B12
Cobalamin (methyl/hydroxo)
B12 (Cobalamin (methyl/hydroxo)) is a longevity & bioregulators research compound. Essential cofactor for methylation, red-cell formation and nerve myelination.
B12 quick facts
| Reported research dose (Injectable) | 500mcg-1000mcg |
| Route | Either |
| Frequency | 2-4x Weekly |
| Half-life | Long (stored) |
| Forms | Injectable, Oral |
| Evidence level | Human (established) |
| Other forms available | Oral — dosed differently |
Injectable bypasses absorption issues — energy floor for a lot of people, especially methylated.
How B12 works
Essential cofactor for methylation, red-cell formation and nerve myelination.
Proposed benefits
Researched for mitochondrial and cellular-energy support, tissue-specific bioregulation and healthy-aging pathways.
Where to get B12
B12 is sold in 2 forms. They are not interchangeable — the dose and the route differ, so pick the one this page describes unless you know why you want another.
Bacteriostatic water is the diluent — sterile water with 0.9% benzyl alcohol, which is what lets a vial be drawn from more than once. It does not come with the vial, and unlike the compound it is bought again every time.
Need bacteriostatic water? Get it at AminoWell USA (my company) → Code CAMERON.
The evidence for B12
Graded by what exists behind each claim.
✅ Clinically validated
- Unambiguous, approval-grade evidence in deficiency. Injectable B12 is standard treatment for pernicious anemia and B12 deficiency, and untreated deficiency causes irreversible neurological damage — subacute combined degeneration of the spinal cord.
- In people who are not deficient, trials are consistently negative for energy, cognition and mood. Large trials of B-vitamin supplementation for cardiovascular prevention lowered homocysteine and did not reduce events.
- Both halves are true at once, and which one applies to you is a blood test rather than a guess.
📊 Correlative data
- Enormous use, much of it in people with normal levels. Deficiency is genuinely common in specific groups — vegans, older adults, anyone on long-term metformin or a proton pump inhibitor, and post-bariatric-surgery patients.
- Serum B12 is an imperfect test. Methylmalonic acid and homocysteine detect functional deficiency that a normal serum level can hide, which is why low-normal results with symptoms deserve a second look.
🧪 Theoretical / extrapolated
- A cofactor for exactly two human enzymes: methionine synthase (recycling homocysteine to methionine, which feeds every methylation reaction in the body) and methylmalonyl-CoA mutase in fatty acid metabolism.
- Being a cofactor is why more is not better. The enzymes run at capacity once saturated; excess is excreted. That is the mechanistic reason the deficiency evidence is overwhelming and the enhancement evidence is absent.
- Folate supplementation can mask B12 deficiency's anemia while the neurological damage continues — the single most important interaction in this entry.
How to read these tiers: they say how much human evidence exists, not how well something works — and ✗ flags harm, never a disappointing trial. How the evidence tiers work →
What B12 actually does
Cobalamin is a cofactor for exactly two enzymes in human biology. Two. Every symptom, every marker and every dosing argument traces back to one of them, and stating them is the fastest way to make sense of a vitamin that is usually described in vague terms.
Enzyme one: methionine synthase, in the cytosol, using methylcobalamin. It takes a methyl group from 5-methyltetrahydrofolate and puts it on homocysteine, producing methionine and regenerating tetrahydrofolate. Two consequences follow immediately. Homocysteine rises when this reaction stalls — but it rises whether the missing piece is B12 or folate, so homocysteine alone cannot tell you which. And folate gets trapped as the methyl form and becomes unavailable for DNA synthesis, which is the “methyl folate trap” and the reason B12 deficiency produces a megaloblastic anemia identical to folate deficiency Esposito 2022.
Enzyme two: methylmalonyl-CoA mutase, in the mitochondrion, using adenosylcobalamin. It converts methylmalonyl-CoA to succinyl-CoA, the step that lets odd-chain fatty acids and several amino acids enter the citric acid cycle. Stall it and methylmalonic acid accumulates. Folate has nothing to do with this reaction, which is why MMA is the specific marker and homocysteine is the sensitive one. Ordering both is not redundancy; it is how you tell the two deficiencies apart.
