library.onepin.app/vitamin-b12 Peptide Education Library
Education only, not medical advice 21+ Every dose is an example to finalize with a licensed provider

OnePin Peptide Library · Metabolic

Metabolic Peptide Prescription drug

Vitamin B12

B12 · Cobalamin · Cyanocobalamin · Hydroxocobalamin

Vitamin B12 (cobalamin) is an essential water-soluble vitamin that plays critical roles in DNA synthesis, red blood cell formation, neurological function, and methylation reactions throughout the body. It is the largest and most structurally complex vitamin, containing a cobalt ion at its center. The two biologically active forms are methylcobalamin (a cofactor for methionine synthase) and adenosylcobalamin (a cofactor for methylmalonyl-CoA mutase).,Injectable B12 is available as cyanocobalamin (the most common and stable synthetic form), hydroxocobalamin (longer-acting, used as first-line in many countries), and methylcobalamin (the bioactive form preferred by some practitioners). Injectable administration bypasses the complex gastrointestinal absorption pathway that requires intrinsic factor, making it essential for patients with pernicious anemia, gastrointestinal malabsorption, or after gastric surgery.,Vitamin B12 injection is FDA-approved for the treatment of B12 deficiency and pernicious anemia. Deficiency can cause megaloblastic anemia, peripheral neuropathy, subacute combined degeneration of the spinal cord, cognitive impairment, and fatigue. Groups at risk include vegans, elderly individuals with atrophic gastritis, patients on metformin or proton pump inhibitors, and those with Crohn's disease or celiac disease.

Quick Start
Route
Intramuscular (IM) or Subcutaneous (SubQ)
Start low
1000mcg
Frequency
Weekly (loading) then monthly (maintenance)
Timing
No specific requirement

IM injection. Weekly. Any time of day.

Start here. Every protocol below is ordered lowest-first. Begin at the smallest effective dose, hold about a week to assess tolerance, and step up only if needed.

Tiered Protocols · lowest first
Quick Start
Conservative start
1000mcg · Intramuscular (IM) or Subcutaneous (SubQ) · Weekly (loading) then monthly (maintenance)
Lowest starting point. Hold about a week to assess tolerance before stepping up.
1000mcg
Weekly (loading) then monthly (maintenance)
Standard
Cyanocobalamin / General Injection
1000 mcg · IM · Weekly
human study · Vidal-Alaball et al. 2005 (Cochrane Database Syst Rev)
1000 mcg
Weekly
Reconstitution CalculatorU-100
050100u
Draw to
units
01

How it works

As methylcobalamin, serves as a cofactor for methionine synthase, which converts homocysteine to methionine. This reaction is essential for DNA methylation, neurotransmitter synthesis, and myelin maintenance. Deficiency leads to elevated homocysteine and impaired methylation.,As adenosylcobalamin (5-deoxyadenosylcobalamin), serves as a cofactor for methylmalonyl-CoA mutase in mitochondria, converting methylmalonyl-CoA to succinyl-CoA in the propionate metabolism pathway. Deficiency causes accumulation of methylmalonic acid (MMA), which is toxic to neurons.,Essential for normal erythropoiesis - B12 deficiency impairs DNA synthesis in rapidly dividing cells (especially red blood cell precursors), producing characteristic large, immature megaloblasts that are ineffective oxygen carriers.

As methylcobalamin, serves as a cofactor for methionine synthase, which converts homocysteine to methionine. This reaction is essential for DNA methylation, neurotransmitter synthesis, and myelin maintenance. Deficiency leads to elevated homocysteine and impaired methylation.,As adenosylcobalamin (5-deoxyadenosylcobalamin), serves as a cofactor for methylmalonyl-CoA mutase in mitochondria, converting methylmalonyl-CoA to succinyl-CoA in the propionate metabolism pathway. Deficiency causes accumulation of methylmalonic acid (MMA), which is toxic to neurons.,Essential for normal erythropoiesis - B12 deficiency impairs DNA synthesis in rapidly dividing cells (especially red blood cell precursors), producing characteristic large, immature megaloblasts that are ineffective oxygen carriers.

02

What to expect

Early
Days 1–7

Days 1-7: Energy improvement in deficient patients. Reticulocyte response begins by day 2-3 and peaks at days 5-8. A sense of well-being often reported within 24-48 hours.

03

Evidence

HumanStrong
AnimalPresent
In-vitroPresent
2006Effect of oral vitamin B-12 with or without folic acid on cognitive function in older people with mild vitamin B-12 deficiency: a randomized, placebo-controlled trial · Eussen SJ, de Groot LC, Joosten LW, et al, American Journal of Clinical Nutrition ↗peer reviewed
2021Effects of Vitamin B12 Supplementation on Cognitive Function, Depressive Symptoms, and Fatigue: A Systematic Review, Meta-Analysis, and Meta-Regression · Markun S, Gravestock I, Jager-Ripoll E, et al, Nutrients ↗review
2024A comprehensive review and meta-regression analysis of randomized controlled trials examining the impact of vitamin B12 supplementation on homocysteine levels · Liu R, Zhao Z, Du W, et al, Nutrition Reviews ↗review
2002Randomized trial of methylcobalamin and folate effects on homocysteine in hemodialysis patients · Koyama K, Usami T, Takeuchi O, et al, Journal of the American Society of Nephrology ↗peer reviewed
04

Interactions & stacking

What's safe to combine, and what belongs in a separate pin.

Keep separate

ALLDo not mix in same syringe - B12 solutions can interact with other compounds.
05

Pharmacokinetics

Illustrative plasma concentration · 24 h
Half-life
~6 days (cyanocobalamin); hydroxocobalamin has longer tissue retention
Peak · Tmax
~1 hour IM (cyanocobalamin); ~2-3 hours IM (hydroxocobalamin)
Elimination
~30 days (cyanocobalamin); hydroxocobalamin retained longer in tissues
Activity
2-4 weeks (cyanocobalamin); 2-3 months (hydroxocobalamin); tissue stores support monthly or less frequent dosing

Storage. Store at controlled room temperature 15-30C (59-86F). Protect from light (B12 is light-sensitive, especially cyanocobalamin). Do not freeze.

06

Regulatory status

FDA-approved for treatment of vitamin B12 deficiency and pernicious anemia. Available by prescription (injection) or OTC (oral supplements). All injectable forms are prescription medications.

Put it to work

Calculate, log & track

Open Vitamin B12 straight into OnePin with your vial and dose pre-filled, then let it handle the syringe math and remind you before the vial runs out.

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Go deeper

The guide & community

The complete Vitamin B12 walkthrough, real protocol discussion and coaching live inside the BlessUp community on Skool.

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