Transcript: Dr. Will Bulsiewicz On The Microbiome: Heal Your Gut, Sidestep Disease & Thrive

Will Bulsiewicz.

Dr. B is in the house. How you doing man?

DR. WILL BULSIEWICZ: I’m great. Happy to be here. I’m happy to be live in front of you right now. Last time I know we did this and I was not only on a zoom call with you, I couldn’t get my microphone to work properly and I was on call and I had a patient in the hospital who was sick and it was just crazy.

RICH ROLL: Well, the audience didn’t seem to care. You didn’t feel distracted to me in any way. That was a very popular episode. People loved it. And I made you promise that if you found yourself in LA that you had to come by. And here we are.

DR. WILL BULSIEWICZ: Here we are. It’s the first time I’ve been in LA in about 15 years.

RICH ROLL: Really?

DR. WILL BULSIEWICZ: So, yeah, seriously, it’s crazy. The last time that I was here, I was actually interviewing for GI Fellowship at UCLA, and this was, you know, I was in my late 20s and clearly not married and no kids, and now it’s my life has completely changed.

RICH ROLL: Yeah, there’s a lot of changes. There’s a lot of stuff to catch up on. You’ve been on quite the trajectory in lockstep with everybody’s growing fascination around all things microbiome and gut health. And your particular skill set and level of interest intersects perfectly with all this emerging science that’s occurring right now that we’re going to get into.

So I’m really excited to sit down with you, and my desire and intention for this particular episode is to have it be a little bit distinct from the first one, where we kind of went into your backstory and covered a lot of ground, of course. But for people who haven’t listened to that or haven’t stumbled across that episode, I mean, definitely go check it out. I think it’s episode 538 from a year and a half ago or something like that.

I would very much like this to be a standalone, comprehensive review of all things microbiome, gut health, why it’s important, and the many ways that we can take action in our own lives to not only sidestep disease, but to live to our healthiest potential.

DR. WILL BULSIEWICZ: Yeah, I mean, I think we could do an incredible episode where we take it all the way from the top. That way you have the introductory material that you need, but we’re going to bring you all the way to the cutting edge. There’s studies that I’m ready to talk about today that have been published in the last few weeks.

Latest Breakthroughs in Microbiome Research

RICH ROLL: Well, let’s come out of the gate hot with the cutting edge. What has got you excited in terms of the latest literature and what we’re discovering about the microbiome?

DR. WILL BULSIEWICZ: I was at a microbiome meeting recently and blown away. And this is coming from the guy who’s nerding out on microbiome studies all day, blown away by what’s happening in cancer research with the microbiome – complete game changer.

So what we’re seeing here is that, first of all, going back a few years, we discovered that cancer has a microbiome.

RICH ROLL: How does that work? A distinct microbiome that is differentiated from how we commonly think about it. Explain that.

Cancer’s Hidden Microbiome

DR. WILL BULSIEWICZ: I’m not even talking about the gut microbiome. So let me start with this. Microbes are everywhere. They cover us from the top of our head to the tip of our toes. They’re most concentrated inside of our gut. But they’re on plants. They’re part of the plant microbiome. They’re in the soil. Obviously, everything that’s alive in this planet either is a microbiome or has a microbiome. Those are the two choices.

So everything has a microbiome. And I thought a tumor would be, you know, I mean, a sterile mass of cells. And a few years ago, they discovered that tumors, cancer, cell cancer tumors, actually have their own microbiome separate from the gut microbiome. They have their own microbiome.

And they took this further. They were taking a look at pancreatic cancer, which is one of our most deadly cancers, and they analyzed the microbiome of the tumor, not the person’s gut microbiome of the tumor, and discovered that a person who has a low diversity within the tumor microbiome has a worse prognosis or a lower likelihood of survival relative to the person whose tumor has a high diversity.

RICH ROLL: So explain what that means, low diversity.

Understanding Microbiome Diversity

DR. WILL BULSIEWICZ: So diversity is looking at sort of the spectrum of different types of microbes, so different varieties of microbes and how strongly they’re represented. So inside of us as humans, inside of our gut microbiome, we could have anywhere from hundreds, up to potentially a thousand different varieties of microbes living inside of our gut. And one of the things that we would look at in terms of the health of the gut microbiome in a human being is the diversity within that system.

RICH ROLL: Sure.

DR. WILL BULSIEWICZ: So what we find Rich is that if you look at ecosystems, whatever that ecosystem may be, you know, it could be the Amazon rainforest, it could be the Great Barrier Reef, and it can be actually our personal gut microbiome, which is an ecosystem. And what we discover, biologists will tell you this, is that diversity within the ecosystem is a measure of health.

RICH ROLL: Right. It makes it more robust and resilient.

DR. WILL BULSIEWICZ: Right. Because there are different players that are there, and they all have different unique skills that they can basically contribute to the greater good. And if you, for example, if you take the rainforest diversity and remove the snakes from the forest. I’m not a huge fan of snakes. You remove the snakes. The problem is that the other animals, they’re not snakes. They’re not really designed to fill that role within the ecosystem.

And so when you remove the snakes, it actually has a ripple effect because all these other animals are being affected by the fact that you have disrupted the balance that exists within that ecosystem.

So, anyway, getting back to the cancer, they discovered that these cancer cells have their own microbiome and that the diversity within that microbiome could indicate prognosis. Now, this is quite fascinating. And so they continued down this path to look into this in more detail. And there have been a number of major discoveries.

First, in acute myeloid leukemia, one of the treatments that they will give people are stem cell transplants. And it’s basically trying to throw Hail Mary and save a person’s life. And there are some people who do great, and there are some people who do not. What they discovered recently is that the microbiome, the gut microbiome of the individual people who received the stem cell transplant actually is difference making. If you have high diversity within your personal gut microbiome and you receive the stem cell transplant, your survival is actually much better.

RICH ROLL: But conversely, if the diversity of the microbiome with respect to the tumor is high, that would correlate negatively with treatment receptivity. Is that what you’re saying? So if the microbiome on the tumor is very diverse and robust, then it’s going to be much more treatment resistant?

DR. WILL BULSIEWICZ: No, actually, more treatment or actually. Actually it does better.

RICH ROLL: Oh, I see. Because I was thinking the diversity of that microbiome is there to support the tumor growth. So the less resistant it is, then, the weaker it is.

DR. WILL BULSIEWICZ: No, actually. So in both cases, a more diverse microbiome, whether it’s inside the tumor or whether it’s the patient’s actual gut microbiome, in both cases, a more diverse gut microbiome is associated with a better prognosis.

Groundbreaking Melanoma Research

So now MD Anderson is taking the ball and running with this. And they’re doing quite fascinating research with melanoma specifically, which is a skin cancer. It’s the most deadly form of skin cancer that exists. And one of the ways that they will commonly treat melanoma is with immunotherapy. Now, they’ve been doing this for about 10 years, and it can be highly effective. But of course, there are people that it does not work for. So how do we determine who are the people that it’s good for versus the people that it’s not good for?

Well, kind of building up to the most recent stuff that’s just from a couple of weeks ago. A few years ago, M.D. Anderson did a study where they gave antibiotics, or they looked at the effect of antibiotics immediately prior to receiving this treatment. For melanoma, antibiotics reduced diversity within the gut microbiome. And what they found is that in doing this, they actually were reducing the effectiveness.

RICH ROLL: That’s fascinating.

DR. WILL BULSIEWICZ: Of their treatment. Taking it a step further, they then took a group of people and they showed that once again, if you have a higher diversity of your microbiome, you are more likely to survive and have a good result from immunotherapy. They gave them a fecal transplant, so they started giving fecal transplants to people. And when you received a fecal transplant to boost your diversity temporarily, people had a better survival and better outcome from immunotherapy.

RICH ROLL: That’s amazing.

The Fiber Connection

DR. WILL BULSIEWICZ: So now bringing it all the way forward to where we are today, more recent research has shown that the diversity within a person’s gut microbiome, their gut microbiome is very relevant to this melanoma. And they’ve identified specific species. And what’s interesting is that the species that you want to have that basically portend a better prognosis are the exact same ones that help us to process and digest our fiber and produce short chain fatty acids.

And these short chain fatty acids, they are the – we can talk about more later if you want to, but they are the product of fiber degradation by our gut microbes.

RICH ROLL: Wow.

DR. WILL BULSIEWICZ: Fiber is the prebiotic. Our gut microbes are the probiotics. And when they come together, the fiber, the prebiotic, with the probiotic bacteria, they basically create this new compound which we would call a postbiotic. And these are the short chain fatty acids, like butyrate.

So they showed in this research that melanoma patients have a better survival if they have higher levels of these butyrate producing microbes in their gut.

RICH ROLL: Wow.

The 20-Gram Fiber Study

DR. WILL BULSIEWICZ: So they did a new study looking at dietary fiber. What happens when people are eating more dietary fiber? And again, this is in the context of treating the melanoma with this intervention immunotherapy. And the cutoff that they used was 20 grams of fiber per day. Now, let me just first comment and say this is actually less than the recommended minimum.

RICH ROLL: Not very much.

