Updated 13th March 2023

Your gut is full of bugs: Why this is great news

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    You may have heard there are bugs in your gut. But do they matter? 

    Today, the evidence shows the answer is a resounding yes. This ecosystem of tiny microbes living in our bodies is one of the most exciting areas in medical research, linked to everything from metabolic to mental health.

    So, while many of us have heard that gut health is essential, few of us understand why and what we should do to support our gut bacteria.

    In this podcast, Jonathan speaks with Will Bulsiewicz to find out when our microbiome begins to form, the most effective ways to support our gut health, and the role these gut bacteria play in controlling our weight.

    Will Bulsiewicz is a board-certified gastroenterologist and New York Times bestselling author of the microbiome book Fiber Fueled.

    If you want to uncover the right foods for your body, head to joinzoe.com/podcast and get 10% off your personalized nutrition program.


    [00:00:00] Jonathan Wolf: Welcome to ZOE science and nutrition, where world-leading scientists explain how their research can improve your health.

    You may have heard there are bugs in your gut, but do they matter? Only 20 years ago, the answer from scientists was no. Today, new evidence shows the answer is a resounding yes. This ecosystem of tiny microbes living in our bodies is one of the most exciting areas in medical research, linked to everything from metabolic to mental health.

    So while many of us have heard that gut health is essential. Few of us understand why and what we should do to support our gut bacteria. In this episode, I'm joined by regular contributor, Will Bulsiewicz to find out. Will is a board-certified gastroenterologist and New York times bestselling author of the microbiome book, "Fiber Fueled".

    He is perfectly placed to give us an introduction to the wild world of the microbiome. We start at the beginning, finding out when our microbiome begins to form, and ending with the simplest and most effective ways to support our gut health. Along the way, we discovered the remarkable ways our romantic relationships affect our microbiome and the role these gut bacteria play in controlling our weight.

    Will, thank you for joining me again today. 

    [00:01:31] Dr. Will Bulsiewicz: It's a pleasure to be here. Thank you for having me. 

    [00:01:33] Jonathan Wolf: Always fun. Why don't we start as we often do with a quickfire round of questions from our listeners around this topic of the microbiome. Are bacteria bad for us? 

    [00:01:43] Dr. Will Bulsiewicz: No, it's actually time for us to reevaluate because most bacteria are good.

    [00:01:48] Jonathan Wolf: Are there bacteria everywhere in our body?

    [00:01:51] Dr. Will Bulsiewicz: I believe the answer is yes. Our old techniques of cultures, cultures of blood and urine, have proven to be inadequate. We're discovering bacteria all over the place, including in our blood. 

    [00:02:01] Jonathan Wolf: Amazing. I didn't know that. Does everyone have a gut microbiome? 

    [00:02:06] Dr. Will Bulsiewicz: Every single person? Yes. Every single person throughout human history has had a gut microbiome. 

    [00:02:12] Jonathan Wolf: Awesome. So if you're listening you have one too. Does your gut microbiome affect your health? 

    [00:02:17] Dr. Will Bulsiewicz: Absolutely. Yes. And in an extremely powerful way, which we're going to talk about today. 

    [00:02:22] Jonathan Wolf: Can gut bacteria change your mood? 

    [00:02:25] Dr. Will Bulsiewicz: Yes. There are studies that indicate that our gut bacteria actually are intertwined with our mood.

    [00:02:30] Jonathan Wolf: Can you change your gut microbiome with food? 

    [00:02:33] Dr. Will Bulsiewicz: Yes. 100%. In fact, changes will take place very quickly. 

    [00:02:37] Jonathan Wolf: And last quick-fire question, can probiotics that you can buy today, help your gut microbiome? 

    [00:02:44] Dr. Will Bulsiewicz: In some cases. But in many cases, the hype is outpacing the science. 

    [00:02:49] Jonathan Wolf: Brilliant. Thank you for that, Will and I'm sure we'll come back to many of those questions as we talk over the next little while, but why don't we start at the very beginning? What is this microbiome thing? 

    [00:03:01] Dr. Will Bulsiewicz: This microbiome thing is the community of microorganisms that are there. They are real, but they're actually rather difficult for us to acknowledge or even wrap our minds around because they are invisible to the naked eye. They're too small. But if we had a microscope, Jonathan, if you were super nerdy like me and you walked around with a microscope, you could take a look at your thumb and discover as many microbes right there as there are people in the entire UK.

    [00:03:34] Jonathan Wolf: Amazing! 

