Vitamins

Vitamin B12

Cobalamin

Strong

Vitamin B12 is essential for nerve function, DNA synthesis, and red blood cell formation. It's found almost exclusively in animal products, making supplementation important for vegans. Absorption decreases with age and certain medications. Deficiency can cause irreversible nerve damage if untreated.

How It Works

B12 serves as a cofactor for two critical enzymes:

Methionine Synthase: Converts homocysteine to methionine (with folate). Essential for methylation reactions throughout the body.
Methylmalonyl-CoA Mutase: Required for odd-chain fatty acid metabolism and certain amino acid pathways.
Myelin Maintenance: Essential for maintaining the myelin sheath around nerves.
DNA Synthesis: Works with folate in DNA production; deficiency causes megaloblastic anemia.
Energy Production: Required for converting methylmalonyl-CoA to succinyl-CoA in the citric acid cycle.

Natural Food Sources

Food	Amount per Serving
Clams	84 mcg per 3 oz
Beef liver	70 mcg per 3 oz
Trout	5.4 mcg per 3 oz
Salmon	4.8 mcg per 3 oz
Tuna	2.5 mcg per 3 oz
Beef	1.4 mcg per 3 oz
Milk	1.2 mcg per cup
Eggs	0.6 mcg per large egg

Safety Information

Contraindications

Leber's hereditary optic neuropathy - B12 may worsen (rare genetic condition)
Cobalt allergy - B12 contains cobalt

Potential Side Effects

Extremely safe even at high doses (rare)
Rare: acne, rosacea flare (high doses) (rare)
Injection site reactions (for IM B12) (uncommon)

Typical Dosage

Optimal: 2 mcg
Range: 2-2000 mcg

RDA is 2.4 mcg for adults. Supplements often contain 500-2000 mcg to compensate for low absorption (about 1.5% at high doses). No established upper limit. Methylcobalamin or adenosylcobalamin are active forms.

Quick Facts

Bioavailability: Absorption requires intrinsic factor (from stomach) and is complex. About 50% of 1 mcg is absorbed via intrinsic factor (saturable). Only 1-2% of high oral doses absorbed via passive diffusion. Sublingual may bypass some absorption issues.
Half-life: About 6 days in blood. Body stores (in liver) can last 3-5 years.
Also known as: Cobalamin, Cyanocobalamin (common supplement form), Methylcobalamin (active form), Adenosylcobalamin (active form), Hydroxocobalamin

May Help With

Related Compounds

Disclaimer: The information provided is for educational purposes only and is not intended to diagnose, treat, cure, or prevent any disease. Always consult with a qualified healthcare provider before starting any supplement regimen.