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).
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.
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.
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.
Each reference below was re-fetched from its PubMed record, and the quoted sentence was confirmed to appear in that abstract and to support the claim it sits under. Follow any of them to read the source.
Exact-molecule evidence boundary: the live abstract reports the quoted finding for Vitamin B12; no broader inference is made.
Vitamin B-12 status was assessed on the basis of methylmalonic acid, total homocysteine (tHcy), and holotranscobalamin (holoTC) concentrations before and after 12 and 24 wk of treatment.
Evidence scope. Exact molecule wording appears in the quoted live sentence. Only the population/model, formulation, route, and outcome expressly stated there are supported.
Claims we could not support
No abstract we checked supports these for this molecule at this route. That is not the same as saying they are false — it marks where the evidence is missing.
Dose/route: 1000mcg; Intramuscular (IM) or Subcutaneous (SubQ); Weekly (loading) then monthly (maintenance). No selected live abstract sentence verified this complete regimen.
Mechanism as written in source JSON. No selected live abstract sentence verified the complete mechanism at the card formulation/route and relevant population/model.
Primary safety claim as written in source JSON. No selected live abstract sentence verified the complete safety claim for this exact formulation and route.
(cyanocobalamin); hydroxocobalamin has longer tissue retention
IM (cyanocobalamin); ~2-3 hours IM (hydroxocobalamin)
(cyanocobalamin); hydroxocobalamin retained longer in tissues
IM/SubQ; ~1-2% oral (requires intrinsic factor)
(cyanocobalamin); 2-3 months (hydroxocobalamin); tissue stores support monthly or less frequent dosing
Renal excretion (excess beyond binding capacity excreted unchanged in urine)
Storage. Store at controlled room temperature 15-30C (59-86F). Protect from light (B12 is light-sensitive, especially cyanocobalamin). Do not freeze.
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.
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