    [00:03:34] Dr. Will Bulsiewicz: And if we were to apply that microscope to everything that's alive on this planet, we would discover that everything that's alive on this planet has a microbiome. It's not just us humans. The plants have them too, the animals, have them too. 

    [00:03:50] Jonathan Wolf: And what's the difference between a microbiome and bacteria? What does it mean?

    Help us understand a little bit more, what this thing is. 

    [00:03:59] Dr. Will Bulsiewicz: So there are different terms that you will see thrown around. And to be completely honest with you, I probably, at some point during this podcast will be guilty of using these terms interchangeably when I probably should not. It's an extremely common thing.

    So the term microbiome is really referring to the genetic code that exists among this huge community of microorganisms. These microorganisms, Jonathan, cover us from the top of our heads. To the tip of our toes, the skin, believe it or not, the eyeball, inside the nose, the mouth, a woman's vagina, even the bladder has a microbiome, but the main place that you will find these microbes is inside our colon.

    That's where they're most densely concentrated. And the microbiome is the term that we described, the genetic material that these microbes living in the colon basically provide to us. They, believe it or not. I have 200 times more genetic material than we have in our genetic code as humans. 

    [00:05:04] Jonathan Wolf: Which is amazing.

    [00:05:06] Dr. Will Bulsiewicz: So essentially what I'm saying is if I look at the whole person, what we'll find is that you are 99.5 microbial in terms of your genetic code and only 0.5% human. 

    [00:05:20] Jonathan Wolf: So I'm hardly a human being at all. I'm almost all microbes from a DNA perspective and just kidding myself, that I'm all a human being, because I can't see all of these microbes, which are around me and inside me.

    [00:05:32] Dr. Will Bulsiewicz: You can't see them, but yet in terms of your DNA, yes, you're a less than 1% human in terms of your DNA, but even in terms of the number of cells that make up your body, I mean, this is again, very hard for us to fathom and understand, but at a minimum. If we look at your human cells, we believe that you have about 30 trillion total cells, and there are about 38 trillion microbes in the colon alone. And so you are less than 50% human. 

    [00:06:02] Jonathan Wolf: Yeah. I think my wife sometimes says that to me when I haven't finished the washing up, but, I think it with a different meaning. 

    [00:06:11] Dr. Will Bulsiewicz: Oh, you animal. Oh, you animal. So, and actually, to introduce another term, an appropriate way to describe us as humans is actually a superorganism. This makes us sound superhuman and in a way, we should feel like that because, without these microbes, we would only be capable of so much.

    And one of the things that we're going to discuss today is how these microbes have actually taken up residence and they contribute to the capabilities that we have in terms of our biological functions. And so we are in fact, a superorganism made up of these microbes. Microbes, by the way, is the word that would describe a single one of these invisible microorganisms, and microbiota is more describing the entirety or the larger pool or community of them.

    [00:06:59] Jonathan Wolf: And they aren't exclusively bacteria, but they are mainly bacteria. Will, is that right? 

    [00:07:05] Dr. Will Bulsiewicz: So these five different types that we would include if we were looking at the entire picture here, but the bacteria are the principal one, they make up the vast majority of the microbes. And the second, most common would be the funghi or yeasts.

    So we all have, for example, candida. Candida is a type of fungi and we all have it. It's a normal part of our microbiome and, beyond the funghi, we also may have these microorganisms called archaea, which are my personal favorite. Archaea are not bacteria. They're not funghi. They are their own individual thing.

    And they, we believe are the longest-lived creatures on the entire planet. Like far, far, far before we ever had dinosaurs 4 billion years ago, there were the archaea. And it's actually quite fascinating to consider this because oxygen has only existed on our planet for the last 2.5 billion years. So actually the archaea were hanging out on this scorched earth for 1.5 billion years, without even having any oxygen.

    [00:08:13] Jonathan Wolf: That's brilliant. And I think one of the things we're already slipping into doing a little bit is we're talking about microbiome and gut microbiome a little bit interchangeably. And I think for the rest of today, we're mainly going to talk about the gut microbiome, but it's definitely worth bearing in mind. As you said that there are many others. My wife is a dermatologist. Therefore she's really interested in the skin microbiome because that's obviously the most important thing for her. And that's this. Today, we're mainly going to talk about the gut microbiome. And as you said, this is by far the most complex microbiome in terms of the number of species.

    And it's always so interesting for us because of the way that the food we eat interacts with it. So if we are thinking about that specifically, the gut microbiome. What's it for? Right? Why do we have one? You said that we've had one for as long as they've been human beings. How comes? 

    [00:08:58] Dr. Will Bulsiewicz: Yeah, let's take a little walk through evolutionary history and consider that the very first human, whoever this person was, had a microbiome.

