Are You Sharing Your Microbiome with Your Romantic Partner or Your Roommate? With Dr. Nicola Segata

Are you sharing your microbiome with your roommate? What about your romantic partner?
In this episode of Causes or Cures, Dr. Eeks talks with microbiome researcher Dr. Nicola Segata about new research showing that we may share parts of our microbiome with the people we live with—including family members, roommates, and romantic partners.
They discuss how our microbiomes are shared between people, why romantic partners show particularly high levels of oral microbiome sharing, and whether kissing may be partly responsible. They also explore the surprising connection between the oral and gut microbiomes and what the findings could mean for our health.
Dr. Segata and Dr. Eeks also discuss whether some microbes are better at spreading than others, what the research does—and doesn't—tell us about cardiometabolic health, whether probiotics can meaningfully change our microbiome, and how much control we really have over the microbial communities living within us.
And if we're sharing our microbiomes with the humans we live with...what about our dogs?

About Dr. Nicola Segata:
Dr. Nicola Segata is a professor and microbiome researcher at the University of Trento in Italy and a principal investigator at the European Institute of Oncology in Milan. He founded his research laboratory in 2013, bringing together computational scientists, experimental biologists, statisticians, and clinicians to study the human microbiome, its diversity, and how it may influence human health and disease. 

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Transcript

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SPEAKER_00 0:00

Welcome to the Cositor Cures Podcast, your gateway to understanding health and groundbreaking medical research in a fun and easy to understand way. With Dr. Ass your house, join us as we sit down with the world's leading doctors and scientists to unravel the mysteries of health. From practical tips on well-being to the latest breakthroughs in medical research, we cover it all. Don't forget to subscribe. Now let's ignite our curiosity and together dive into today's episode.

SPEAKER_02 0:31

Hello everybody, and welcome to this episode of Causes or Cures. I'm Dr. Eeks, your host, and glad you're here. So, we share a lot with the people we live with. Apparently, even our microbiomes. New research suggests our microbiomes overlap with those of romantic partners, family members, and roommates. But what about the other creatures sharing our homes? Like our dogs, cats, of course, I asked about that in the podcast. My guest today is Dr. Nicolai Segata, a researcher joining us from Italy, who is going to talk to us about his work in this area. So we're gonna talk about who we're swapping microbiomes with, how the microbes get from one person to another, and whether any of this could affect our health. It's a good one. It's really interesting. So let's connect and see where this goes. Alright, everyone, we are connecting with Dr. Nicolai Segata, and hopefully I didn't massacre your name. Um, but thanks for being here. And before we get started talking about you know the microbiome and that kind of thing, do you mind telling our listeners a little bit about you and what you do?

SPEAKER_01 1:48

Sure. So thanks for the invitation. And uh yes, uh, my name is Nicola Segata, I'm a professor at the University of Trento, Italy, Northeast Italy. Uh, where uh where I have my lab, 30 people also working doing research in microbiome in the microbiome field, both from uh the idea of trying to understand more about uh this uh uh complementary part of our cells, this microbial complement of our cell, but also trying to understand how to apply it in the biomedical field, especially.

SPEAKER_02 2:18

Nice. So wait, where are you in Italy?

SPEAKER_01 2:21

Is it uh it's trying to is uh northeast uh on the Dolomites, uh close to Lake Garda, uh maybe it is.

SPEAKER_02 2:30

Okay, I I was in Italy once a while ago. It's it be it's beautiful country. I definitely want to go back, but um, I was just trying to, in my head, like, okay, where are you?

SPEAKER_01 2:40

Um between Verona and the Border Pitostria.

SPEAKER_02 2:44

Okay, okay, nice, nice, lucky you. And you have 30 people in your lab?

SPEAKER_01 2:49

Yeah, more or less uh that's the number of researchers, uh PhD students, postdocs, and uh uh researchers working.

SPEAKER_02 2:57

Okay, so the study that I was looking at um that caught some headlines, and you found that people who live together share microbes. So I let's start there. Like, how much of our microbiome is really our own? How much are we borrowing from people around us?

SPEAKER_01 3:15

Yes, so this is uh I think an extremely interesting uh question that we start asking ourselves a few years ago. And uh the reason why we started asking it uh was that uh we know that babies in the in utero are sterile if the pregnancy is physiological and normal. But already a few days of life, the baby is colonized by tons of microbes. Right? So the question was where are these bacteria coming from? The other observation uh was that uh when we look at the microbiome, so for maybe if we want to define a microbiome is the uh is the full set of bacteria, viruses, archaea, and fungi that are colonizing our body, our gut uh environment, our own cavities, skin, and so on and so forth. And uh when we were analyzing uh the microbiome of different people, we always found a different composition. And different composition means that if you and I, for example, are sharing some species, as Crickia coli, maybe in my gut and also in your gut, and a few other species are probably common. But when we look at the specific strain, the specific variants of this bacterium, uh, most of the cases is a completely different bacteria, right? And so the microbiome of each of us is extremely unique, way more unique than our own genome, for example. So, you know, we need to get these microbes from from somewhere, and our microbiome is extremely complex. So we start asking ourselves where are we getting our microbes from, and what are the main, the many sources that have to be uh there uh to explain why we all collect different microbes here and there.