DR. WILL BULSIEWICZ: It’s not very much.

RICH ROLL: Probably more than most people are eating.

DR. WILL BULSIEWICZ: Yes. So in this cohort of people where this cutoff is 20 grams of fiber, so they considered it to be if you’re more than 20 grams of fiber, you’re a high fiber consumer. I’m just going to tell you the minimal recommended amount for a woman is 25 grams of fiber.

RICH ROLL: And you’re probably eating, I don’t know, 200 grams of fiber a day.

DR. WILL BULSIEWICZ: I’m supercharged on as much fiber as possible. The average for a man, the minimal recommended amount for a man is 38 grams of fiber. Right. So even at 20 grams, we are low. 71% of the people in this study did not hit 20 grams of fiber.

And what they discovered is that the people who were the high fiber consumers, this 29%, they had a significantly improved survival after the immunotherapy for melanoma on the high fiber diet.

RICH ROLL: Wow.

DR. WILL BULSIEWICZ: And when they broke this down. So check this out. This is where my mind is blown when I saw this. For every 5 grams that you increased your fiber consumption, you increase your survival by 30%.

RICH ROLL: That’s an insane number. That’s crazy. So the most general takeaway from that is if you are suffering from cancer and you’re about to undergo treatment or you’re currently undergoing treatment, you should be boosting your fiber intake as much as possible.

The Microbiome’s Role in Cancer Treatment

DR. WILL BULSIEWICZ: So I would expect that that would be true. We can’t necessarily apply that to every single cancer. But here’s what I can say. What we just saw.

RICH ROLL: It’s not going to hurt you.

DR. WILL BULSIEWICZ: No, it’s not going to hurt you. Yeah. This 5 grams of fiber translating into a 30% greater survival is giving me deja vu. From a colon cancer study that came out in 2018, where if you increased your fiber intake after you were diagnosed with colon cancer. Now these are, by the way, people who did not have metastatic colon cancer. Okay, so because metastatic’s a totally different animal.

But among people who do not have metastatic colon cancer, if you increased your fiber intake after you were diagnosed, for every five grams that you increased your fiber intake, you saw an 18% increased likelihood of survival.

RICH ROLL: Wow.

DR. WILL BULSIEWICZ: So we’re seeing the pattern showing up among different types of cancers. And further study is going to push this even further along. Melanoma is where we have the most robust research, because MD Anderson has really taken an interest in this particular topic.

But I think this is the future. This is where people are going to be looking. And what’s exciting, Rich, is that this is not just us describing the microbiome. We’re talking about manipulating the microbiome by quite simply eating plants to save people’s lives.

Tumor Microbiomes and Treatment Potential

RICH ROLL: Right. That’s wild. On that idea of a tumorous growth having its own unique microbiome. What has been learned about the quality of that microbiome or the particular microbial ecology of that in terms of how it can be manipulated to produce a favorable outcome with respect to treatment?

DR. WILL BULSIEWICZ: So I haven’t seen any research specifically looking at the use of the tumor microbiome to create interventions that can improve cancer care. But this has become a very hot topic within the cancer space. And there’s more research that’s ongoing because first they did this study with the pancreatic cancer showing that you lived longer if you had a high diversity of your tumor microbiome.

And so now what they’re doing is they’re looking at different types of tumors. Step one is you first sort of describe what you’re seeing and then step two is going to be, so how do we manipulate this? And they do believe that these microbes, Rich, are playing a role. This is part of the thought process here.

They do believe that these microbes that are literally a part of this tumor are playing a role in the ability of your cancer treatment, whatever it may be, whether it be chemotherapy or immunotherapy, to actually get access to the tumor cells and basically disrupt them.

RICH ROLL: It would follow logically from the idea that fecal transplants can be at least temporarily effective, that with respect to say, a skin cancer, that there could be some kind of microbial topical ointment or treatment that could be rubbed on this, or in turn for an internal tumor, for there to be some kind of injection to the tumor with some kind of microbial solution that would increase that diversity or somehow make that tumor a better candidate for treatment.

DR. WILL BULSIEWICZ: I completely agree. And some of what they’re saying, for example, the researcher out of MD Anderson that’s doing this melanoma research, what she said in this meeting recently is that she believes that as we continue to unpack this particular topic and understand this new finding that the tumor has a microbiome, that this is going to radically transform cancer care and allow us to become so much more effective than we currently are in terms of our therapeutics. So super exciting.

The Revolutionary Nature of Microbiome Science

RICH ROLL: I mean, in terms of just human biology in general, the science that’s coming out on the microbiome is the most interesting to me, with maybe the exception of some neuroscience stuff. But I mean, it’s mind blowing stuff. And it’s this thing that was there all the time that we didn’t understand at all and essentially ignored, and now we’re just tiptoeing into the most basic understanding of it, and each new study or discovery is just more mind blowing than the one that preceded it.

DR. WILL BULSIEWICZ: That’s so true. And I think that part of it for me is it reminds me to have a sense of humility with the science because there’s so much about what we understand today that 15 years or 20 years from now, we’re going to look back at the conversation that you and I are having and saying, “Wow, we have completely changed how we feel about stuff on these particular topics.”

Twenty years ago, I mean, was there anything on this planet less valuable than poop?

RICH ROLL: Right, Right.

DR. WILL BULSIEWICZ: It’s like, who would even possibly care about poop or the microbes that produce those smells? Why would we care about that? And now what we’ve discovered is this is a radical source of information about human health that completely is transforming cancer care. Right.

And at the same time, scientists are fighting over, you know, there’s these fossilized poops, they call them fecaliths. And scientists are fighting over who gets to have ownership of fecaliths because they want to study old poop and see what does that mean and what does that tell us?

RICH ROLL: Right. It’s like the mosquito and the amber in Jurassic Park.

DR. WILL BULSIEWICZ: Exactly.

RICH ROLL: And also, the analogy that popped into my mind was the microbiome is to human biology, as is dark matter to astronomy. It’s sort of like this thing that we don’t really understand that we’re just only beginning to understand that has just, you know, massive implications in terms of how we think about life. Life in general.

The Microbial Universe Within Us

DR. WILL BULSIEWICZ: I think that’s very true. And I also think that there are these planes of existence that if we – it all depends on – are you zooming out or are you zooming in? If you zoom in on our gut, you discover this community, this thriving, vibrant community of microorganisms that are as alive as you and I are, Rich.

And it’s very hard for us to conceptualize this and understand this because they’re invisible to us, but they are there, and they have personalities just like you and I do. They have cliques or groups of friends. They have different skill sets, and they have different dietary needs. So they’re very, very similar in many ways to humans.

And think about Mother Earth. Right? And if we zoom out, if we were standing on the moon right now, you don’t see you and I here having this conversation. Right. But yet the Earth has this microbiome.

RICH ROLL: Right?

DR. WILL BULSIEWICZ: We are the microbiome as humans.

RICH ROLL: Yeah.

DR. WILL BULSIEWICZ: And sometimes I feel like with this.

RICH ROLL: It’s the perfect organization of the universe, from the smallest thing to the largest thing. And it always kind of, you know, it’s always in lockstep – it’s idea of looking at everything holistically. If you telescope out and you see our freeways, they’re like arteries, and each car is like a cell delivering something to some part of this larger organism.

And these mechanisms scale up from the thing that we can’t see all the way to the laws of the universe. And I think the kind of implications for that in terms of medicine and health is to – and we’re seeing this – is to think about human health in a more holistic way.

And I think the danger, or kind of not really the danger, but the predilection of the scientist or the researcher and the scientific method in and of itself is to look at things in isolation. Right. And it becomes tricky, and that’s how we’ve made tremendous progress. But we cannot be myopic to how those variables are functioning within the construct of a much more – an infinitely more complicated system.

DR. WILL BULSIEWICZ: That’s completely true. We look at things in isolation because we have simple human brains. And so we’re only able to really understand things in a sort of a linear way, when in fact, our body is this confluence of multiple things that are bumping into each other by a fraction of a millisecond. And it’s all coming together to form you and I having this conversation.

COVID-19, Isolation, and Immune System Impact

RICH ROLL: Yeah, yeah, yeah. I want to turn attention for a few minutes and talk a little bit about our immune system and how our microbiome plays into that. When we first – when we did our first episode, it was early days of COVID and we talked a little bit about how to keep our immune systems healthy and to make sure that our microbiome is diverse as, you know, something necessary to combat disease.

Here we are two years later. We’re sort of beginning to come out of this period. So I’m interested in what you’ve learned over the last two years in terms of how COVID has impacted us. I mean, we’ve been in this era in which we’ve been forced to socially isolate. We’ve restricted our exposure to other human beings and a multiplicity of environments. We’ve over sterilized everything.

This has to have an impact on not only our microbiome, but the robustness of our immune system to combat disease in general. And of course, you know, these protocols were necessary and public health demanded them. But at the same time, I think it’s important to really take a look at how we were living and now, how to make appropriate adjustments moving forward.

Were there any studies that have – I’m certain people are going to study this period of time in the context of the things I just mentioned. But what are your thoughts?

