Vitamin B12 (Methylcobalamin)
Drives nerve myelination, red blood cell formation, and DNA synthesis — deficiency is common in vegans, vegetarians, and older adults.
Vitamin B12 is an essential water-soluble vitamin that plays critical roles in neurological function, DNA synthesis, and red blood cell formation. Deficiency is common, especially in vegetarians/vegans, older adults, and those with absorption issues. Methylcobalamin is the active, neurologically-preferred form, while cyanocobalamin is cheaper but requires conversion.
Essential cofactor for methionine synthase
Supports nerve sheath integrity
Required for healthy red blood cell formation
How Vitamin B12 works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
500-1000mcg daily for maintenance; higher for deficiency
Loading: For deficiency: 1000-2000mcg daily or injections as directed
Can be taken without food
| Form | Type |
|---|---|
| 💊Methylcobalamin (sublingual) | Recommended |
| 💊Adenosylcobalamin | Alternative |
| 💊Hydroxocobalamin | Alternative |
| 💊Cyanocobalamin (cheapest) | Alternative |
Methylcobalamin is the active form. Sublingual absorption bypasses GI absorption issues.
Minimum: 4 weeks
Optimal: 12 weeks
Cycling: Not required
Note: Sublingual forms bypass absorption issues. Methylcobalamin is preferred for neurological benefits.
Improved energy, especially if deficient
Better memory and mental clarity
Prevention/reversal of neurological symptoms
Essential to supplement; B12 only found in animal products
Higher doses often needed due to reduced absorption
Metformin reduces B12 absorption; supplementation often needed
Reduce B12 absorption; consider supplementation
Tip: Take with food
Tip: Reduce dose if persistent
Tip: Discontinue if symptoms occur
Top studies from 40+ peer-reviewed papers
Abdelwahab OA et al. • Irish journal of medical science (2024)
“All IM, oral, and SL routes of administration of vitamin B12 can effectively increase the level of vitamin B12 without significant differences between them, as thought previously.”
Zhang N et al. • The American journal of clinical nutrition (2024)
“Our meta-analysis found that the folic acid combined with vitamin B12 and vitamin B6 supplementation strategy significantly reduced the risk of stroke in areas without and with partial folic acid fortification.”
Bokayeva K et al. • International journal of molecular sciences (2024)
“Our study provides valuable insights into the nutritional status of PKU patients, but further research is required to confirm these findings and explore additional factors influencing vitamin status in PKU.”
Markun S et al. • Nutrients (2021)
“Vitamin B12 supplementation is likely ineffective for improving cognitive function and depressive symptoms in patients without advanced neurological disorders.”
Xia Y et al. • BMJ (Clinical research ed.) (2025)
“Oral methylcobalamin significantly lowered the severity of hand-foot syndrome by reducing the incidence of grade ≥2 symptoms without unexpected safety concerns in women with HER2 negative early breast cancer who were receiving adjuvant capecitabine treatment.”
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