5 ways relationships change your gut health | Prof Tim Spector

Summary

---

ZOE Science & Nutrition

Episode: 5 ways relationships change your gut health
Guest: Prof Tim Spector
Host: Jonathan Wolf
Date: February 5, 2026

---

Episode Overview

In this episode, host Jonathan Wolf interviews Professor Tim Spector—a leading expert on the gut microbiome—about how our relationships and environment influence our gut health. The conversation explores how gut bacteria are shared, the lifelong consequences of early microbial exposures, and the surprising impact of human connection and cleanliness on our microbiome.

---

Key Discussion Points & Insights

1. Rapid-fire Q&A: Gut Microbe Myths and Facts

• Most bacteria are not harmful:
  “Do most bacteria cause disease?”
  “No.” (Tim Spector, 01:22)
• We aren’t born with a microbiome:
  “Are we born with a fully formed gut microbiome?”
  “Nope.” (Tim Spector, 01:27)
• Contact shapes our microbes:
  “Is our gut microbiome influenced by who we live with?”
  “It is.” (Tim Spector, 01:32)
• Pets generally help:
  “Is having a pet good for our gut microbiome?”
  “Usually, yes.” (Tim Spector, 01:37)
• Anxious microbes may be catchy:
  “If we spend time with someone with anxiety, could their gut bugs make us more anxious?”
  “It could.” (Tim Spector, 01:46)
• Soil contact may help:
  “Can bacteria from soil benefit our health?”
  “Sometimes.” (Tim Spector, 01:52)
• Microbes and mind-blowing new science:
  “What’s the most surprising new thing you’ve learned about gut bacteria?”
  “...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 gonna be seeing some dramatic developments in the next few years.” (Tim Spector, 02:00)

---

2. Where Do Our Gut Microbes Come From?

Birth & Early Life

• Microbial inheritance begins at birth:
  Babies are effectively sterile before birth. The messy birthing process purposely exposes the newborn’s mouth to microbes from the mother’s birth canal and gut—setting up their initial microbiome.
  “It’s the birthing process that is so messy and dirty... our mouth, as we’re coming out, is getting full of microbes... that give us our building blocks...” (Tim Spector, 02:59)
• Evolution designed birth for microbial transfer:
  “It’s been designed as a way of transmitting the microbes from one generation to another into the gut of the newborn... natural selection. That’s why the birthing process has been developed in this way.” (Tim Spector, 04:29)
• Microbial profile changes through childhood:
  Babies’ early microbes (especially Bifidobacteria) train the immune system and digest breastmilk. These decrease once breastfeeding ends, and the child’s microbiome becomes more diverse and adult-like by age four. (Tim Spector, 05:51–07:30)

Cesarean Section vs. Vaginal Birth

• C-section babies miss out initially:
  Without exposure to vaginal and gut microbes at birth, C-section babies have altered early microbiomes, leading to higher allergy and weight risks that largely normalize by adulthood.
  “They’re born much more sterile and it takes longer for them to get those microbes inside them...” (Tim Spector, 08:08)
  “So by that time it’s got out of the system. I think it’s only really the first few years... that you are compromising the kid.” (Tim Spector, 12:43)
• Seeding C-section babies is unproven:
  Swabbing babies with vaginal microbes after C-section is practiced in some places, but conclusive benefits are lacking.

Antibiotics & Early Diet

• Antibiotic use in early childhood matters:
  More courses in infancy, especially alongside C-section, increase the risk of lasting microbiome disruption and health impacts. Even low-dose exposure (such as antibiotic-fed meat) is risky. (14:33)

---

3. How We Continue to Acquire Microbes

People, Pets, and Our Environment

• We share microbes with those around us:
  Physical contact, shared environments, and social groups all serve as reservoirs for microbial exchange.
  “When your baby’s picked up by someone... they will be transmitting their microbes, which might be on their skin from their saliva, but also gut microbes, in tiny amounts all over...” (Tim Spector, 16:25)