SPEAKER_02 5:01

Yeah, that's true. But people think of like food, right? Like what your diet.

SPEAKER_01 5:05

Food, yes, food, we studied food, uh food uh is full of microbes, fermented food uh is composed by microbes, no, in the fermented food or even yogurt or stuff like that, uh you know, microbes are an active part of the uh of the food. We eat the food, so the food we know has a lot of impact on our health, on our microbiome. But actually, there are very, well, a relatively limited set of bacteria that can live both in the food and also in our gut. Our gut is uh is an environment in which oxygen is completely absent. And bacteria, they usually either love oxygen or ate oxygen. Those that are living in the food, they have to be tolerant at least to oxygen, otherwise they won't they will not live. So this is just one of the reasons, but but uh there are uh we estimated up to 3% of the micro strength in the food that can also be present and colonize our gut environment. I'm not telling that the food has not impact on the gut microbiome because as soon as the food arrives, it will stimulate our microbiome, we'll give compounds for our microbiome to grow and stuff like that. But in terms of providing direct uh microbes that will then become part of our cell is relatively limited. So we we had to look for other sources. And going back to the babies, to the uh little babies, what we did, and this was a few years ago here in Trento, what we did was to sample the microbiome of pregnant women before, of course, they were giving uh birth, and then the baby already had one day of life. And what we found, this was already probably seven or eight years ago, or even more actually, what we found was that the strains, the variance of the microbes that we found in the baby, 50-60 percent of them were only were also fine only in the corresponding mother. No other mothers have the same strain. So, you know, it has to be that the baby was getting uh the microbes directly from the mother already actually during delivery. And in fact, when we look at uh you know normal delivery or uh cesarean section, we see that the amount of microbes in the baby from the mother is much, much higher in normal pregnancy because there is contact during delivery compared to cesarean section. So this is clearly one uh source of uh the microbial diversity, but this is the source of microbial diversity in the newborns, right? So few days of life. There is a lot going on between the microbiome of a newborn to our adult uh microbiome. So this is the mother at birth is not the only uh reason for our microbiome composition.

SPEAKER_02 7:56

Not the only source, but I guess could you call it the foundation?

SPEAKER_01 8:01

Yes, I think the foundation is a very nice name, and uh uh and also you know the founding the founding role clearly has more importance than those that arrive later. No, for sure, the first microbes arriving to our gut are the first stimulating our immune system, and our immune system has a memory, so the first one arrives clearly uh uh probably has a much higher impact than those that are coming uh later.

SPEAKER_03 8:29

Right, right, right.

SPEAKER_01 8:30

But of course, we change a lot, no, uh we change our diet, we change our biophysical conditions, so also the microbes have to change uh during uh years.

SPEAKER_02 8:44

Yeah, it's just interesting to think about because the microbiome, the importance that it has now, you know, in health, it, you know, and every everybody's talking about the microbiome. And I mean, obviously, more people understand it better than others, like you understand it better than me and probably a bunch of other people out there, but it's just become this hot term, you know.

SPEAKER_01 9:03

It is a hot term, yes. And uh with this, there are a lot of uh nice aspects of it. We we get the opportunity to study it in depth, but also we need to be careful because something that is not uh frequently appreciated is this huge diversity. And let me try to explain it another way. We know a lot about SARS-CoV-2 right now, right? Uh SARS-CoV-2 is a virus, it has been in a human population since six years more or less now, right? And uh we learn that for SARS-CoV-2 there are so many different variants, right? Uh variants with different violence, variants with different transmissibility, and so on and so forth. Oh, that's the microbes yes, the virus of COVID, yes, yes. And uh, if we think about the microbes in our gut, they have been in the human uh population since hundreds of thousands of years, not six years, right? And uh so they had an opportunity to develop so many different variants that is really huge. For any bacterial species that is my gut and in your gut, uh, there is very, very little chance that it's the same variant, the same strain, right? Yeah, and uh this has a lot of implications because, like uh the COVID virus SAS-2, uh, different variants mean different phenotypes, different functions, different uh conditions, uh, and this is true also for our microbes. So if we if I tell you the list of microbes of bacteria and species in my gut, uh this is only telling a little bit of the uh of what my specific microbes can do. And this is something that if we understand it, then everything is way more complex than what uh uh sometimes the microbiome is uh considered.

SPEAKER_02 10:52

Yeah, well. So in your study were people living together, romantic partners, and you looked, I guess, at the oral bacteria, the bacteria in the mouth, and then the bacteria in the gut, what what did you find? What would our listeners be interested in?

