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Moderate evidenceVitamins & minerals

Methylcobalamin

The methylated coenzyme form of vitamin B12. It corrects B12 deficiency reliably, but the common claim that it is better absorbed or better used than cheap cyanocobalamin is not supported by evidence.

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What the science says

  • Oral B12 corrects deficiency Moderate evidence

    A Cochrane review of 3 randomized trials (153 people) found oral B12 around 1000 µg/day normalised serum B12 as well as intramuscular injection, at lower cost. Evidence quality was rated low, mainly because the trials were small and short.

  • Not shown to beat cyanocobalamin Moderate evidence

    A review of cobalamin metabolism concluded that the coenzyme forms (methyl- and adenosylcobalamin) are unlikely to be superior to cyano- or hydroxocobalamin for preventing or treating deficiency, because all absorbed B12 is processed and re-converted inside cells regardless of the form swallowed.

  • Diabetic nerve symptoms Limited evidence

    A 2026 meta-analysis of 13 randomized trials (834 patients) found B vitamins improved some neuropathy screening scores and sural nerve conduction in diabetic peripheral neuropathy, but had no significant effect on pain, with high heterogeneity and mixed risk of bias.

Dosage & safety

Studied dose500–1000 µg/day orally for maintenance; 1000–2000 µg/day when correcting a deficiency. Sublingual and swallowed tablets perform similarly.
SafetyVery well tolerated with no established upper limit; excess is excreted. The important caveat is diagnostic: self-treating anemia or neurological symptoms with B12 can delay finding the cause (pernicious anemia, malabsorption). Metformin and long-term proton-pump inhibitors lower B12 and are common reasons for a genuine deficiency.

How to take it

TimingTiming does not matter, though some people find B12 mildly activating and prefer mornings.
With food?With or without food.
Worth knowingSublingual tablets are not better absorbed than swallowed ones — there is no reason to pay more for them.

Interactions

With medications

  • metformin

    Long-term metformin lowers B12 absorption and is a common cause of genuine deficiency. have B12 checked periodically rather than assuming a supplement covers it

  • proton-pump inhibitors and H2 blockers

    Reduced stomach acid impairs release of B12 from food, lowering levels over years. have B12 checked if you take them long term

With other supplements

  • high-dose folic acid or folate

    Folate can correct the anemia of B12 deficiency while nerve damage continues unnoticed. check B12 status before taking high-dose folate

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

Frequently asked questions

Is methylcobalamin better than cyanocobalamin?

No: a review of B12 metabolism concluded methylcobalamin is unlikely to beat cyanocobalamin for preventing or treating deficiency, because all absorbed B12 is re-converted inside cells whatever form you swallow. The evidence grade for that conclusion is moderate.

Can oral methylcobalamin replace B12 injections?

A Cochrane review of 3 trials found oral B12 around 1000 mcg/day normalised blood B12 as well as injections, at lower cost, though the trials were small. Methylcobalamin corrects deficiency reliably like other forms.

How much methylcobalamin should I take per day?

Methylcobalamin is typically taken at 500–1000 mcg/day for maintenance and 1000–2000 mcg/day when correcting a deficiency. Sublingual tablets are not better absorbed than swallowed ones.

Does methylcobalamin help diabetic neuropathy?

The evidence is limited: a 2026 meta-analysis of 13 trials found B vitamins improved some neuropathy scores and nerve conduction but had no significant effect on pain. If you take metformin, which lowers B12, have your B12 checked periodically.

Scientific references

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