Vitamin B12 (Cobalamin)
Also known as: Cobalamin, Methylcobalamin, Cyanocobalamin
Vitamin B12 supports normal blood and nerve function. People on plant-based diets or with absorption issues commonly explore it. Testing can identify a real need. Excess is generally excreted.
Snapshot
What this page can tell you: NIH ODS notes on B12's low toxicity, the medications that lower it, and who is at higher deficiency risk.
What it cannot: That B12 supplements boost energy or treat any condition if you're not deficient. Informational only.
🧩 Stack insights — how this fits into a schedule
Metformin; acid reducers (PPIs/H2 blockers) — NIH ODS: metformin and stomach-acid reducers (e.g. omeprazole, cimetidine) can lower vitamin B12 over time. B12 itself has not been shown to cause harm even at high doses. Older adults and people eating little animal food are at higher deficiency risk.
Relationship insights are informational only — they describe what is commonly discussed or studied, not what you should take. Not medical advice; review your routine with a clinician or pharmacist.
🕒 Timing
When: Morning
Food: With or without food
Timing is flexible; some prefer morning as part of a routine.
💊 Common use range
250–1,000 mcg
No commonly cited upper limit; excess is largely excreted.
Ranges are informational, not a recommended dose. Talk to a professional about what is right for you.
🤔 Worth considering?
Evidence vs. effort: Limited evidence relative to burden
Low-burden and important for people with low B12 (for example restrictive diets, older adults, or certain medications). Benefits without a shortfall are less clear; a level can be checked with a professional.
A general summary, not a recommendation. Whether something fits your situation is worth discussing with a healthcare professional.
⚠️ Commonly noted interactions (supplements)
None listed.
Often about absorption or timing rather than danger — separating doses is common. This list is not exhaustive.
🧭 Caution level
No major caution categories flagged in our data for this item.
Caution level is an informational summary of commonly discussed caution categories and doses — not a safety rating, approval, or medical advice. Low caution does not mean safe for you.
🩺 Medication caution categories
None flagged here, but always review your full routine with a professional.
🏥 Surgery & procedure caution
Not typically a surgical concern; share your supplement list.
If you have a procedure scheduled, bring your full supplement list to your surgical and anesthesia team. Do not stop prescribed medication unless your clinician tells you to. Do not start or stop supplements based only on this app.
✅ Quality checklist
- Prefer products with third-party testing or a certificate of analysis (COA).
- Check the label for the exact form and the elemental or active amount per serving.
🧩 Commonly paired with
🔁 Alternatives
🗣️ Questions for a professional
- Is Vitamin B12 (Cobalamin) appropriate alongside my medications and health history?
- Is there a test or check that would tell us whether I actually need it?
🛡️ Safety notes (source-reviewed)
- NIH ODS: B12 has not been shown to cause harm even at high doses (no upper limit).
- Metformin and stomach-acid reducers (PPIs, H2 blockers) can lower B12 over time.
- Vegetarians/vegans and older adults are at higher risk of deficiency.
⚖️ Evidence limitations
- Supplementation mainly helps people who are deficient or at risk; a blood test can guide need.
❓ Frequently asked
Can you take too much B12?
NIH ODS says B12 has not been shown to cause harm even at high doses, and there is no established upper limit. It is water-soluble, so excess is largely excreted.
What lowers B12?
NIH ODS notes metformin and stomach-acid reducers can lower B12 over time. Vegans and older adults are also at higher deficiency risk.
🔬 Evidence snapshot
Essential for red blood cell formation, DNA synthesis, and nervous-system function; per NIH ODS, evidence for benefits beyond correcting a deficiency is inconclusive.
🧪 Forms & quality
Needs evidence review — no source-reviewed information yet. We only show dose and monitoring details after they have been checked against reputable sources.
See the supplement glossary for what form names like "L-", chelated, or standardized extract mean.
📏 Dose & monitoring
No established Tolerable Upper Intake Level. NIH ODS notes B12 has a low toxicity profile even at high doses, as excess is not stored.
Evidence vs. burden: Limited evidence relative to burden
Labs that may be worth discussing: B12 / folate
These are discussion prompts, not required tests. A healthcare professional can advise what makes sense for you.
😐 Commonly reported side effects
- Uncommon; rare skin reactions reported
Non-exhaustive and individual.
🔄 Cycling & breaks
Not typically cycled.
📅 Daily use notes
Often used daily or a few times weekly at higher doses. Testing can confirm need.
📋 Source review status
Source-reviewed — last reviewed 2026-07-02
Placeholder.
📚 References
- NIH ODS - Vitamin B12 (Health Professional Fact Sheet)NIH ODS — Verified no-UL/low-toxicity note and absorption interactions (metformin, PPIs, H2 blockers).
- NIH ODS — Vitamin B12 (Consumer Fact Sheet)NIH ODS — Full text reviewed 2026-07-03. Verified: 'has not been shown to cause any harm, even at high doses' (low toxicity, no UL); acid inhibitors (omeprazole, lansoprazole, cimetidine, ranitidine) and metformin can lower B12; vegetarians/vegans and older adults (3-43%) are at higher deficiency risk.
Verified against the source shown. See the research-status page for how review works.
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