SPEAKER_01 11:07

So this was the the the set the other step, right? So we said uh if the microbes in the gut and the oral cavity of humans are almost only found in the gut oral cavity of other humans, it has to be transmission. It has to be that uh like pathogens, like uh viruses, like other pathogens are really transmitted between individuals. So the first thing we did was to uh look at how many strains were shared between uh individuals that were unrelated. So individuals that in theory never met in person. And when we do that, there is, as I was telling, there are only very, very few strains in common. 0.07 percent of the strains between two RV individuals are uh the same. Then we look at people that uh uh the persons that were living together since at least two or three years, and we found that we're sharing up to 20 or 30 percent of their microbiome. So this means that basically, in the by just sharing the same house environment, built environment with another individual, the order of a few years uh the microbiome, some of one of the individuals is reshaped by the microbiome of the other. This is true for the gut, for the gut and microbiome, also for the oral microbiome. And clearly there are conditions acting on that, then kissing uh is definitely one of them. So there is, of course, very direct transmission of microbes uh with kissing, and some of them are really uh then colonizing the the mouth of the individual. So for the oral cavity, two individuals living together with romantic relation and kissing, they are sharing up to 50% of their microbiome after a few years or or months. After a few years, is that uh or is yes, after a few years, let's say two, three years, or even a few months, like six months uh sometimes is enough to see so romantic partners.

SPEAKER_02 13:08

Romantic partners shared the most oral microbes.

SPEAKER_01 13:13

So it's like kissing is changing the microbiome initially, is really is really making this the microbes in one individual jumping in the other individual, right? And some of them are remaining there. Of course, you know, if you live with someone like students or people just sharing a house without any uh romantic involvement, even in that case we see sharing, less sharing, but there is in any case sharing. And if you think about the pathogens, is what it happens most of the time. If uh you know a kid gets an intestinal bug from the taker and he comes home, you know, 99% uh probability the world family will have that bug sooner or later.

SPEAKER_02 13:56

So I understand pathogens, and maybe this is a stupid question. So apologies if I sound stupid, but when when you say that two people just living together share some of the same uh gut microbes, is that because they're eating similarly, or is like there's something happening where uh microbes actually jump into this other person?

SPEAKER_01 14:17

Exactly. So I I I I do understand that this seems a little bit gross, but it's actually that it's just jumping. Uh microbes in our gut are really we have to think of ourselves as uh humans uh in a cloud of microbes. Most of our gut microbes are in the gut, yes, but the gut is is is not uh you know is connected with the outside world. And and so microbes uh, irrespective of hygienic conditions, I have to say, uh, we bring our microbes. So if we interact with someone, we interact, also our microbes are interacting. And some of our microbes are really jumping as pathogens. Again, when we have uh you know intestinal pathogens, right? When they arrive in a family, they will jump and we can be careful, right? We can wash our hands, wash, but but uh even you know, there can be only one single cell. We even we'll never see, it's difficult to trace, and it's enough to jump from one individual to another.

SPEAKER_02 15:17

Okay, okay. So should couples take comfort in the fact that they're sharing microbes, or should we be like slightly horrified? I guess we don't like with the way you said it, it's kind of like makes you think about romances or even living with someone in a different way.

SPEAKER_01 15:32

So microbial diversity, so the number of different microbes in our gut is associated with healthy uh conditions. So, you know, I can say that the more microbes we can get in contact with, the better our microbiome can select which of them to have and the overall diversity of it. So the the way I see it is that our social interaction interactions are shaping our microbiome. The more interaction we have with other individuals, the more opportunity we have to get in touch with potentially uh beneficial microbes. You may say also with potential pathogens, sure. Right, but that's the case. Let me give you another example. I mentioned the daycare. I have three kids, and when they went to the daycare, um they always brought home uh pathogens at the beginning at the list. So I wanted to study them and I wanted uh to understand whether they were bringing home also some good microbes and not only uh bad microbes. So what we did here in Trento actually was to collect microbiome samples from uh babies before they met for the first time at the daycare, and then we followed them uh through one full year, sampling them weekly uh while they were starting to interact in the same in the same class. And we found crazy transmission patterns. For example, we found one strain, one bacterium that was present in the mother of a baby that was both in the mother and the baby. Then the baby went at the daycare and uh uh it got another individual in the same class, another baby, uh, it transmitted the the the bug to this other baby. Then this baby uh transmitted it at home to both the mother and the father. And the father had a different strain to start with. So, you know, this is a story of a father basically in which one gut microbe was replaced by the microbe coming from a mother of another uh baby through uh transmission of the takea.

SPEAKER_03 17:37

Oh wow.

SPEAKER_01 17:38

And we have tons, we have tons of these uh examples actually.

SPEAKER_02 17:42

So, and this was a beneficial microbe?

