About Vitamin B12
Essential for nerve function, DNA synthesis, and red blood cell formation. Methylcobalamin and adenosylcobalamin are the two naturally active coenzyme forms, while cyanocobalamin is synthetic and requires conversion. Absorption depends on intrinsic factor, which declines with age—sublingual or liposomal forms can help bypass this. Vegans and adults over 50 are at highest risk of deficiency.
What Vitamin B12 supports
- Boosts energy production
- Maintains healthy nerves
- Forms red blood cells
How much Vitamin B12 to take
Clinical studies typically use 250–5000 mcg of Vitamin B12. RDA is 2.4 mcg but supplements typically provide 250–5000 mcg due to low absorption.
- RDA
- 2.4 mcg
- Effective range
- 250–5000 mcg
Forms of Vitamin B12 compared
- MethylcobalaminPremiumMethylated coenzyme — supports nerves and methylation directly.
- AdenosylcobalaminPremiumMitochondrial cofactor — pairs with methyl-B12 for full coverage.
- HydroxocobalaminPremiumSlowly converts to active forms; long tissue retention.
- CyanocobalaminBudgetSynthetic, requires conversion
Clinical evidence
Strong clinical evidence. Essential for nerve function and red blood cell formation; deficiency common in vegans and adults over 50
NIH Fact Sheet