Two folate supplements sit on the drugstore shelf.
One is labeled “Folic Acid.” The other is labeled “5-MTHF” or “Methylfolate.”
Both are called “folate.” Both are recommended in pregnancy and general nutrition. The prices can differ by several times over. Which one should be chosen, and on what basis?
To answer this question with precision, one must trace folate’s journey inside the body — and recognize that some people complete that journey, while others do not.
The three faces of folate
Although the word “folate” is used as a single term, the molecule actually comes in different forms.
Folic Acid ── Fully synthetic. Cheap and stable. The mainstream supplement form. Does not exist in nature. Folinic Acid ── Semi-natural form. Closer to body-active than Folic Acid. 5-MTHF (Methylfolate) ── The actually-used active form in the body. The closest to the natural form found in leafy greens and liver.
Ingesting Folic Acid does not mean it is used as-is. It must first be converted to 5-MTHF inside the body. The enzyme that performs this conversion is MTHFR (methylenetetrahydrofolate reductase).
The MTHFR polymorphism: roughly half of Japanese
The MTHFR enzyme has a common polymorphism that reduces its activity. The most studied is the C677T variant.
- CC genotype (no variant) ── Enzyme activity ~100%
- CT genotype (one variant) ── Enzyme activity ~65%
- TT genotype (both variants) ── Enzyme activity ~30%
In studies of Japanese populations:
- CC ~ 30%
- CT ~ 50%
- TT ~ 15% (varies by region, 10–20%)
In other words, roughly 65–70% of Japanese have below-average efficiency in converting Folic Acid to 5-MTHF. For TT-genotype carriers, no matter how much Folic Acid is consumed, only about one-third arrives as active form.
This is the central point when choosing a supplement.
Why it ripples through the entire body
When 5-MTHF is insufficient, what happens? Saying “the folate cycle slows” is true at one level, but more precisely, methylation reactions across the whole body become impaired.
5-MTHF is the carrier of methyl groups (-CH₃). These methyl groups are used in:
- DNA methylation ── Regulation of gene expression
- Neurotransmitter synthesis ── Serotonin, dopamine, norepinephrine all require methylation steps
- Homocysteine recycling ── The reaction that converts homocysteine (a cardiovascular risk marker) back to harmless methionine
- Detoxification ── Hepatic methylation reactions
- Creatine synthesis ── Muscle energy
- Phospholipid synthesis ── Cell membrane maintenance
When 5-MTHF runs low, all of these slow down slightly. “Vaguely tired,” “low mood,” “cardiovascular concerns” — the diffuse complaints sometimes hide a methylation slowdown.
Homocysteine — the visible marker
In precision nutrition, blood homocysteine is treated as the indicator for “is methylation running?”
- Clinical reference: < 15 µmol/L
- Precision nutrition ideal: < 7 µmol/L
When homocysteine is elevated, supplementation with folate (as 5-MTHF), vitamin B12 (methylcobalamin), and vitamin B6 (P5P) is recommended — these are the cofactors for the homocysteine-to-methionine reaction.
For those with blood homocysteine above 10 µmol/L, suspecting MTHFR polymorphism and switching to active folate (5-MTHF) often produces meaningful drops within 3–6 months.
How to read the supplement label
When buying folate at the drugstore, scan the ingredient list for these keywords:
✅ 5-MTHF or 5-Methyltetrahydrofolate ✅ Quatrefolic (a well-known branded 5-MTHF) ✅ L-Methylfolate Calcium
❌ Folic Acid (synthetic, less suitable for MTHFR carriers) ❌ Just “folate” or “葉酸” alone (often Folic Acid)
The active form is typically 2–3× more expensive. But for those with MTHFR variants, paying twice for something that delivers makes more economic sense than paying once for something that barely converts.
Leafy vegetables (spinach, broccoli, asparagus) provide folate already close to its 5-MTHF form. Eating it is best. Supplements should be considered backup for what diet doesn’t cover.
Not “does it work” — “does it arrive”
Health-supplement discussion is often framed as “does it work or not.” But in precision nutrition, an earlier question matters.
“Has it actually reached your cells in its active form?”
For Folic Acid, MTHFR carriers can’t convert it in time. For B12, absorption differs between methylcobalamin and cyanocobalamin. For magnesium, bioavailability varies dramatically between oxide and glycinate forms.
The real criterion when choosing a supplement is not “does it work” but “does it arrive.”
To live cleanly and beautifully is, perhaps, to choose with one more layer of care what is sent into your own body.
This article is for informational purposes and is not medical advice. Consult a physician or registered dietitian for supplement selection and dosing. Pregnant individuals should consult an obstetrician about folate intake.