5 ways relationships change your gut health | Prof Tim Spector

Welcome to Zoe Science and Nutrition, where world-leading scientists explain how their research can improve your health. Strep throat, food poisoning, pneumonia, all examples of nasty microbes that spread easily from person to person. But not all bacteria that spread between people are bad. Some can actually transfer health benefits. Good microbes that live in our gut, skin and elsewhere can also be transferred from other people and the environment around us. So how can healthy gut microbes be transmitted? What are the potential benefits? Is a healthy gut microbiome contagious? Today I'm joined by Professor Tim Spector, a leading expert on the gut microbiome, one of the world's top 100 most cited scientists, and my scientific co-founder here at Zoe. this episode, Tim will help us answer these questions and explain how to maximise the benefits of sharing good microbes with friends and family. Tim, thank you for joining me today. A pleasure as always, Jonathan. So you know the rule. We're going to kick off with a rapid fire Q&A from our listeners. You ready to go? Ready. Do most bacteria cause disease? No. Are we born with a fully formed gut microbiome? Nope. Is our gut microbiome influenced by who we live with? It is. Is having a pet good for our gut microbiome? Usually, yes. If we spend time with someone with anxiety, could their gut bugs make us more anxious? It could, Jonathan. Can bacteria from soil benefit to our health? Sometimes. And finally, what's the most surprising new thing that you've learned about gut bacteria? Well, I've known for a while how important it is for our metabolism and our immune system. But what's really struck me is the latest research showing how important it is for our brain and our mental health. I think that's really striking. And I think this is where we're going to be seeing some dramatic developments in the next few years. That sounds incredibly exciting. And actually, I'm looking forward to this whole podcast, because obviously we talk a lot about the bacteria that live in our gut and things like eating 30 plants and more fibre and also the way that our sleep and stress, all of these things can affect us. But we're talking about something different today, which is really exciting. So instead of focusing on the bacteria that are already inside us, we're going to talk about how those bacteria get there in the first place and i hope at the end a bit about how we might be able to get some more of the good ones so tim when does our gut microbiome you know this collection of bacteria start well since humans evolved we've basically been passing on our microbes from one generation to another as the sort of basic core building block set so it comes from our mothers so when we're in the womb essentially for all intents and purposes we're sterile in terms of microbes and it's the birthing process that is so messy and dirty and our mouth is designed to be in the right place through the birth canal that it's getting the microbes from the birth canal and the intestine so that our mouth as we're coming out is getting full of microbes and in the next few out as they develop and give us our building blocks for what then carries on. So it allows the child to have sufficient microbes that they can break down breast milk and survive. And then it uses that base to slowly build up for the next few years. But it takes really about four years until we have a proper functioning gut microbiome that resembles the adult form. And so when a fetuses in the womb there are no microbes inside its gut it's empty and then is it just by chance what you're describing that like they pick up some microbes as they're being born but equally well they could pick them up over the following few weeks or is there something more controlled about this it's controlled by evolution essentially we've had millions of years that all mammals go through this this birth process and it's been designed as a way of transmitting the microbes from one generation to another into the gut of the newborn. And so it's not by chance. This is basic natural selection. That's why the birthing process has been developed in this way, that as well as trying to ensure survival at the same time, it is a way of the mother passing on the microbes. And there are changes in the later stage of pregnancy in women, both in the vagina and in the gut microbiome where those microbes are changing specifically so they can be passed on to the child. So you're saying that you can actually see in the mother changes in their microbes in order to almost pass on this sort of inheritance of specific bugs? Precisely yes and that's in all mammals. That sounds crazy. Yeah but it's you know it just shows how important these microbes are to our survival and why it's been important for millions of years. And are those microbes that passed on and the microbiome, you know, when we're just a little baby, the same as the microbiome that I would have now as an adult? No, you'll still have traces of them, but at each stage of life, they form a particular purpose. So the ones you're getting the very first stages are the bifidobacter that are designed to break down breast milk and also to start the discussion with your immune system. So they're training your immune system. They're breaking down the breast milk into sugars that you can actually eat. So they're the key things. And you obviously don't need those as much when you're no longer drinking breast milk. So does that mean that there are bugs that were only useful in that first year that just sort of disappear and I don't have any more? Yes, or they might go down to really low levels. So there'd be the predominant species, these bifidobacteria that are really focused on breaking down the milk products, which are highly complicated structures that we still don't totally understand, but they're broken down into the bits that the baby can then use. and