Vitamin B12 (Methylcobalamin)
Also known as: methyl B12, mecobalamin, MeCbl, methylcobalamine
Methylcobalamin is one of the two coenzyme forms of vitamin B12 that the body uses directly, in this case for the methionine synthase reaction that recycles homocysteine and supports methylation. It is the preferred B12 in methylation, energy, nerve-support, and sublingual products and is marketed as not requiring the cyanide-removal step that cyanocobalamin does. Bioavailability reviews find the forms broadly comparable as B12 sources, so form choice is mostly about positioning and stability. No UL exists.
Research summary
Cofactor for methionine synthase, transferring a methyl group from 5-MTHF to homocysteine; interconverted in cells with adenosylcobalamin.
Dosage
Daily amounts, of compound.
| Lowest studied | Typical range | Highest studied | Upper limit |
|---|---|---|---|
| 2 mcg | 100–1,000 mcg | 2,000 mcg | — |
Doses are mcg methylcobalamin. RDA 2.4 mcg; DV 2.4 mcg; no UL. Oral B12 trials at 1,000 to 2,000 mcg/day in deficient patients (mostly cyanocobalamin) are the basis for high-dose oral use, and the same range is standard for methylcobalamin products; a 6-month randomized trial used methylcobalamin with methylfolate and P5P in adults with elevated homocysteine. Sublingual lozenges are common but the passive absorption route works with swallowed tablets too. Light-sensitive; store protected.
Standardization: ≥98% methylcobalamin or 1% trituration
Source material: semi-synthetic from fermentation-derived cobalamin
As supplied: Typically a 1% trituration on a carrier (0.1 mg powder per mcg); neat material for mg-level lozenges
Forms of Vitamin B12
| Form | Typical dose | Element % | Formats | Price |
|---|---|---|---|---|
| Vitamin B12 (Methylcobalamin) | 100–1,000 mcg | — | Capsule, Tablet, Powder, Liquid, Gummy | mid |
| Vitamin B12 (Cyanocobalamin) | 100–1,000 mcg | — | Capsule, Tablet, Powder, Gummy, Liquid, Softgel | low |
| Vitamin B12 (Adenosylcobalamin) | 100–1,000 mcg | — | Capsule, Tablet, Powder, Liquid | high |
Format suitability
- Capsule
- Powder
- Tablet
- Softgel
- Gummy
- Liquid
Light-sensitive and less stable than cyanocobalamin in liquids and gummies; use opaque packaging and overage. Popular in sublingual tablets.
Formulation notes
Pairs with L-5-MTHF and P5P in methylation formulas. Metformin and acid suppressants lower B12 status.
Sources
- Vitamin B12 — Health Professional Fact SheetNIH ODS
- Comparative Bioavailability and Utilization of Particular Forms of B(12) Supplements With Potential to Mitigate B(12)-related Genetic Polymorphisms. (Paul C, 2017)PubMed
- Oral vitamin B12 versus intramuscular vitamin B12 for vitamin B12 deficiency: a systematic review of randomized controlled trials. (Butler CC, 2006)PubMed
Related ingredients
Vitamin B12 (Cyanocobalamin)
VitaminCyanocobalamin is the synthetic, highly stable form of vitamin B12 used in most supplements and fortified foods.
Typical: 100–1,000 mcg
Folic Acid
VitaminFolic acid is the fully oxidized, synthetic form of folate used in food fortification and most supplements.
Typical: 400–800 mcg
Vitamin B6 (Pyridoxine HCl)
VitaminPyridoxine hydrochloride is the standard, inexpensive, and highly stable form of vitamin B6 used in nearly all multivitamins and B-complex products.
Typical: 1.7–50 mg
L-5-Methyltetrahydrofolate (L-5-MTHF)
VitaminL-5-methyltetrahydrofolate is the main circulating form of folate and the form cells use directly for homocysteine remethylation, so it bypasses the MTHFR enzyme step that is less active in people carrying the common 677C>T variant.
Typical: 400–1,000 mcg
Thiamin HCl (Vitamin B1)
VitaminThiamin hydrochloride is one of the two standard water-soluble salts of vitamin B1 used in supplements (the other is the mononitrate).
Typical: 1.5–100 mg