Unmetabolised Folic Acid: The Hidden Risk in Your Prenatal Vitamin
You’ve been told folic acid is essential for a healthy pregnancy. But did you know that high levels of unmetabolised folic acid (UMFA) have been detected in nearly every pregnant woman studied in Australia?
Mandatory folic acid fortification – meaning every slice of bread, breakfast cereal, and vitamin tablet fortified with folic acid might be contributing to a buildup of unmetabolised folic acid in your system and routine use of prenatal supplements means many women are exceeding the upper limit of 1000 mcg of folic acid daily. This could actually impair the very thing folate is supposed to support—healthy pregnancy.
Too much folic acid can:
Suppress MTHFR enzyme activity
Reduce 5-MTHF levels (the active, protective form)
Increase homocysteine, a known risk factor for infertility and miscarriage
Alter egg and sperm DNA methylation—a process essential for embryo development and pregnancy outcomes
Increased risk of cancer, autism, and birth defects in some studies
It’s especially problematic for women with MTHFR polymorphisms, but research now shows even those without the gene variant are not immune. Excess folic acid still disrupts methylation and contributes to fertility issues.
Perhaps most concerning is its association with pseudo-MTHFR deficiency in animal studies. This means even if you don’t have the gene variant, UMFA may still impair the methylation process—affecting sperm and egg quality, pregnancy outcomes, and even long-term health of your child.
UMFA is a sign your body isn’t coping with synthetic folic acid. Switching to 5-MTHF allows your body to bypass the metabolic bottleneck and get straight to work supporting healthy DNA, methylation, and foetal development.
If you’re preparing for pregnancy, here’s what to look for in a prenatal: ✅ 5-MTHF instead of folic acid
✅ Active B12 (methylcobalamin or hydroxocobalamin)
✅ Chelated or glycinate iron and magnesium for better absorption
✅ Choline to support neural development
✅ Iodine and selenium for thyroid and egg health
And what to avoid: ❌ Folic acid (especially 400 mcg+ if you have MTHFR or fertility concerns)
❌ Cyanocobalamin (a cheap form of B12)
❌ Generic “multis” not designed for preconception/pregnancy
The right prenatal supports:
DNA methylation
Egg and sperm quality
Early foetal development
Your mood, energy and hormone balance
Some prenatal formulas I love include
Ever Natal
Naturobest Multi for Women
Much Love,
Megan