that sends chemical signals to the immune system it starts training it what what is normal food what's an alien bug all these kind of things start to to happen so that as the baby's growing the immune system is also learning from this interaction and so the the microbes that are being formed are also giving the baby this idea of early warning sensors about its environment and that's the other important piece it's not just breaking down the food it's also So sort of sensing the environment of that baby and whether the immune system should be worried or upregulated or calmed down. But the early microbes are really very different to the adult. And it's not as varied as the adult one is at all. So it's really much focused on these narrow aims. So it's not a very diverse microbiome at that stage. And it's also very flexible. So you see these really massive changes just from a slight change in diet. A virus might come through. Weaning produces really big changes, things that you don't see as dramatically in older children. So you're describing there like a vaginal birth, right, Tim? What happens to babies who are born by cesarean? That's really interesting. And of course, in many countries, that's nearly 50% of births now. and it's not what evolution had designed for us and it means that they're not getting the normal dose of microbes into the mouth they would be getting through a vaginal birth so they're born much more sterile and it takes longer for them to get those microbes inside them and there are quite big differences in the immune systems of babies born naturally and through cesarean section and studies have shown that the microbes being different gives an increased risk of allergic diseases atopy and get increases in weight as well in cesarean section babies it seems to be this effect doesn't last forever so that cesarean section babies do catch up which is nice because I was a cesarean section baby so it's nice to have felt that I've caught up a bit but it also might explain why you know I had lots of asthma and allergy as a kid so everything is slightly delayed and there are some scientists who believe that you should be seeding the microbiome of babies who've had a cesarean section this means that you should mimic what nature did and put a swab between the legs of the mother giving birth and smear the baby's face with those microbes to do that and there's still some scandinavian hospitals that practice this but the studies have not been conclusive that that actually materially changes the health of that baby so far so the jury's still out about whether you can trick the process you know have a cesarean section and still have that same natural birth i've experienced two births in my life which are my own children and I'm not a doctor, I haven't seen it in my life, a vaginal birth is a pretty messy experience in terms of what I've seen. Well, now you know why. I mean, it's designed to be messy. It's interesting, you know, so that's part of it. And you were describing, I think you were quite careful about the words, but it sounds like you're saying that historically babies evolved where not only are they getting sort of microbes that might come out of the mother's vagina, but actually they're ending up basically being exposed to like the poo of their mother as well. I just want to make sure I'm really clear about that, which I think to me as a modern person sounds sort of disgusting and unhygienic and dangerous. But it sounds like you're saying, on the other hand, that the C-section, which is completely sterile and avoids all of that, means weirdly that you don't get the same set of bugs and you could end up actually having more allergies and things as a little child than otherwise. Yeah, exactly. You're getting microbes from the vagina and the rectum, the lower part of the gut. And the fact that the mother's microbes have been changing in the last trimester precisely for that mean that, you know, that's the ones they want to pass on to the baby. And this is where they get these important bifidobactors from that then they can use to train the immune system and break down the milk. And when I think about how much we are really careful about cleanliness when babies are very little for a very good reason, And I can't really imagine a doctor replicating sort of the experience that you have through vaginal birth. You were describing trying to expose the baby to these bugs. But most doctors have not been very keen on that, and particularly microbiologists. They're worried that you'd be giving them potentially a bug to the baby. So there might be some streptococcus or something that you don't want to give them, which is slightly counterintuitive on the one hand. Because, well, that's what nature designed. But you're also saying that modern science is saying, well, you could give it. So most doctors are anti it and we still don't have the real definitive science to say which is actually best. I mean, obviously, natural delivery is always going to be the healthier, better option, as is breastfeeding. And, you know, the best of both worlds for the baby's gut is to have a natural birth and breastfeed. The worst is to have a cesarean section and bottle feed. Then you get more extreme differences in the microbiome. And whenever we talk about this, I think about how hard it is to be a mother and all the pressure about doing everything perfectly. So I think I also heard you say, like, if you do have a C-section, then in fact, in the longer term, your child will be fine. And that this sort of balances out over time. Tim, is that correct? Yes So we done some studies We looked at our twins for example their microbiomes of those that had C 40 years before and those that haven shown any differences in their adult microbiome so by that time it got out of the system so i think it only really the first few years of life that you are compromising the kid and that's why you might get more weight gain more allergies in