• Mouth, skin, and gut microbes are different:
  Each niche (mouth, skin, gut) has adapted bacteria, and swapping is easier between same environments (oral to oral, etc.). Oral microbes are shared simply by being in the same room and talking.
  “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...” (Tim Spector, 18:29)

• Closeness trumps genetics:
  Couples, housemates, and communities share more gut microbes than relatives who don’t live together.
  “Closeness is more important than genetics. So a couple living together are gonna share more strains than identical twins. Unless those identical twins are sharing a bed...” (Tim Spector, 23:24)

• Pets boost microbial diversity:
  Both dogs and cats deliver environmental microbes. Dogs, as omnivores, overlap more with us. Even previously skeptical Tim admits cats help.
  “Dog owners have more diverse and healthier gut microbes... Cat owners are also healthier... Anyone listening, I’m sorry about being rude about cats in the past.” (Tim Spector, 35:46 & 36:52)

• Larger social groups and rural living help:
  “People living in rural communities have a more diverse, healthier gut microbiome than people living in cities on average.” (Tim Spector, 28:46) “...if you move from a city into a farm, within a few years, you would start getting the benefits...” (Tim Spector, 29:26)

---

4. The Good, the Bad, and the Contagious

• You can inherit ‘bad’ bugs too:
  “You can take rodents with mental health issues... You make that mouse anxious. That’s probably the best evidence we have that transmitting microbes can actually alter the mental health of someone else.” (Tim Spector, 25:41)
• Obesity transmission in animal studies:
  Sharing gut microbes from obese mice makes recipient mice gain weight.
• Short-term relationships can still pass microbes:
  Intimate contact, even for a week, can affect the recipient’s gut biome if the microbes find a niche. (Tim Spector, 28:10)

---

5. Cleanliness—Finding the Sweet Spot

• Sterility may be unhelpful or harmful:
  Excessive sterilization (toys, dummies, hands) can limit microbial exposure, increasing allergy and immune risk.
  “The advice to sterilize everything is outdated now. For every one infection that you might prevent... you could actually be causing more longer term problems.” (Tim Spector, 32:30)
• Immune system training:
  “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... we end up with this epidemic of allergic diseases.” (Tim Spector, 33:28–34:37)
• Don’t skip basic hygiene after the bathroom or handling raw food, but don’t obsess over everyday dirt.

---

6. How to Maximize Good Microbes—Actionable Advice

Practical Steps for All Ages

• Get a pet:
  “Yes, I think you should. Actually, the science does support having a dog... Cat owners are also healthier...” (Tim Spector, 35:46)
• Embrace gardening & nature:
  Dig in the dirt, garden, walk in parks, and avoid over-sterilizing afterwards—especially if the dirt is healthy.
  “Go for walks in parks more often. And of course avoid doctors and antibiotics whenever you possibly can.” (Tim Spector, 36:54)
• Eat a diverse, plant-based diet:
  “Your diet can in a way bring in your garden into your health in the same way that me telling you to go gardening...” Eat a variety—aim for 30 different plants per week (fruits, vegetables, legumes, grains, seeds), plus fermented foods.
  “Try to get three portions of fermented foods in your diet, all of these will increase your good bugs relative to your bad bugs...” (Tim Spector, 39:38)
• Eat organic and don't over-scrub produce:
  Residual dirt may bring beneficial microbes.
• Socialize and join groups:
  Clubs, cafes, community gardens, and pubs expose you to a greater variety of microbes.
  “Try and join a club where you meet people... get out and you have an allotment... cafes, try and get a range of people...” (Tim Spector, 42:14)
• Physical contact matters:
  Living closely—especially intimate relationships—leads to greater microbe sharing.
• Keep the windows open:
  Ventilate your home to bring in more environmental microbes.

If You’re Lonely or Living Alone

• Social connections matter beyond mental health—they also boost microbial diversity.

