Methylfolate (5-MTHF)
The active form of folate your body actually uses. Essential for energy, mood, DNA repair, and keeping homocysteine low — especially important if you have MTHFR gene variants.
Methylfolate is the bioactive form of vitamin B9 — the form your cells actually use for methylation, DNA synthesis, and neurotransmitter production. Unlike folic acid (the cheap synthetic form), methylfolate doesn't need to be converted by the MTHFR enzyme, making it the smarter choice for the 40–60% of people with MTHFR gene variants.
Good for you if: You have MTHFR gene variants, elevated homocysteine, are planning pregnancy, experience brain fog or low mood, or want to support your methylation cycle alongside B12.
Dive deeper into the researchCommon side effects
- Overstimulation or anxiety if starting at too high a dose (start low)
- Insomnia — best taken in the morning, not at night
- Mild headache or irritability during the first few days
What does methylfolate do?
Methylfolate is your body's methyl donor — it provides the methyl groups needed for hundreds of chemical reactions. The three most important ones:
- Recycles homocysteine — Methylfolate donates a methyl group (via B12) to convert homocysteine back to methionine. High homocysteine is a cardiovascular and cognitive risk factor.
- Makes neurotransmitters — The methylation reactions powered by folate are essential for producing serotonin, dopamine, and norepinephrine. This is why folate deficiency is linked to depression.
- Builds and repairs DNA — Every cell division requires folate for DNA synthesis. This is why it's critical during pregnancy and for general cellular repair.
What can you expect?
- More energy — improved methylation means better cellular energy production, especially if you were deficient
- Better mood — many people notice reduced brain fog and improved emotional resilience within 2–4 weeks
- Lower homocysteine — typically drops 20–30% within 4–8 weeks when paired with B12
- Healthier pregnancy outcomes — adequate folate dramatically reduces neural tube defect risk
Some people with MTHFR variants feel a noticeable difference switching from folic acid to methylfolate. Others don't notice much — the benefit may be happening in your labs rather than your energy levels.
How to take it
400–800 mcg methylfolate daily with breakfast — take it in the morning since it can be mildly stimulating. Pair with methylcobalamin (B12) for the methylation cycle to work properly.
If you have MTHFR C677T homozygous: start at 400 mcg and titrate up to 1,000–5,000 mcg based on homocysteine levels and how you feel. For pregnancy: 800–1,000 mcg is standard.
Some people — especially those with MTHFR variants who have been undermethylating for years — can feel overstimulated or anxious when they start methylfolate. Begin with 400 mcg and increase gradually over 1–2 weeks.
Which form to buy?
L-Methylfolate (5-MTHF) — branded as Quatrefolic or Metafolin — is the preferred form. It's the biologically active isomer and doesn't require any conversion. This is what you want.
Folic acid is the synthetic form found in cheap multivitamins and fortified foods. It has to be converted through multiple steps including the MTHFR enzyme. If you have MTHFR variants, this conversion is impaired, and unmetabolised folic acid accumulates in your blood.
Folinic acid (5-formyl-THF) is another active form that bypasses MTHFR. Some practitioners combine it with methylfolate for broader coverage.
Want to see if methylfolate is actually working for you?
eterni tracks your homocysteine and folate levels before and after — so you know your methylation cycle is running properly.
Get early accessFrequently Asked Questions
What's the difference between folic acid and methylfolate?
Folic acid is the synthetic form of folate found in cheap supplements and fortified foods. Your body has to convert it through several steps — including one that depends on the MTHFR enzyme — before it can use it. Methylfolate (5-MTHF) is the already-active form that your body uses directly. If you have MTHFR gene variants (about 40–60% of Indians do), you convert folic acid poorly, and methylfolate bypasses this problem entirely.
How do I know if I have an MTHFR variant?