    There has never been even a second in the history of humanity that we were free from our microbiome. So we have co-existed and co-evolved with these microbes from the very beginning. We rose and we fell together. And when we live and when we thrive, the good news is that they get fed and they can thrive as a result of that.

    And so as we went through human evolution together, what happens, and this is like very clear, if you look at this from a scientific perspective, is that we grew to trust these microbes. And the reason why is because they are more quickly adaptable. We as humans, like we are creatures of habit and we are not rapidly adaptable, we can't change that quickly, but our microbes can change. They can change actually very quickly. In fact, a new generation of them is potentially spawned every 20 minutes. So literally just during the time that you and I are having this conversation, we are going from, you know, something that's a child of microbe all the way up to a great-grandparent microbe.

    And so as we moved through human evolution, we have to consider that, you know, humans radiated out from Africa. And as we radiated out across this globe, we encountered many different environments that posed their own unique individual challenges. And we were fighting for survival and there were no supermarkets to feed us.

    Many people died of starvation. And so we needed these microbes basically to help, to support this quest for human survival. And so they took up a very important role. First of all, indigestion of our food, where we could radiate out across the globe and eat a wide variety of foods and many different climates and ecosystems, and still have the capacity within our digestive system to break down and process that food, our microbes do it for us.

    Second of all, they're involved in our metabolism, our immune system, our hormones, our mood, our brain health, and our genetic expression. And so when you look at this entire picture, just coming from my perspective as a medical doctor, we're basically talking about everything that matters for human health, and the part about it that is so bizarre is that, what appears to be the most important thing for human health, isn't even human. And we didn't even recognize how important this was until like less than 20 years ago. 

    [00:11:52] Jonathan Wolf: Tell us a bit more about that. And, I think one of the questions I love, I've heard other people talk about it is this idea that maybe we should think about the microbiome as an organ of the body, you know, less than 20 years ago, we suddenly discovered the liver.

    Right? And for all of human history and human science, we never realized we had a liver, which for those of you who are not doctors listening from any of us, it's like, it's quite important. Right? Will, like it's an important thing to have a liver. Is that correct? In your medical opinion. 

    [00:12:20] Dr. Will Bulsiewicz: You cannot sustain a human wife without a liver. 

    [00:12:24] Jonathan Wolf: Okay. So this is the analogy. I'm not a, I'm not a doctor that I've been given, so it's like a really big deal, but we never knew that it existed until 20 years ago. So I guess two questions, firstly. Is it fair to talk about it as being like an organ? And then I guess the follow on question is how's it possible we didn't know it existed 20 years ago? 

    [00:12:44] Dr. Will Bulsiewicz: So first of all, it absolutely is fair to talk about it as an organ. In fact, I think that it's time for us to do that. And there are certainly leaders of science who would agree with this perspective. An organ Is something that plays a central role in human health and supports our ability to do the things we need to do from a biological perspective.

    And so by that definition, very clearly these microbes, particularly the gut microbiome, you know, recognizing that once again, like we need our microbes for proper digestion, metabolism, immunity, hormone balance, mood, brain health, and genetic expression. We need them. And what it would look like without them is not a healthy human being.

    So in that sense, we have to think of this as an organ. And in that regard, we should be therefore nurturing the health of that particular organ. This should be very important to us now, why is this like suddenly a brand new discovery? Well, Jonathan, it's not that we didn't know that there were microbes. That's not the reality. The issue is that first of all, we didn't have the tools to study them because it turns out I'm going to get a little bit nerdy for a moment. I hope people don't mind, but there are different types of microbes. And some of them, we call them anaerobic. And anaerobic basically means that they exist in an environment where there is no oxygen.

    [00:14:18] Jonathan Wolf: So this is like the extreme example of your archaea, which we know, you know like they're a relatively small part of what's in our microbiome, but that's your example that they were there even before there was any oxygen on earth. 

    [00:14:28] Dr. Will Bulsiewicz: Yeah. They don't need oxygen to survive, which seems weird because we view that all creatures need oxygen to survive, but that's not actually true.

    So these anaerobic microbes exist in an environment where there is no oxygen. Well, that actually turns out to be our colon. And so this environment that they're in 99% of the microbes that are there, they can't grow on a culture plate because that requires us to expose them to oxygen, which actually kills them.

    So we lacked the tools to study them and simultaneously we made assumptions and we all know what happens when we make assumptions. It often forces us to fall straight on our faces. And so the assumption was these microbes, yes they're there, but gosh, like, they're responsible for poop and like, you know, foul smells.

