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Essential for energy, nerves, and blood cells. 20% of adults over 60 are deficient. Vegans need this.
Essential for energy, nerves, and blood cells. 20% of adults over 60 are deficient. Vegans need this. 500-1000mcg daily or 2500mcg weekly. Best form: Methylcobalamin.
B12 (cobalamin) is a water-soluble vitamin needed for DNA synthesis, red blood cell formation, and nerve function. It's only naturally found in animal foods. Your body stores it for years, so deficiency develops slowly and sneakily.
B12 acts as a cofactor for enzymes involved in DNA synthesis and methylation. It's required for converting homocysteine to methionine (important for heart health) and for maintaining the myelin sheath around nerves. Deficiency causes irreversible nerve damage if prolonged.
Different forms of Vitamin B12 have varying absorption rates and best uses. Here's how they compare:
| Form | Bioavailability | Best For |
|---|---|---|
| Methylcobalamin | 50% | Active form. No conversion needed. Preferred for most. |
| Cyanocobalamin | 45% | Most stable and studied. Body converts to active forms. |
| Adenosylcobalamin | 50% | Mitochondrial form. Sometimes combined with methyl. |
| Hydroxocobalamin | 55% | Injection form. Longest retention time. |
Our recommendation: Methylcobalamin for most people due to superior absorption and tolerability.
Vitamin B12 has 3 strongly-evidenced benefits and 1 moderately-evidenced benefits.
Resolves fatigue caused by B12 deficiency
Prevents/treats peripheral neuropathy
Deficiency causes brain fog, memory issues
Lowers homocysteine (cardiovascular risk marker)
Both work. Methyl is the active form (no conversion needed). Cyanocobalamin is cheaper and more stable. For most people, doesn't matter. MTHFR gene variants may do better with methyl.
Full evidence-based analysis for each form and variant:
About this information: Our analysis of Vitamin B12 is based on peer-reviewed research from PubMed, ClinicalTrials.gov, and NIH databases. These statements have not been evaluated by the FDA. Supplements are not intended to diagnose, treat, cure, or prevent any disease.
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Track it alongside your other supplements for interaction checking.