those first few years immune system is not working as well as nature intended it could also be something to do with the antibiotics you're getting often routinely with cesarean sections that just slipped in you know by the anaesthetist without really much discussion as you know antibiotics have their problems and a lot of children are now getting many courses of antibiotics in those first few years without the mother being given full understanding of what's going on because we we treat them as having no real downsides although they can save life obviously they also come with a little cost to our immune systems and so if i have repeated antibiotics as a small child which is definitely my experience because i was growing up in the states and i think that's has been and continues to be even heavier use in the u.s that can have an impact on the microbes that i end up having when i'm an adult they haven't defensively shown that they've shown it in mouse models and they've shown it in epidemiology as well as you can do it's very hard to follow people over that length of time with those detailed records. But in general, that is true. But there might be different responses of people. So on average, yes, that's going to be true. But some people might be able to cope with antibiotics without any problems. Others are very sensitive. And is one course of antibiotics in my childhood going to have the same impact as having, you know, 20? No, the more courses you have, the worse. But there's also some evidence from animal studies that if you have small amounts of antibiotics, say from antibiotic-fed meat, that can also have a negative effect on your gut microbes. So we talked in a way about how you might not get the ones that you might have otherwise, but how do I get new ones? So you said that my microbiome is actually very simple as a baby when I'm built to be breastfeeding or if I am breastfeeding, but we know that once you're an adult, it's very complicated. There are all of these different species, where do they come from? For decades, we've been led to believe that the brain is completely separate from our body. We thought low mood was just chemicals and that cognitive decline was an inevitable part of aging, a roll of the dice we had no control over. But at Zoe, we know the science says otherwise, and the truth is far more revealing. There's growing evidence to suggest that our brain doesn't act alone. It's in a constant partnership with our gut. If you've been feeling that afternoon fog or noticing that your memory isn't quite what it once was, it might not be age, it might just be your menu. Your diet is actually one of the most powerful ways that you can protect your brain's lifespan and improve your energy levels. So how do you use this science to get a 10-year head start on a healthier brain? We put everything you need into a new guide called Eating for Better Brain Health. Inside, you'll find five strategic, easy to implement tips from my Zoe co-founder, Professor Tim Spector, along with science-backed recipes designed to feed your gut and your mind. And the best part? It's much easier than you think to make a change. Longevity isn't all about luck. It's a strategy and it starts with the next thing you put on your plate. Most people wait until they notice a decline to start caring about their brain. But longevity isn't luck. It's a choice you make before you need it. Don't leave your cognitive future to chance. Go to zoe.com slash brain health right now to claim your guide. That's zoe.com slash brain health or click the link in the show notes. Well, they come from all around us. They come from other humans. So when your baby's picked up by someone, whether it's a mother or a family member or a friend, they will be transmitting their microbes, which might be on their skin, from their saliva, but also gut microbes in tiny amounts all over. So babies like sucking things. So if you put your finger in a baby's mouth, they're going to be getting some of those microbes from other people. And that's generally how they gain these microbes slowly over time. And it seems to me the more people they come into contact with, the more different microbes they're going to be getting. And the environment also plays a role. So some of these will be in the air, some will be on surfaces. And there's a difference between sharing microbes in the mouth and sharing microbes in the gut, interestingly. So we did this big study of transmission. It was led by Nicholas Segata's team in Trento, looked at tens of thousands of people and looking at relationships and show there was a clear difference in how you gain your microbes in your mouth, which is actually from, put it bluntly, everyone's spitting in micro doses all around. Babies don't get all their oral microbes from their mother. They get it from everyone else in the family spitting at them. But this tells us what's happening all around us. So Tim, is that a bit the equivalent of how I get a cold? I'm thinking back to like what we learned in COVID, that if you are in a room with someone else who's sick, after 15 minutes you get the virus is this something similar in this case about my mouth bacteria yes even as we're speaking here there's probably a sort of cloud in the middle here of these you know little microbes that uh we're exchanging whereas we're much less likely to be exchanging our gut microbes jonathan you'd be pleased to know well what i'm thinking tim is i now want to step back away from you but unfortunately i need to stay near the microphone so i'm sorry so we probably need to touch more intimately to swap our gut microbes and that's why babies share most of their gut microbes with their mother for the first three years and that drops over time but it's a really close relationship whereas the oral microbiome is not shared as much with the mother it's the same with everyone in their family i think you're saying that the microbes that are in our gut are not the same