Folate (methylfolate vs folic acid)
Summary
Supplements contain folic acid or methylfolate (5-MTHF). Periconceptional folic acid lowered neural tube defects by about 69% in Cochrane-reviewed trials (grade A). Methylfolate raised red-cell folate as well as or better than folic acid in two trials. US guidance still names 400 mcg/day folic acid for people who could become pregnant. The adult UL is 1,000 mcg.
Key facts
- Folic acid (synthetic; fortified foods and most supplements); 5-MTHF / methylfolate (the main active form)[1]
- ODS: 5-MTHF bioavailability is the same as or greater than folic acid. Trials: equimolar 5-MTHF raised red-cell folate more (n=144) or the same (n=104)[1][3][4]
- Neural tube defects with periconceptional folic acid ↓ (A); homocysteine ↓ (A); first stroke in adults with high blood pressure in China ↓ (B)[2][6][5]
- RDA 400 mcg DFE (600 pregnancy, 500 breastfeeding). UL 1,000 mcg/day of folic acid from supplements and fortified food[1]
- Methotrexate; antiepileptics (phenytoin, carbamazepine, valproate); sulfasalazine[1]
- 5 graded human outcomes on this page
- October 8, 2026
How it works
EstablishedFolate coenzymes carry one-carbon units for DNA and RNA synthesis and for converting homocysteine to methionine (established). Folic acid must be reduced to tetrahydrofolate and converted to 5-MTHF; people with the MTHFR 677C>T variant make 5-MTHF less efficiently (established).[1]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
At a glance: strongest evidence per outcome
| Outcome | Grade | Effect | Strongest evidence | Rows |
|---|---|---|---|---|
| Energy | Grade A | Worsened | Systematic review · n = 6,708 · 2015 | 3 rows |
| Heart | Grade A | Worsened | Meta-analysis · n = 2,596 · 2005 | 2 rows |
Every graded row
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Neural tube development in pregnancy (periconceptional folic acid) | Worsened | Grade A | Systematic review · n = 6,708 · 2015 5 trials; women with and without a previous pregnancy affected by a neural tube defect Form: folic acid, alone or with other vitamins and minerals · Dose: Daily folic acid (amount varied by trial) · Duration: Around conception Neural tube defects were lower with daily folic acid (RR 0.31; 95% CI 0.17 to 0.58; 6708 births), high-quality evidence. Recurrence was also lower (RR 0.34; 1846 births). | 26662928 (opens PubMed)Source [2] |
| Blood homocysteine by folic acid dose | Worsened | Grade A | Meta-analysis · n = 2,596 · 2005 25 randomized trials with individual participant data Form: folic acid (with or without B12 or B6) · Dose: 0.2, 0.4, 0.8, 2.0 and 5.0 mg/day · Duration: Varied across trials Homocysteine fell 13%, 20%, 23%, 23% and 25% across the doses; 0.8 mg/day or more was typically needed for the maximal effect. Added vitamin B12 lowered it a further 7%; B6 had no effect. | 16210710 (opens PubMed)Source [6] |
| First stroke in adults with high blood pressure (CSPPT) | Worsened | Grade B | RCT · n = 20,702 · 2015 Adults with hypertension and no history of stroke or heart attack in China Form: folic acid in a single pill with enalapril vs enalapril alone · Dose: 0.8 mg/day folic acid (with enalapril 10 mg) · Duration: Median 4.5 years First stroke occurred in 2.7% vs 3.4% (HR 0.79; 95% CI 0.68-0.93). Heart attack and all-cause death did not differ. | 25771069 (opens PubMed)Source [5] |
| Red blood cell folate: methylfolate vs folic acid | Improved | Grade C | RCT · n = 144 · 2006 Healthy women aged 19-33 Form: [6S]-5-MTHF vs folic acid vs placebo · Dose: 416 mcg/day 5-MTHF (equimolar to 400 mcg folic acid), 208 mcg/day 5-MTHF, or 400 mcg/day folic acid · Duration: 24 weeks Red blood cell folate rose significantly more with 416 mcg 5-MTHF than with 400 mcg folic acid or 208 mcg 5-MTHF. Plasma folate plateaued after 12 weeks. | 16825690 (opens PubMed)Source [3] |
| Blood folate: methylfolate vs folic acid at low doses | No effect | Grade C | RCT · n = 104 · 2002 Women of childbearing age (18-49) Form: [6S]-5-MTHF vs folic acid vs placebo · Dose: 113 mcg/day 5-MTHF or 100 mcg/day folic acid · Duration: 24 weeks Plasma and red-cell folate rose at similar rates with both forms (no significant difference in slopes). | 12421850 (opens PubMed)Source [4] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Folic acid | Varies[1] | About 85% bioavailable with food and nearly 100% without food, vs about 50% for food folate.[1] | High intakes can produce unmetabolized folic acid in blood; its health significance is not well understood.[1] | The neural tube, homocysteine and stroke trials |
| 5-MTHF (methylfolate, L-methylfolate) | Varies[1] | Same as or greater than folic acid (ODS). Equimolar 5-MTHF raised red-cell folate more than folic acid over 24 weeks (n=144); a lower-dose trial found no difference (n=104).[1][3][4] | No form-specific tolerance data in our sources.[1] | Blood folate status; ODS notes some people with the MTHFR 677C>T variant might benefit, though research is inconclusive |
Studied doses
Doses studied in human trials ranged from 100 mcg to 5 mg/day of folic acid, and 113 to 416 mcg/day of 5-MTHF, for 24 weeks to a median of 4.5 years. Amounts above 1,000 mcg/day of folic acid exceed the adult UL.[6][3][4][5][1]
Intake reference: Adult RDA: 400 mcg DFE/day; 600 mcg DFE in pregnancy and 500 mcg DFE while breastfeeding. CDC recommends 400 mcg/day folic acid for people who could become pregnant. Adult UL: 1,000 mcg/day of folic acid from supplements and fortified foods.[1] The UL applies to synthetic folic acid only, not food folate, and not to people under medical supervision. NIH ODS fact sheet (updated November 30, 2022).