SPEAKER_01 17:46

This is a kermasemucinifila, this specific case, which is a bacterium which is actually now used as a next generation probiotic. So, yes. Okay, okay to be a beneficial microbe.

SPEAKER_02 17:56

So when you say that it replaced the strain that was in the father, was that just because like it was better for him?

SPEAKER_01 18:06

All right, that we don't know, it just changed it. I mean, it replaced a strain of the same species present in the in the father, because of course the father had uh so many microbes. Yeah, and uh we observed so many such intricate uh you know transmission patterns, and we tried to summarize them, and what we saw was that the baby, the first babies at the first day of daycare, they didn't share any strain, all completely different microbiome. After four months, they had already 30% of their micro micro of the microbes that they had in their gut coming from the other baby at the daycare. So, and only of course the baby in the same class, right? Other daycare in the city didn't have any any any transmission. And I told you that the babies also get microbes from the mother and the family. But these babies that started daycare at uh more or less one year of age in four months got way more microbes from the other baby at the day babies at the daycare compared to the microbes that they got from the family, considering the time you know from birth to uh to death time. So going to the daycare completely changed their microbiome. Uh, and uh so you can think about uh a role, uh a role of social interaction, even in early age, which can deeply shape our microbiome, so our microbiology, and so uh at some point, to some extent, also our own biology, our health.

SPEAKER_02 19:39

Yeah. I mean, and it just kind of makes me think of like if your microbiome can be changed by like where you're going and who you're hanging out with, it just makes me view health in like a totally different way. Kind of like it's like fascinating and it's also a little bit like creepy, like, oh, should I should I like live with these people? Like, what's their microbiome like?

SPEAKER_01 20:02

Yeah, you can one can think to choose you know the pattern based on microbiometching. No, I'm joking, of course. But but yes, I think what we learn is that uh most of the microbes that are in our cell are are kind of everywhere uh where we go, right? And this is well known in microbiology that most microbes are kind of everywhere, is our environment is our biology that selects which of them can colonize our cell, right? And so encountering a lot of microbial sources will allow us to have more diversity and decide you know which are the microbes that are specific to ourselves.

SPEAKER_02 20:42

And that is more diversity is good.

SPEAKER_01 20:44

And in this way, we kind of sorry more diversity is good, is it more diversity in general is good in general? Okay, there is a reason, no, because uh microbes are performing different functions. The more diversity of mushroom of uh microbes you have, the more diversity you have of functions, for example, digesting food. Fibers are very good for us because microbes can degrade them and uh produce uh immunomodulatory compounds. So the more microbes you have able to digest different kinds of fibers, the the better.

SPEAKER_02 21:21

Now, you also found that many of the bacteria in our mouths eventually end up in our gut. Is that fair to say? And I think people, I mean, and you know, you think about the mouth and the gut, at least with the microbiomes, like right, because you always hear about oral microbiome, and then you hear about gut microbiome, at least in like the mainstream media, you view them as different.

SPEAKER_01 21:41

So this kind of is a different they are indeed very different. They are very different, but of course they are connected and they are connected in one direction. So the oral microbes arrive to the gut. Uh, there are few oral, typical oral microbes that are found and detectable in the gut, but they are not. Many, except in some conditions. For example, in some diseases, some diseases that are interacting with the status of our stomach, for example, may change this because most of our microbes they die out in the stomach because of the different uh pH and other conditions, and so they are arriving not really alive into the gut. But for example, people that are um under proton pump inhibitor drugs, uh, they change the pH of the stomach, and so there is more info. So, what we found actually is that there is very little overlap between the oral and the gut microbiome, uh, except in some cases in which there are something not really physiologically uh working out. Uh, the question we asked was a little bit more nuanced because the idea was to understand whether there were some oral microbes more able than others to adapt to the gut environment, and that seems to be the case. Uh, but we study it as a different way to study transmission, right? There's transmission between individuals, or there can be transmission between uh body sites of the same individual.

SPEAKER_02 23:10

It also makes me think of you know, like probiotics that are always advertised and stuff like that. And there's always that question like, does it make it to your gut? Like, is it really gonna help you? What do you think of that?

SPEAKER_01 23:21

Like, we are studying it. We are studying it. There are probiotics of multiple different uh uh also generations, I would say. And this is a very interesting question. So, first of all, you know, probiotics can be beneficial even if they don't survive into the gut, because they are arriving, they arrive alive and they have an interaction with the other bugs, and they also have interaction with our immune system. So, even if they die after a few hours, in any case, they may have done something. I'm not saying that they always do something good or they are not doing anything, but this is a kind of a different question. But if the question is how many of these microbes are colonizing our gut, that then is more the exception that they rule. Because because of what is called colonization resistance, and also because what are the traditional, at least the probiotics are are bacteria that are uh easy to be stored in a matrix uh like yogurt or other uh you know pills in which uh it's not that you don't have oxygen. So again, uh most probiotics are chosen by the possibility of delivering into the gut rather than on their supposed uh effect.