And the transport fact that explains why the usual blood test is nearly useless. Circulating B12 is carried on two proteins. Transcobalamin carries roughly 10–30% of it and is the only fraction cells can take up through the CD320 receptor. Haptocorrin carries the rest and delivers to essentially nothing — it is metabolically inert. A standard serum B12 measures both and therefore reports mostly the fraction that cannot be used. That is why functional deficiency with a normal serum B12 is common, and it is the single most important thing this page can tell a reader Murphy 2021 Wolffenbuttel 2023.
Cell, rodent, human — and where it stops
Step one, the biochemistry and the clinical syndrome, which are not in dispute Wolffenbuttel 2023 Esposito 2022.
Step two, the diagnostic question, in humans. The clinical utility of serum total B12 against holotranscobalamin — the transcobalamin-bound, deliverable fraction — has been assessed by clinical indication in a real-world laboratory population Murphy 2021. The practical upshot is that the two tests answer different questions, and which one to order depends on why you are asking.
Step three, the route question, and the answer is not the one the injectable market implies. A systematic review and network meta-analysis of 13 studies and 4,275 patients compared routes for correcting deficiency. The intramuscular route ranked first for raising B12 levels (mean difference 94.09 pg/mL against oral), with sublingual second (43.31 pg/mL) — but these differences did not reach statistical significance, and the authors concluded all routes can effectively raise the level Abdelwahab 2024. The injection ranked first and did not beat the tablet. The reason is that roughly 1% of any oral dose is absorbed by passive diffusion, entirely independent of intrinsic factor — so 1,000 mcg by mouth delivers about 10 mcg regardless of whether the intrinsic-factor pathway works, and daily requirement is a few micrograms.
Step four, the effect question in people who are NOT deficient, and this is where the page has to be honest. A systematic review, meta-analysis and meta-regression of 16 randomized controlled trials and 6,276 participants found no evidence for an effect of B12 alone or of B-complex supplementation on cognitive function subdomains, and no overall benefit for depressive symptoms in patients without advanced neurological disorders Markun 2021. The energy and mood benefits people report are, in randomized aggregate, not there in people who were not short to begin with. The obstacle to reading that as “B12 does nothing” is real and worth naming: those trials largely enrolled people who were not deficient, and correcting a deficiency and supplementing a sufficiency are different interventions. Which is exactly why the measurement matters more than the dose.
B12 pharmacokinetics — how much of it actually gets in
The card says “long (stored)”. That is true and it obscures a two-compartment system with wildly different time constants.
The storage compartment. The liver holds on the order of 2–5 mg of cobalamin against a daily requirement of a few micrograms, which is why dietary deficiency takes years to become symptomatic and why the deficiency that presents acutely is almost always an absorption failure rather than an intake failure. Enterohepatic recirculation of biliary B12 is part of that stability — and it is also why an absorption defect drains the store faster than a dietary shortfall does, because the recycled fraction is lost too.
The plasma compartment, which is where a large injection goes. Transcobalamin and haptocorrin binding capacity is finite and small. A 1,000 mcg injection saturates it immediately, so the great majority of that dose is filtered and lost in urine within a day — renal clearance of unbound cobalamin is the dominant fate of a large parenteral dose. The retained fraction is roughly 10%. Which reframes the 2–4x weekly schedule: it is not maintaining a level, it is repeatedly overfilling a small bucket and paying for what runs over.
The oral barrier, and the loophole that makes tablets work. Dietary B12 must be released from protein by gastric acid and pepsin, bound by haptocorrin, released again by pancreatic proteases, bound by intrinsic factor from parietal cells, and absorbed by cubilin receptors in the terminal ileum. That pathway is saturable at about 1.5–2 mcg per dose and is the one that fails in pernicious anemia, after gastric surgery, and on long-term acid suppression or metformin Esposito 2022. The loophole is passive diffusion, which absorbs about 1% of any dose and does not need intrinsic factor at all — and that 1% is what makes high-dose oral therapy work even in pernicious anemia Abdelwahab 2024.
The injectable comparator, quantified. Injection ranked first by 94.09 pg/mL and the difference was not statistically significant Abdelwahab 2024. So the injection buys certainty of delivery and adherence, not a different biochemical destination. The form matters more than the route: cyanocobalamin is a synthetic, stable form carrying a cyanide moiety that has to be removed intracellularly, while hydroxocobalamin binds plasma proteins more avidly and is retained substantially better per injection Temova Rakusa 2022 — which is why European practice uses hydroxocobalamin every two to three months where American practice uses cyanocobalamin monthly.
