Vitamin B12
Also known as: cobalamin, methylcobalamin, cyanocobalamin, b12
Recommended Dosage
500–2000 mcg
Vitamin B12 (cobalamin) is essential for nerve myelination, DNA synthesis, red blood cell formation, and methylation reactions. Deficiency is common in vegans, vegetarians, the elderly (due to declining intrinsic factor), and metformin users, and can cause irreversible neurological damage if prolonged. Methylcobalamin is the preferred form for neurological support, while sublingual or intramuscular routes bypass potential absorption issues in the gut.
TL;DR: Critical for nerve function, DNA synthesis, and red blood cell formation. Vegans, elderly, and metformin users are at high risk of deficiency. Methylcobalamin preferred for neurological benefit.
Quick Facts
Evidence
Grade A
Studies
2
Interactions
2
Forms
1
Evidence Rating: Grade A — Strong Evidence
Multiple high-quality RCTs, systematic reviews, or meta-analyses with consistent findings.
Interaction Warnings
Metformin reduces B12 absorption by up to 30%. Supplement B12 if on long-term metformin.
Acid suppression reduces B12 absorption from food; may need higher supplemental dose.
Important Notes
- Vegans and vegetarians are at high deficiency risk
- Methylcobalamin is better retained than cyanocobalamin for neurological use
- Sublingual or intramuscular preferred for pernicious anemia
Clinical Evidence (2 studies)
Vitamin B12 deficiency and cognitive impairment in the elderly
Langan RC and Goodbred AJ (2017) — Am Fam Physician
B12 deficiency independently associated with cognitive decline and neurological damage; methylcobalamin preferred for neurological benefit
View on PubMedHomocysteine-lowering interventions for preventing cardiovascular events
Martí-Carvajal AJ et al. (2017) — Cochrane Database Syst Rev
B12 + folate lower homocysteine, associated with reduced stroke risk
View on PubMedAlternatives to Consider
These supplements target similar goals and may be worth considering alongside or instead of Vitamin B12.
Vitamin D3
Grade AEssential hormone precursor. Most people in northern latitudes are deficient. Strong evidence for immunity, bone health, and mood.
Omega-3 Fish Oil
Grade AEssential fatty acids with strong evidence for cardiovascular and mental health. EPA-dominant for mood; triglyceride form for absorption.
Folate (Vitamin B9)
Grade AEssential for DNA synthesis, methylation, and mood regulation. ~40% of people have MTHFR variants reducing conversion — use methylfolate. Always pair with B12.
Related Supplements
Vitamin D3
Grade A — Strong EvidenceEssential hormone precursor. Most people in northern latitudes are deficient. Strong evidence for immunity, bone health, and mood.
Folate (Vitamin B9)
Grade A — Strong EvidenceEssential for DNA synthesis, methylation, and mood regulation. ~40% of people have MTHFR variants reducing conversion — use methylfolate. Always pair with B12.
Omega-3 Fish Oil
Grade A — Strong EvidenceEssential fatty acids with strong evidence for cardiovascular and mental health. EPA-dominant for mood; triglyceride form for absorption.
Vitamin B6
Grade A — Strong EvidenceEssential coenzyme for neurotransmitter synthesis (serotonin, GABA, dopamine). Strong evidence for PMS. Deficiency common in those on OCP or with poor diet.
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⚕️ Important Disclaimer
This information is for educational purposes only. It is not medical advice. Always consult a healthcare provider before starting any supplement regimen, especially if you take medications or have health conditions.
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