right approach is specific and should come from your GP or midwife. Please follow professional and NHS guidance rather than acting on a supplement label.4
Choosing a folate or B complex supplement
If you want the active form, look for "methylfolate" or "L-5-MTHF" named clearly on the label, rather than just "folic acid". In a B complex, it is ideally paired with active B12 (methylcobalamin) and active B6 (P5P), since these nutrients work together.
- Methylfolate (L-5-MTHF) named on the label, not just "folic acid" or "folate".
- Paired with methylcobalamin (B12) and P5P (B6), which work alongside folate.
- Sensible doses, shown as a percentage of your daily reference intake.
- A short, clearly labelled ingredient list.
Prime Vitality Methylated B Complex Ultra uses L-5-MTHF methylfolate alongside methylcobalamin and P5P, so the active forms are there together.
Frequently asked questions
What is MTHFR in simple terms?
MTHFR is a gene that tells your body how to make an enzyme of the same name. That enzyme helps turn folate and folic acid into methylfolate, the active form of vitamin B9 your body uses.
Is it bad to have an MTHFR variant?
No. MTHFR variants are very common and inheriting one is a normal part of human variation. On its own, carrying a variant is not a diagnosis or a medical problem. If you have specific concerns, speak to a healthcare professional.
What is the difference between folic acid and methylfolate?
Folic acid is a synthetic form that the body has to convert through several steps. Methylfolate (L-5-MTHF) is the active form the body uses directly, so it does not rely on that conversion.
Do I need a special supplement if I have an MTHFR variant?
Not necessarily. Many people simply choose folate in its active methylfolate form so the conversion step is not a factor. Whether you need anything specific is best discussed with a healthcare professional.
Should I get an MTHFR test?
MTHFR testing is a clinical decision. Health services do not routinely test healthy people, and a result on its own does not dictate any particular supplement. If you are considering it, speak to your GP, especially if you are pregnant or planning a pregnancy.
Is methylfolate safe to take daily?
Methylfolate is widely used as a daily supplement. Follow the directions on your chosen product and do not exceed the stated dose. If you are pregnant, breastfeeding, taking medication or managing a health condition, check with your doctor or pharmacist first.