What would have to be true, and how you would know it was not
Three predictions. The first is the test almost nobody orders; the third argues against the reason most people buy this.
1. Methylmalonic acid is the marker that answers the question, and it should fall if there was ever a real deficit. Order methylmalonic acid (MMA) with homocysteine and folate at baseline, before the first injection. MMA rises only with B12 deficiency; homocysteine rises with either B12 or folate. Prediction: a raised MMA falls into range within weeks of adequate repletion by any route, and a normal MMA at baseline means the injections have nothing to correct. The order matters — once repletion starts, both markers normalize and the question becomes unanswerable for months.
2. Serum vitamin B12 will go very high and it will mean nothing. Order vitamin B12 alongside the pair above. Prediction: after a course of injections it runs far above the reference range, because the assay measures haptocorrin-bound and unbound cobalamin as well as the deliverable transcobalamin fraction Murphy 2021. A high B12 on treatment is a measurement of the injection, not of the person. That is why holotranscobalamin exists, and why a raised serum B12 in someone NOT supplementing is worth a conversation rather than reassurance.
3. The prediction that cuts against it: fatigue and mood will not track the dose in a person who was not deficient. Sixteen randomized trials and 6,276 participants found no effect on cognitive subdomains and no overall benefit for depressive symptoms Markun 2021. The falsifiable, personal version: score energy and mood daily for two weeks before starting, continue through eight weeks, then stop injections for four weeks while continuing to score. Prediction: in someone whose baseline MMA and holotranscobalamin were normal, the scores will not track the injections. If they do, that is a real personal finding and the baseline markers say it was not a cobalamin deficit.
What nobody has tested yet
Four things nobody has settled about one of the most-injected molecules in the world.
Nobody has run a randomized trial of B12 injections in people with normal serum B12 and RAISED methylmalonic acid. That is precisely the group in which the biochemistry says a functional deficit exists and the standard test says it does not Murphy 2021. Every negative supplementation trial Markun 2021 enrolled by serum B12, which is the wrong screen. The trial that would justify or end the whole injectable wellness market has not been done.
Nobody has compared hydroxocobalamin against cyanocobalamin head to head on a functional endpoint. The retention difference is a formulation fact Temova Rakusa 2022. Whether it produces different MMA normalization or different symptom outcomes at matched dosing intervals has not been tested, and it determines the correct dosing frequency for the injectable form.
Nobody has established the frequency at which the injection stops being wasted. Roughly 90% of a 1,000 mcg parenteral dose is excreted. Whether a smaller, more frequent dose retains more total cobalamin than a large infrequent one is an ordinary pharmacokinetic question, it would change practice for millions of people, and no published study answers it.
Nobody has quantified the metformin and acid-suppression effect prospectively in supplement users. Both impair the intrinsic-factor pathway Esposito 2022, and both are extremely common in exactly the population the Vault serves. Since high-dose oral works through passive diffusion Abdelwahab 2024, the mechanistic prediction is that oral supplementation should be sufficient even on metformin — and that has not been demonstrated with functional markers.
B12 — its own safety story, not its class's
B12 is close to non-toxic, which is exactly why the risks worth naming here are diagnostic rather than pharmacological.
The real hazard is masking, and it is a mechanism. B12 and folate both correct the megaloblastic anemia, because both restore methionine synthase output and free trapped folate. Only B12 corrects the neurological damage, because the mutase reaction and the myelin consequences depend on adenosylcobalamin. So giving folate to someone with an unrecognized B12 deficiency fixes the blood count — the thing that would have prompted investigation — while the subacute combined degeneration of the spinal cord continues Esposito 2022. That is why the order of testing matters more here than the dose, and it is the strongest argument on this page for measuring before supplementing.
A raised serum B12 in someone who is NOT supplementing is a finding, not a reassurance. Because haptocorrin carries most circulating cobalamin, conditions that raise haptocorrin — liver disease, some myeloproliferative disorders, some solid tumors — raise serum B12 Wolffenbuttel 2023 Murphy 2021. A high value on a routine panel in an unsupplemented person deserves a clinician's attention rather than a shrug, and almost nobody treats it that way.
