VitaminWell-studiedVitamin

Vitamin B12 (Methylcobalamin)

Also known as Vitamin B12

Half-life

~6 days

What is Vitamin B12 (Methylcobalamin)?

Active form of B12. Critical for nerve function, DNA synthesis, and red blood cell formation.

How Vitamin B12 (Methylcobalamin) works

Coenzyme for methionine synthase (methylation cycle) and methylmalonyl-CoA mutase (fatty acid metabolism). Methylcobalamin is the neurologically active form, directly supporting myelin synthesis.

Benefits & uses

Energy/reduces fatigue
Red blood cell production
Nerve health
Cognitive support

Common uses: Energy, nerve health, methylation support, homocysteine reduction.

Cognitive

Vitamin B12 (Methylcobalamin) dosage

Typical dose: General: 500–1000 mcg/day sublingually or oral. Deficiency repletion: 1000 mcg/day. Injection: 1 mg weekly.

Vitamin B12 (Methylcobalamin) half-life

~6 days (plasma); stored in liver for years

Vitamin B12 (Methylcobalamin) side effects

Very safe. Excess excreted. Sublingual or injection may be needed if oral absorption is poor.

Essentially non-toxic — water-soluble and excreted
High doses may rarely cause acne-like eruptions
Injection site reactions (IM route)
Very well tolerated (water-soluble, low toxicity)

Commonly stacked with

Vitamin B9 (Folate)Vitamin B6 (P5P)

Track Vitamin B12 (Methylcobalamin) in Protokol.

Log doses, model half-lives, check interactions, and line it all up against your bloodwork. Free on iPhone and Android.