Most replayed moment: The hidden battle inside your gut | Tim Spector & Nicola Segata

**SPEAKER_1** (0:01)
Hello, and welcome to ZOE Recap, where each week, we find the best bits from one of our podcast episodes to help you improve your health.
Professor Tim Spector often refers to the microbes in our guts as mini-pharmacies. This is because they provide us with powerful chemicals that help support our health. But not all gut microbes are on our side. In fact, there's an ongoing battle in our digestive system between the beneficial bugs and those that wish to do us harm. I'm joined by Tim Spector and Microbiome Researcher Nicola Segata to explore this microscopic war and explain how simple changes to your diet could help tip the balance towards the good guys.

**Nicola Segata** (0:46)
Gut bacteria are trillions of single micro-organisms present in our gut, thousands of species more or less in each of us, and they are part of an ecosystem that are an interface between the food we eat, our environment, and our health. So the diet, the food we eat is broken down by gut bacteria, that they are in turn producing molecules, small molecules that are then arriving in our blood and in our system, and so they are having an impact on us.

**Tim Spector** (1:15)
I call them mini-pharmacists is the way I describe it.

**Nicola Segata** (1:17)
Yeah, they are mini-pharmacists, yes. In addition, they also interact with our cells, with our immune system, so they are directly touching and interacting with us.
So if you have the good bacteria that are able to produce good little molecules, because metabolites is good, otherwise not. So it's like an amplifier of our diet. The good bugs are amplifying the good effect, the positive effect of an healthy diet, and vice versa, they can actually be detrimental for our health in other situations. So we need to push, increase our gut ecosystem to be an ally for us.

**Tim Spector** (1:53)
So you want to improve, have more of these good pharmacies, and you want to have less of the bad ones, doing the Breaking Bad type home chemistry and producing these nasty chemicals.

**SPEAKER_1** (2:05)
And is this real? Is there such a thing as like a good bug and a bad bug?

**Nicola Segata** (2:11)
It's not so much black and white. And also in our research, we see that there are bacteria that tends to be associated with better health and better diet. But we also need to consider that our gut microbes are very personalized to each of us.
So it's only with big, big numbers that we can tell apart which tends to be good in which situation from those that are likely not to be there. But as Tim was saying, it's also about the diversity of them. Because the more we have, the more good function they can bring to us. There is no single bacteria that can make all the work that is supposed to be done in the gut.

**Tim Spector** (2:46)
So some of them, bad ones, for example, may be quite harmless in small numbers. But when the conditions are bad, they're fed the wrong foods, they have a so-called inflammatory environment, maybe the acidity changes slightly. Then they can grow to an extent that they produce chemicals that influence everything around them, and they become bad guys.
There is this transition, and so it's best to think of this as a bit of a war between the good guys and the bad guys. The more good guys you've got, the more you can squeeze out the bad guys, so that it doesn't matter if they're around because they're in small numbers, and they're just playing around, and really any chemicals they produce are just so diluted, you don't really feel the consequences. But the real problems are when you lose your good bugs, and suddenly the bad guys multiply, and then you're really in trouble because you're producing all kinds of chemicals that attract even more unhealthy microbes, and the whole thing starts to go downhill very fast.

**SPEAKER_1** (3:50)
The three of us sitting here, will we all have roughly the same bugs inside our gut?

**Nicola Segata** (3:56)
Not really. I think we have around 30-40 percent of species in common.

**Tim Spector** (4:01)
At the level, when you get even below the species level, the sub-species level, it's probably even less than that is, but we're only sharing of 10-15 percent. All of us have a unique set of some microbes that the others wouldn't have. Even if you took 1,000 people, you'd find nearly everyone has something unique to them.
There's a broad pattern that might be similar, but the more fine detail you get, the harder it is to find things in common. Even in, as we discovered, Nicola and I, when we looked at this, even in identical twins who have identical genes in every cell in their body, but their microbes are really only slightly more similar than unrelated people.