Now that I have actual time to look at the article, this one is less a concern, since they did do small human trials (n = 7). That's still not enough to prove an effect and control for the many confounding factors. And I don't give much status to the correlation study, since it's still relatively small and neither direct (Measuring for the effect and not just "change in population") nor conclusive. kleinbl00: I ended up in a discussion with a guy who had taught a class including microbiome-related topics, and his conclusion after a head-first dive into the literature was: A lot of it is crap and the field as a whole is still quite immature. There's not many benchmark references for how the biome changes across different timescales with the many many possible diets a human may have on a given week / month. Seeing a change in proportion of bacterial populations in the stools is a far cry from even a smoking gun in a system as complex as the human gut. Still, this one made it into nature... (Not that they don't mistakenly accept crap on a semi-annual basis)- Mice ain't human. Can this happen in humans? Will it happen if I sprinkle splenda on my tea every day? Do I need a suppository to see the effect? What's the evidence to support the presence of this effect already in humans?