    So why would we care about that? And then what happens, Jonathan, is that roughly 2005, 2006, there were two major things that were simultaneously taking place. We discovered a laboratory technique called 16s rRNA. That allowed us to, for the first time go beyond the culture plate and discover this blooming community of 38 trillion microbes living inside of us.

    And the second thing that happened is that the amount of information that exists within a bowel movement is completely overwhelming to the computers of the 1990s. And we needed faster, stronger computers to actually be able to handle this amount of information. Because once again, you may think that we are complicated humans, but from a genetic perspective, we're actually rather simple compared to the amount of information that exists again within a bowel movement.

    So better computers. New laboratory techniques. 2005, 2006 happens. And all of a sudden, whoa, this is amazing. This is crazy. And we spent about 15 years just kind of describing what we were seeing, but what's really exciting, Jonathan is that we're entering into the phase where manipulation of the microbiome is actually becoming a technique that we can apply to medicine to help us get better outcomes for our patients.

    [00:16:53] Jonathan Wolf: So that's really interesting. I think so far our listener might say, okay, you convinced me, there's a lot of these things and they're diverse and it's different, but why do you believe they matter? Will, right? Like why aren't they just, you know, hitching a ride? How do we know that actually, they have this effect on our health that you were talking about earlier?

    [00:17:13] Dr. Will Bulsiewicz: Jonathan, we have these examples where manipulation of the gut microbiome becomes very powerful in terms of the effects that it can have on our body. And so initially we're doing research studies where we were describing, oh, in the setting of, for example, lupus or Crohn's disease or ulcerative colitis in the setting of these auto-immune conditions, we are seeing a change in the microbiome.

    That we would describe as dysbiosis. Dysbiosis is the word that we use. That means that there's a loss of balance within the microbiome. And if I were to sort of zoom everyone in using a microscope and you would look at what's happening when there's dysbiosis, essentially there are a loss of the good microbes, less good guys.

    There are more bad guys. They're kind of showing up more prominently. And then finally there's been damage or injury to the lining of the intestine. And you have broken down the barrier and created what we call, increased intestinal permeability, which some people might call leaky gut. And so this is what exists when a person has dysbiosis.

    So first we were describing it. Now we're moving into how do we make it better? And can this be used to improve, you know, for example, health. And there are a number of examples, but Jonathan, one of the things that I perhaps we will do another ZOE podcast on in the future is the microbiome and cancer research where we now have studies, I'm not going to dive too deep into this because I think it would be much better as a complete episode, but we now have studies where when you give a fecal transplant in combination with cancer therapy, people do better. When you manipulate the microbiome with antibiotics and you actually cause harm to the microbiome, people do worse with their cancer therapy.

    And so now we're starting to come to a new era where manipulation of the microbiome is the next phase of us figuring out how we can actually use this to our advantage for better human health. 

    [00:19:29] Jonathan Wolf: And I think I should clarify, right? Will, that you're not saying one should never take antibiotics. Cause I think that's one of the important messages we always want to give but to recognize that in certain cases it can have an impact. 

    [00:19:40] Dr. Will Bulsiewicz: Without a shadow of a doubt. In my mind, the greatest discovery in the history of medicine was the discovery of penicillin. Prior to this, the top causes of death were all infections. If we go back to prior to World War II, in many of the wars that took place, the soldiers were not actually dying from the bullet wounds. In many cases, they were dying from the infection that took place after the bullet wound.

    And so accelerating up to world war two. This is when penicillin was discovered and it completely changed everything. And all of us enjoy years that are added to our life expectancy. As a result of antibiotics, they serve their purpose in a powerful and very important way. The problem that we have is the overutilization of sterilizing techniques that could be antibiotics, but it could also be the sterilizing of our food, and this overutilization of antibiotics when they're not necessary, is the problem that exists because not only is that negatively affecting our personal gut microbiome, but the other thing that it's doing is it's creating resistance to those antibiotics. So antibiotics should be reserved for situations where we actually truly need them. 

    [00:20:56] Jonathan Wolf: And, you know, at the same point you were talking about impacts on various sorts of health.

    What's the evidence for the way that it can impact our metabolism and our weight? Because I think a lot of the initial studies around the microbiome actually really started in this area, didn't they? 

    [00:21:12] Dr. Will Bulsiewicz: Yeah, they did. So some of the completely eye-opening studies from around 2006, where showed that you could actually transfer a body habitus, meaning a body shape through the microbiome in mice.