Fiber’s Protective Role Against COVID-19

DR. WILL BULSIEWICZ: Yeah, totally. So I think that the conversation about cancer is a nice segue into this type of conversation about the immune system and how it interacts with our gut microbiome. Because basically looking at those cancer studies effectively, what we’re saying is that the gut microbiome has a direct impact on your immune system’s capability of doing its job.

And that’s because 70% of the immune system is literally right there, separated from your gut microbiome by the most thin single layer of cells. So 70% of the immune system on one side, 38 trillion microbes on the other side, constant communication across this little barrier that’s there, and they’re talking to one another.

And so when it comes to COVID-19, this becomes very relevant because of some of the things that we’ve learned. When you and I got together back in June of 2020, I made a prediction that I believed that fiber would be one of the keys in protecting ourselves from COVID-19. And I was basing that not on actually a COVID-19 study, but instead on data that actually was looking at infections with a respiratory virus in an animal model.

And they did this study in an animal model where basically they gave these animals a high fiber diet versus a low fiber diet. And the prediction of the scientists was that the high fiber diet, because it’s anti-inflammatory, that it would actually reduce the effectiveness of the immune system and when they infect them with a respiratory virus, that these animals would be more prone to death because of the high fiber diet. They found the opposite.

And when they went to unpack this, they were like, “What is going on here?” They dove deeper and they discovered that the key was that the fiber was coming into contact with these gut microbes. So the listeners at home can already hear a pattern of what’s happening here. And the gut microbes release the short chain fatty acids. The short chain fatty acids enter the bloodstream, leave the gut, enter the bloodstream, travel to the lungs, and in the lungs are actually able to manipulate the immune system to protect against this respiratory virus.

So in these studies, the mice that were on the high fiber diet, they were less likely to die, they had better lung function, and they had less severe illness. Well, if you fast forward through the pandemic, what’s fascinating, Rich, is that for me, as someone who really values high quality research information, I’m looking for trends, I’m not looking at single studies.

RICH ROLL: Yeah, and we have to be cautious about what we can extrapolate from a mice study.

DR. WILL BULSIEWICZ: 100%. We always have to be cautious because many times it doesn’t translate. This is why we want to see, okay, so we have the preclinical study or the animal model study, and now what happens in humans, we need to see that.

And so there was a study that was published in the journal Gut, which is one of the top two gastroenterology journals on the planet, where they were looking at the gut microbiome of people with COVID-19. And what they discovered is that, number one, there were clear disturbances of the gut microbiome if you had COVID-19. But there was actually a signature pattern that as the COVID-19 became more severe, this signature pattern became even more entrenched in the microbiome.

And that pattern was, to be very specific, it was the loss of the specific bacteria that produce the short chain fatty acids. Severe COVID-19 was associated with the loss of short chain fatty acid producing microbes. It would lead you to believe that the fiber is a relevant part of determining whether or not a person has severe or mild COVID-19.

And it wasn’t until very recently that we had a study that came out among healthcare workers from six countries. Frontline people being exposed to the virus and looking at dietary patterns and health outcomes. And they found in this study that people who were eating a plant based diet had a 73% reduced likelihood of having moderate to severe COVID-19.

RICH ROLL: That’s amazing. Did that factor, was this pre vaccination or did it factor in vax vs non vax people or were these people vaccinated?

DR. WILL BULSIEWICZ: The data that was collected for the study was pre vaccination. It was published post vaccination, but the data was collected pre vaccination. So these were people that were unvaccinated. And the pescatarian diet did pretty well as well. It was a 59% reduction of moderate to severe Covid 19 among that group. Well, pescatarian diet, I mean, there’s no meat, there’s no dairy, there’s no eggs, but there is fish and there’s a lot of plants.

RICH ROLL: Right, right. Is it possible to interpret from that data the extent to which the diversity of plant foods in the diet were the thing moving the needle versus the absence of animal foods or other unhealthy foods? How do you parse that? It’s one thing to just say the plant based people did better, but what is actually the active component in this?

DR. WILL BULSIEWICZ: Well, we don’t have the granularity to go into great detail about what was the diversity of plants within their diet. What we do know is that these are people that are eating a plant based diet. And so the clear assumption there is that this is a high fiber diet relative to a low fiber diet.

But then on the flip side, what was interesting in this study is that there was an additional finding. The people who did the worst had a specific dietary pattern as well. It was low carb. The people who were eating a low carb diet, again, they did the worst, plant based, did the best. And if you were to line this up and compare low carb to plant based, what you would discover is that the people who were consuming a low carb diet had a 3.8 times higher likelihood of developing moderate to severe COVID 19.

RICH ROLL: That’s interesting. I would have thought the people who were doing the worst would be people who would be on the McDonald’s diet, which isn’t necessarily low carb, but just tons of processed foods and refined grains, et cetera.

DR. WILL BULSIEWICZ: You know, I think it brings forward questions about the low carb diet. And we don’t with this particular study have the answers of what are the specifics of what was their low carb diet. But I think it’s within reason to assume that people who described their diet as a low carb diet were doing a general ketogenic type diet, which in many cases is low fiber, where you’re basically reducing your plant intake, you’re going low on fiber, and you’re cranking up the animal products.

Now, if we bring in a nutritionist who’s highly facile in this space, could they craft a diet that’s higher in fiber and yet still low carb? Yes, they could, but that’s not the way that real people eat in the real world.

RICH ROLL: Right, right. If you’re just eating broccoli or something like that. Right.

DR. WILL BULSIEWICZ: Yeah, there’s plants that if we start getting a little more technical with the low carb diet, because some people will do this in trying to protect the space.

RICH ROLL: Yeah, plant based low carb diet is a thing.

DR. WILL BULSIEWICZ: That’s right. And there’s also clean keto where you’re specifically looking to get your dietary fiber and yet you’re still predominantly getting your calories from fat. But there are still some issues with these types of diets. I mean, you can’t do that without eliminating fruit. You just can’t.

RICH ROLL: Right. So that’s interesting. So essentially the takeaway is the people who, if you can interpret that data, the takeaway would be that people who were amping up their fiber in their diet just fared better in general.

DR. WILL BULSIEWICZ: Yeah. So now here we are, we’re just a few minutes into this episode, and we’re already seeing a pattern in the real world of where fiber and the gut microbiome are impacting our gut, are impacting the ability of our immune system to properly do its job. Whether it’s cancer care, whether it’s the real world protection from the pandemic, we’re already seeing this pattern exist.

The Pandemic’s Impact on Microbiome Health

DR. WILL BULSIEWICZ: Going back to your original question, do we have data about the pandemic itself and the effect of the pandemic on people’s gut microbiomes. I haven’t seen any good high quality data to really unpack that conversation. But what we do know is this. We know that people do better when they’re close to other people. We know that in terms of their gut microbiome and the diversity within that, we know that people have a healthier gut microbiome when they’re under less stress. But we’ve all been under tons of stress, right.

And we know that people have a healthier gut microbiome when they’re spending more time outdoors. And literally, there’s a study where they took a group of adults and they had them stick their hands into soil for two weeks. That’s all they did. They put their hands in the dirt. They weren’t even gardening. They were just hands in the dirt for two weeks and they had healthier gut microbiomes at the end of the two weeks.

RICH ROLL: Right. I would think that there was probably a lot less hands in the dirt over the last two years. And all told, if you were to canvas the entire global population, I would suspect that there is a reduction in microbiome diversity just as a result of the lifestyles we were compelled to lead over the last two years.

DR. WILL BULSIEWICZ: There is data about the increase in, for example, mood disorders. There’s data about the increase in substance abuse during the pandemic. And obviously, these are things that have a direct impact on the gut microbiome in a negative way.

The Microbiome Mass Extinction

RICH ROLL: Yeah. And is there not a loss of microbiome diversity? It’s sort of a crisis. Right. The more the world becomes developed and industrialized, the less sort of species diversity we’re seeing in the microbiome at large. Right. In the same way that we’re experiencing mass species extinction of animal and plant life as a result of the way that we live.

DR. WILL BULSIEWICZ: Yeah. It’s a bit unnerving to talk about, but there is a mass extinction that’s taking place within the gut microbiome. If you compare our gut microbiome to, for example, the Hadza, which is a tribe of hunters and gatherers that live in Tanzania. And they do have these studies, Rich, where they will take a look at people who immigrate to the United States, coming from third world countries.

And what they discover is, I mean, look, I would expect that if you come to the United States, you don’t just show up and change your diet on day one. To some degree, you’re still eating most of the same foods. And, yeah, you’re probably starting to integrate some of our stuff that we have, or perhaps going out to restaurants. But literally within three months of arriving in the United States, there already is a disturbance and a reduction of the gut microbiome in people who are emigrating to the United States.

RICH ROLL: And even within the Hadza community. I mean, they’re suffering encroachment on their native lands and there’s a loss of biodiversity within their ecosystem, so their dietary habits have begun to shift as well.

DR. WILL BULSIEWICZ: Yeah. Because we can’t help but…

RICH ROLL: We should say, being the population of people who have demonstrated the greatest diversity within their microbiome.

