By Kirstie Vesseur, Registered Clinical Nutritionist (CNA), Legacy Nutrition, NZ and Australia.
If you're planning a pregnancy in New Zealand, your GP will probably hand you a script for funded folic acid. It's good advice: folate before conception is one of the most effective things you can do to prevent neural tube defects such as spina bifida. But if you've had an MTHFR gene result, or you've read that folic acid "doesn't work" for some women, you may be wondering which form to take.
Here's the honest answer, and why I usually recommend a good prenatal with methylfolate over folic acid on its own.
Folate, folic acid and methylfolate: what's the difference?
- Folate is the natural form found in leafy greens, legumes, avocado and liver.
- Folic acid is the synthetic form used in funded tablets and in fortified bread flour. Your body has to convert it, in several steps, into the active form.
- Methylfolate (L-5-MTHF, or "5-methyltetrahydrofolate") is the active form your cells actually use. It skips the conversion steps.
Where MTHFR comes in
The MTHFR enzyme performs the last step of that conversion. A common variant, C677T, slows it down:
- One copy (heterozygous, about 40% of people of European descent): the enzyme works at about 65% capacity.
- Two copies (homozygous, about 10 to 12%): about 30% capacity, and often higher homocysteine.
Methylfolate goes around this bottleneck. Folic acid also has to pass through a slow liver enzyme (DHFR) first. At higher doses, some of it circulates unconverted, as "unmetabolised folic acid", and we don't yet fully understand what that means long term. You can read more about the gene in my MTHFR and methylation guide.
So is folic acid bad?
No, and this matters. Folic acid is the form used in the trials that proved folate prevents neural tube defects, and it still raises folate levels in women with MTHFR variants. Taking folic acid is far better than taking nothing.
Methylfolate is well absorbed and raises blood folate at least as well as folic acid. It's the form I prefer, especially for women with MTHFR variants, high homocysteine, or a history of miscarriage. There just isn't a neural tube defect trial for it yet. That's why the choice of product matters.
Why a good prenatal beats folic acid on its own
The funded folic acid tablet is folate only. A well-formulated prenatal covers the other nutrients that matter before and during pregnancy:
- Iodine 150 mcg: essential for your baby's brain development. NZ soils are low in iodine, and the Ministry of Health recommends a supplement for every pregnant and breastfeeding woman.
- Active B12: folate and B12 work together. Low B12 is common in women who eat little red meat.
- B6, choline and zinc: needed for methylation and early development.
- Iron: Thorne Basic Prenatal contains 45 mg, so check ferritin and don't double up without advice. Many women start pregnancy with low ferritin. See my guide to iron deficiency in women.
- Vitamin D: many NZ women are low through winter.
What I recommend
- Start at least 3 months before trying, and keep going through the first 12 weeks at minimum. Most women stay on a prenatal throughout pregnancy and breastfeeding.
- My go-to: Thorne Basic Prenatal, 3 capsules a day. It gives 1 mg methylfolate, 150 mcg iodine, active B12, B6, iron and 1,000 IU vitamin D3. Take it with food to avoid nausea.
- If cost is a barrier: the funded options are a folic acid 0.8 mg tablet daily, plus a separate iodine 150 mcg tablet (NeuroTabs). Take these rather than nothing.
- Higher risk (you or your partner has a neural tube defect, a previous affected pregnancy, a family history, insulin-treated diabetes, or you take epilepsy medication): NZ guidance is high-dose folic acid, 5 mg on prescription. If you have a BMI over 30 or coeliac disease, ask your GP too, as some guidelines include these. Don't swap high-dose folic acid for methylfolate without medical advice.
- Eat your folate too: 2 cups of leafy greens a day, ½ cup legumes most days, plus avocado, asparagus and broccoli.
Should you test?
You don't need an MTHFR test to take methylfolate, and guidelines don't recommend the gene test to assess clotting or miscarriage risk. Blood tests are more useful. Ask your GP for B12, active B12, folate and homocysteine. They show how your body is actually handling folate, which matters more than the gene alone.
Getting ready for pregnancy?
Start with my free Fertility Fast Start: 7 things to do this month, plus a 30-day checklist. GROW is my 16-week preconception programme for you and your partner, covering nutrients, testing, meals and cycle tracking. Book a free 30 minute assessment to see if it's right for you, or get the Fertility and Preconception Blueprint.
Have heavy periods or adenomyosis as well? Read the adenomyosis diet. Struggling with mood before your period? Read PMDD: nutrition and supplements that help.
References
- MRC Vitamin Study Research Group. Prevention of neural tube defects: results of the Medical Research Council Vitamin Study. Lancet. 1991;338(8760):131-7.
- HealthEd. Folic acid and spina bifida, iodine and iodine deficiency (HE4147). Health New Zealand Te Whatu Ora.
- Healthify He Puna Waiora. NeuroTabs (iodine). healthify.nz.
- Hickey SE, et al. ACMG practice guideline: lack of evidence for MTHFR polymorphism testing. Genet Med. 2013;15(2):153-6.
- Crider KS, et al. MTHFR 677C→T genotype is associated with folate and homocysteine concentrations in a large, population-based, double-blind trial of folic acid supplementation. Am J Clin Nutr. 2011;93(6):1365-72.
- Obeid R, et al. Is 5-methyltetrahydrofolate an alternative to folic acid for the prevention of neural tube defects? J Perinat Med. 2013;41(5):469-83.
- Pietrzik K, et al. Folic acid and L-5-methyltetrahydrofolate: comparison of clinical pharmacokinetics and pharmacodynamics. Clin Pharmacokinet. 2010;49(8):535-48.
General education only, not medical advice. Talk to your GP or midwife about the right folate dose for you.