SPEAKER_02 24:38

Okay, so you're saying that this billion-dollar industry is probably not matching up to their promises, but maybe they're doing something good while they're still hanging around.

SPEAKER_01 24:49

Exactly, yes. I I think we need we will need much more you know critical studies, clinical trials looking at that. But probiotics are a different kind. There are probiotics that are in the medical field and probiotics that are more in the wellness uh field.

SPEAKER_03 25:05

Right.

SPEAKER_01 25:05

And so also there it depends also on the claim of each uh uh that each probiotic we make. But I can tell you something else because we are studying transmission, and so you asked about uh the probiotic transmission, but there is another artificial transmission which is even more gross, um, but it's called fecal microbiota transplantation. And it's actually the medical, very strict medical practice in which you take fecal material from an ealth individual and you put it to the gut of a recipient. This is a medical procedure, and this is what we call artificial transmission, right? Babies interacting, families live in the same house, this is natural, this is natural transmission, but in in medicine there is FMT, fecal microtransplantation, and this is uh artificial transmission. And we study uh this transmission in the same exact way we study natural transmission. So we are studying showing when FMT works for which diseases, and which are the microbes that are able to uh engraft, colonize the recipient from the donor. In most of the cases, if the fecal microbial transplantation procedure is done well, you can get you can change in one procedure 50% of the microbiome of the recipient. So you can reprogram completely the microbiome of someone.

SPEAKER_02 26:29

Wow. And that could be beneficial to people.

SPEAKER_01 26:33

Well, this is done absolutely, yes, this is done for specific diseases, is a clinical practice, is a validated and uh you know suggested clinical practice for some diseases, including, for example, well, specifically for uh infection by crossidoid is difficile. This is a bacterium pathogen colonizing and being uh yeah, especially is is very bad for hospitalized people that have uh immunological problems. Yeah, and in this case, uh FMT is the clinical practice, it's working much, much better than antibiotics. Antibiotics are kind of killing everyone but the pathogen, because the pathogen is resistant, and so the pathogen in the gut doesn't have any competition to you know to grow even more, and so you give more antibiotics, it's actually not beneficial, it's actually uh increasing the problem. With transplantation, you reput an LT microbiome around the pathogen, then as a consequence, basically uh dies out or decrease the relative the abundance uh of it. You know, there have been clinical trials here, and the clinical trials were interrupted because it was unethical to continue with the control arm. So this means that uh it is an extremely successful uh procedure. For other diseases? Yeah, for other diseases that is more of a question. There are studies ongoing. Uh the last thing we tried was actually in the cost in the context of oncology. There are some oncological treatment, immunotherapy, that is deeply acting on the immune system. Uh, it's working very well in immunotherapy, but it's working very well only in a subset of individuals. We showed that by changing the microbiome of a person that is not responding to immunotherapy, in some cases you get this person to start responding to neurotherapy.

SPEAKER_03 28:33

Wow.

SPEAKER_01 28:34

And so this can be really huge uh consequences. It's still early phase, but uh we have some published studies that are clinical trials showing that uh this is at least uh very pronounced.

SPEAKER_02 28:47

Wow, for cancer. Jeez. Yeah, that's that's so it and that's kind of like what because when you hear microbiome, I'm always thinking of like a okay, diseases that are like in the gut, but potentially it could be used for I mean disease.

SPEAKER_01 29:04

Absolutely.

SPEAKER_02 29:05

So yeah.

SPEAKER_01 29:06

Our microbiome uh is deeply in connection with our immune system, and our immune system controls not only pathogens, but the immune system controls cancer, controls tumors, controls uh autoimmune diseases, right? Yeah, so looking at the microbiome is kind of another or a complementary way to look at our immune system. And so that's why the microbiome can be implied in very many uh diseases. I'm not saying that you know everything is microbiome related, but uh if we consider ourselves as a very complex system, the microbiome is a complex system in the complex system that has an impact on many, many factors.

SPEAKER_02 29:51

Many things, because like the immune system we know is connected to like almost everything, too. And and then I mean even the microbiome and mental health. I've read a couple things on that. Like the I guess the vagus nerve, the vagus.

SPEAKER_01 30:05

So absolutely. So there are also indications there. So mental health is extremely multifactorial, right? So uh is a series of causes, and indeed the microbiome at the it has been indicated, implied in some of these causes. The gas brain axis is one of the most difficult uh area within the microbiome to be studied, but uh but yes, there is a lot of research and uh it's very promising also there.

SPEAKER_02 30:32

It makes you think about our treatments now versus what treatments might look like in the in the future, you know, with all this research going on, like how different they'll look. One thing that so some of the bacteria that spread most easily were associated with poorer cardiometabolic health. So, what does that mean? Does that mean unhealthy microbes are better at spreading, or is that jumping too far ahead in the evidence? Is that alarming?