species of microbes as might be in our mouth or might be, I don't know, on things that are just out there in the environment. Is that right? Yes. Every microbe has a particular environment it likes. So the ones that are sitting on this desk here are ones that like oxygen. They might also like our skin. So we might be able to hop onto our skin and like that the ones in our mouth will have to be certainly adapted to the acidity of our mouth and be able to cope with saliva but also quite like oxygen because there's a fair bit of oxygen going on whereas the ones in our gut generally don't like oxygen and like again different conditions so when we're swapping them they've got to be swapped to like an equivalent place so we need to get microbes actually only really are happy living inside the gut without air which makes me think well that is relatively hard to get those microbes onto me as a child or as an adult compared to the ones you're describing for my skin which which like the oxygen is is that right tim yes so very different talking about in your mouth on your skin in your gut they're all important though so we mustn't just focus just on the gut skin microbes are incredibly important for preventing skin diseases and keeping us healthy and oral microbiome is really important for fighting tooth decay and preventing heart disease etc so all these things are important but they we have to think of them slightly differently and there are a few oral microbes that can live in your gut. So they can obviously pass through. And there's a overlap between the mouth microbes and those in the small intestine as well. But each one has a little niche where they're happiest. Some can survive, but they're not very happy. So we get our oral microbiome basically just been around other people talking to us. And I now have this vision that, you know, if you're in like a Mediterranean environment, it's much better than if you're in, I don't know, finland and in my experience they're a bit quieter more reserved like the more the people around you like gesticulating and talking wildly the more oral microbiome sharing that's going on is this what you might be surrounded by you know 10 naked people in a sauna so there's different ways of combining socially but yes in general the bigger the family group or the social group the more you're going to be sharing your microbes and this is what the science is telling us as well and it comes back also to this idea of the hygiene hypothesis that the larger the family the less allergic diseases less atopic diseases and this is from an epidemiology colleague of mine david strachan who had worked out from looking at thousands of families that if you were either the the last born in a in a series of of kids or that it was a large family you were less likely to get allergies than if you're a small family or you're the first born. And it's this exposure to bugs and dirt and everything else that was basically helping your immune system. So it's this link between the more microbes you've got, the more diversity of microbes means that you have a tougher immune system, which means that it's much better trained. So it's not going to react and give you peanut allergy or asthma or eczema. So how am I picking up my gut microbes from the world around me as I'm going from one year's old to today? We don't know precisely, but there have been studies done to show that wherever people are touching surfaces, you'll find some gut microbes. Not as many, but if you go to the bathroom, studies have shown that you can find gut microbes all over the place we are literally surrounded by microbes everywhere and so it it might just be by touching a surface putting your hand in your mouth drinking a coffee generally between people you usually need more intimate contact so that's why we find that couples living together are going to be much closer in their gut microbes than say siblings living apart say that again so you're saying that you can tell whether or not you know i'm living with my wife or one of my siblings versus if we are not living in the same place from my gut microbes yes we'd be able to tell whether you have specific strains that you and your wife are sharing as opposed to you and your sister for example now with the latest science it's quite easy to do and that's what we did in our nature study so by looking at the precise strains which are very you know one below species level we know this one has been shared between people and so that's that's how we know that these effects are really real so if you want to show your gut microbes you cohabit with someone ideally you know you're in a close or sexual relationship but it's it's the physical closeness that's important and as soon as that starts to move away you lose it and and that closeness is more important than genetics so a couple living together are going to share more strains than identical twins unless those identical twins are sharing a bed which is unlikely so there's like a big sharing of microbes if you have a sexual partner yes exactly and is there still a big sharing like if you're in a household and i'm i guess i'm also thinking about kids is that also going on yes i mean the mother child one is the strongest of all that starts to fade away after the age of five and gets less and less then you've got people living in the household together and then as those relationships get more distant then it starts to fade apart but you can find differences we found strains that were similar in people living in the same village they weren't sexual partners or anything so just being in the same community you will have these same gut microbes in common these particular strains so your own gut is reflecting your environment and your social group I love this idea that my microbiome which is sort of like an organ right that's how you describe it to me Tim like it's like having my liver or something is almost a snapshot of all the people that I've met