You can find out through genetic testing — services like 23andMe, Mapmygenome, or a targeted MTHFR panel ordered by your doctor. The two main variants are C677T and A1298C. Having one copy (heterozygous) reduces MTHFR activity by about 35%. Having two copies of C677T (homozygous) reduces it by 70%. If you have elevated homocysteine without an obvious cause, MTHFR variants are worth checking.
Can I take methylfolate without knowing my MTHFR status?
Yes — methylfolate works for everyone, regardless of MTHFR status. It's the form your body actually uses. Taking methylfolate instead of folic acid is a sensible default choice. If you do have MTHFR variants, it's essential. If you don't, it still works just as well as folic acid.
Does methylfolate help with depression?
There's clinical evidence for this. Methylfolate at 15 mg/day has been shown to improve response to antidepressants (SSRIs/SNRIs) in people who weren't responding well to medication alone. It's thought to work by supporting the methylation reactions needed to produce serotonin, dopamine, and norepinephrine. It's not a standalone treatment for depression, but it can be a meaningful adjunct.
How it works in your body
Methylfolate (5-MTHF) is the primary circulating form of folate in blood. It enters cells and donates its methyl group to vitamin B12 (cobalamin), which then passes it to homocysteine via methionine synthase, converting homocysteine to methionine. Methionine is then converted to S-adenosylmethionine (SAMe), the body's universal methyl donor.
SAMe methylates over 200 substrates including DNA (gene regulation), neurotransmitters (mood), phospholipids (cell membranes), creatine, and proteins. After donating its methyl group, SAMe becomes S-adenosylhomocysteine, then homocysteine — completing the cycle. Without adequate methylfolate, this cycle stalls, homocysteine accumulates, and downstream methylation reactions fail.
The MTHFR enzyme converts dihydrofolate to 5-MTHF in the final activation step. The C677T variant reduces enzyme activity by 35% (heterozygous) to 70% (homozygous), making direct supplementation with 5-MTHF the logical workaround.
What the studies show
- MTHFR prevalence: The C677T variant is found in 40–60% of South Asian populations. Homozygosity (TT) occurs in 10–15%, significantly impairing folate metabolism.
- Homocysteine: Methylfolate (0.4–5 mg/day) + B12 reduces homocysteine by 20–35% in 4–12 weeks, with greater effects in those with MTHFR variants or baseline deficiency
- Depression adjunct: L-methylfolate at 15 mg/day improved SSRI response in treatment-resistant depression patients (Papakostas et al., multiple RCTs). FDA-approved as medical food (Deplin) in the US.
- Pregnancy: Adequate folate reduces neural tube defect risk by 70%+ — and methylfolate may be more effective than folic acid in women with MTHFR variants
- Unmetabolised folic acid (UMFA): High folic acid intake without adequate MTHFR activity leads to UMFA accumulation, which has been associated with impaired immune function in some studies
Side effects & safety
Methylfolate is generally well-tolerated, but some people experience side effects — especially when starting:
- Overstimulation/anxiety — the most common complaint, especially in people with MTHFR variants who start at high doses. Start at 400 mcg and titrate up.
- Insomnia — methylfolate can be mildly stimulating. Take it in the morning.
- Irritability or mood swings — can occur in the first week as methylation ramps up. Usually self-resolving.
- Headache — mild and transient in some people
- Nausea — rare, and usually from taking on an empty stomach
Who should be careful: People on anti-seizure medications (folate can reduce their effectiveness). Anyone with bipolar disorder should consult their psychiatrist before supplementing, as methylfolate may trigger hypomania in susceptible individuals.
Which labs to check
- Serum folate — optimal above 20 ng/mL. Below 6 ng/mL is deficient.
- RBC folate — a better long-term marker than serum folate. Reflects folate status over the previous 3–4 months.
- Homocysteine — should be below 10 µmol/L. The key functional marker. If elevated, check folate, B12, and B6.
- MTHFR genotyping — one-time genetic test to check for C677T and A1298C variants
- Methylmalonic acid (MMA) — to rule out concurrent B12 deficiency (folate alone won't fix B12 problems)
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