DR. WILL BULSIEWICZ: Correct, correct, correct. But we can’t leave them alone. We’re very curious, and we want to study them and interact with them. And then when we study them and interact with them. Oh, what’s that you have in your hand? Oh, that’s a cell phone. And then the young Hadza tribe members don’t want to be a part of it, and they decide to leave the tribe.

RICH ROLL: Yeah. I had David Choe in here, the artist, and he’s gone and lived with them for months at a time to basically refresh his soul. And he has amazing stories about that culture.

Long COVID and the Microbiome Connection

What are we learning about long COVID? But it’s still early days in terms of understanding what that is, how long it’ll last, what the long term repercussions are from that. But how are you thinking about this and understanding it and what kind of studies do we need to do to better understand it in general and also the role that the microbiome plays in it?

DR. WILL BULSIEWICZ: Yeah. So long COVID is the manifestation of symptoms that will carry on for months, potentially, after you’ve had COVID 19. It’s a very personal response. You can’t really describe it as one particular symptom. It could be any of a number of different symptoms that people experience.

And there’s actually a study that just came out in December, Rich, that showed that people who have long COVID have once again, a disturbance of their gut microbiome. And when you drill down and you take a closer look at what’s going on there, it starts to bring parallels to what we were seeing in the COVID 19 study, where the gut microbiome of people with long COVID is once again disturbed, and there is a loss of the short chain fatty acid producing microbes.

So we don’t yet have a dietary intervention study or any sort of dietary study in association with long COVID. But it is my expectation, if I were to make a prediction, my prediction is that either in 2022 or early 2023, we’re going to see a dietary study that’s going to tell us that fiber is protective from long COVID.

RICH ROLL: Yeah, it’s really weird and disorienting, this whole thing, because some people get COVID, they recover very quickly. Other people suffer very dire consequences. And it appears from a layperson’s perspective that there’s some level of randomness in terms of who’s suffering from long COVID and who isn’t. I’m sure it correlates with other kind of health complications that people have. But from what you’re saying, it makes sense that we should be looking at the microbiome and the correlations between these two.

DR. WILL BULSIEWICZ: 100% and the microbiome is unlikely to explain everything, but is likely to explain a very large part of it.

RICH ROLL: It’s not like Bitcoin. It doesn’t solve everything.

DR. WILL BULSIEWICZ: I wish it did. I wish it did.

RICH ROLL: But it is something that we’ve never really looked at in depth until current times. And to the extent that it can shed light on matters like this, I mean, I think it’s super interesting.

DR. WILL BULSIEWICZ: Every time we look, we find something interesting. And you mentioned that there may be these other risk factors, and really the risk factors you’re referring to are metabolic things. So, for example, obesity, high blood pressure, type 2 diabetes. And if you go and look under the hood, what you discover is that in every single thing that I just mentioned, there’s disturbance of the gut microbiome. So, once again, this is a player in all of these different conditions.

Microbiome and Metabolic Health

RICH ROLL: Yeah, and just to put a finer point on that, you’re often one to say that the idea of the microbiome gets conflated in this reductive definition of just being about gut health, but really what it is is it’s about metabolic health. Right. And to the extent that we can tend to our microbiome, it will improve our metabolic health, which, of course, the downstream implications are that we become better and more resistant at fighting off all of these chronic ailments that are a result of problems with our metabolic health.

DR. WILL BULSIEWICZ: Metabolic health is associated with inflammation. Inflammation comes from the immune system. We describe these things in their own separate way, but they’re not separate. You know, this is all part of the confluence of factors that make us human beings, and they’re completely integrated.

Defining the Microbiome

RICH ROLL: Yeah. Well, we’re well into this podcast, and we have yet to define our terms here. So if somebody stumbled into this episode and this is their introduction to the microbiome, and their only kind of association is that the microbiome means, like bacteria in our digestive system. Perhaps we should take a few minutes to kind of really define what we’re talking about in terms of what is the microbiome and why is it important?

DR. WILL BULSIEWICZ: Yeah, the microbiome is a community of these invisible microorganisms, and there’s several different varieties that are there, but they’re covering every external surface that’s a part of us as humans. So they’re covering our skin. If we were to literally look at our thumb, there’s as many microbes right there on our thumb as there are people in the UK. They’re inside our mouth, inside our nose, inside a woman’s vagina.

But they are most concentrated inside our intestines, specifically our colon, which is the large intestine. In that spot, you will find that there are about 38 trillion microbes. And 38 trillion is a pretty ridiculous number. It’s hard to know exactly how to put this into perspective. There’s about 100 billion stars in the sky. So if we were to take all the stars in the sky, all the stars in our galaxy, and shrink them down to a ball, we would have to place 100 galaxies full of stars into your large intestine. And even that actually is only a fraction of our gut microbiome.

RICH ROLL: That’s a good one. How’d you come up with that?

DR. WILL BULSIEWICZ: I’m a math nerd.

RICH ROLL: It’s impossible to wrap your head around that big of a number.

The Co-Evolution of Humans and Microbes

DR. WILL BULSIEWICZ: Yeah, it is impossible. It’s completely ridiculous. But that’s a part of who we are. Every single one of us has a microbiome. And in this conversation that you and I are having, when we talk about the microbiome, typically this is what we’re going to be referring to is the gut microbiome specifically.

And these microbes, they’re a part of human history going all the way back to the very beginning. There’s never been a moment where a human being did not have a microbiome. Whoever that first human was, they had a microbiome. And from that point, moving forward to today, three plus million years of human evolution, it was never exclusively human evolution. It was always co-evolution. We were rising and falling with these microbes.

And that process galvanized the relationship that we have with these microbes, where we grew through evolution to really trust these microbes because we gave them tasks that we completely need them to do the job for us to be healthy humans. So starting with digestion. Digestion is access to nutrients. If we don’t get access to nutrients, we don’t live. And we need them when we rely on them for the digestion of many of our foods. We’ve talked about our metabolism, our hormones. Let me also inject our immune system, our metabolism, our hormones and our mood, our brain health, our cognition, the expression of our genetic code. They are powerful.

Microbes and Genetic Expression

RICH ROLL: Explain the one about the expression of the genetic code. Is that in reference to our ability to express certain genetic dispositions, like if our microbiome is out of kilter, then we’re not able to basically function because our genes are underexpressed that are intended to perform a certain function? Or what do you mean by that?

DR. WILL BULSIEWICZ: If you go back to the year, it was roughly 2000, 2001, and they were wrapping up the Human Genome Project. And this is Francis Collins, who just recently retired, but at the time he was one of the most preeminent, well respected scientists at the NIH. And Bill Clinton was the president, and he called a press conference along with Tony Blair. And in the Rose Garden, they have all these people there to announce that they had just cracked the genetic code.

And the reason that this was such a big deal from their perspective is that they sincerely believed that once we crack the human genetic code, we’re going to basically have the path to curing cancer or stopping heart disease.

RICH ROLL: Right.

DR. WILL BULSIEWICZ: And they really believed that that would be the truth. And the problem is, here we are, and it’s more than 20 years later, and clearly that is not the truth. Clearly it has not worked out the way that they thought that it was going to work out.

And that’s because we are not a set of predetermined health outcomes in a genetic code. Instead, our genetic code is more like a series of switches. And you can turn them on or you can turn them off. And whether or not you do that is going to determine what actually happens with our body. But the question is, who’s sitting at the switchboard and flipping the switches? And the appearance is that these are the gut microbes.

RICH ROLL: Right.

DR. WILL BULSIEWICZ: They’re in control of basically flipping the switch and determining whether or not we have health conditions or we don’t.

The Complexity of Microbiome Research

RICH ROLL: Yeah, and what’s fascinating about that is cracking that genetic code through the Human Genome Project seemed like an impossible task. Now we’re capable of doing it, but we’re dealing with a very limited set of variables in that context. Right. And now analogously, we have like the Human Microbiome Project and the American Gut Project, which seem like the microbiome version of that same way of trying to understand it, except with like an infinite number of complex variables, because you’re dealing with hundreds of thousands of millions of microorganisms and different species.

DR. WILL BULSIEWICZ: Well, there’s the complexity of the microbiome. There are the challenges of measuring the microbiome. Like, if you take a stool specimen, you are representing what’s happening in the rectum far more than you are representing what’s happening in the right colon. There’s a geographic element. There may be specific spots within your colon where specific things are happening and not necessarily in other locations. So how do we measure that? That’s really hard.

And it’s dynamically evolving literally by the second, because the half life of these microbes is so quick, they could be turning over every 20 or 30 minutes a new generation. And so in an hour, in the time that you and I sit and we have this conversation, we may have cranked out five, six generations of microbes. So there are these challenges that exist.

And the other part of it is the amount of information that exists. So our human genome is actually quite small. Right. It’s very easy for us to get egotistical about this because we’re such big, strong humans, and that’s the way we see ourselves. Yet if you look at the genetic code that we carry as a part of us, 99.5% of our genetic code is not human. It comes from these microbes. And only 0.5% of our code is actually human.