over time there's something sort of really cool about that although there are some people i've met who may be a bit unsavory so perhaps you know maybe you like it to be more selective we been talking about all these good gut bugs that you pick up to like build out an adult microbiome Can you also pass on the bad gut bugs Absolutely, yes. Most of these studies are in animals, in rodents, and they've done lots of transmission studies to show that you can do this. The first ones really showed that you could transmit things like obesity. so you took an obese animal and you then took its droppings and you put it into the feed of another mouse and it would gain weight so that was the first sign this was happening although those effects were quite small and what's been interesting recently is that the evidence is really building that you can take rodents with mental health issues they get very anxious and you take their droppings and you can transmit them and put them into another mouse that was normal and you make that that mouse anxious so that's probably the best evidence we have that transmitting microbes can actually alter the mental health of someone else and that's quite mind-blowing really to think that you know if in your family you're surrounded by all these anxious folk and you're swapping gut microbes there is the potential that some of those microbes could be working in an unhelpful way on your own mental health but the opposite could also be true so if you're if with someone who's really happy and really relaxed hopefully you want to be getting their microbes as well and it's still a bit unclear about which microbes work better and I think it's going to be very personalized to say, are you more likely to be a recipient of them or are you more likely to be a donor of them? That we don't know in humans yet. But we do now know for the first time sort of what the good bugs and the bad bugs are. Is that right, Tim? Yes, we're starting to understand that. And I think our recent Zoe paper in Nature was one of the first to get a comprehensive ranking score of healthy bugs and unhealthy bugs. but we haven't done it for every disease and we haven't really yet done this for mental health you know and how it affects the brain so we're just starting this journey but i think this will be really interesting because we'd all love to be able to say well how can i get all the good bugs and how can i somehow fight off all my friends bad bugs and just take the good stuff and if i you know meet someone once or date someone for a week is that going to make much of a difference i think the answer is it could do so say you're intimate with that person jonathan you would definitely be swapping oral and gut microbes with that person and if it turned out they were giving you some that had a niche in there that you know their bugs could fill easily then yes that would change your microbes permanently. Perhaps the healthier you are, the less likely it is to be disturbed by the other person. What about the environment more broadly? Can I change my gut microbiome if I just go and live in the countryside? The studies definitely show that people living in rural communities have a more diverse, healthier gut microbiome than people living in cities on average we also know that if you spend the first few years living in a rural environment and farms etc your immune system is much better you're going to get less allergies and problems but if you've been brought up in a farm and then you move into a city it seems you know you're not really protected long term so you perhaps have to live there more permanently you lose those microbes as you go into a city so that probably means that if you move from a city into a farm within a few years you would start getting the benefits of that and we know that you're getting the benefits of many more beneficial microbes you're getting microbes that are coming from soil microbes that are coming from animals all these things that you're not getting in cities where in the cities you're just getting microbes that love dry conditions you get more bad bugs more what they call pathogenic microbes when you swab houses in cities than you do in the countryside. So it is quite different, but we don't really yet know how we could use this as therapy. But definitely whenever you can, it shows us we should be going out in the countryside, hugging some trees, doing some gardening, getting dirty. Just going out into nature or getting your hands dirty, why is that going to help me? You'll be exposing yourself to microbes that are in the earth and the soil and some of those are also found in food so in vegetables and other things like this so some of them might be able to take hold inside your gut this is still we don't know very much about the interaction between all those different soil microbes and the human ones it's all still work in progress but it is really interesting that people who do spend a lot of time playing with soil or gardening do have better mental health than people that don't and it's one theoretical possibility that a lot of this is due to some of these microbes that is that is improving their gut health which then feeds back into their brain and does that mean that when we're outside in the environment and or gardening or whatever we should ignore all the advice that i feel that we've had pretty much the last 50 years which is like you must wash your hands all the time after doing this and never touch your mouth because actually it's what you're saying is it's it's not just being out in the environment it's getting my hands dirty and ultimately putting this in my mouth so that ends up in my gut is that what has to happen if i'm to get the benefit it does yes obviously you're to select which bit of earth you're taking whether you know it's not in the local park where you know your dogs have been um having a poo but um generally yes if it's in a healthy space you shouldn't be worrying about