    Let me share a fascinating twin study where they took two identical human twins one was obese and one was skinny. Okay. So they have the same genetic code yet they are not the same in terms of their body habitus. One is obese. One is skinny. And they actually took a microbiome specimen from these humans and transferred it into mice and then fed these mice, the exact same food.

    So one mouse receives the microbiome from an obese human and the other mouse receives a microbiome from a skinny human. These mice receive the same food and they consume the same number of calories. And yet the mouse that receives the obese microbiome becomes obese. And the mouse that receives the skinny microbiome becomes skinny, even though they're eating the same number of calories, it challenges in many ways, the calories-in, calories-out paradigm that many people have been suggesting is everything that matters in terms of our weight balance.

    We are more complicated than that. And part of what's necessary when we evaluate our metabolism is to actually look at the gut microbiome. And now here we are. And we, if we look at, you know, for example, the measures of our metabolism, our blood lipids, our blood glucose, our own research, ZOE published in June of 2020, and natural medicine shows us that the gut microbiome actually plays a very powerful role in the way that our body, for example, will have a blood sugar after a meal or how high our blood whip is, will raise after a meal. So like with regard to the blood lipids, our gut microbiome is more important than the food that we are eating. We can predict a person's elevation of their blood lipids based upon their gut microbiome, more powerfully than even what is on the plate in front of them.

    That's insane. And that's some of our own research. 

    [00:23:36] Jonathan Wolf: It's amazing. Right. And I think if you're listening to this right now, you're like, okay, so you sort of convinced me, Will, these bacteria, my gut, they sound like they're quite important. I liked the idea of getting the bacteria with the skinny person I suspect some of them will be saying. And I certainly liked the idea of getting the bacteria of the person who's really healthy, and is still looking great when they're 90, you know, I'd like some of what she's having and wish had a lot of questions around sort of the start of that process. So we had a lot of questions about the microbiome for infants, birth what's going on there. So, you know, maybe start at the beginning. Do we have a microbiome before we're born and what happens during this process and afterward, Will? 

    [00:24:19] Dr. Will Bulsiewicz: Yes. So this is, I think, such a fascinating study on what it means to be human and the relationship that we have with our microbes. So as I walked through this, I think it's going to really open many people's eyes.

    First of all, earlier in the episode, you asked me are microbes everywhere? And I said I believe the answer is yes. And part of the reason that I say that is we once thought that the baby was sterile inside the mom's womb. And now there is new data that has emerged to indicate that the baby already is starting to form their microbiome before they're even born.

    So a baby is not completely sterile, but when the mom's water breaks, the barrier that separates the external world from the baby is now removed. And part of introducing the baby to this new world is exposure to these microbes because they are everywhere. And in a traditional sense, a baby would pass through the birth canal and come out of the vagina, and the mom's vagina has a microbiome, but what's fascinating is that late in the third trimester of pregnancy, the vaginal microbiome actually undergoes changes.

    And prepares for delivery of the baby.

    [00:25:43] Jonathan Wolf: Amazing. 

    [00:25:43] Dr. Will Bulsiewicz: And we see the arrival of microbes. I mean, this is just, this is almost science fiction, but it's real, you see changes where there are certain microbes that you would be more likely to describe as being in the gut microbiome than in the vaginal microbiome.

    And they start showing up basically as a welcoming party. The child passes through, and this is like nature's supercharged, probiotic. Welcome to the world. Our first gift is a new microbiome. Here's your new suit. And so then the child is born. And so I'm a young dad and we're expecting a new baby and just a few weeks.

    And one of the things that people will frequently do is skin on the skin between the baby and the parent. And there's actually a sharing of microbes. That's taking place immediately by that skin-on-skin contact. So we are introducing this baby to a new microbial world. It's not a sterile world. This is a microbial world in which we exist.

    And now the child will start to grow and develop his or her own microbiome. And one of the things that really actually changes this is whether or not the child is breastfed. And it turns out when we think about evolution, Breast milk is evolved by nature to be the perfect food for infants. And, you know, I do feel compelled to say this real quick, that one of the most stressful things that I've ever dealt with in my entire life, despite all of the years of medical training and sick people was actually when our daughter was born and she was struggling to breastfeed.

    And I fully recognized that it's not something that's possible for everyone. There may be milk banks that are available to individuals if that's something that they want to look into if they struggle with this. But I also want people to know that it's not required to have a healthy child to breastfeed your child. But it can contribute to a healthy child. 

    [00:27:47] Jonathan Wolf: And I think that's really important because as a father with two children, there's a lot of pressure about being a good parent and even more I think about being a good mother. And this is yet another thing where you can feel that you fail. So I think that's very important.