SPEAKER_01 31:00

Yeah, I think uh well, we we should start from the baseline that all our gut microbes are transmissible. Because they have to be transmissible because otherwise they will die with individuals they are colonizing, right? So uh given that uh most of the gut microbes cannot live outside a human gut, they need to be able to jump. So all species are transmissible to some extent to all gut microbial species. Um indeed, we it seems that those that are pro-inflammatory are slightly more transmissible than the others. This may be that uh inflammatory bacteria are probably more adaptable to another uh gut environment. And so every gut is slightly different because you know our nutrition is different, so on and so forth. So probably these pro-inflammatory or supposedly pro-inflammatory microbes are slightly more able to adapt to whatever condition they they they they find because you know inflammation is something harsh to deal with, and pro-inflammatory ones are probably uh feeling a little bit better. But this is actually also for us is an open question because uh we need to understand it uh better. And poor cardiometabolic health just means that they uh it means uh bacteria that are associated with uh uh diabetes or with obesity or with uh you know cardiac uh potential issues. I exactly yes. Yeah.

SPEAKER_02 32:29

Okay, okay. So would you say the people we live with subtly influence our long-term health through the microbes we share?

SPEAKER_01 32:39

I definitely they influence our microbiology and our self. And as a consequence, yes, to some extent, also our our health, yes. And it's not only the people we live with, but the lifestyle of the people we live with, right? Because uh, you know, an healthy diet, uh plant-based, diverse diet is extremely relevant for our gut microbiome. So, you know, if you are if in your family you are the only one eating extremely well, you will still have the influence of the bacteria uh colonizing people that are you know fast food-based diet, and and and the those will have an effect.

SPEAKER_02 33:21

What about your dog or your cat?

SPEAKER_01 33:25

Nice question. In the study, I mentioned you before at the uh daycare, we sample not only the babies, but also the parents, the educators at daycare, the siblings, and also the pets. Uh, cats and dogs. Uh, when we look at the microbiome of the pets and the babies, we did find few strains in common. So strains that were present in the dog and also in the baby uh and in the gut. We didn't find any with the adults, with the mothers and the fathers. Maybe there is you know more intimate connection between the babies and their pets than the adults. Overall, the pet microbiome and the gut microbiome are quite different, so there is not a lot of transmission. I'm not saying that you should safely kiss your dog you know routinely, because also in this case we talk about pathogen, and also in this case we talk about the effect on our immune system of bacteria that are coming, and maybe they will die, yes, but they may live some uh yeah, you know.

SPEAKER_02 34:28

Okay, so not necessarily uh easily transmissible from dog to human, but the button is a big thing.

SPEAKER_01 34:38

Yeah, when we say transmission is actually both transmission and colonization, right? Because uh for our techniques that are metagenomics based, well, that is a uh methodological aspect there, but yeah, what we see are the microbes that are stably colonized in the gut of someone. We cannot see microbes that are out to your gut and disappear in a second. So it can be that the dog is giving me tons of microbes every second, right? But none of them remain in my gut. In that case, we don't see transmission, but it doesn't mean that there is no transmission, it's just that the transmission doesn't give rise to a stable colonization of those microbes in our pass through, but they can't build a house that they can be passenger, right? So so I think there are these are very two very different uh phenomena: the ability to jump from one individual to another and the ability to remain in that individual.

SPEAKER_02 35:32

Okay, okay, that makes sense. So is there anything people can actually do to build a healthier microbiome with without like asking their roommates, like, hey, what's going on with your microbiome? Because I want to see how you're influencing me.

SPEAKER_01 35:48

Yeah, I think that that there are a lot of uh actions one can take to improve the microbiome. But these actions are all on improving the microbiome, the microbes that we have, right? So an healthy diet, a diet especially with a large diversity of plant-based foods. So not only plant-based foods, but the diversity, different types of fibers, different types of polyphenols and things like that are what are really improving our uh gut microbiome. So these are general stuff that can really improve our microbiome. At the same time, if you close someone, you know, in a bubble and they eat perfectly nicely, but they don't have the opportunity to get in touch without their microbes, they will not end up with an healthy microbiome. So, you know, healthy diet is uh is necessary, but you we also need to interact with other people to get our microbes.

SPEAKER_02 36:40

And what like what about living in like you know, people are hyperclean, and then there's other people who are like, I guess it's like the hygiene hypothesis or whatever, but um, what are your thoughts on that?