this and you shouldn't and you should be encouraging your children also to to get dirty without being obsessional about it and there's quite a lot of evidence that houses that you know are over sterile and do obsess too much about that side of things have a negative impact on on children's health their immune system being over sterile is bad i think that's quite a surprising message right we are generally told that we need to keep the environment of our children really clean and there are a million products sold i remember when my kids were really little that you would like spray on all your toys and sterilize them and wipes and you're saying actually that that's not just unnecessary but but might even be harmful that's great i think that the advice to sterilize everything is outdated now for every one infection that you might prevent which is extremely rare you could actually be causing more longer term problems so it's getting the risk and benefits properly balanced but there were studies of of showing randomizing people with toddlers and dummies when the dummy fell out as it invariably does they sterilized it and put it back and another one where they just put it back in the mouth without sterilizing it and allergy rates were lower in the ones that they hadn't sterilized so sometimes doing less is better and i think that's really surprising you just talk me through what's going on therefore so why is it that exposing your children to like the dummy that's fallen on the floor why on earth would you end up being healthier as a result the current theory is the dirty dummy that gets put back in has extra microbes on it that the baby has not been used to and this ends up going into the mouth and some of them going down into the gut, basically educating the immune system that it doesn't have to worry about these microbes. These are fine. There are small amounts of it. They're not going to do me any harm. I don't have to overreact. And the more times this happens, the more you're educating, training the immune system so that it doesn't overreact and fight back. Whereas the sterile dummy kid is hardly getting any microbes. the immune system you know it's just waiting around for something to do and then when it gets hit with you know some cow's milk or some peanuts at some point it then overreacts so that is a simplistic way of looking at it but it's i think we're moving into this idea that you know often eating and eating microbes is a way of training our immune systems for the rest of our lives and if we are too protective that's why we end up with this epidemic of allergic diseases that's all absolutely fascinating i'd love to talk about how we can use all of this to support our health and maybe just start like with me so i'm constantly trying to get more of the good bugs inside and tim as you know like when i first started at zoe and we right re-analyzed my samples. I had about 20 of the 50 good bugs. And about two and a half years ago, I'd grown that up to 38 by following all of your advice about what to eat. And then I took these really heavy antibiotics after I smashed open my toes. And we retested and I'd gone down to six good bugs. And I've been steadily working and eating as well as I can. And I've got it back up to 23. So it's a lot better than six, but it's only half of the 50 good bugs that you've identified. So my question is, how can I get more of the good bugs in my gut? And I'd love to talk about some of the different practical things that I might do. And just listening to some of the things you said, for example, like, should I go and get myself a dog? Yes, I think you should, actually. The science does support having a dog. there have been several studies now showing that dog owners have more diverse and healthier gut microbes than non-dog owners and i used to be very rude about people who had cats when i was talking about this five years ago but there have been some recent studies also showing that cat owners are also healthier and that you can get some of the microbes from cats into into your gut itself now we share more closely our gut microbes with our dogs they're more interchangeable because our diets are similar we're both omnivores whereas cats are rather different and really meat eaters so we don't know entirely why cats are beneficial but it could just be that they're bringing in lots of stuff from the garden all kinds of other microbes are there so anyone listening i'm sorry about being rude about cats in the past. I apologise, but science moves on. So a pet is one thing definitely you should get, Jonathan. Yes. I would suggest you do a bit more gardening. Do you like gardening? I do like gardening. Get dirty. Do that more often. Go for walks in parks more often. And of course, avoid doctors and antibiotics whenever you possibly can. Science suggests you can catch good gut bugs from your healthiest friends. Why not share this episode with your good friend to tell them that their microbes are the best gift you've ever been given? You might never think about a shared social occasion with them in the same way again. What about the food that I eat? So clearly, I mean, one of the things that has happened is that I have expanded that number a lot from when I first had those antibiotics. Are there live microbes also on the food? Because we haven't really talked about that yet today. there are live microbes on food and you may remember Jonathan we published this study on vegans vegetarians and omnivores a really big study and it clearly showed us that each of those different groups had a certain signature you could see in their gut microbes so the vegans and the vegetarians were showing microbes related to the plants they were eating these are species you probably won't have heard of enterobacter and citrobacter that you getting on the plants you can then detect in your stool samples so they're lasting all the way through and they're different to people who are mainly on on meat diets