Vitamin B12

Cobalamin: cyanocobalamin, methylcobalamin, hydroxocobalamin, adenosylcobalamin

Water-soluble vitamins

Aliases / common names

Cobalamin; methyl B12; cyanocobalamin

Natural food sources

Animal foods: fish, shellfish, meat, eggs and dairy; fortified foods for plant-based diets.

Main wellness functions

Supports red blood cell formation, nervous-system function, DNA synthesis and homocysteine metabolism.

Deficiency signs

Megaloblastic anemia, numbness, tingling, gait changes, cognitive or mood changes and glossitis.

Recommended intake

Adults: 2.4 mcg/day. Children: about 0.9-2.4 mcg/day. Pregnancy: 2.6 mcg/day. No established UL.

Excess intake effects

No clear toxicity; acne-like eruptions are occasionally reported with high-dose products.

Contraindicated / caution groups

Vegans, older adults, people using metformin or acid-suppressing medicines, and bariatric surgery patients may need monitoring.

Common dosage forms

Tablets, capsules, sublingual tablets, sprays, drops, injections in clinical care.

Common product strengths

25-1,000 mcg; high-dose oral/sublingual products often use 500-5,000 mcg.

Use precautions

Neurologic symptoms should be assessed promptly; folate alone may mask anemia.

Supplement notes

Absorption depends on intrinsic factor; large oral doses can still partly absorb passively.

This information is for general nutrition education and product reference only. It does not replace medical diagnosis, treatment or individualized dietary advice.