---

7. Notable Quotes & Memorable Moments

• “Our microbiome is a snapshot of all the people we’ve met over time.” (Jonathan Wolf, 25:08)

• “Closeness is more important than genetics. So a couple living together are gonna share more strains than identical twins.” (Tim Spector, 23:24)

• “Most microbes are our friends and we don’t want to kill them all off... our body, our immune system, our physical and mental health absolutely depend on them.” (Tim Spector, 47:02)

• “The same advice to avoid depression and loneliness is the same advice you would give to someone to increase their lifespan... the missing link is our gut health and our microbiome, and they’re all coming together.” (Tim Spector, 43:21)

• “For every one infection that you might prevent, which is extremely rare, you could actually be causing more longer term problems. So... sometimes doing less is better.” (Tim Spector, 32:30)

---

Timestamps for Important Topics

| Time | Topic/Quote | |----------|----------------------------------------------------------------------------------------------------------| | 01:18 | Rapid-fire Q&A with Prof Spector | | 02:00 | Gut microbes and their surprising link to brain health | | 02:59 | Passage of microbes during birth | | 08:08 | Gut microbiome differences in C-section vs. natural birth | | 12:43 | Long-term catch-up by C-section babies | | 14:33 | Impact of early antibiotics and food-borne antibiotics (meat) | | 16:25 | Microbe sharing through touch, environment, and air | | 18:29 | Importance of close and intimate contact vs. casual for sharing gut microbes | | 23:24 | Closeness vs. genetics in sharing microbiomes | | 25:41 | Transmission of "bad" bugs, including mental health effects in rodent studies | | 28:46 | Rural life vs. city for microbial diversity | | 32:30 | Over-sterilization and allergy rates—"outdated advice" | | 35:46 | Pets improve gut bacteria diversity; cats and dogs | | 39:38 | Plant-based diets, fermented foods, and microbial transfer via food | | 42:14 | Socializing, clubs, and community as ways to boost your microbiome | | 43:21 | Overlapping advice for microbiome, mental health, and happiness | | 47:02 | “Most microbes are our friends...” synthesis of the episode's key message |

---

Key Takeaways

• Your gut, oral, and skin microbiomes are distinct—and shaped by birth, touch, cohabitation, pets, environment, and diet.
• Early life exposures (birth route, breastfeeding, antibiotics) set the stage, but adult microbial health is dynamic and influenced by social and environmental context.
• Intimate contact (especially sexual partners) is the most powerful way to share gut microbes among adults, more than genetics or friendship.
• Clean isn’t always better: reasonable hygiene remains key, but over-sterilization limits microbial diversity and may drive allergies and immune problems.
• Plant-heavy, diverse diets (with some “dirt” left on produce) and fermented foods feed a healthy microbiome.
• Pets (especially dogs), gardening, and outdoor activity boost diversity, as does socializing and sharing your home.
• Loneliness and social isolation impact not only mental health, but also microbial health—so seek out connections for a healthier mind and gut.

---

Summary by ZOE Science & Nutrition Podcast – Listen, learn, and build a healthier, more connected self—microbes included.

Transcript

[A]

Welcome to Zoe Science and Nutrition, where world leading scientists explain how their research.

[B]

Can improve your health.

[A]

Strep throat, food poisoning, pneumonia. All examples of nasty microbes that spread.

[B]

Easily from person to person.

[A]

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.

[B]

A leading expert on the gut microbiome.

[A]

One of the world's top 100 most cited scientists and my scientific co founder here at Zoe. In this episode, Tim will help us answer these questions and explain how to maximize the benefits of sharing good microbes with friends and family.

[B]

Tim, thank you for joining me today.

[C]

A pleasure as always, Jonathan.

[B]

So you know the rule. We're going to kick off with a rapid fire Q and A from our listeners. You ready to go?

[C]

Ready.

[B]

Do most bacteria cause disease?

[C]

No.

[B]

Are we born with a fully formed gut microbiome?

[C]

Nope.

[B]

Is our gut microbiome influenced by who we live with?

[C]

It is.

[B]

Is having a pet good for our gut microbiome?

[C]

Usually, yes.

[B]

If we spend time with someone with anxiety, could their gut bugs make us more anxious?

[C]

It could.

[B]

Jonathan, can bacteria from soil benefit our health?

[C]

Sometimes.

[A]

And finally, what's the most surprising new.

[B]

Thing that you've learned about gut bacteria?