SPEAKER_01 36:51

The hygiene hypothesis uh uh is extremely interesting, is usually referring more to the influence of microbes and uh hygiene on the immune system, like because we think about allergies and things like that. We studied transmission in different hygienic conditions, and we didn't find any difference, to be honest. So we look at uh families that were trying to live super clean and families that were living in way more rural conditions without access to hygienic facilities and things like that. And we saw that the transmission is pretty much the same. Now, this again seems pretty gross, but I think the point is that again, no matter what we do, we go around with our microbes and we transmit them. And what is the difference in whether one transmission will end up in colonization is whether they stick well in our gut. Uh, but this has nothing to do with the with the gene, right? If something arrived, if if a bacterium arrives to my gut, then it's interaction there that decides whether uh the microbe will will stay alive or not.

SPEAKER_02 38:00

That's interesting. So, like, because there's always been like especially in the wellness circles, everybody's always worried about cleaning supplies. I and I I don't like some of the cleaning supplies, I get nervous about them.

SPEAKER_01 38:10

But yeah, I'm not really don't don't get me wrong. Don't get me wrong. Pathogens are really you know affected by hygienic conditions because we clean stuff and the pathogens will go away. So it's important, I don't know. For example, in hospitals, no, we know in hospitals that are pathogens that are hospital-based and they are there in the hospital, right? And it's very difficult to get rid of them. So hygienic conditions there, cleaning, you know, doors, door handles, for example, stuff like that is extremely important. But in terms of transmitting our healthy and non-pathogenic fracture of the microbiome, uh, that has little impact.

SPEAKER_02 38:52

Little effect. Okay, that that's that's good to know.

SPEAKER_01 38:56

What's one thing you hope listeners take away from your research that you feel like maybe headlines are missing or well specifically with this line, yeah, specifically with this line of results, I do think that uh we need to understand that our microbiome is kind of a you know is a is not a silo. Our microbiome is in contact with the environmental microbiome and with the microbiome of other people. So we have to think as our microbiome as a dynamic system interacting with uh with everyone. And so our social interaction, our physical interaction, our sharing the space with someone on a bus this morning have an effect on our microbiome. And the effect on our microbiome means having an effect on ourselves because we are half microbes and half uh humans, right?

SPEAKER_02 39:43

So that half change should I should I sit next to this person on the subway? Let me let me do you think they'll be good or bad for my microbiome.

SPEAKER_01 39:53

Let's say that looking at them will not tell you much because we will need you will need to ask them a lot of questions about their diet, their you know, conditions.

SPEAKER_02 40:03

And I feel like the New York City subway, you built a lot of like diversity.

SPEAKER_01 40:07

Yes. Yes, you know, but at the same time, I think uh uh yeah, these are kind of jokes, right? Because I think at the end, the important thing is that we get in touch with a lot of different microbes, and this gives the opportunity to our gut and our old cavity to select which of them we link to ourselves. So I don't think it's a huge problem at the end, uh, who we are sitting with. Uh the point is that we should not live in a bubble isolated by other humans because that is not uh bubbles are big. It's not even what evolution uh set up for us, no, because we co-evolve with our microbes, we co-evolved in a social environment, and this is the imprinting we have in our old cabinet.

SPEAKER_02 40:48

After spending years studying the microbiome, has it impacted some of your decisions or your behavior? Or like do you think about it at all?

SPEAKER_01 40:57

Well, I was telling about uh the kids at the daycare, and now I'm not afraid anymore of interacting with that. No, I'm joking. Uh yes, I think uh especially uh you know the impact of the diet and our long-term diet, because I'm not worried about what I ate yesterday, I can do exceptions, stuff like that. But the diet over our 20 or 30 years is impacting a lot the composition of our microbiome and also the health associations of our uh microbiome. Not only diet, lifestyle in general, and things like that. And this is something that we know, and a lot of the recommendations of an healthy lifestyle are overlapping with the gas microbiome. But what I'm excited the most for the future is that we should be able to find how to modify our microbiome, maybe via transmission, in a uh more precise and personalized way to really try to improve and improve the microbiome more than what general recommendations that are good for health in general can do on our side.

SPEAKER_02 42:04

Uh, what research are you working on next? Sounds like you're doing a bunch of things.

SPEAKER_01 42:09

Yeah, yeah, the the aspects about transmission are really exciting for us because it's a nice example in which fundamental studies of the gut microbiome and the role microbiome are then impacting uh also the clinical practice, like with the fecal microbial transplantation, for example. So we are excited both are trying to better profile our microbiome. So 20-30% of the microbes in your gut are completely unknown. Nobody saw them, nobody characterized them, uh, nobody gave a name to those microbes. So we need to improve that, and that is one of the fundamental questions that we are moving uh ahead. And at the same time, learning how the diet changes our microbiome in a reproducible and precise way is another hot topic for our lab. And also the applications in cancer, for example, are extremely intriguing because it can literally have an impact on the life of people. So we are lucky enough that uh with our approach, we can really look at different aspects.

SPEAKER_02 43:17

So sometimes you'll hear Americans say when they travel to Europe and then they like lose weight even though they eat a ton of food. And like Italy, we like everybody goes to Italy for the food, right? Like the Italian food. So I'm curious: like, has something happened to their microbiome? Or is it just American food? It's like so processed.

