Form Comparison

Cyanocobalamin vs Methylcobalamin

How cyanocobalamin and methylcobalamin differ in potency, absorption, tolerance, and cost.

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Quick verdict. Both use the same absorption pathways, and cells strip the attached group and rebuild both active cofactors, so dose matters more than form. Cyanocobalamin is cheaper, more stable, and the form in most deficiency trials; its cyanide content is toxicologically trivial. Choose methylcobalamin if you prefer a cyanide-free form, smoke heavily, or have advanced kidney disease, where cyanide clearance is slower; MTHFR variants are a folate issue and do not require methyl B12.

Side by Side

Cyanocobalamin Methylcobalamin
Absorption High High
How it is absorbed Bound by intrinsic factor and absorbed in the terminal ileum; this route saturates at about 1.5-2 mcg per dose. About 1% of a large oral dose also crosses by passive diffusion, which is why 1,000 mcg oral doses work even without intrinsic factor. Same intrinsic factor and passive diffusion pathways as cyanocobalamin. Cofactor for methionine synthase in the cytosol.
Typical dose 25-1,000 mcg daily; 1,000-2,000 mcg for malabsorption 500-1,000 mcg daily
Common uses general supplementation, deficiency treatment, fortified foods general supplementation, neuropathy (limited evidence)
Side effects Very well tolerated. The cyanide content is toxicologically trivial. Very well tolerated.
Cost Low Moderate
Also called vitamin B12 methyl B12, mecobalamin
Labels in index 871 848

When to Choose Cyanocobalamin

Choose cyanocobalamin when you want the most studied, stable, and cheapest form. Synthetic and the most stable form. Converted in cells to methylcobalamin and adenosylcobalamin. Most clinical trials used it.

Cyanocobalamin

The best-studied oral form and the one used in the trials of high-dose oral therapy. Stable and inexpensive.

What to look for: 1,000 mcg tablets for malabsorption or treatment; 25-100 mcg daily for vegans with normal absorption.

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When to Choose Methylcobalamin

Choose methylcobalamin when you prefer a cyanide-free active form and accept a modest premium. Less stable to light. Cells strip the methyl group on uptake and rebuild both active cofactors, so the form taken matters less than the dose.

Methylcobalamin

Fine, but not superior. Cells rebuild the active cofactors regardless of the starting form.

What to look for: Light-protective packaging and the same microgram dose you would use for cyanocobalamin.

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Products on Titrate

In Titrate's index of NIH label data, 871 labels named as vitamin B12 products list cyanocobalamin and 848 list methylcobalamin.

Open supplement search

Supplement Search loads one category at a time. Choose the B-Complex tab, then type a form such as "cyanocobalamin" under Must contain, or a form to avoid under Must not contain.

Related

References

NIH Office of Dietary Supplements. Vitamin B12: Fact Sheet for Health Professionals.

Berlin H, Berlin R, Brante G. Oral treatment of pernicious anemia with high doses of vitamin B12 without intrinsic factor. Acta Med Scand. 1968;184(4):247-258.

Stabler SP. Vitamin B12 deficiency. N Engl J Med. 2013;368(2):149-160.

Lam JR, et al. Proton pump inhibitor and histamine 2 receptor antagonist use and vitamin B12 deficiency. JAMA. 2013;310(22):2435-2442.

Aroda VR, et al. Long-term Metformin Use and Vitamin B12 Deficiency in the Diabetes Prevention Program Outcomes Study. J Clin Endocrinol Metab. 2016;101(4):1754-1761.

Wang H, et al. Oral vitamin B12 versus intramuscular vitamin B12 for vitamin B12 deficiency. Cochrane Database Syst Rev. 2018;3(3):CD004655.