Vitamin B12: The Complete Guide
Methylcobalamin vs cyanocobalamin, who actually needs a lozenge, and why vegans cannot skip this one
Vitamin B12 is required for myelin, DNA synthesis, and homocysteine handling. Deficiency is a neuropathy and anemia problem — not a focus hack. This guide covers who needs a lozenge, what to test, and why NOW methyl 1,000 mcg is enough for most plant-based eaters.
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This content is for general informational and educational purposes only. It is not medical advice, diagnosis, or treatment. Consult a qualified healthcare provider before starting any supplement, peptide, or health protocol. Read our full health disclaimer.
Frequency
Daily lozenge if diet or labs say so
Duration
Ongoing on vegan diets; reassess after labs if omnivore
Level
Beginner
Key Takeaways
- 1Vegan diets, metformin, PPIs, and older adults are the usual reasons to supplement
- 2Test B12 and MMA if symptoms or diet risk — do not megadose for ‘energy’ if replete
- 3Methylcobalamin and cyanocobalamin both work; pick a cheap lozenge you will use
- 4Greger will let you skip most capsules; he will not let you skip B12
Who this is for
- ·Plant-based eaters building a Daily Dozen kitchen
- ·Anyone with a low B12 or high MMA
- ·Omnivores who were sold B12 as a pre-workout
Who Needs It
Strong EvidenceAnimal foods are the reliable dietary source. A strict plant-based diet without a supplement is a planned deficiency.
Metformin, proton-pump inhibitors, and atrophic gastritis impair absorption. Age-related intrinsic-factor decline is why many clinicians supplement older adults even if they eat meat.
Forms and Dose
Strong EvidenceCyanocobalamin is cheap and well-studied. Methylcobalamin is the coenzyme form in NOW’s lozenge. For almost everyone the difference is branding.
1,000 mcg daily is a convenient lozenge, far above the RDA, and appropriate as vegan insurance. Correcting frank deficiency may use injections — that is a clinician call.
Labs
Moderate EvidenceSerum B12 can look ‘normal’ while MMA is high. If neuropathy or anemia is in play, ask for MMA and a proper workup — high-dose lozenges can mask folate issues on some panels.
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For educational purposes only. Not medical advice. Read our health disclaimer.
Sources
Key references cited in this guide. Links open the original publication or abstract.
- Vitamin B12 deficiency — reviewAm Fam Physician, 2013
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