or processed diets so your diet can in a way bring in your garden into your health in the same way that me telling you to go gardening so the more plants you eat the more of these you going to be getting in your diet so that's why diet is such an important part of improving your health as opposed to these other lifestyle measures it's definitely the predominant one so more plant-based foods ideally if you can have organic you're going to get slightly more of the these and less of the pesticides on them that'd be fine tuning that diet and if you know the produce is coming from say an organic source that you trust don't worry about trying to scrub every last inch of earth off it that earth will probably be doing you some good as well so they're sort of classical things plus the 30 plants a week are quite crucial to this same rules about giving polyphenols so you're brightly colored brightly tasting plants to feed any gut microbes that are there and then fermented foods trying to get three portions of fermented foods in your diet all these will increase your good bugs relative to your bad bugs as well as all these these lifestyle measures. And if I were to choose to live with someone who's got a much healthier gut microbiome, so I can find someone like you, Tim, who's got almost all of the 50 good ones. I'm not available, Jonathan. Yes, but let's say I could. And in that situation, would I slowly improve my health, even without making any changes to my diet probably yes i mean the data we have is at one point in time we haven't followed couples up together but my guess is that's what would happen i don't know how much you would improve but you would definitely improve so it's definitely worth picking the best partner you can get the healthiest partner and maybe that's all part of you know why we select mates because we want them to be healthy but it's also a reason that if you're improving your diet you also want to improve the diet of your partner as well because they can have also a negative effect on you so you want them as healthy as possible mentally and physically and i'm thinking now about the opposite which is you know loneliness and we've had a number of really interesting podcasts with scientists explaining that sort of living on your own and lack of social interaction has like a really negative impact on your health. And I'm thinking out of this conversation that it's also likely to have a negative impact on my microbiome. Is that right? That's right. Strangely, they have done studies, and we did some of this as part of this transmission paper, showing that people that live in small groups or have very small network of friends or living on their own had on average worse microbial health than people that had lots of friends or lived in a large community so it looks like at least some of the the idea that loneliness is bad for your health your mental health and physical health you you tend to die earlier if you're lonely could be due to the partly to the effect of on the gut microbes as well and so if i'm listening to this am i and i am living on my own what are the like the key actionable advice that you would give to someone like that in order to sort of maximize the health of their microbiome i would say try and join a club where you meet people whether it's a walking club there are gardening clubs you could do so you you get out and you're have an allotment and you can meet other people you want to be going for walks in parks you want to be getting outdoors more so you don't want to be stuck indoors in air conditioning you want to be opening your your windows all the time and you want to perhaps go to the pub more socialize go to cafes try and get a range of people that you can meet up with and this will help your mental health and your gut health it's interesting that what you're describing is almost the same advice you give for someone if you were just thinking about sort of their mental health and the implications of being lonely tim i'm sort of struck by how much like the right thing to improve you know your microbiome access bugs feels almost like the same thing to live a happier life as a human being exactly i think what we're seeing is a real confluence of these ideas that the same advice to avoid depression and loneliness is the same advice you would give to someone to increase their lifespan longevity and we've talked about blue zones and how people in those zones are in these large communities they're never lonely you know they're always interacting with other people and then you know the the missing link is is is our gut health and our and our microbiome and they're all coming together you know the advice is virtually always the same but for different reasons and i think this is where the science is is really helping us understand because it must makes it much easier to take action of advice when you understand the scientific basis behind it. One of the things I'm struck by is how much you've talked about cleanliness in one way or another. And I'm also struck by this story you told me a while ago about visiting this tribe, the Hadza, who were hunter-gatherers, you said, and also this work where you've described that the microbiomes that we have today are just completely different to the sort of microbiomes that human beings had before, like running water and soap. Is there almost like two different ways of living as human beings, the way that we would have done until very recently where there was no soap and washing our hands, and then there's the world that we've been in after this? And what does that mean for us? Well, I think there's a halfway house. I think there are groups like the Hadza that live perfectly healthy without soap and water. but as soon as those groups get into big cities and you end up in slum situations you end up with terrible dysentery and childhood death etc and what we've done in the west is go to an extreme where we're giving everyone antibiotics we're