[CrHn3]

I’m not sure what you take away from that meta analysis, but to me it does not seem to be about diversity as much as which groups of bacteria are associated with general improved health outcomes and disease. If you have more alpha diversity because you have more pathogenic strains, it does not necessarily mean it’s better.

Some studies have found no differences in alpha diversity[1] when looking at outcomes like longevity. Maybe alpha diversity is the byproduct of healthy flora but it could be possible to engineer a microbiome that was more advantageous for a given population that was less diverse.

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7762384/