Professor Tim Spector

And over six weeks, you get really quite dramatic improvements in your gut microbes with eating this.

So you really push up the good bugs and squash out the bad bugs about several times more than you would get just by having a traditional probiotic.

So this fertilizer approach...

Does seem to work.

And this is the study where we also showed the improvements in mood after a few days, which surprised me because I wasn't even thinking about that when we planned the study.

So we weren't expecting that.

That was my point, really, on these.

Because we thought it would just be gut.

It was like, OK, do I get to the toilet more often?

Is it improving my gut microbes?

And so it was a real bonus to see these brain effects.

So we've got a new scoring method for gut bugs, which we published last month in Nature.

And so we used to talk about diversity.

And on previous podcasts, I think we've talked about diversity, which is the number of different species.

But we've got a better way of looking at that now, which is to take 100 most important bugs that change with diet that everybody's got because we're all different.

It's very hard to compare your bugs with my bugs because we only share 20%.

So this looks at 100 common bugs that we've both got, 50 good and 50 bad.

And what we want in an intervention is to see the good bugs that are associated with good diet and good health outcomes, good blood tests, are going up and the bad bugs associated with inflammation going up.

Poor diets and bad health outcomes are going down.

And that's exactly what we saw.