Evidence explainerFolate (methylfolate vs folic acid)

Methylfolate vs Folic Acid: What the MTHFR Gene Hype Gets Wrong

If you have heard you "can’t process folic acid," you are not alone. Methylfolate raises blood folate at least as well, but the birth-defect evidence, and the official advice, rests on folic acid.

By Kymata Health editorial teamPublished October 9, 2026Last reviewed October 9, 2026

Medical review pending. Written by our editorial team from the studies cited below; a credentialed clinician has not reviewed it yet. Educational only, not medical advice.

Key takeaways

  • NIH says methylfolate (5-MTHF) bioavailability is the same as or greater than folic acid [1].
  • In a 24-week trial of 144 women, equimolar 5-MTHF raised red-cell folate more than folic acid; a lower-dose trial of 104 women found no difference [2][3].
  • The birth-defect evidence comes from folic acid: periconceptional folic acid lowered neural tube defects (RR 0.31) in a Cochrane review [4].
  • CDC recommends 400 mcg/day of folic acid for anyone who could become pregnant, including people with the MTHFR 677C>T variant [1].

The evidence, graded

Pulled from our monograph evidence tables. Grades follow our evidence-grading policy.

Two forms of the same vitamin

Folic acid is the synthetic form in fortified foods and most supplements; 5-MTHF (methylfolate) is the main active form in the body [1]. Folic acid is about 85% bioavailable with food and nearly 100% without, compared with about 50% for natural food folate [1].

What MTHFR actually means

People with two copies of the MTHFR 677C>T variant convert folate to 5-MTHF less efficiently [1]. NIH describes the research as inconclusive and says some people might benefit from 5-MTHF, but CDC still recommends 400 mcg/day of folic acid for pregnancy planning regardless of MTHFR status [1].

The head-to-head trials

In a 2006 double-blind trial, 144 healthy women aged 19 to 33 took 416 mcg of 5-MTHF, 208 mcg of 5-MTHF, 400 mcg of folic acid or placebo for 24 weeks [2]. Red-cell folate rose significantly more with 416 mcg of 5-MTHF than with folic acid [2]. In a 2002 trial at much lower doses (113 mcg vs 100 mcg), 104 women saw blood folate rise at similar rates with both forms [3].

Both measured blood folate, a marker, not birth outcomes [2][3].

Why folic acid is still the official advice for pregnancy

The outcome evidence is for folic acid. In the Cochrane review of 5 trials, daily folic acid around conception lowered neural tube defects (RR 0.31, high-quality evidence) and their recurrence [4]. That is why CDC names folic acid specifically [1].

Reading the label

Labels list mcg DFE (dietary folate equivalents). 400 mcg of folic acid is listed as 680 mcg DFE [1]. The adult upper limit is 1,000 mcg/day of folic acid from supplements and fortified foods [1]. Too much has its own problems, especially for older adults; see folic acid and B12 after 50. Full details on the folate monograph.

Keep reading

Full monographs

Related articles

Browse the full Supplement & Nutrient Encyclopedia or all supplement articles.

References

  1. [1]Folate: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements, 2022.
  2. [2]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. PMID 16825690
  3. [3]Increases in blood folate indices are similar in women of childbearing age supplemented with [6S]-5-methyltetrahydrofolate and folic acid. J Nutr, 2002. PMID 12421850
  4. [4]Effects and safety of periconceptional oral folate supplementation for preventing birth defects. Cochrane Database Syst Rev, 2015. PMID 26662928

Folate (methylfolate vs folic acid) and other dietary supplements are not intended to diagnose, treat, cure or prevent any disease, and these statements have not been evaluated by the FDA. Talk to your clinician or pharmacist before starting a supplement, especially if you take prescription medicines. This page has no product or affiliate links.

Keep reading: Supplements and vitamins

Supplements and vitamins: every page →Supplement & Nutrient Encyclopedia →Browse all topics →

Previous in this topicMethylcobalamin vs Cyanocobalamin: Is the “Active” B12 Worth Paying More For?Premium B12 bottles say methylcobalamin and warn about the "cyanide" in cyanocobalamin.Next in this topicMK-7 vs MK-4: The Two Kinds of Vitamin K2, and Why Their Doses Differ a ThousandfoldOne K2 label says 100 mcg, another says 45 mg.NAC and Glutathione: What GlyNAC Trials Actually MeasuredNAC is sold as a glutathione builder, and GlyNAC pairs it with glycine.Nicotinamide Riboside Benefits: Higher NAD+, One Walking Result, No Metabolic GainsNicotinamide riboside (NR) clearly raises NAD+ in people.Potassium and Blood Pressure: What the Trials Found, and the Doses They UsedMost trials find that extra potassium lowers blood pressure by a few points, most in people with high readings.

Evidence-graded supplement stacks →