The Claim
Mycobacterium tuberculosis has lost the genetic capacity to synthesize vitamin B12 during evolutionary history, while retaining the ability to import vitamin B12 from external sources, a trait not observed in its ancestor Mycobacterium canettii or in environmental mycobacterial species, indicating an evolutionary adaptation to utilize host-derived vitamin B12 as a virulence factor.
What the research says
Supports is higher
Support is ahead, but a single strong opposing study can change this.
These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.
Mycobacterium tuberculosis no longer produces vitamin B12 on its own but can take it from the human host, unlike its ancestral relatives and environmental relatives that still make it; this change is linked to its ability to cause disease by relying on the host's vitamin B12.
See the scientific wording
Mycobacterium tuberculosis has lost the ability to synthesize vitamin B12 during evolution, unlike its ancestor M. canettii and environmental mycobacteria, but retained the capacity to import it, suggesting evolutionary adaptation to exploit host B12 as a virulence factor.
The bacteria lost the ability to make vitamin B12 themselves but kept the tools to steal it from the host. They use that stolen vitamin to make an essential amino acid called methionine, which they need to grow and cause disease. When the host doesn't have enough vitamin B12, the bacteria can't make enough methionine and can't spread. The bacteria also shut down their backup system for making methionine when vitamin B12 is available, making them completely dependent on the host's supply.
What the research says
1 studyStudy: Dependency on host vitamin B12 has shaped Mycobacterium tuberculosis Complex evolution
The tuberculosis bacteria can't make their own vitamin B12 anymore, but they can steal it from your body — and they need it to make you sick. When mice didn't have enough B12, the bacteria couldn't cause as much disease, proving they rely on you for it.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.