SPEAKER_01 43:36

Yeah, I wouldn't talk about the Italian diet because I I I would be very biased toward it. So uh it's not very scientific, maybe. But yes, I think there is an impact on the different diet or the different uh places, but also the the thing that you are traveling. Traveling means getting in touch with uh different environments, even the water, you know. So there is both the fact. Of moving in another population with other microbiomes and other lifestyle and diet and so on and so forth. But even the act of moving, right? The act of traveling in a different continent will have an impact on the microbiome.

SPEAKER_02 44:16

Fascinating. It's like connected to everything everything. And you're just not, you're never alone, I guess.

SPEAKER_01 44:22

You're never alone, and you're never alone, even if uh you're alone as a human, right? Because even in the environment, uh, in the food, as we started this uh chat with, uh, there are microbes there. So we live in a world of microbes. Uh the world is actually ruled by microbes because there are order of orders of magnitude more microbes than humans on Earth, and we are in contact with them every time, unless you can like live in a sterile bubble, which is not a good idea because you will not survive long.

SPEAKER_02 44:53

So you said the world is ruled by microbes?

SPEAKER_01 44:56

Yes, yes.

SPEAKER_02 44:57

Oh, yes, that's awesome.

SPEAKER_03 44:59

Too strong.

SPEAKER_02 45:00

No, like I love it. It's like it sounds sci-fi, but it's not. That's why I really liked it.

SPEAKER_01 45:07

It sounds science fiction, but it's like that's microbes went on Earth billions of time uh years before us, and I don't know what happens with the crazy situation, uh, but uh if I'm sure that uh if something bad happens, uh humans will live this world way, way before microbes. It's gonna be impossible to kill uh all uh to have instinction of our microbes on Earth. It's gonna be impossible.

SPEAKER_02 45:35

You we're not gonna be able to do it. It's in it's impossible.

SPEAKER_01 45:40

We can mess up the world so much uh to to make uh you know humans uh extinguished.

SPEAKER_03 45:46

Yeah, yeah.

SPEAKER_01 45:47

But but it's not gonna be possible for bacteria, they will be here after us for sure.

SPEAKER_02 45:53

That's so interesting.

SPEAKER_01 45:54

Um, I guess, yeah, uh it's fascinating to think about, but I guess humans we have our pride and like we like to think we're yeah, it's quite an anthropocentric uh view, but you know, there are microbes in extremely uh extreme environments, no, in volcanoes, uh you know, in the true definition of resilience.

SPEAKER_02 46:16

Yeah.

SPEAKER_01 46:17

Yeah, they're called extremophiles and uh they are very extreme, yes.

SPEAKER_02 46:21

Wow. Well, this was fast fascinating. Thank you, Dr. Sagat. I appreciate your time um and joining in. And I think uh, you know, because it's great to hear from someone who actually studies this stuff and knows these nuances and you know can give that to people versus just the bits we see sometimes, you know, in our attention deficit world, I guess.

SPEAKER_01 46:44

My pleasure. That's been a nice start, thank you.

SPEAKER_02 46:48

Yeah, thanks so much. Are you watching the World Cup?

SPEAKER_01 46:51

Uh which World Cup? Sorry, but uh I'm joking.

SPEAKER_02 46:55

Italy didn't qualify, so uh I know, I was surprised by that, but I haven't been following. I mean, I used to follow, you know, but I'm not sure why you didn't qualify, but well, yeah, it's a it's a long story, but uh yeah, I think uh the teams that are there now I I think are uh probably stronger than Italy.

SPEAKER_01 47:15

So I have an idea. No, I don't know. Maybe Argentina Norway. Norway.

SPEAKER_02 47:21

Norway looks good, yeah. The that guy with the yeah, the big blonde guy, yeah. He's he's a good stronger.

SPEAKER_01 47:27

And they eliminated it Italy in the in the pre-qualifying.

SPEAKER_02 47:31

So oh, okay. So maybe they'll take it all the way to the end. Well, take care. It's a pleasure meeting you. Good enjoy the rest of the day. Thank you. Bye. Bye. Take care. Bye. Bye. All right, thank you guys for tuning in. I hope this episode makes you think differently about the people you live with, your romantic partners. Maybe you'll add an updated question to your dating profile. Please tell me about your microbiome. Before we start dating, I gotta know about your microbiome. Uh I don't know, you do you. Anyhow, don't forget to subscribe, stick around, subscribe to the Eeks Weekly, my newsletter that goes out once a week. If you like bizarre, weird, true public health stories. And now it's time for the closing quote. This one is from microbiome researcher Rob Knight. And here it is. The three pounds of microbes that you carry around with you might be more important than every single gene you carry around in your genome. Ha. Alright. That's it for today. Uh I hope you tune in next time, and goodbye for now.