[C]

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 gonna be seeing some dramatic developments in the next few years.

[B]

That sounds incredibly exciting and actually I'm looking forward to this whole podcast. Cause obviously we talk a lot about the bacteria that live in our gut and things like eating 30 plants and more fiber 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?

[C]

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 hours, 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 property, functioning gut microbiome that resembles the adult form.

[B]

And so when a fetus is 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?

[C]

It's controlled by evolution, essentially. We had millions of years that all mammals go through 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.

[B]

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?

[C]

Precisely, yes. And that. That's in all mammals.

[B]

That sounds crazy.

[C]

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.

[B]

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?

[C]

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.

[B]

So does that mean that there are bugs that were only useful in that first year? They just sort of disappear and I don't have any more?

[C]

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.

[B]

And.

[C]

And that sends chemical signals to the immune system. It starts training it, what is normal food? What's an alien bug? All these kind of things start to happen so that as the baby's growing, the immune system is also learning from this interaction. And so 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 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.

[B]

So you're describing there like a vaginal birth, right, Tim? What happens to babies who are born by Caesarean?

[C]

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 caesarean section. And studies have shown that the microbes being different gives an increased risk of allergic diseases atop. And you get increases in weight as well in caesarean section babies. It seems to be this effect doesn't last forever. So the cesarean section babies do catch up, which is nice because I was a caesarean 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 that. 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.

[B]

I've experienced two births in my life which are my own children.

[C]

I'm not a doctor.

[B]

I haven't seen them in much life. A vaginal birth is a pretty messy experience in terms of what I've seen.

[C]

Well, now you know why. I mean, it's designed to be messy. It's interesting, you know, so that's part.

[B]

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 micro 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.

[C]

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 bifidobacters from that then they can use to train the immune system and break down the milk.

[B]

And when I think about how much we are really careful about cleanliness when babies are very little for very good reason, 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.

[C]

But most doctors have not been very keen on that, and particularly microbiologists 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 your the baby's gut is to have a natural birth and breastfeed. The worst is to have a caesarean section and bottle feed. Then you get more extreme differences in the microbiome.

[B]

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?

[C]

Yes. So we've done some studies. We looked at our twins, for example, their microbiomes of those that had C sections 40 years before and those that hadn't haven't shown any differences in their adult microbiome. So by that time it's got out of the system. So I think it's 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 by the anesthetist 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 treat them as having no real downsides, although they can save life, obviously they also come with a little cost to our immune systems.

[B]

And so if I have repeated antibiotics as a small child, which was definitely my experience, cause I was growing up in the States and I think that's has been and continues to be even heavier use in the US that can have an impact on the microbes that I end up having when I'm an adult.

[C]

They haven't definitively 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 very sensitive.

[B]

And is one course of antibiotics in my childhood gonna have the same impact as having, you know, 20?

[C]

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.

[B]

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. And there are all of these different species, where do they come from?

[A]

For our scientific co founder, Professor Tim Spector, the quest for better brain health is deeply personal. Tim watched his mother live with dementia for years. And he's long known about his own genetic risks for high blood pressure. Recently, Tim underwent comprehensive brain testing. And despite his expertise, his scans revealed something startling. High exposure to microplastics. It was a wake up call that our environment and our biology are under constant pressure. This led Tim to double down on the nutrition principles that we've developed here at Zoe that protect cognitive longevity. And we've compiled those principles into a brand new guide called Eating for Better Brain Health. This isn't just generic advice. This is your brain gut blueprint. Inside we break down five core strategies like pivoting your protein to clear your vascular highways. We even include the kimchi kick breakfast recipe to lower your inflammatory response. As Tim says for 40 years, we've been going down the wrong path, treating the brain as something different from the rest of the body. Stop leaving your brain health to chance. Learn exactly how to rewire how you think, starting with what's on your plate. Download the guide for [e-mail] brainhealth that's zoe.com brainhealth or click the link in the episode description.

[C]

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 Sagata's team in Trento, Looked at tens of thousands of people and looking at relationships and showed 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.

