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Comment by n8henrie | Hacker News Reader

All of the commenters so far (and the article's title) seem to assume that this is causative of good health. Why is that?

I'm aware that fecal transplants can help cure C diff infections.

Do we have randomized, placebo-controlled evidence that suggests that gut biodiversity is causative of (and not just associated with other lifestyle features causing) good health? It's hard for me to imagine a good way to design such a study.

I thought the rigorously performed research regarding eg probiotics had mostly been disappointing.

Is there any reason to think that food that is good for human health would not also be good for gut flora health, thus heavily confounding much of the non-interventional research?

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Study after study fail to disprove the hypothesis that gut microbiome diversity is a strong correlate with longevity.

Here's a meta study for you:

Here we introduce the MicrobiomeHD database, which includes 28 published case–control gut microbiome studies spanning ten diseases. We perform a cross-disease meta-analysis of these studies using standardized methods. We find consistent patterns characterizing disease-associated microbiome changes.

What more do people want? Why is this something people fight?

[1]https://www.nature.com/articles/s41467-017-01973-8

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/

The IMPRINT study has given us a lot of information using shotgun metagenomic sequencing of longitudinal fecal samples: https://www.cell.com/cell/fulltext/S0092-8674(21)00660-7

There seem to be windows where bacterial populations are in flux until the microbiome stabilizes around 3 years of age. It is difficult to modify the microbiome after that. I think our models have to shift so that we prioritize early intervention, especially for those at risk for dysbiosis (like premature and c-section babies).

A recent study of centenarians seemed to indicate a correlation between a diverse gut biome and long life: https://www.nature.com/articles/s41564-023-01370-6

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