Folate

Folate is vitamin B9. Your body uses it to build DNA, divide cells, make red blood cells and convert homocysteine into methionine.^[1] It works closely with vitamin B12 in this last step. When folate is low, that conversion stalls and homocysteine builds up.

If you have heard you should take folate for fertility, pregnancy planning, low energy or low mood, this page covers the forms that work best, how much you need and what the research actually shows.

Forms of folate

The folate you get from food is a natural mix of polyglutamate forms. Your gut absorbs about 50% of it.^[1]

Supplements use one of two main forms.

Folic acid is the synthetic, fully oxidised form added to most multivitamins, fortified flour and most prenatals. Bioavailability is high, around 85% with food and close to 100% on an empty stomach.^[1] Your body has to convert folic acid to the active form, 5-methyltetrahydrofolate (5-MTHF), through an enzyme called MTHFR. About one in ten women of European descent carries two copies of an MTHFR variant that significantly slows this conversion. A larger fraction carries one copy.^[1]

5-MTHF (also written L-methylfolate or methylfolate) is folate already in the active form. Your body uses it directly, regardless of MTHFR status. Bioavailability is at least equal to folic acid and avoids the build-up of unconverted folic acid in the bloodstream that some studies have flagged as a concern.^[1]

How much you need

The European Food Safety Authority recommends 330 µg of dietary folate equivalents per day for adult women. Pregnancy and breastfeeding raise that need to 600 µg and 500 µg respectively. Women planning to conceive are usually advised to take 400 µg of folic acid or 5-MTHF daily for at least one month before conception and through the first trimester.^[2]

Many women fall short on intake. In the United States around 17% of women aged 19 to 30 do not meet folate requirements from food, with wider gaps in some groups.^[1] Heavy alcohol use, methotrexate, sulfasalazine and some antiepileptic medications all reduce folate levels or absorption.^[1]

The science on women's health

Fertility and conception

Folate's strongest evidence base is in preventing neural tube defects, which is why public health guidance has recommended preconception supplementation for decades. The role in fertility itself is harder to pin down. A 2021 Cochrane review of preconception lifestyle advice for people with infertility found low-quality evidence overall, with no clear difference in adequate folic acid use between intervention and control groups.^[3] A Mendelian randomisation study published the same year found that genetic variants raising homocysteine, the same pathway 5-MTHF feeds, were associated with lower offspring birthweight.^[4] The signal is mechanistic, not yet a proven dose-response in healthy women.

Energy and mood

A 2021 systematic review of folate in psychiatric disorders concluded that 5-methylfolate used as an add-on to standard treatment improved outcomes in major depressive disorder, including postpartum and post-menopausal depression, with minimal side effects.^[5] A 2025 systematic review focused specifically on micronutrients in postpartum depression rated the folate evidence as insufficient, citing methodological inconsistency between studies.^[6] Both reviews flagged the same gap. Women's mental health research is under-powered.

The biology is consistent. Folate is required to make serotonin, dopamine and noradrenaline. When folate or B12 is low, that synthesis slows. Whether supplementing changes how you feel depends on where you started.

EU authorised health claims

Under EU law, folate is officially authorised to carry the following health claims:

• Folate contributes to maternal tissue growth during pregnancy
• Folate contributes to normal amino acid synthesis
• Folate contributes to normal blood formation
• Folate contributes to normal homocysteine metabolism
• Folate contributes to normal psychological function
• Folate contributes to the normal function of the immune system
• Folate contributes to the reduction of tiredness and fatigue
• Folate has a role in the process of cell division^[2]

References

[1] National Institutes of Health, Office of Dietary Supplements. Folate: Fact Sheet for Health Professionals. ods.od.nih.gov/factsheets/Folate-HealthProfessional

[2] Commission Regulation (EU) No 432/2012 establishing a list of permitted health claims made on foods. Official Journal of the European Union, 25 May 2012. eur-lex.europa.eu

[3] Boedt T, Vanhove AC, Vercoe MA, et al. Preconception lifestyle advice for people with infertility. Cochrane Database of Systematic Reviews 2021;4:CD008189. doi.org/10.1002/14651858.CD008189.pub3

[4] Kjaergaard AD, Wu Y, Ming WK, et al. Homocysteine and female fertility, pregnancy loss and offspring birthweight: a two-sample Mendelian randomization study. European Journal of Clinical Nutrition 2022;76(1):40-47. doi.org/10.1038/s41430-021-00898-2

[5] Lam NSK, Long XX, Li X, et al. The potential use of folate and its derivatives in treating psychiatric disorders: a systematic review. Biomedicine & Pharmacotherapy 2022;146:112541. doi.org/10.1016/j.biopha.2021.112541

[6] Voros C, Sapantzoglou I, Athanasiou D, et al. Invisible links: associations between micronutrient deficiencies and postpartum depression. Life (Basel) 2025;15(10):1566. doi.org/10.3390/life15101566