[B]

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 15 minutes, you get the virus. Is there something similar in this case about my mouse bacteria? Yes.

[C]

Even as we're speaking here, there's probably a sort of cloud in the middle here of these little microbes that we're exchanging, whereas we're much less likely to be exchanging our gut microbes. Jonathan, you'd be pleased to know.

[B]

Well, what I'm thinking, Tim, is that I now want to step back away from you, but unfortunately I need to stay near the microphone, so I'm sort of.

[C]

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.

[B]

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. Is that right?

[C]

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 they might be. 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 they also quite like oxygen. Cause 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 gotta be swapped to like an equivalent place.

[B]

So we need to get microbes that 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 light the oxygen. Is that right, Tim?

[C]

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 our oral microbiome is really important for fighting tooth decay and preventing heart disease, et cetera. 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.

[B]

So we get our oral microbiome basically just being around other people talking to us. And I now have this vision that if you're in a Mediterranean environment, it's much better than if in, I don't know, Finland. And in my experience, they're a bit quieter and more reserved, like the more that people around you, like Gesticulating and talking wildly, the more oral microbiome sharing that's going on. Is this what's happening?

[C]

But in Finland, you might be surrounded by 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 last born in a series 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 firstborn. 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.

[B]

So how am I picking up my gut microbes from the world around me as I'm going from 1 years old to today?

[C]

We don't know precisely, but there've 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 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.

[B]

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.

[C]

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 share your gut microbes, you cohabit with someone. Ideally, you know you're in a close or sexual relationship, but it's the physical closeness that's important. And as soon as that starts to move away, you lose it. And that closeness is more important than genetics. So a couple living together are gonna share more strains than identical twins. Unless those identical twins are sharing a bed, which is unlikely.

[B]

So there's like a big sharing of microbes if you have a sexual partner?

[C]

Yes, exactly.

[B]

And is there still a big sharing, like if you're in a household? And I guess I'm also thinking about kids. Is that also going on?

[C]

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.

[B]

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 unsavoury. So perhaps, you know, maybe you'd like it to be more selective. We've 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?

[C]

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. And 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 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 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 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 gonna 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.

[B]

But we do now know for the first time, sort of what the good bugs and the bad bugs are. Is that right, Tim?

[C]

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 unhealth bugs. But we haven't done it for every disease, and we haven't really yet done this for mental health 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 somewhat fight off all my friends, bad bugs, and just take the good stuff?

[B]

And if I meet someone once or date someone for a week, is that going to make much of a difference?

[C]

I think the answer is it could do. So, say you are intimate with that person, Jonathan, you would definitely be swapping oral and gut microbes with that person. And if it turned out that 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.

[B]

What about the environment more broadly? Can I change my gut microbiome if I just go and live in the countryside?

[C]

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, et cetera, 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'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. The. 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, you know, 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 and getting dirty.

[B]

Just going out into nature or getting your hands dirty. Why is that going to help me?

[C]

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 improving their gut health, which then feeds back into their brain.

[B]

And does that mean that when we're outside in the environment 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 not just being out in the environment, it's getting my hands dirty and ultimately putting this in my mouth so that it ends up in my gut. Is that almost what has to happen if I'm to get the benefit?

[C]

It does, yes. Obviously, you gotta select which bit of Earth you're taking, whether it's not in the local park where you're dogs have been having a poo, but 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 get dirty without being obsessional about it. And there's quite a lot of evidence that houses that are over sterile and do obsess too much about that side of things have a negative impact on children's health. Their immune system being over sterile is bad.

[B]

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 spray on all your toys and sterilize them and wipes. And you're saying actually that that's not just unnecessary but might even be harmful.

[C]

That's correct. 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 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.

[B]

And I think that's really spiritual. Could you just talk me through what's going on? Therefore. So why is it that exposing your children to the dummy that's fallen on the floor, why on earth would you end up being healthier as a result?

[C]

The current theory is that 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, into the gut. Basically educating the immune system that it doesn't have to worry about these microbes. These are fine, they're 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 like 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 is just waiting around for something to do. And then when it gets hit with some cow's milk or some peanuts. At some point, it then overreacts. So that is a simplistic way of looking at it. But I think we're moving into this idea that 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.

