Methylfolate

What methylfolate is

Folate is a B vitamin that the body needs to make DNA and to modify proteins. Folic acid is the synthetic form found in tablets and fortified foods; it has to be converted in several steps into the active form 5-methyltetrahydrofolate. Methylfolate supplies this form directly.

In the EU, calcium L-methylfolate and a glucosamine salt are authorized as methylfolate sources for dietary supplements. The BfR summarizes the studies as follows: the bioavailability of calcium L-methylfolate is comparable to that of folic acid, but it feeds directly into folate metabolism and leads to higher folate concentrations in red blood cells. For higher amounts, the EFSA therefore converts methylfolate into folate equivalents with a factor of 2, folic acid with 1.7.

How it is supposed to work

Methylfolate supplies the methyl group with which homocysteine is turned back into methionine, and so keeps the methionine cycle going. Through this metabolic pathway, folate is linked to the production of messenger substances in the brain. This is where the idea of using methylfolate for depression comes from, especially when folate metabolism is impaired.

The first part of the chain is well measured in humans. In a study with 167 healthy adults, 113 µg methylfolate daily over 24 weeks lowered homocysteine by 14.6 percent compared with placebo, the equimolar amount of folic acid by 9.3 percent. Plasma and red blood cell folate rose comparably in both groups.

The MTHFR question

The enzyme MTHFR produces 5-methyltetrahydrofolate in the body. The most common gene variant is called C677T, and it is so widespread that, according to the CDC, more people in the US carry one or two copies of it than none. A common piece of advice is that carriers should avoid folic acid and take only methylfolate.

The CDC explicitly contradicts this: people with an MTHFR variant can process all forms of folate, including folic acid. At the same folic acid intake, the blood folate level in the TT variant is on average only about 16 percent lower than in the CC variant, and intake determines the blood level more strongly than the genotype. The American professional society for medical genetics, ACMG, considers the MTHFR test to be of little clinical use in thrombosis work-ups. Methylfolate is therefore a good option for carriers, but not a necessary one.

Experience reports from practice

In an observational study from the US, 554 people with depression rated their experience after about 3 months on 7.5 or 15 mg methylfolate, mostly in addition to an antidepressant. The score on the PHQ-9 self-test fell by a mean of 8.5 points; 67.9 percent responded, 45.7 percent reached remission. There was no comparison group, and the study was funded by the manufacturer of the product used. This is an experience report on a large scale, not proof of efficacy.

In 2026, an integrative family practice retrospectively analyzed 50 patients with anxiety or depression who received personalized nutrient treatment, partly with methylfolate. 72 percent improved clinically, regardless of MTHFR genotype. Here too, a control group is lacking.

What the studies show

Papakostas 2012, the key trials

Two multicenter, double-blind trials with a sequential parallel-group design over 60 days in people whose depression did not respond adequately to an SSRI. In the first trial, with 148 patients and 7.5 mg in the first 30 days, there was no difference from placebo. In the second, with 75 patients and 15 mg throughout, methylfolate was superior in response rate and symptom reduction; the number needed to treat was about 6. Side effects did not occur more often than with placebo.

Maruf 2022, the meta-analysis

Systematic review of 9 papers with a total of 6,707 patients, only a small proportion of whom were included in the meta-analyses. Response rate on the Hamilton scale: risk ratio 1.25 across 3 studies with 483 patients. Symptom improvement: standardized mean difference minus 0.38 across 4 studies with 507 patients. The authors speak of possibly modest efficacy.

Venn 2003, homocysteine

Randomized, placebo-controlled trial over 24 weeks with 167 healthy adults who received 100 µg folic acid, 113 µg methylfolate or placebo. Homocysteine fell by 14.6 percent with methylfolate and by 9.3 percent with folic acid, so methylfolate was significantly stronger. The increases in folate levels did not differ.

Where the data stop

For the prevention of neural tube defects, folic acid is the tested form: the Cochrane review found a risk ratio of 0.31 across 5 studies with 6,708 births. For methylfolate, this protection has not yet been demonstrated in studies; the CDC names folic acid as the only form with a proven protective effect. The BfR nevertheless explicitly recommends 400 µg folic acid or an equivalent amount of other authorized folate sources for prevention. In depression, the finding rests on few studies, the first of the two key trials was negative, and the positive trial used 15 mg. That MTHFR carriers benefit particularly rests mainly on a post hoc analysis with 75 patients, which the authors themselves describe as needing confirmation. Comparative data demonstrating better tolerability than folic acid cannot be found in the reviews analyzed.

Status, approval and legal

Methylfolate is authorized in the EU as a folate source for dietary supplements. For dietary supplements, the BfR proposes a maximum amount of 200 µg folic acid or an equivalent amount of other folate sources per daily dose, and explicitly recommends 400 µg folic acid or an equivalent amount of methylfolate daily for women who may become pregnant and for pregnant women in the first trimester. In the US, methylfolate in the depression doses is sold as a prescription-only medical food.

Safety

In 2023, the EFSA confirmed the tolerable upper intake level for adults, including pregnant and breastfeeding women, at 1,000 µg per day, and it explicitly applies to folic acid and methylfolate combined. The critical point is an undetected vitamin B12 deficiency: high amounts of folate can mask the anemia of a B12 deficiency while the nerve damage progresses. The earlier assessment based this on a folic acid intake of 5 mg per day or more. Whether methylfolate has this effect to the same extent is theoretically disputed; the EFSA applies the upper limit anyway. The depression doses of 7.5 to 15 mg are far above it; in the controlled 60-day trials, side effects did not occur more often than with placebo, and long-term data on such amounts are lacking. Anyone taking high doses should know their B12 status and have this supervised by a physician.

Sources

• Maruf et al., Pharmacopsychiatry 2022
• Papakostas et al., Am J Psychiatry 2012
• Sarris et al., World J Biol Psychiatry 2022 (WFSBP/CANMAT)
• Venn et al., Am J Clin Nutr 2003
• CDC, MTHFR Gene Variant and Folic Acid Facts, 2026
• De-Regil et al., Cochrane Database Syst Rev 2015
• EFSA NDA Panel, EFSA Journal 2023 (upper limit for folate)
• BfR, proposed maximum levels for folic acid, 2024 update
• Shelton et al., Prim Care Companion CNS Disord 2013
• Xie et al., Medicine (Baltimore) 2025