So when they cracked the human genetic code, they were basically working with 1/200th of the available genetic information. And the amount of information that exists in stool is completely absurd, to the point that the computers of the 90s were incapable of handling this. And this is part of the reason why we really weren’t able to take a look until, like, 2005, 2006, there was a laboratory breakthrough, and there was also our computers were able to finally catch up and handle it.

And Rich, some of the studies that you’ve mentioned, like the Human Microbiome Project and the American Gut Project, these are powerful studies. We will talk about stuff that we have found from them. But on the flip side, the science is evolving so quickly that you start up these big, massive studies and then you discover that your laboratory technique is completely outdated within five years. That’s what’s happening.

RICH ROLL: It’s crazy, but I would think at some point, with the supercomputing ability that we have and the kind of technology that we have in terms of analyzing massive data sets will come into play and elucidate certain things that we’re not going to be able to see in a microscope.

The Future of Personalized Nutrition

DR. WILL BULSIEWICZ: Yeah, that’s very true. And I think that this is where the future exists. And so this is actually something that I’m actively a part of right now, which is to take a look at personalized nutrition and the way in which we have different personal responses to the same intervention. You give two people the exact same diet, get two radically different results.

And the way that we’re approaching this is to use the microbiome as sort of the starting point to ask these questions. What do the gut microbes say about what’s happening with the human body? And the more people that we collect as a part of these scientific experiments, the more robust the data becomes. If you had 10 people, it would be completely worthless. But what happens when you have 10,000 or 100,000 or a million people, and suddenly these supercomputers are basically able to run complex algorithms and identify patterns that exist that actually can be applied to the individual person in a very powerful way?

RICH ROLL: Right, so talk a little bit about that. I mean, you’re in the middle of a big life change. You’ve left your medical practice. You’re now medical director at this company called Zoe that is doing this very thing.

DR. WILL BULSIEWICZ: Yeah, yeah. So a lot has changed for me. And, you know, Fiber Fueled came out in May of 2020, was a New York Times bestseller, and here we are, and it’s sold basically 200,000 copies.

RICH ROLL: Congrats.

DR. WILL BULSIEWICZ: Thank you. And with that, discovered that there was an opportunity for me to try to do something even bigger. So my mission throughout all of this was just quite simply to provide ways to help people who need it. And it started in a clinic, one on one, and then it became an Instagram account, and then a book.

And now I’m seeing opportunities to get out there and do something on an even bigger scale where I feel like I can impact millions of people. And part of it is more books, part of it is courses and things like that. But part of it is also being a part of the future. And I think that the future is in the microbiome and personalization. That’s where I think it is.

Individual Responses to Diet

RICH ROLL: So walk me through the personalized nutrition thing. We talked a little bit about it before the podcast, and I think it would be instructive for people to hear about that because it’s really interesting. It’s emerging, and I think might be a salve to people who have struggled to adopt a certain dietary protocol and aren’t seeing the results that everybody told them they would have.

DR. WILL BULSIEWICZ: Yeah. So we know this. There is no one size fits all. And that’s because we are completely unique individuals. We each have a gut microbiome that is completely distinct. There are no two people that have, in the entire planet, 8 billion people. There are no two people that have the exact same gut microbiome. You take identical twins and you look at how much their microbiome overlaps and it’s only about 35%.

RICH ROLL: Wow. Even when they grow up in the same house.

DR. WILL BULSIEWICZ: Exact same house.

RICH ROLL: So it’s not twin studies where they go and lead completely different lives.

DR. WILL BULSIEWICZ: No, they’ve done these studies. Tim Spector, who’s one of my colleagues at Zoe, he actually is responsible for the Twins UK registry, which they’ve been running, I believe, since the 90s and have done some of the best genetic research. And what they’ve done is they’ve actually taken some twins that cohabitate and even they have completely different gut microbiomes and completely different responses to the exact same foods.

RICH ROLL: That’s wild.

DR. WILL BULSIEWICZ: And we see this in clinical trials. Because the problem, Rich, is that we may do a randomized control trial and the goal is weight loss. This is just a hypothetical here. I’m not describing actual data, but let’s pretend that it’s plant based versus keto. And in this study, the plant based diet wins. The average person consuming the plant based diet loses four pounds. The average person consuming a ketogenic diet loses three pounds. And this is statistically significant. So we call, oh, plant based is better.

What do you say to the person who gained five pounds on a plant based diet? What do you say to the person who lost 20 pounds on a ketogenic diet? Different people have different responses to the exact same dietary intervention. We are not the norm.

RICH ROLL: All you have to do is go on Twitter to realize that’s the case.

DR. WILL BULSIEWICZ: Yeah. And none of us are average. To expect the average results is ridiculous because none of us are the average in every single measure. We are going to be our own unique personal selves.

So if you go back to 2016, I was actually at a microbiome meeting and there was a study that blew my mind where basically what they did is they took microbiome specimens. This was done out of the Weizmann Institute in Israel. They took microbiome specimens and they had people wear a continuous glucose monitor and record in an app what they were eating during the week. And integrating this information, blood sugar, food and microbiome, they were able to distill it down to the microbiome could predict your response to individual foods.

RICH ROLL: Wow.

Predicting Food Responses Through Microbiome Testing

DR. WILL BULSIEWICZ: And they applied this to a validation group. So they first started with a study group, they built their model, and then they applied this to a second group, and it proved to actually be true, that they could actually predict robustly what your response to an individual food was going to be based upon your microbiome alone.

So enter this company, Zoe. Zoe starts in about 2017. Completely off my radar at this point. I’m not aware that they exist, but they start in 2017 and they basically do three years of clinical trials. And it builds up to June of 2020, which is right around the time that you and I got together for our first podcast, where at the American Society of Nutrition, they present for the first time their data that basically shows that they have the ability, using microbiome testing, an app, continuous glucose monitor, and blood lipids, they can use the microbiome to predict what is your blood glucose going to do with a specific food. What is your blood lipid going to do with a specific food.

So they’re taking it a step further, looking at our metabolism, our blood sugar and our blood lipids, which, by the way, are cardiac risk factors that we can then integrate into a model of looking at what is our risk of, for example, having obesity or a heart attack.

RICH ROLL: It’s super interesting. We work with levels. They’re a sponsor of the show, so I’ve spent plenty of time with a CGM and it’s been really interesting to kind of try to understand when I see these spikes and valleys and I try to extrapolate from that, like, “here are the foods I should avoid, here are the foods I should eat.”

But I found also that it’s easy to jump to conclusions that might not be correct in that stress, sleep, physical exercise, all of these things play into it. It’s much more complicated than a very binary, like, “don’t eat this food or do eat this food.” But to introduce the microbiome into this obviously makes it a much more robust data set from which to make predictions and kind of advise behaviors and dietary protocols.

But how do they do… Sorry, I didn’t mean to interrupt. But like you say, well, they take into consideration the microbiome. But like, if I’m, let’s say I’m a… Walk me through this, like, I’m a consumer, I want to do this. How do they take a sample of my microbiome? And then how does that get factored into how these sort of decisions are made about what to avoid and what to lean into?

The Consumer Testing Process

DR. WILL BULSIEWICZ: Yeah. So if you are a consumer partaking in this scientific project, I mean, basically this is citizen science. So anyone can decide that they want to contribute to the science that’s taking place in this space. You receive a kit, and what you’re going to do is you’re going to first submit a stool specimen that ultimately is going to be your microbiome test.

In that kit, you’re also going to receive some muffins. These muffins are standardized meals. That way we can compare Rich Roll’s results to Will Bulsiewicz’s results. We’re having the exact same meal and we can see what our CGM, what our continuous glucose monitor does. But the other thing that we do is we do the blood lipid testing so we can see after a meal what happens to our blood lipids when we’re eating this particular meal that’s controlled.

During the week, you wear your CGM and you enter into the app what foods you’re eating. And that information that you’re entering into the app is then integrated into these supercomputers. We have more than 10,000 people who have signed up so far. 10,000 is a hell of a lot better than 1,000 people or 100 people. And we’re going to keep going higher and higher. And with every single person who signs up, we become more robust in our ability to powerfully predict what specific foods are going to do well.

So what’s exciting about it is that in June, after they presented their results, they published a paper in Nature Medicine, literally the top journal on the planet. We’ve published multiple papers now in Nature Medicine, Nature, Endocrinology, Gut. I mean, basically the highest level scientific journals. And this is all predating in many ways, the release of a consumer product.

So what we have is we have something where the science is being done first and then it’s offered to the consumers after the validation is already there. And to me, that’s what attracted me, because I don’t want to be a part of something that isn’t actually proven to work. But I actually respect the integrity to have the gall to spend that much money on science before you’ve even sold a single kit. Three years.

RICH ROLL: Talk a little bit, because we’re on the subject of weight management, the relationship between metabolic health and weight management and how the microbiome plays into that.

The Microbiome’s Role in Weight Management

DR. WILL BULSIEWICZ: The microbiome has a powerful role in our weight balance. Now, this is obviously not the only thing, and it’s in some ways a little bit difficult to separate from our dietary pattern because our dietary pattern will affect our gut microbes. But what we do know is this.