[B]

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 with me. So I'm constantly trying to get more of the good bugs inside. And Tim, as you know, when I first started at Zoe and we reanalyzed 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've said. For example, should I go and get myself a dog?

[C]

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 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 even 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 apologize. But, you know, 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?

[B]

I do like gardening.

[C]

Get dirty, do that more often, go for walks in parks more often. And of course avoid doctors and antibiotics whenever you possibly can.

[A]

Science suggests you can catch good gut.

[B]

Bugs from your healthiest friends.

[A]

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.

[B]

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.

[C]

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're getting on the plants that 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 meat based 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're 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 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 doing you some good as well. So they're so classical things. Plus the 30 plants a week are quite crucial to this. Same rules about giving polyphenols, so your 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 of these will increase your good bugs relative to Your bad bugs, as well as all these lifestyle measures.

[B]

And if I were to choose to live with someone who's got a much healthier gut microbiome than me, let's say I can find someone like you, Tim, who's got almost all of the 50 good ones.

[C]

I'm not available, Jonathan.

[B]

But let's say I could. Let's say I could. And in that situation, would I slowly improve my health even without making any changes to my diet?

[C]

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 why we select mates, because we want them to be healthy. But it's also a reason that. But 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.

[B]

And I'm thinking now about the opposite, which is 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 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?

[C]

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 idea that loneliness is bad for your health, your mental health, and physical health, you tend to die earlier if you're lonely. Could be due to the. Partly to the effect on the gut microbes as well.

[B]

And so if I'm listening to this and I am living on my own, what are the key actionable advice that you would give to someone like that in order to maximize the health of their microbiome.

[C]

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 get out and you 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.

[B]

So it's interesting that what you're describing is almost the same advice as 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 the right thing to improve your microbiome access bugs feels almost like the same thing to live a happier life as a human being.

[C]

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. 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 missing link is our gut health 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 really helping us understand because it makes it much easier to take actionable advice when you understand and the scientific basis behind it.

[B]

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?

[C]

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, et cetera. 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 we take the learnings from both and we say, okay, well, let's do enough so that we're not not going to get salmonella and dysentery every time we're eating. But at the same time, we are maximizing our good bugs. We're not killing them off. Now we have this new knowledge that we didn't have 20 years ago. 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 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.

[B]

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, 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.

[C]

Exactly. So we went too far down that road. Now we just have to have a bit of a correction. 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 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.

[B]

Amazing. Tim, thank you so much. I think it was really interesting to understand, I think, a part how 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 were born. And that therefore if you have a C section, you know, you have more risks of things like allergies as a child. And that 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 drop 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 bug. So you could have a good gut microbiome, but a bad skin microbiome. And so you know, the sort of the advice 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 then 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 getting 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 and give them a hug, give them a hug. Which is good advice if you're really English like me. So yes, have 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 that the food we eat matters. And a big part of that is 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 aircon's on and the windows 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 out as you can imagine hosting this podcast, running Zoe, juggling family life. It all keeps me pretty busy. So I try as best I can to stay energized and show up well in all those parts of my life by fueling my body with the right food, by exercising, and by adding a scoop of daily 30 to my meals every day. If you haven't heard of Daily 30 yet, it's the gut supplement designed by our gut health scientists here at Zoe. It's made of over 30 high quality hand picked plants including seaweed, fungi and.

[A]

Different types of fiber.

[B]

Better yet, it contains ingredients that support gut health, digestion and energy, which is ideal for packed calendars and busy lives.

[A]

Simply add one scoop a day to.

[B]

Any meal for an extra boost of fibre and plant diversity. And because it tastes delicious on just about anything and adds a satisfying crunch.

[A]

It quite quickly slots into your life, becoming a daily healthy habit you'll always have time for.

[B]

By the way, whenever we talk about Daily 30 as a good source of fiber, we're required to say that it contains 4 grams of total fat per serving. Obviously that's all amazing healthy fats from plants, so order yours [e-mail] Daily30 thanks for listening and see you next time.