Why Pregnant Women with MTHFR Need Methylfolate, Not Folic Acid

If you have MTHFR and you're pregnant — or planning to be — the difference between folic acid and methylfolate is worth understanding properly.

Standard guidance recommends folate supplementation before and during pregnancy to reduce the risk of neural tube defects. That advice is well-founded: neural tube closure occurs in the first four weeks, often before a pregnancy is confirmed. For women with MTHFR variants, the form of folate is the part that gets overlooked.

Why folic acid is a poorer fit with MTHFR

Folic acid is the synthetic, oxidised form of vitamin B9. Before your body can use it, it must pass through several enzymatic steps, the last of which requires the MTHFR enzyme. In women with the C677T variant, that step is reported to run at reduced capacity. The result is that folic acid supplementation may not reliably deliver active folate. The mechanism is explained in more detail in active vs inactive B vitamins.

Unmetabolised folic acid

When conversion is slowed, unmetabolised folic acid (UMFA) can accumulate in the bloodstream. Research has examined possible effects on natural killer cell function and folate receptor pathways, though this remains an active area of study rather than settled science.

Methylfolate in pregnancy

Methylfolate (5-MTHF) bypasses the MTHFR step entirely — it is the form cells use directly. For women with MTHFR variants, it is generally regarded as the more appropriate form, but this is a decision to make with your GP or midwife, not independently.

Beyond folate

Folate alone is not the whole picture. Methylcobalamin B12 is the cofactor for the remethylation reaction that processes homocysteine, and P-5-P B6 supports the transsulphuration pathway. All three are supplied together across our methylated B vitamin range.

Related reading: MTHFR and recurrent miscarriage and postpartum methylation depletion.

NeuroThrive™ products are food supplements and are not intended to diagnose, treat, or cure any medical condition. Supplementation during pregnancy should always be discussed with your GP or midwife. NeuroThrive MTHFR Support is not a prenatal supplement and is not specifically formulated for pregnancy. Always seek professional guidance for pregnancy-specific nutritional needs.