    [00:27:59] Dr. Will Bulsiewicz: People feel very guilty, right? They feel very guilty, but so Jonathan, back to the breast milk, what's fascinating. And like, I mean, honestly, mind-bending is that what they have discovered very recently in the last few years in breastmilk are these chains of sugars that they described as human milk oligosaccharides and these human milk oligosaccharides there are over 200 varieties of them, yet none of them have any direct nutritional value for the child. So what are they doing there? And the answer is that human milk oligosaccharides are prebiotics. They are food for the baby's developing gut microbiome. Mom evolved 200 varieties of fiber to help to fuel the developing microbiome in this newborn child. 

    [00:28:56] Jonathan Wolf: Which is mad, isn't it. And I heard a talk on this about four or so years ago, and particularly about one of these strains, right? Which is b infantis, which is supposed to be sort of optimized, right? For the particular fiber that is in the mother's breast milk. And I got so convinced about this, that I convinced my wife, that we had to give this to our now two-year-old. So like yet more pressure to layer on top of what is, as we just said, a really tough time, right. In the first few months, I have no control tests. So I don't know whether, in fact, it was a good idea whether it made a positive impact or not. Although I think there is some really interesting sort of randomized controlled trials around this, right Will?

    [00:29:37] Dr. Will Bulsiewicz: Yeah, so we, and we can talk about some of the data that surrounds breastfeeding versus bottle feeding. One of the trends that are taking place in the formula space is actually to introduce fiber into the formula. Now, again, fiber has no nutritional value to the child directly, but the fiber is fuel for the microbiome.

    The difference is that adding some, inulin, for example, that's one type of fiber. And that's not the same as 200 plus varieties of human milk oligosaccharides. And so that's where nature is just so powerfully, intelligent and recognizing what our individual needs are. That's galvanized through human evolution, microbial co-evolution.

    So, anyway, so the child is breastfed, it enhances specific species of microbes, particularly the bifidobacterium that you were mentioning, Jonathan. And this child starts to mature. Their microbiome is developing, and then it explodes around six months of age. When the child starts to introduce to solid food. Again, you are feeding the species within the microbiome, but the other thing that you're doing is you are introducing microbes.

    And so the child starts to really take off in terms of the variety of species within their microbiome. And this process accelerates to where by the time a child is two to three years of age, they're a little one they're physically small, but their gut microbiome is very big, just as big as us adults. And so it really brings forward the importance of nurturing during this critical period of time from birth up to age two to three, where these are the formative years for the microbiome.

    For most of our adults, the microbiome is going to be determined during this time and we want to protect it. And so going back to the data that you were asking about Jonathan, we have very interesting research studies that show a consistent path. Where if a child is born by cesarean section, and by the way, both of my children have been born by cesarean section.

    You can have healthy kids who are born by cesarean section, but if a child is born by cesarean section, bottle-fed, or exposed to antibiotics during these formative years, these first two years, we ended up seeing the same downstream pattern later on in life. Which is increased the likelihood of metabolic diseases including obesity and type two diabetes and an increased risk of immune-mediated issues that include, for example, asthma or food allergies.

    Or even some auto-immune diseases such as celiac disease. 

    [00:32:27] Jonathan Wolf: So all of that can sound a bit depressing. And I always think one of the things about this podcast and ZOE is this idea that actually you can take a lot more control than maybe you think otherwise that a lot of this is all trouble. So let's say that's happened in your own previous life as a child or indeed with your children, what can you do to help improve your gut health, and the health of your microbiome? I think it's a great place may be to focus on towards the end of this really interesting chat. 

    [00:32:54] Dr. Will Bulsiewicz: Yeah. So the beauty of it is, that, your gut microbiome, no matter what you have done and what you've been through your gut microbiome, forgives you.

    And wants to have a good, healthy relationship with you. And, it's important to see and understands that ultimately our gut microbiome ends up being this image that reflects our environment. And environment I'm using in a very broad sense in that it includes your nutrition. So the, three pounds. Then, you know, one and third kilos of food that you consume on a daily basis is perhaps the most important thing in terms of shaping your microbiome.

    And when you change what you eat in less than 24 hours, you will see changes in your gut microbiome. That's how malleable it is, but it also includes, you know, whether or not you're getting a good night's rest, exercise, moving your body, spending time outdoors. What is the environment in your home? Do you have pets?

    And then I think that there's one thing that I would want to bring forward because, you know, let me be the first to say that as an author of a nutrition book, It's way too easy for me to fixate on nutrition for an entire hour and not actually comment on one of the most important parts, which is our relationships that we have.