sterilizing everything we're having food out of plastic sterile containers and we're not being exposed at all and i think the sweet spot is somewhere in the middle that you know we take the learnings from both and we say okay well let's do enough so that we're not going to get salmonella and dysentery every time we're eating but at the same time we are maximizing our our good bugs we're not killing them off now we have this new knowledge that we didn't have 20 years ago you know we're acting in a much more sensible way so i think we can still realize that having running water and basic sanitary conditions washing your hand after going to the toilet is absolutely still essential for our health, but not be obsessing so much about all kinds of sterility so that we remove it from helping our gut and our immune system. So like a lot of things somehow, it's not that we're doing things wrong, but maybe we've taken them too far or a bit like antibiotics, as you said, like it saves so many lives, but it doesn't mean you should just sort of pop it each time you have a sore throat because it does turn out that it has disadvantages as well exactly so we went too far down that road now we just have a bit of a correction uh and it's not like we're going to throw away antibiotics we'll still use them but we should just be realizing they have a downside and we should still sterilize some things but just realize that if you overdo it there's a downside so it's it's just being sensible and realizing that microbes basically most of them are our friends and we don't want to kill them all off because our body our immune system our physical and mental health absolutely depend on them amazing tim thank you so much i think it was really interesting to understand i think about how you know the science has been moving on and your understanding of things is different so all the cat owners on the podcast can be feeling much better the thing i'm most struck by is that if you want to actually exchange the most bugs then you're going to do that with a sexual partner. But if they have bad bugs, that could actually mean that you're going to put on weight or even become more anxious. So, you know, you really are sharing this sort of invisible world, which is extraordinary, that we now understand that our mothers are giving us this like parcel of microbes at the point that we're born and changing their own microbiome to give it to us at the point that we're born and that therefore if you have a c-section, you have more risks of things like allergies as a child. And indeed, if you take a lot of antibiotics as a child, this has a long-term impact. I'm really struck by your view of cleanliness, that it matters if you're living in a city, otherwise you could get some infectious disease. But actually, we've gone too far. And that you said that there were these studies where they looked at kids where if when they dropped the dummy on the floor, they just put it back in their mouth, they actually end up healthier than if you're sort of sterilizing that each time. And so we've sort of, again, sort of got too far in terms of not allowing them to ever get their hands dirty. And then the other thing I'm struck by is we talk a lot about the gut microbiome, but today you've been talking also about the importance of the oral microbiome in our mouth and our skin microbiome, and that they're all completely different. So you can't, it's not the same buck. So you could have a good gut microbiome, but a bad skin microbiome. And so, you know, the sort of the advice I've been talking about is to access all of these. But then pragmatically, what I took away from this was I need to get a dog. And apparently the dog's gut microbiome shares more bugs with me than a cat. So cat seems okay, but dog is better. Start gardening, because not only is it good for my general mental health, but maybe the microbes I'm going to be exposed to help there. Visit friends. So if you're not living in a big extended group with lots and lots of other people, then you want to be out with other people because that's about exposing this give them a hug which is good advice if you're really english like me so yes some interaction get out into nature and that's again it's not just because you feel good in five minutes from that better sense but you're saying there's also this exposure to these microbes so the food we eat matters and a big part of that is like eating these 30 plants to feed maybe the small amounts of microbes in my gut but also there actually will be microbes on the food and don't feel you obsessively have to strip everything off because in general those will be will be healthy keep the window open because you said if the air con's on and the window's closed actually i'm going to be exposed to a lot less and then finally don't obsessively clean around the house because actually most microbes are our friends not our enemy and if we sort of reduce this sense of being at war with them all we can actually not only be healthier but it sounds like have better mental health. You got it. I'll end this episode with something I think you'll like, a free Zoe gut health guide. If you're a regular listener, you know just how important it is to take care of your gut. Your gut microbiome is the gateway to better health, better sleep, energy and mood. The list just goes on. But many of us aren't sure how to best support our gut. I wasn't sure before doing Zoe, which is why we've developed an easy to follow gut health guide. It's completely free and offers five simple steps to improve your gut health. You'll get tips from Professor Tim Spector, Zoe's scientific co-founder and one of the world's most cited scientists, plus recipes and shopping lists straight to your inbox. We'll also send you ongoing gut health and nutrition insights, including how Zoe can help. To get your free Zoe gut health guide, head on over to Zoe.com slash gut guide. Thanks for tuning in and see you next time.