Vitamin B12 (Cobalamin)

Overview

Vitamin B12 (or cobalamin) is a water-soluble vitamin essential for energy production, nervous system function, and red blood cell formation.
It plays a key role in DNA synthesis, amino acid metabolism, and neural protection through myelin formation.
Naturally found in animal products, it is often supplemented in vegetarians, vegans, and older adults due to reduced absorption or dietary intake.

What the Evidence Shows

Domain	Evidence Level	Observed Effects
Energy & fatigue	High	Corrects fatigue and low vitality when deficiency is present.
Nervous system & cognition	High	Prevents neurological disorders linked to demyelination.
Cardiovascular health	Moderate	Lowers homocysteine, a cardiovascular risk factor.
Cognitive decline & aging	Moderate	Potential protective effect in synergy with B6 and folate.

Overall level: High for deficiency prevention and treatment; moderate for cognition and vascular health.

Mechanism of Action

Acts as an enzymatic cofactor for methionine synthase and methylmalonyl-CoA mutase.
Enables homocysteine conversion to methionine → supports cardiovascular protection.
Promotes myelin sheath formation → ensures efficient nerve transmission.
Required for ATP production via folate metabolism.
Deficiency leads to macrocytic anemia and progressive neurological impairment.

💊 Dosage & Forms

Use Case	Recommended Dose	Frequency	Preferred Form
General intake (adults)	2.4 µg/day	Daily	Balanced diet
Vegetarians / seniors	250–500 µg/day	Daily	Sublingual methylcobalamin
Therapeutic supplementation	1000 µg	1–2× per week	Oral, sublingual, or injection
Pregnancy / breastfeeding	2.6–2.8 µg/day	Daily	Under medical supervision

💡 Tip: Prefer methylcobalamin (active natural form) or hydroxocobalamin (long-acting injectable form).

Useful Synergies

Combination	Main Effect
B12 + Folate (B9)	DNA synthesis and anemia prevention.
B12 + Vitamin B6	Reduces homocysteine.
B12 + Magnesium	Nervous system support.
B12 + Iron	Optimizes red blood cell production.

🟢 Proven Benefits

Boosts cellular energy production.
Prevents anemia and chronic fatigue.
Protects the nervous system and cognitive function.
Contributes to normal protein and fat metabolism.

🟡 Still Under Study

Direct preventive effects on Alzheimer’s or depression (insufficient evidence).
Role in athletic performance outside deficiency.
Potential synergy with probiotics for improved absorption.

⚠️ Risks & Interactions

Consult a healthcare professional in cases of anemia, digestive disorders, or during pregnancy/breastfeeding.
High doses are generally safe but may mask other deficiencies (e.g., folate).
Certain medications (PPIs, metformin, antacids) reduce B12 absorption.
May interact with folate or high-dose vitamin C supplements when taken simultaneously.
Rare: mild acne or skin rashes at very high doses (>2000 µg/day).

✅ Quality Tips

Choose an active form (methylcobalamin) for superior absorption.
Take on an empty stomach or in sublingual form for best bioavailability.
For vegans: prefer certified plant-based supplements (gelatin-free).
Check serum B12 and homocysteine during long-term supplementation.

Sources

https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/
https://www.canada.ca/en/health-canada.html
https://examine.com/supplements/vitamin-b12/
PubMed — Clinical Review on Vitamin B12 Deficiency
NIH/ODS — Vitamin B12 Fact Sheet
Health Canada — Dietary Reference Intakes
Examine.com — Vitamin B12 Overview