    And part of that is the relationships with others. So real quick, Jonathan, this is new research that actually I find to be very exciting, where they have shown that we share microbes with our spouse. And actually, we share more microbes with our spouse than we do with our siblings, even though we are in the same family and we share genetics, we actually have more microbes in common with our spouse.

    [00:34:57] Jonathan Wolf: And again, I'm thinking my wife would say that given the way that I clean up after dinner, that's not surprising, but it's that, is that the explanation or. 

    [00:35:05] Dr. Will Bulsiewicz: Well, kind of the things they did in this study is they actually controlled for the food.

    [00:35:10] Jonathan Wolf: Okay. 

    [00:35:10] Dr. Will Bulsiewicz: And they actually discovered that even after controlling for food, there was this connection between your partner that you cohabitate with.

    [00:35:18] Jonathan Wolf: So it's not just my mess is what you're saying.

    [00:35:20] Dr. Will Bulsiewicz: It's not just your mess, you're off the hook, man.

    [00:35:23] Jonathan Wolf: Okay. Well, I don't think so, but thank you. 

    [00:35:25] Dr. Will Bulsiewicz: Well, at least for this, at least for this friendly, safe place that we have here during the ZOE podcast, and then you have to go back to real life.

    [00:35:33] Jonathan Wolf: Go downstairs

    [00:35:35] Dr. Will Bulsiewicz: but in this study, Jonathan, what was fascinating is that they discovered that partners who feel very emotionally connected to one another, share more microbes together than partners who, for example, feel distant and separated. And we are social creatures. 

    [00:35:54] Jonathan Wolf: Oh, that's amazing. So there might be some new relationship tests.

    I love the idea of this, where we can both get our microbiome sequenced and you can figure out how well the relationship is going with like, an external scientific test. It's going to completely blow the minds of the marriage relationship business. 

    [00:36:14] Dr. Will Bulsiewicz: Now that would be interesting and perhaps quite controversial, but that would be an interesting thing for us to do. Well, there are a number of ways that you can look at this. One is that we share microbes. And we don't even realize that many of the things that we just accept as normal human behavior is actually us expressing a connection with one another through microbes. They've researched kissing and we share a hundred million microbes with a good kiss.

    If I see you in London, Jonathan, I'm either going to shake your hands or give you a big high five, and either way we are sharing microbes when we do that. Right? And so, but the other thing is that we are social creatures. And if you want to tear a person apart, you isolate them. But if you want to bring out the best in the human being, then you surround them with others who love them and support them and make that clear.

    And so when we feel loved and supported, we are our best versions of ourselves. So. What I wanted to bring forward in the west in sort of this, these last moments is that yes, it is our relationships with others. But the other thing too, that's important, like very important is the relationship that we have with ourselves.

    We have to love ourselves. And if there are things that are unsettled that are bothering us, there are actually physiologic ways. This is not woo-hoo. This is actually science. There are physiologic ways during times of stress. Our pituitary glands will release a hormone called CRH corticotropin, releasing hormone.

    And that will set off a cascade of stress responses that if you follow it down to the gut microbiome, you will discover that the gut microbiome becomes disturbed. We use the word dysbiosis, and this is why in times of stress, many of us will manifest digestive symptoms like diarrhea or abdominal cramping, or bloating, the gut is connected to our mood.

    And if you have something that is unsettled like that, we could use the word trauma, and that could be big trauma, but it could also just be something that's bothering you or a stressful job situation or something going on at home someone who's sick. And those things can unfortunately activate this stress response.

    And be the thing that's holding us back. And the reason that I wanted to bring that up real quick is that I think it's important because there are people who exist. I've seen these people so many times, they are often in front of me as patients where they do everything right. They eat right. They sleep, they exercise and they're not better.

    And the reason why is because the thing that's holding them back is that there is something that is unsettled and it needs to be addressed. So I thought it'd be important to bring that in as part of the discussion. 

    [00:39:12] Jonathan Wolf: I think that's brilliant. I think just before we wrap, I think we always love to try and provide a sort of as much actionable advice as possible.

    So clearly we'll talk a lot more on food in many podcasts, but if I said, Will, you know, if somebody is listening to this, they're really convinced that their gut microbiome matters to them. And they're saying: can you give me like three tips around food? Cause you've talked about some of the things that are on three tips around something that we can do around food that might be able to be positive for my gut health?

