Methylcobalamin vs Cyanocobalamin: Which Vitamin B12 Is Better?
Last updated: August 2026 · Reviewed by the FactoWiki Editorial Team for clarity and source accuracy
For most people it makes little practical difference. Cyanocobalamin is more stable, cheaper and is what the large trials used. Methylcobalamin is a form the body uses directly and is retained somewhat better. Both raise B12 status effectively.
Key takeaways
- Cyanocobalamin is stable, cheap and well-evidenced.
- Methylcobalamin is retained slightly better; the clinical difference is small.
- The cyanide in cyanocobalamin is trivial except in specific rare situations.
What separates them
Cyanocobalamin is synthetic and contains a cyanide molecule, which the body removes and excretes. The amount is minute and irrelevant for almost everyone. Methylcobalamin and adenosylcobalamin are the two forms the body actually uses; supplementing methylcobalamin skips a conversion step and studies suggest slightly better tissue retention.
Why cyanocobalamin remains standard
It is more chemically stable, cheaper, and it is the form used in most of the research establishing B12 supplementation works. The conversion the body performs is not a bottleneck in ordinary circumstances. For general repletion, it does the job.
Where methylcobalamin may be preferable
People with impaired kidney function, since cyanide clearance is reduced, and smokers who already carry a higher cyanide load. Some people with MTHFR variants prefer methylated forms, though the evidence that this changes B12 outcomes specifically is thin. Hydroxocobalamin is the form typically used for injections in the UK.
Key ingredients to understand
The ingredients most relevant to this question, with what the evidence actually supports:
- Vitamin B12 — Vitamin B12 is an essential nutrient for healthy nerves, red blood cells and energy metabolism. Deficiency is a well-recognised and treatable…
- Folate — Folate (vitamin B9) is an essential vitamin best known for preventing neural-tube birth defects and for lowering homocysteine. Supplements…
- Folic Acid — Folic acid is the synthetic form of folate, and in pregnancy it is one of the most clearly proven supplements in existence — it prevents neural…
- Iron — Iron is an essential mineral the body uses to carry oxygen in the blood. Supplements clearly help when you are iron-deficient — improving anemia…
Frequently asked questions
Which should I buy?
Cyanocobalamin unless cost is irrelevant to you or you have kidney impairment or smoke. Both work.
What dose?
Maintenance for vegans is often 25–100 mcg daily or 1,000 mcg weekly. Correcting a deficiency uses more, under medical guidance.
Is sublingual better?
Trials comparing sublingual with oral generally find them equivalent. Oral is fine.
Related on FactoWiki
- All health answers
- Ingredient evidence guides
- Vitamin B12 — ingredient guide
- Folate — ingredient guide
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