The claimEvidence A · guideline-tier
Spirulina = vegan B12 source
The evidence
Contains pseudo-B12 that cannot activate human B12-dependent enzymes — may even displace real B12 at receptors.
The mechanism, in brief
Spirulina strictly speaking is not algae — it's a cyanobacterium (mainly *Arthrospira platensis* and *Arthrospira maxima*). These are among the oldest photosynthetic life on Earth, with close relatives in 3.5-billion-year-old fossils.
Sources (1)
- Karkos, P. D., Leong, S. C., Karkos, C. D., Sivaji, N., & Assimakopoulos, D. A. (2011). Spirulina in clinical practice: evidence-based human applications. Evidence-Based Complementary and Alternative Medicine, 2011, 531053.