Frequently Asked Question
Health & NutritionVitamin 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.
Supported by 7 cited sources
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 Office of Dietary Supplements. NIH ODS: B12/Iodine/Vitamin D fact sheets.
- NIH Office of Dietary Supplements. 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)
- European Food Safety Authority (EFSA). EFSA animal welfare scientific opinions (species-specific; .
- EFSA and national animal welfare authorities (species-specific slaughter welfare reviews; .
Sources:
- NIH Office of Dietary Supplements. NIH ODS: B12/Iodine/Vitamin D fact sheets.
- NIH Office of Dietary Supplements. 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)
- European Food Safety Authority (EFSA). EFSA animal welfare scientific opinions (species-specific; .
- EFSA and national animal welfare authorities (species-specific slaughter welfare reviews; .
Sources:
- NIH Office of Dietary Supplements. NIH ODS: B12/Iodine/Vitamin D fact sheets.
- NIH Office of Dietary Supplements. 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
- European Food Safety Authority (EFSA). 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)
Caveats: Deficiency risk exists in any population with inadequate intake, not just vegans.
Sources & Evidence
7 sources cited across 4 claims
1
B12 is made by microorganisms, not animals or plants
MechanisticVitamin B12 sources and bioavailability — Watanabe F, et al. (2014)
Cyanocobalamin (vitamin B12) as a feed additive — EFSA (European Food Safety Authority)View source ↗
Vitamin B12 - Fact Sheet for Health Professionals — NIH Office of Dietary Supplements (2024)View source ↗
EFSA animal welfare scientific opinions (species-specific; . — European Food Safety Authority (EFSA)View source ↗
2
B12 supplementation is reliable for vegans
GuidelineVitamin B12 sources and bioavailability — Watanabe F, et al. (2014)
Cyanocobalamin (vitamin B12) as a feed additive — EFSA (European Food Safety Authority)View source ↗
Vitamin B12 - Fact Sheet for Health Professionals — NIH Office of Dietary Supplements (2024)View source ↗
EFSA animal welfare scientific opinions (species-specific; . — European Food Safety Authority (EFSA)View source ↗
3
Animal agriculture also uses B12 supplements
ObservationalVitamin B12 sources and bioavailability — Watanabe F, et al. (2014)
Cyanocobalamin (vitamin B12) as a feed additive — EFSA (European Food Safety Authority)View source ↗
EFSA animal welfare scientific opinions (species-specific; . — European Food Safety Authority (EFSA)View source ↗
Vitamin B12 - Fact Sheet for Health Professionals — NIH Office of Dietary Supplements (2024)View source ↗
4
B12 deficiency can cause irreversible damage
Guideline