    [00:39:43] Dr. Will Bulsiewicz: Absolutely. So if I'm afforded three opportunities, three tips, the first thing that I would do is to say that we need to increase the consumption of plant food in our diet. Now, this is not necessarily applicable to every single person. You might be 90% plant-based and that is a very healthy diet. And I celebrate you, but in the US, and this is not radically different than the UK, the average person is only 10% plant-based and that means we have a lot of room to increase our plant food consumption, because these are the foods that our microbes who love to eat. 

    The second rule is from a dietary perspective. And this applies to everyone, no matter how healthy your diet is, is that we need more variety in our diet. The food system actually doesn't want this to happen. 75% of the calories that come from plants come from only three plants, wheat, soy, and corn. So if it's going to happen, if we're going to eat more variety of plants, it has to come from within.

    We have to be the ones to initiate this despite the system. And so I encourage everyone to focus, make this a focus with your food with every meal. Eat a wider variety of plants. 

    And the third thing is that we're in an exciting time because science is validating things that we've believed to be true yet didn't yet have the research studies to back them up until recently. And just in the last year, new science from Christopher Gardner, who's one of my partners on the ZOE scientific advisory board. He's at Stanford University. And in collaboration with Justin and Erica Sonnenberg also at Stanford University, they looked at an intervention where people consumed more fermented food and in just 10 weeks of increase in their fermented food consumption, they were able to increase the diversity within their gut microbiome and reduce measures of inflammation. That's powerful. 

    [00:41:41] Jonathan Wolf: That's amazing. Isn't it? Well, Will, thank you very much. You know, this was an introduction. I am sure we're going to come back to many of these topics, given that gut health is one of the things we were sort of passionate about on this podcast, but I'd like to just try and sort of summarizing what we've covered today.

    So we start off by saying, what is the microbiome? And the answer particularly in the gut microbiome is trillions of main bacteria inside our guts. And then we said: Can it be an organ? And I think your answer was, you know, from your perspective, you know, it is an organ. Then you talked about a number of studies that really shows, you know, I guess sort of real scientific proof for why the microbiome works of which you gave this in a really amazing one, I've heard before where they took the microbiome from two twins, one of whom was overweight and the other not. And you could actually carry that over to mice, even though they were eating exactly the same food. And so really shows this real causal impact. And then we talked a little bit about sort of how the microbiome develops from birth.

    I think you shared this fascinating information that maybe, you know, as a baby, we're not even completely sterile inside the womb, despite being sort of wrapped up in this protected state. But certainly from the point that your mother's waters break, then suddenly you're getting exposed to all of these bacteria from your mother, which had maybe been specially curated for you.

    And then there are many other things beyond food, which I think is particularly interesting because we tend to really fixate a lot on food. You talked about sleep, you talked about exercise, and then you talked about social interactions. And some really interesting new research that apparently will tell me how close I am to my spouse based upon how many bacteria we share.

    So I'll go and discuss that tonight and talked a lot about stress also in the way that it might be having a very negative impact in general, on your life and also here. And then finally, we wrapped up with three really simple food tips that you could take away. And I think you said, firstly, increase the amount that's coming from plants.

    Secondly, eat more variety in your diet. So more different plants. And the third thing is to eat more fermented foods and there are now some studies coming along suggesting that that can really, really have an impact. 

    [00:43:51] Dr. Will Bulsiewicz: Yeah, and I think that's a very impressive summary of this entire podcast and listening through it. It just makes it very clear that we've covered a lot of very important ground, but, you know, I hope that what the listeners receive from this is that they are convinced that nature has decided that we are the best version of ourselves as super organisms when we have a healthy relationship with our gut microbiome. And we really knew nothing about this relationship until very recently, but now we are finally empowered with new knowledge and new science that is transforming our ability to nurture that relationship and bring out the best in all of us.

    And that's really exciting. Super exciting. 

    [00:44:34] Jonathan Wolf: Thank you so much, Well, really enjoyed that.

    [00:44:37] Dr. Will Bulsiewicz: Thank you, Jonathan. 

    [00:44:40] Jonathan Wolf: Thank you to my friend, Dr. Will Bulsiewicz for joining me on ZOE science and nutrition today, we hope you enjoyed today's episode. If you did, please be sure to leave us a review and subscribe. If you're interested in learning more about ZOE and our program, which starts with a microbiome test to discover the best foods for your body, you can head to join ZOE.com/podcast and get 10% off your personalized nutrition.

    Finally, if this episode left you with any questions, please send them in on Instagram or Facebook. And we will try to answer them in a future episode. As always. I'm your host, Jonathan Wolf, ZOE science and nutrition is produced by Fascinate Productions with support from Sharon Feder and Megan McPherson here at ZOE.

    See you next time.

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