The form-specific points, which are small but real. Cyanocobalamin carries a cyanide group that must be removed intracellularly; the quantity is trivial for almost everyone and is a genuine consideration in advanced renal impairment and in people with Leber hereditary optic neuropathy, for whom hydroxocobalamin is used instead. Cobalamins are also light-sensitive and degrade in solution Temova Rakusa 2022 — a clear vial left on a windowsill is losing potency, which is a storage fact and not a scare.
Acne is the commonest reported effect of high-dose B12 and it has a plausible mechanism. Supplementation appears to shift the transcriptional activity of skin Cutibacterium acnes toward porphyrin production, which is inflammatory in the follicle. It is reversible on stopping and it is dose-related. Trivial medically, and worth knowing before someone blames a different compound in their stack.
What is genuinely low risk. There is no established upper limit for B12 and no toxicity syndrome at supplement or injection doses; excess is renally cleared. The realistic costs are money, injections that were not needed, a misleading serum value, and the masking problem above, which is the only one that can actually hurt somebody.
Sources read for this page
- Wolffenbuttel BH, et al. Vitamin B12. BMJ 2023 · PMID 37984968
- Abdelwahab OA, et al. Efficacy of different routes of vitamin B12 supplementation for the treatment of patients with vitamin B12 deficiency: A systematic review and network meta-analysis. Irish Journal of Medical Science 2024 · PMID 38231320
- Markun S, et al. Effects of Vitamin B12 Supplementation on Cognitive Function, Depressive Symptoms, and Fatigue: A Systematic Review, Meta-Analysis, and Meta-Regression. Nutrients 2021 · PMID 33809274
- Murphy MJ, et al. Personalising laboratory medicine in the real world: Assessing clinical utility, by clinical indication, of serum total B12 and Active-B12 (holotranscobalamin) in the diagnosis of vitamin B12 deficiency. Annals of Clinical Biochemistry 2021 · PMID 33715445
- Temova Rakusa Z, et al. Vitamin B12 in Foods, Food Supplements, and Medicines: A Review of Its Role and Properties with a Focus on Its Stability. Molecules 2022 · PMID 36615431
- Esposito G, et al. Pernicious Anemia: The Hematological Presentation of a Multifaceted Disorder Caused by Cobalamin Deficiency. Nutrients 2022 · PMID 35458234
B12 — safety, from the human record
Not a prediction. This one has been studied in people. What follows is drawn from the human record — trials, labels and pharmacovigilance — rather than from what the mechanism implies. Where the way it is used here differs from what was studied, the card says so. How evidence is graded here →
What the mechanism predicts
Derived from the molecule, not a trial.
- An essential cofactor for methylation, red-cell formation and nerve myelination. It is water-soluble, has no established toxicity ceiling, and excess is renally cleared — so a toxicity profile is the wrong frame for it entirely.
- The real risks are diagnostic rather than toxic, and there are two. Supplementing before testing destroys the ability to interpret a B12 result, and treating a deficiency with B12 alone can correct the anemia while a coexisting folate or neurological problem progresses — which is why the deficiency workup belongs with a clinician.
What has actually been reported
- Genuinely benign at ordinary intakes. Acne and rosacea flares are reported with high-dose supplementation, most consistently with cyanocobalamin.
- A high serum B12 is not a good result. Elevated B12 in someone not supplementing is associated with liver disease, renal disease and some hematological malignancies, and warrants a look rather than a shrug.
- The methyl versus hydroxo versus cyano question is largely unresolved in trials; hydroxocobalamin has a longer half-life, cyanocobalamin has the most stability and the most evidence.
How to reduce the risk
Same mechanism as the prediction.
- Test first, supplement second. This is the entire mitigation and almost nobody does it in that order.
- If you are on metformin, on a plant-based diet, over 60, or on acid suppression, put a B12 with MMA on the annual list.
- Neurological symptoms with a low B12 are a clinician's problem, not a supplement's. Oral replacement is adequate for most people, but the workup for why it was low is the part that matters.
What it does to your bloodwork
A fact about the assay.
- Draw B12 before you start, not after. Once supplemented, serum B12 tells you about the supplement.
- MMA and homocysteine are the functional tests and they are what settles a low-normal serum B12 — MMA rises in B12 deficiency, homocysteine rises in B12 *or* folate deficiency.
- Folate alongside, always. The two are interpreted together and treating one without checking the other is the classic error.