So there’s a number of studies that we’ve seen through the years. First of all, if you take a group of people who are overweight or obese, you will discover that there are changes in their gut microbiome, and that’s categorically there. And there is a loss of diversity within the gut microbiome, which is a theme that we’ve been talking about. So it’s quite fascinating because they have these studies where they will look at a mouse model and they will go back and basically do fecal transplants into mice.

RICH ROLL: This is the study. A lot of people know about this study, right? Like the fecal transplants from, like take a fecal sample from an obese mouse and put it into a thin mouse and then suddenly the thin mouse becomes obese and vice versa.

DR. WILL BULSIEWICZ: Yeah, they have ones where they’ll take identical human twins. But among the identical human twins, one is obese and the other is skinny. And they’ll take a stool specimen from the obese human, transfer it to a germ free mouse, and they’ll take a stool specimen from the skinny human, transfer it to a germ free mouse, and then they feed these two mice the exact same diet, the exact same number of calories, they eat all their food and then you get different results in terms of their body habitus.

One becomes obese, the other becomes skinny, and it coincides with the microbiome that they received. So the writing has been on the wall that the gut microbiome is a critical part of determining our weight balance.

The Role of Satiety in Weight Management

And there’s a number of different parts to this. I think one of the big things Rich, that is not discussed enough in the obesity space is satiety, actually feeling full when you eat a meal. Because we eat a diet that’s a fast food, junk food diet devoid of fiber. And as a result of that, we actually have studies from Kevin Hall at the NIH where on this type of ultra processed diet, people overeat because they’re hyper palatable foods. You want more and you’re not triggering your natural satiety hormones to stop you when you’re supposed to feel full.

RICH ROLL: Is that because they’re nutrient deficient? What is the relationship between that satiety impulse? It’s really a nervous system trigger to the brain, right, to stop eating. What is the relationship between that signal and the nutritional value of the food you eat? Because it’s not just the distension of your stomach, right?

DR. WILL BULSIEWICZ: Yeah. No, there’s a number of different hormones that are produced actually by gut microbes that ultimately will go to the brain and tell us that we feel full. And what we’ve discovered is that fiber actually plays a critical role in this pathway in terms of the release of these hormones, so that we do feel full.

And there’s an interesting study that they did where they compared two burgers that they fed to a group of people. And the burgers were completely matched and identical, not only in terms of calories, but in terms of macronutrients. So same carbs, fat and protein. The difference between the two burgers is that one was a pork and cheeseburger and the other was a tofu based burger. And in this study, what they discovered is that people actually felt more full on the tofu based burger than they did on the pork and cheese based burger.

RICH ROLL: As a result of the fiber content.

DR. WILL BULSIEWICZ: The fiber content was the major differentiator there.

RICH ROLL: That’s really interesting. Yeah, really interesting. But when you look at, you had mentioned this study earlier with, we were talking more generally about studying people who eat low carb or plant based and average weight loss numbers. But there’s the outlier, the person who goes on the plant based diet and instead of losing the average five pounds, ends up gaining 10 pounds or whatever it is. That brings us back to this topic of what their microbiome looks like, what their satiety situation is and how to address that.

Predicting Metabolic Health Through Microbiome Analysis

DR. WILL BULSIEWICZ: Right. This is where, when we conduct our research through Zoe, we’re discovering that you can predict a person’s visceral fat deposits, which is basically a measure of obesity. You can predict that more reliably with the microbiome than you can with a person’s body mass index.

RICH ROLL: Yeah, that’s wild.

DR. WILL BULSIEWICZ: I mean, that’s crazy because we always look at the body mass index as sort of being the measure of obesity. It literally is the measure of obesity. A person is considered obese when they have a certain body mass index. But in this case we can actually predict their visceral fat, which is the bad fat, much more reliably with the microbiome.

And when they broke this down even further, looking deeper, taking a deeper dive into the metabolism, using these tools, visceral fat percentage, but also the microbiome, the continuous glucose monitor, the blood lipid tests, they were able to ultimately identify specific microbes that were associated with a healthy metabolism.

So we now have 15 specific microbes that are associated with a healthy metabolism and 15 specific microbes that are associated with an unhealthy metabolism. And so we can look at these particular 30 microbes and it does provide us with some inferences about the health of this ecosystem, the gut microbiome, and what that ultimately means for a person’s metabolic health.

RICH ROLL: Right. So the science minded person inside of me thinks, well, if we know what these 15 are that promote better metabolic health, why not just inject them into people’s guts? And that would solve the problem. I’m sure it’s more complicated than that, though.

The Complexity of Microbiome Intervention

DR. WILL BULSIEWICZ: Yeah, well, that’s an idea that we kind of were hoping to be true from the very beginning. And this is the genesis of probiotics, right? So we’ve been trying the probiotic thing for a very long time and with frankly, pretty mediocre results. Now, this is not to say that there aren’t people who benefit from probiotics. There certainly are. The challenge that we have is how do you identify the specific people that will benefit from that specific probiotic? And it may be the personalization that we’re missing.

So perhaps with personalization, we are in fact capable of producing probiotics for that individual microbiome that will completely, for example, transform their metabolism. That may be possible, but the other challenge that exists is that this is a complex ecosystem that’s closed off to the outside.

So it’s kind of like having a high school and you’re the new kid who just showed up. And how is this new kid going to integrate into this culture that already exists and the cliques that already exist and whatnot at the high school? You just don’t know until you actually see it play out.

The Microbiome’s Predictive Power

RICH ROLL: Right, right, right. What you were talking about earlier reminded me of something that I read that was along the lines of, when you analyze somebody’s gut microbes, you can predict with something like 90% accuracy what their BMI is. Does that ring true to you? I can’t remember exactly what the quote was or where I read it, but the idea being that really understanding the quality of one’s microbiome is such an accurate predictor of other things. You can extrapolate from that and understand things about this person’s health without looking at anything else.

DR. WILL BULSIEWICZ: Yeah. So what we know, based upon our Nature Medicine paper from June of 2020, is that if you were to look at each one of these individual factors – we could look at your blood glucose after a meal, we could look at your blood lipids after a meal, we could look at your weight. And what we’re going to do is we’re going to identify what are the factors and how prominent are they in terms of their ability to predict.

And there’s a number of different factors. So clearly, the foods that you choose are a factor in terms of your blood glucose response, and your microbiome is a part of that, too. How much is the microbiome represented relative to your diet? Well, what we found in our study is that the diet is more powerfully represented to the microbiome, but the microbiome is still part of that for blood glucose.

RICH ROLL: Sure.

DR. WILL BULSIEWICZ: But what’s fascinating is that blood lipids was the opposite. So your triglyceride level after a meal is actually predicted more by your microbiome than it is by the foods that you’re choosing to eat.

RICH ROLL: Wow. So, in other words, by tending to your microbiome in the most robust way possible, to promote metabolic health and everything that that considers is a means by which you can better control your blood glucose.

DR. WILL BULSIEWICZ: Yeah.

RICH ROLL: And blood pressure and nutrient absorption and everything else.

DR. WILL BULSIEWICZ: And potentially our immune system and potentially your mood and you could go down the line and all your digestion and access to nutrients. So this is a powerful thing. And I think what’s exciting about it and what creates hope for people is that you are not cursed with the microbiome that you were born with.

You have the ability to shape and change that microbiome and make it your own through the choices that you make. And the choices that you make today could literally alter your gut microbiome by tomorrow.

Microbiome Malleability and Lasting Change

RICH ROLL: And how robust are those adaptations? Let’s talk about malleability. If it’s possible, and it appears from the science that it is, to change your microbiome, if you do a fecal transplant, it’s only a temporary thing. So how do you promote lasting, sustainable, long term, healthy changes in your microbiome? Obviously we can just adopt a high fiber diet, but what are the other things that we should be doing to make this as permanent as possible?

DR. WILL BULSIEWICZ: Well, permanent results come from consistency.

RICH ROLL: Yeah. Persistent habits. Right.

DR. WILL BULSIEWICZ: And being sustained. Yes, exactly. So that one week cleanse or that 30 day fad diet, they’re not really helping you. So at the end of the day, what you want is you want small changes that you repeat every single day moving in the right direction. And if you’re willing to do that, small changes that become healthy habits start to really add up in terms of what they can do with your gut microbiome over the course of time.

Treating Inflammatory Bowel Diseases

RICH ROLL: We do see people who have certain types of autoimmune diseases or ulcerative colitis, things like that. I personally have friends that suffer from this terribly and have tried all manner of microbiome related protocols to repair their gut lining, et cetera, with pretty mixed results.

So, because I’m sure there’s a lot of people listening or watching to this who have some version of that that they’re dealing with right now and are perhaps frustrated by doing this battery of probiotics or adopting a really high fat diet and then adopting a really high fiber diet and really never being able to find a solution that has lasting benefits. How do you think about that?

DR. WILL BULSIEWICZ: Yeah. So I’ve taken care of many of these patients throughout my career as a gastroenterologist, taking care of patients with ulcerative colitis and Crohn’s disease. These are the people who have the deepest dysbiosis. Crohn’s disease and ulcerative colitis are inflammatory bowel diseases. They are literally a condition where your immune system is attacking your microbiome. So it’s not even an autoimmune issue. It’s an attack on your microbiome.

