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Moderate evidenceVitamins & minerals

Methylated B-Complex

B-complex using 5-MTHF and methylcobalamin instead of folic acid and cyanocobalamin. The active forms do raise folate status effectively, but the popular claim that MTHFR carriers need them is not supported by outcome trials.

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What the science says

  • Active folate raises folate status as well as folic acid Moderate evidence

    A systematic review and meta-analysis in women of childbearing age found the active form of folate improved folate biochemical parameters comparably to folic acid, with less unmetabolised folic acid in circulation. Comparative trials confirm both forms raise serum and red cell folate.

  • No proven clinical advantage for MTHFR variants Limited evidence

    Direct comparisons show differences in folate species in blood after supplementation, but no randomized trial has shown better health outcomes from methylfolate in people carrying MTHFR C677T. The genotype-based recommendation runs ahead of the evidence.

  • B vitamins and cognition Limited evidence

    A systematic review and meta-analysis of B vitamin supplementation in older adults found no reliable improvement in global cognitive function despite lowered homocysteine. Lowering a marker is not the same as protecting the brain.

Dosage & safety

Studied doseTypical products supply 400–800 µg of (6S)-5-methyltetrahydrofolate and 500–1,000 µg of methylcobalamin, with B6 usually 1.3–25 mg. Pregnancy folate requirements are met by 400–800 µg/day of either form.
SafetyHigh-dose B6 above roughly 50 mg/day taken long term can cause peripheral neuropathy. Folate in any form can mask B12 deficiency anaemia while nerve damage progresses, so check B12 first. Some people report irritability or insomnia with methylated forms; B vitamins also interact with methotrexate, levodopa and some anticonvulsants.

How to take it

TimingTake it in the morning — some people find B vitamins, especially the methylated forms, disturb sleep if taken late.
With food?Take it with food, which reduces the nausea B vitamins can cause on an empty stomach.
Worth knowingHave B12 checked before starting: folate at these doses corrects the anaemia of B12 deficiency while the nerve damage quietly continues.

Interactions

With medications

  • methotrexate

    Methotrexate works by blocking folate metabolism, and supplemental folate can reduce its effect at oncology doses. Do not add folate without your oncologist's or rheumatologist's instruction

  • levodopa taken without carbidopa

    B6 speeds the breakdown of levodopa before it reaches the brain, reducing its effect. Do not take high-dose B6 with plain levodopa; modern carbidopa combinations are far less affected

  • phenytoin and some other anticonvulsants

    Folate and phenytoin lower each other's blood levels, which can reduce seizure control. Do not start folate supplements without drug-level monitoring

  • metformin and long-term proton pump inhibitors

    Both deplete B12 over time — a reason to check levels rather than a reason to avoid the supplement. Ask for a B12 level rather than guessing

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Do I need methylfolate if I have an MTHFR mutation?

No randomized trial has shown better health outcomes from methylfolate in people carrying MTHFR C677T, so the genotype-based recommendation for a methylated B-complex runs ahead of the evidence (limited). Active folate and folic acid both raise serum and red cell folate.

Is methylfolate better than folic acid?

A meta-analysis found active folate (5-MTHF) improved folate status comparably to folic acid, with less unmetabolised folic acid in circulation (moderate evidence). In pregnancy, 400–800 mcg/day of either form meets folate requirements.

Does a methylated B-complex improve memory?

A meta-analysis of B vitamin supplementation in older adults found no reliable improvement in global cognitive function despite lower homocysteine. Lowering a marker is not the same as protecting the brain, so the evidence for a methylated B-complex and memory is limited.

What are the side effects of a methylated B-complex?

Long-term B6 above roughly 50 mg/day can cause peripheral neuropathy, and folate in any form can mask B12 deficiency anaemia while nerve damage progresses, so check B12 first. Some people report irritability or insomnia with methylated forms, so take it in the morning with food.

Scientific references

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