What it overlaps with
- Metformin causes B12 malabsorption with long-term use — that is the most common real-world reason someone in this audience needs it.
- Proton pump inhibitors and H2 blockers reduce absorption of food-bound B12. Nitrous oxide inactivates B12 and can precipitate acute neurological deficiency in someone already marginal.
- High-dose biotin interferes with the immunoassays used for B12 and many other markers — a testing artefact, not a nutrient interaction.
Don't run this if
- Leber's hereditary optic neuropathy, where cyanocobalamin specifically is contraindicated.
- Not a contraindication but a sequencing rule: do not start it before the diagnostic bloods are drawn if deficiency is the question.
The honest unknown
- Whether supplementing a normal B12 does anything at all in people without deficiency, malabsorption, metformin use, a plant-based diet or a relevant genotype. The correction of deficiency is well established; the benefit above it is not.
Not medical advice. If you take prescription medication or have a diagnosed condition, check this with a pharmacist or doctor.
B12 — interference & stacking
Predicted from mechanism, not from an interaction study. How mechanism-predicted claims are made →
What B12 moves on your bloodwork
Expected direction, not a measured one.
- hs-CRP (High-Sensitivity C-Reactive Protein) — ↓ expected to fall
Where these work, systemic inflammation is the plausible readout.
What to do: hs-CRP is cheap and moves. Baseline and 12 weeks. - HbA1c (Hemoglobin A1c) — ↓ expected to fall
Improved mitochondrial and metabolic function should show here if the effect is real at all.
What to do: The honest use of these markers is as a falsification test: if nothing moves in 12 weeks, the compound is not doing much for you. - Comprehensive Metabolic Panel (CMP) — ◆ worth watching
Liver and kidney function — the standard baseline for anything run long term.
What to do: Twice a year is enough on a stable protocol.
This class is where honest expectation-setting matters most: the markers above are how you find out whether anything happened, and for most of these compounds that question is genuinely open.
- How to work up to it, and when not to
- When to take it, and why that window
- Cycle length
- Time off between cycles
- Fasted or fed, and when in the day
- How the forms differ in dose
- Coach Cam's personal notes
- Which compounds push the same lever, and why the dose adds up faster than people count
- What blunts it — the stacks that waste your money
- What compounds the risk, so a side effect arrives sooner than any one of them suggests
- Coach Cam's read on running it alongside the rest of your protocol
Everything above is free and stays free. Skool is where it becomes a plan — B12 in an order, with the rest of what you're running.
Unlock in Skool — $10/mo →Bloodwork to run alongside B12
Baseline first, then again at 8–12 weeks.
| Marker | What it’s watching for |
|---|---|
| hs-CRP (High-Sensitivity C-Reactive Protein) | Chronic low-grade inflammation is the process most of these target |
| ApoB (Apolipoprotein B) | Counts the particles that actually cause plaque, unlike LDL-C |
| HbA1c (Hemoglobin A1c) | Glycation, which is the other half of the ageing story |
| Comprehensive Metabolic Panel (CMP) | Liver and kidney — the two organs that clear everything you take |
| Complete Blood Count (CBC) with Differential | The cheapest broad screen there is |
The Longevity Baseline panel covers these in one order — 13 markers, $219.10 with the discount applied.
Check results you already have → · All 103 markers A–Z
B12 — frequently asked questions
What is B12?
B12 (Cobalamin (methyl/hydroxo)) is a longevity & bioregulators research compound. Essential cofactor for methylation, red-cell formation and nerve myelination.
Is the full B12 protocol on this page?
The reported research dose is on this page, along with how B12 works and the evidence behind it. The protocol — how to work up to it, frequency, cycle length, time off, what not to stack it with and Coach Cam's notes — is inside Skool.
What is the half-life of B12?
B12 has an approximate half-life of Long (stored), which is part of what determines how often it's dosed.
What forms does B12 come in?
B12 is available as: Injectable, Oral.
What's the evidence behind B12?
Current evidence level: Human (established). B12 is offered for research purposes only and is not an approved medicine.
What B12 is used for
B12 appears under 1 goal in the goal router.
Related Longevity & Bioregulators compounds
Where this goes next
The pages here are the frameworks. The protocols — the dosing, the order to correct things in, the week-by-week schedule and what to retest — are inside Skool.