So how do I counsel my own patients? And what is the conversation that I say? There’s no shortcuts. There’s no quick fixes. This is a chronic inflammatory disorder, and we have to set – frustration comes from unmet expectations. So setting proper expectations from the very beginning ends up becoming one of the keys to getting good results.

And the other thing that becomes key is actually knowing what direction to go. We have to basically plot the proper path, and then we just walk down that path, not trying to be perfect, but just moving in the right direction. And if we do that consistently over the course of time, we are maximizing our results.

People who have these conditions, there is a genetic predisposition. It would be unfair to pretend that this is just exclusively a dietary thing. And I don’t think they should carry that burden of guilt in any way, because you didn’t do anything wrong. We’re all eating junk food, right?

RICH ROLL: Right.

DR. WILL BULSIEWICZ: So it’s just that that junk food…

RICH ROLL: It can be a result of significant antibiotic use as a young person and things like that as well. Right.

DR. WILL BULSIEWICZ: There’s so many different factors that can disturb and disrupt the gut microbiome and ultimately put you in a position where a disrupted gut microbiome with a genetic predisposition leads to the activation of these conditions. And once you have it, there is no cure. To say that there’s a cure is not accurate. There is remission. Remission basically means that your disease is not active. And if you have a permanent remission, that is as close to a cure as we can ever get.

So how do we accomplish that? Well, to me, this is not exclusively diet and lifestyle, and this is not exclusively medications. And any approach that ignores the other side is not taking advantage of the opportunities that we have to make a person better.

So what we need is we need to bring the best of diet and lifestyle into these patients in a sustained way that develops healthy habits. And at the same time, if a person has Crohn’s disease and ulcerative colitis and they’re in my clinic and they’re actively flaring. Let me be perfectly honest with you, Rich. I’m not worried about their diet in that moment, because when the forest is burning, you don’t plant new trees. You put the fire out.

So you have to put the fire out first. Now that the fire is out, you have this scorched earth. And we can rebuild the forest. But rebuilding the forest doesn’t happen overnight. We have to plant the trees, and we have to allow them to mature with the right fertile conditions in order for the forest to grow back.

So to be more specific, with these particular conditions, like ulcerative colitis and Crohn’s disease, I would change their diet, I would change their lifestyle. And my expectation is that we’re looking at at least months. And I don’t mean two months. I mean like six months or 12 months or more than that for us to really fully see the effect of what we’re trying to do.

RICH ROLL: I would suspect that the personalized nutrition piece could be very beneficial in this context.

DR. WILL BULSIEWICZ: I think that there’s going to be a future in this particular arena when it comes to personalized nutrition. Now, that would be a bit different than what we’re currently doing with Zoe, because you have to understand that the outcome that we’re looking at with Zoe is a metabolic outcome and not a digestive health outcome.

RICH ROLL: Got it.

DR. WILL BULSIEWICZ: So we would need to basically pivot towards a different health outcome. But we could still apply the idea, using the exact same tools in many ways to figuring out how to help these people.

The Brain-Gut Connection

RICH ROLL: Let’s shift focus. I want to talk a little bit about the brain gut connection, and in particular, the relationship between mental health and the microbiome.

DR. WILL BULSIEWICZ: But these things are not separate. They’re integrated. Our gut, its best friend, is the brain. Our brain’s best friend is the gut. And they are in constant communication with one another. Talking literally right now.

There’s a number of different ways that the gut will communicate to the brain upstairs. It can send signals through the vagus nerve, which is an information superhighway. It can create neurotransmitters. So we have a number of different neurotransmitters that are produced in the gut. 90% of serotonin is produced in the gut. Serotonin is the happy hormone. It makes us feel vibrant with energy. It makes us feel uplifted in terms of mood.

That’s not mostly produced in the brain. That’s mostly produced in the gut, because in the gut, it’s actually involved in our motility, in our rhythm. But there are also serotonin precursors. One is called 5HT that actually produced in the gut crosses the blood brain barrier.

The point is that there are a number of different short chain fatty acids are another example. There’s a number of different ways that our gut is able to basically create signaling molecules that will then travel through the bloodstream, approach the blood brain barrier, and potentially affect the blood brain barrier or even cross the blood brain barrier into the brain and affect mood, cognition, our memory.

RICH ROLL: It’s so insane. It’s crazy. I mean, hence the phrase the gut being the second brain. And for me, it calls into question our sentience. If our gut has so much power and influence over all of these things and the impulses that are being sent to our brain, what is you? How do we think about our independence of thought and decision making? I mean, we all know, “oh, my gut is telling me this,” but it truly is in so many ways.

DR. WILL BULSIEWICZ: Yeah. Rich, you are a superorganism. You are a superorganism. You are not Rich Roll functioning in isolation. You have this entire community of living creatures that, yes, they’re invisible, but they are there and they are a part of what makes you who you are.

And that includes potentially the cravings that you have for food. That includes your mood or how you think or your memory. And so it’s just quite fascinating to imagine that they can be that powerful. But I don’t think that they’re powerful to the point that I’m just a zombie walking around, being controlled by my gut microbes. I don’t think it’s like that.

Microbes and Food Cravings

RICH ROLL: Sure. But the cravings thing is really fascinating. I think we talked a little bit about that last time. But there are all these studies. I think there’s studies with chocolate in mice. When you do a fecal transplant of a mouse that really likes chocolate and put it into another one that is indifferent, or maybe they’ve done this in humans. I think those cravings shift, which is bananas.

And it’s interesting in thinking about that because I’m sure you’ve heard people come to you and say, “well, I was plant based, but I was really like, my body was telling me I needed X, I needed meat, I needed this, or whatever.” And it’s like, well, is that really your body telling you that it has a need that’s not being fulfilled?

DR. WILL BULSIEWICZ: Or…

RICH ROLL: Or do you have a certain microbial ecology in your gut that thrives off that kind of food and needs the microbes in those foods in order to survive? So it’s signaling your brain to please feed it.

DR. WILL BULSIEWICZ: Right. And we do that perhaps with sugar, for example. And you get these cravings for sugar that exist in the evening. Is the sugar actually good for you? No. But there are microbes that thrive when you consume that sugar. And they may be sending signaling molecules that are basically motivating you to go and do this.

RICH ROLL: And does it not follow then if you shift your diet and start eating healthy foods, let’s say suddenly you’ve never eaten kale and broccoli and spinach and stuff like that, and suddenly you start eating that over time, you’re seeding your gut with a new ecology of microflora that will in turn, once it takes root, crave a different type of microbe and will thus signal your brain to crave those healthy foods because that’s what it needs. And suddenly the cravings for French fries and ice cream dissipate and are commandeered by cravings for these healthier foods.

DR. WILL BULSIEWICZ: What happened with you when you changed your diet?

RICH ROLL: Yeah, it did. And I talk about it all the time. People don’t believe me or think you’re a little lunatic or something like that, but I’m telling you that it is true. And unless you’ve experienced it, you think it’s an exaggeration.

The Taste Bud Transformation

DR. WILL BULSIEWICZ: Yeah. So my favorite foods, my favorite food, a celebratory meal for me, if you were to go back 10 years ago, was a ribeye steak. That’s what I would get. I would go get a ribeye steak and a glass of red wine.

When I was working in Savannah, this was probably 2013 or 2014, I had the week from hell when I was on call. So my daughter was a newborn and I literally did not see her awake all week because I was leaving to go to the hospital at 4:30 in the morning and I was coming home at night at 10:30 or 11:00.

So this is the week that goes on all week, and then I get to the end and it’s Friday, turn over the pager to someone else. Okay, cool. I’m off the clock now, man. You deserve a treat. I’m going to treat you right now. And I went out to Logan’s Roadhouse, which when I was in college used to be in Nashville at Vanderbilt. That used to be one of my favorite places to get a steak.

And so I went to Logan’s Roadhouse in Savannah, Georgia, and I got a ribeye and a glass of red wine. And I took like, first of all, it smelled different. And then I took two bites and I was just like. And this was not an ethical thing. This was quite simply that it did not taste good.

And I was a little embarrassed because here’s this huge steak and you know that the server is going to freak out when they realize that you’re not eating it. So I covered it all up with my napkin and I got my bill and I got out of there as quickly as I could and had realized because it had been probably 18 months since I’d had a steak, that my taste buds had completely changed.

RICH ROLL: Yeah.

DR. WILL BULSIEWICZ: And you know, it’s kind of interesting, just another anecdotal piece of evidence, because I sincerely believe that this is the truth. And I’ve seen this a billion times where people shift their diet and there’s a shift in the taste buds that takes place. It just lags. It takes a little time to catch up. But that lag is not months.

RICH ROLL: Right. But you got to stay in it to win it.

DR. WILL BULSIEWICZ: You got to stay in it. And so I’m convinced that what mom eats during pregnancy ultimately determines the taste buds of the child during, like when they’re an infant. And the way that I know this is, if anyone’s had broccoli sprouts, I mean, look, I’m a huge fan for their health benefits. They’re bitter as hell.