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Medicines
- MethotrexateNIH fact sheetA folate antagonist. People using it for cancer should consult their oncologist first, as folate could interfere; folate might reduce GI side effects of low-dose methotrexate for rheumatoid arthritis or psoriasis.[1]
- Antiepileptic medicinesNIH fact sheetThese drugs can lower serum folate, and folate supplements might lower blood levels of the drugs.[1]
Medicines that can lower levels
- SulfasalazineNIH fact sheetInhibits folate absorption and can cause folate deficiency.[1]
Who should be careful
- Vitamin B12 status
- Large amounts of folate can correct the anemia but not the nerve damage of B12 deficiency, and may worsen B12-related anemia and cognitive symptoms. B12 status matters, especially for older adults.[1]
- High intakes
- Intakes above 1,000 mcg/day of folic acid exceed the UL. Concerns under study include unmetabolized folic acid, effects on precancerous lesions, and an association between 1,000 mcg/day or more around conception and lower child cognitive test scores.[1]
- Pregnancy planning
- CDC recommends 400 mcg/day folic acid, not 5-MTHF, for people who could become pregnant, including those with the MTHFR 677C>T variant.[1]
- Before you start
- Talk to your pharmacist or clinician before adding this supplement, especially if you take prescription medicines, are pregnant or breastfeeding, or have a chronic health condition.[1]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Articles about Folate (methylfolate vs folic acid)
Plain-English answers to common questions, built on the evidence above.
Frequently asked questions
Is methylfolate better than folic acid?
For raising blood folate, it is at least as good: ODS says 5-MTHF bioavailability is the same as or greater than folic acid, and one trial found more red-cell folate with equimolar 5-MTHF. But the birth-defect evidence comes from folic acid trials, and CDC recommends folic acid for people who could become pregnant.[1][3][2]
What about the MTHFR gene variant?
People with two copies of the 677C>T variant convert folate to 5-MTHF less efficiently. ODS says research is inconclusive and some might benefit from 5-MTHF, but CDC still recommends 400 mcg/day folic acid for pregnancy planning regardless of MTHFR status.[1]
What does mcg DFE on a label mean?
Dietary folate equivalents adjust for absorption: 1 mcg of folic acid taken with food counts as about 1.7 mcg DFE (1 mcg DFE = 0.6 mcg folic acid). So 400 mcg folic acid is listed as 680 mcg DFE.[1]
Can you get too much folic acid?
The adult UL is 1,000 mcg/day of folic acid from supplements and fortified foods. About 5% of men and women aged 51–70, and of men 71 and older, exceed it, mostly from supplements. High folate can hide the anemia of B12 deficiency.[1]
Does folic acid lower homocysteine?
Yes. In a meta-analysis of 25 trials, folic acid lowered homocysteine by 13–25% depending on dose, with most of the effect by 0.4–0.8 mg/day.[6]
Sources
- [1]Folate: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements, 2022. fact-sheet
- [2]Effects and safety of periconceptional oral folate supplementation for preventing birth defects.. Cochrane Database Syst Rev, 2015. systematic-review
- [3]Red blood cell folate concentrations increase more after supplementation with [6S]-5-methyltetrahydrofolate than with folic acid in women of childbearing age.. Am J Clin Nutr, 2006. RCT
- [4]Increases in blood folate indices are similar in women of childbearing age supplemented with [6S]-5-methyltetrahydrofolate and folic acid.. J Nutr, 2002. RCT
- [5]Efficacy of folic acid therapy in primary prevention of stroke among adults with hypertension in China: the CSPPT randomized clinical trial.. JAMA, 2015. RCT
- [6]Dose-dependent effects of folic acid on blood concentrations of homocysteine: a meta-analysis of the randomized trials.. Am J Clin Nutr, 2005. meta-analysis
What changed
- First draft. Every evidence-row PMID checked with NCBI E-utilities (esummary + efetch abstract) and re-read in an independent adversarial pass.