Frequently Asked Question
HealthVitamin B12 (critical)
Last reviewed: January 9, 2026
Summary
Vitamin B12 is made by microorganisms, not animals or plants. In modern food systems, B12 is obtained via animal products largely because animals accumulate it through microbial synthesis (often supported by supplementation strategies) and because hygiene reduces incidental B12 from soil/water. Vegans reliably meet needs via B12 supplements or fortified foods.
Evidence Summary
- B12 is synthesized by bacteria/archaea; humans must obtain it from diet/supplement.
- Major health authorities recommend B12 supplementation/fortified foods for vegans.
- B12 is commonly used as a feed additive in animal agriculture and/or supported via cobalt supplementation (ruminants), meaning “meat as B12 source” can be indirect supplementation. Evidence quality: High (biochemistry + authoritative guidance) Limitations / nuance: “You could get B12 from unwashed produce” is
Supporting Evidence
Sources:
- NIH ODS: B12/Iodine/Vitamin D fact sheets.
- NIH ODS nutrient fact sheets.
- Watanabe F, et al.. Vitamin B12 sources and bioavailability (2014)
- EFSA (European Food Safety Authority). Cyanocobalamin (vitamin B12) as a feed additive
- NIH Office of Dietary Supplements. Vitamin B12 - Fact Sheet for Health Professionals (2024)
- EFSA animal welfare scientific opinions (species-specific; .
- EFSA and national animal welfare authorities (species-specific slaughter welfare reviews; .
Sources:
- NIH ODS: B12/Iodine/Vitamin D fact sheets.
- NIH ODS nutrient fact sheets.
- Watanabe F, et al.. Vitamin B12 sources and bioavailability (2014)
- EFSA (European Food Safety Authority). Cyanocobalamin (vitamin B12) as a feed additive
- NIH Office of Dietary Supplements. Vitamin B12 - Fact Sheet for Health Professionals (2024)
- EFSA animal welfare scientific opinions (species-specific; .
- EFSA and national animal welfare authorities (species-specific slaughter welfare reviews; .
Sources:
- NIH ODS: B12/Iodine/Vitamin D fact sheets.
- NIH ODS nutrient fact sheets.
- Watanabe F, et al.. Vitamin B12 sources and bioavailability (2014)
- EFSA (European Food Safety Authority). Cyanocobalamin (vitamin B12) as a feed additive
- EFSA animal welfare scientific opinions (species-specific; .
- EFSA and national animal welfare authorities (species-specific slaughter welfare reviews; .
- NIH Office of Dietary Supplements. Vitamin B12 - Fact Sheet for Health Professionals (2024)