Rankings / Essentials — Vitamins & Minerals

Vitamin B12 (methylcobalamin / cyanocobalamin / hydroxocobalamin)

Essentials · Vitamin

Tier A+

Reviewed by Read Off Label · Last reviewed · How we grade

vitaminmethylationotc
8.4 / 10
Tier A+
Ev 8 Bn 8 Sf 9

Bottom line

Read Off Label grades Vitamin B12 (methylcobalamin / cyanocobalamin / hydroxocobalamin) as A+ (8.4/10) based on strong evidence, strong benefit magnitude, and a low-risk safety profile.

Deficiency is common and underdiagnosed: 10-30% of adults over 50 lose intrinsic factor or parietal cell function; metformin and PPIs accelerate it.

Studied, labeled, or reported-use context: 2. — OTC (oral / sublingual); Rx; not individualized guidance.

What the evidence says

Deficiency is common and underdiagnosed: 10-30% of adults over 50 lose intrinsic factor or parietal cell function; metformin and PPIs accelerate it. Methylmalonic acid (MMA) is more sensitive than serum B12 for tissue deficiency. Cyanocobalamin and methylcobalamin both work in non-deficient people; hydroxocobalamin is used clinically for B12 malabsorption.

Mechanism

Cofactor for methionine synthase (remethylates homocysteine to methionine — the source of methyl groups for DNA/histone/neurotransmitter methylation) and methylmalonyl-CoA mutase (odd-chain fatty acid and BCAA catabolism)

Studied, labeled, or reported dose & route

2.4 mcg/day RDA; 500-1000 mcg/day oral or sublingual methyl-/hydroxocobalamin typical; 1 mg IM monthly for malabsorption

This records doses and routes described in studies, approved labeling, clinical practice, or documented use. It is not individualized guidance and does not establish safety; context changes with indication, formulation, health history, monitoring, and other medicines.

Citations

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Common questions

What does the evidence show about Vitamin B12 (methylcobalamin / cyanocobalamin / hydroxocobalamin)'s effects?
Read Off Label rates the evidence for Vitamin B12 (methylcobalamin / cyanocobalamin / hydroxocobalamin) as Strong and the benefit magnitude as strong, producing an overall grade of A+ (8.4/10). Deficiency is common and underdiagnosed: 10-30% of adults over 50 lose intrinsic factor or parietal cell function; metformin and PPIs accelerate it.
What safety findings are reported for Vitamin B12 (methylcobalamin / cyanocobalamin / hydroxocobalamin)?
Vitamin B12 (methylcobalamin / cyanocobalamin / hydroxocobalamin) has a low risk profile in the database. Low (extremely well-tolerated; rare acneiform eruption with high-dose injection) Legal status: OTC (oral / sublingual); Rx (IM hydroxocobalamin for malabsorption).
What doses or routes are reported for Vitamin B12 (methylcobalamin / cyanocobalamin / hydroxocobalamin)?
2.4 mcg/day RDA; 500-1000 mcg/day oral or sublingual methyl-/hydroxocobalamin typical; 1 mg IM monthly for malabsorption This is context from studies, approved labeling, clinical practice, or documented use; it is not individualized guidance and does not establish safety.
How does Vitamin B12 (methylcobalamin / cyanocobalamin / hydroxocobalamin) work?
Cofactor for methionine synthase (remethylates homocysteine to methionine — the source of methyl groups for DNA/histone/neurotransmitter methylation) and methylmalonyl-CoA mutase (odd-chain fatty acid and BCAA catabolism)

This is an independent synthesis of published research by a non-clinician. Scores are opinions supported by citations, not prescriptions. See the full disclaimer and methodology for how this score was produced and what it does and doesn't mean.