RICH ROLL: It’s an acquired taste. Don’t tell Doug Evans that. Well, he’s going to start calling you.

DR. WILL BULSIEWICZ: I have him every day. He calls me. He calls me all the time anyway. Yeah, all right. I’m a big Doug Evans fan. I love that guy. But you know broccoli sprouts, I have them every single day in my smoothie. They’re an acquired taste, but they’re intensely bitter. And I embrace the bitter because that is the phytochemical, the sulforaphane that’s fighting cancer inside my body.

But like, how do you take a seven month old child and put broccoli sprouts on a tray and they smashed them? How do you explain that? And this was not a one time event.

RICH ROLL: This is every single day. That’s your experience.

DR. WILL BULSIEWICZ: That was my son. That was my son Liam, who’s five. But like when he was six, seven months old and he started to eat solid food, we were putting broccoli sprouts on his tray and he was smashing them. And all I can say is I’m pretty sure that mom’s diet ultimately parlays into the child’s microbiome and their dietary preferences.

The Gut-Brain Connection and Mood Disorders

RICH ROLL: Yeah, super interesting. Back to this idea of the gut brain connection. What is the science saying about people who suffer from some level of mood disorder or depression? Is there any interesting research coming out about how treating the microbiome can produce positive results?

DR. WILL BULSIEWICZ: Not in the way that we have with the cancer research. And I think part of that is the investment of money into cancer research. That’s out there, but I think it’s going to come.

Here’s what we do have. We first have dietary data and we have interventional data, like not epidemiology studies, but instead an interventional trial where we will ramp up a person’s fiber intake and we will see improvement of mood disorders. So I’m talking about things like depression. And so we have these dietary interventions, but at the same time, more recently we have microbiome data. So we can see actually in the microbes a specific pattern that exists among people that have mood disorders. This is true of both anxiety and also major depression.

RICH ROLL: What about people who are suffering from some form of trauma or PTSD? Does that overlap?

DR. WILL BULSIEWICZ: Oh man, I want to talk about that. So let me hold that for a moment and then come back in just a second.

So in the microbiome, here’s what we’re seeing. We first of all see a loss of diversity, again, a trend that we’ve been talking about this whole time. But also the specific microbes have been altered. There are more inflammatory microbes. These are the microbes that have been associated with poor health outcomes. And simultaneously we see in these people that suffer, for example, with major depression, with less of the anti inflammatory, short chain fatty acid producing microbes.

So part of the theory or idea behind this and like, why is the fiber intervention valuable to a person with a mood disorder? The fiber intervention is valuable because it can change the microbiome and it can also lead to the production of more short chain fatty acids. And we believe that the anti inflammatory nature is helping to combat the inflammation of depression. Depression is an inflammatory disorder.

RICH ROLL: That’s super interesting. I’ve never heard anybody say depression is an inflammatory disorder.

DR. WILL BULSIEWICZ: It 100% is.

RICH ROLL: Explain that a little bit more.

Depression as an Inflammatory Disorder

DR. WILL BULSIEWICZ: Well, basically our body has an inflammatory mechanism and we evolved to have this with good reason. So if we go back to the time of like cavemen, paleolithic times, the top causes of death were infection and injury. And so inflammation is the way that we fight infection. Inflammation is the way that we heal from an injury. Inflammation is supposed to be our friend.

But you fast forward to 2022 and our modern lifestyle is basically activating these inflammatory mechanisms in a chronic smoldering way. So it’s not the big burst of inflammation that you would get from, say, an infection or a big injury, but what it is is it’s just kind of perpetual activation of the immune system to create inflammation.

And that inflammation is tied to most of the major health related issues that we see as problems in 2022. So that includes coronary artery disease, that includes cancer. And I’m here telling you, and I don’t think this is a big shock, but that includes mood disorders like anxiety and depression.

RICH ROLL: Wow.

DR. WILL BULSIEWICZ: So now, Rich, what we don’t have is, so we have food and mood, we have microbes and mood, but what we’re missing is the full cascade. Food translating into microbes translating into mood. And that’s a study I’m working on.

RICH ROLL: Right, meaning we don’t have it because it hasn’t been adequately looked at.

DR. WILL BULSIEWICZ: It’s tough because you need the right data in order to do this.

RICH ROLL: Yeah, that’s a tough study to conduct properly.

Zoe Research and Data Collection

DR. WILL BULSIEWICZ: So what we’re doing. One of the things that’s interesting is with Zoe, when people participate, they have the app and they can enter into the app how they’re feeling on a daily basis. So they could enter in their energy levels. And it’s done on what we call a visual analog scale, where you basically slide a bar from 0 to 100.

Now this visual analog scale is actually a validated measure, meaning that it’s been proven through research to be valid and consistently useful for clinical research when it comes to anxiety. So people enter into the app whether or not they’re feeling anxious. And we can measure this for 14 days. And now using the Zoe data, even though the entire thing was built for metabolism, we have the ability to go back and look at what are they eating, what does their microbiome say and what is their mood.

RICH ROLL: Right. It seems like there should be an API where that data set would be supplemented with the data that you would get from say, Whoop, that’s tracking heart rate variability, sleep states, respiratory rate, et cetera, skin temperature, to be a more accurate predictor rather than just consumer reporting, which obviously is, you know, can be problematic.

DR. WILL BULSIEWICZ: So we have the large scale consumer reporting where we’re going to hopefully have millions of people who participate and that’s going to be intensely powerful because the number of people. But where we started going back to what predates 2020 and the release of the commercial product was a clinical trial called Predict 1. And in the Predict 1 trial, we actually, Matthew Walker actually has been working with us.

RICH ROLL: Oh, cool.

DR. WILL BULSIEWICZ: And so he’s the sleep expert for those who don’t know. And we actually published a sleep study very recently looking at our data, because we actually did collect that. We had people wearing the accelerometer and collecting the sleep data so that we could actually do those types of analyses. So the predict one study was not done. It was over 1000 people and it was not done using the at home kit. It was instead done more like a clinical trial.

Sleep and Blood Sugar Connection

RICH ROLL: Yeah, yeah, I think that’s really important. I just noticed in wearing a CGM that the quality and duration of my sleep had a major impact on my body’s ability to stabilize blood sugar. And I don’t know like what’s causing what, but there’s definitely a relationship and an interplay there.

DR. WILL BULSIEWICZ: There’s an explanation for that. So. And this comes back to the interconnection between our gut microbes and our circadian rhythm. All life on this planet, Rich has a circadian rhythm. All life that includes us as humans. And by the way, what I mean by circadian rhythm, microbes.

RICH ROLL: Do microbes go to sleep?

DR. WILL BULSIEWICZ: The microbes have a circadian rhythm too. Because what happened is that once life came to Earth 4.5 billion years ago, the first life we believe were the archaea, which are some of the microbes. And these archaea actually may be inside our colon right now. So these dinosaurs from 4.5 billion years ago are a part of the human gut microbiome.

There’s one evolutionary fact that was true of every single form of life on this planet. Regardless of where you lived or what your diet was or anything else. The sun rose in the morning and it fell at night. So we all evolved to embrace that. And as a result, we all have a circadian rhythm. Plants have a circadian rhythm, humans have a circadian rhythm, and our microbes have a circadian rhythm.

And if you look at your insulin sensitivity, which basically means your ability to tolerate sugar and keep your blood sugar under control during the day, your insulin sensitivity peaks early in the morning as a result of these gut microbes. And as the day goes on, you become more insulin resistant. So in other words, if I feed you the exact same meal for breakfast and for dinner, and you’re doing the continuous glucose monitor, you will actually see a higher blood sugar in the evening compared to the morning. And that is the result of your gut microbiome.

RICH ROLL: Right. And probably a slower to baseline as well.

DR. WILL BULSIEWICZ: Yep.

Building Abundance Through High-Fiber Foods

RICH ROLL: Right, Yep. That’s super interesting. The science here is mind blowing. It’s cool. Let’s shift gears to getting really practical with respect to caring for our microbiome. There’s many things that we can do, but obviously the low hanging fruit here and the most impactful is what we’re putting in our mouth. Right.

So let’s get really specific on food. We’ve talked enough about fiber, but when we’re thinking about high fiber foods, what should we be thinking about and what types of foods are you suggesting that we build into our diet? Because one of the things, just to underscore this, that is a mantra for you, is that moving towards this sort of microbiome, promoting lifestyle and diet is not about reducing things or removing things from your diet. It’s about building more abundance into it.

The Power of Plant Diversity

DR. WILL BULSIEWICZ: 100% and we can thrive, we should thrive on abundance and variety as opposed to restriction. So the key point is this. All plants contain fiber. Only plants and mushrooms contain fiber. That’s the only place that you’ll find it. Not all plants contain the same fiber. There are specific types of fiber.

And if you go and you look at the word prebiotic. So prebiotic is a term that I want to introduce to the audience, which basically means food or fuel for these gut microbes. Being that they are as alive as you and I are, they need food just like you and I. We have to feed them. Their preferred food is fiber. We’ve been talking about that throughout this entire episode.

They consume the fiber and they don’t just get rid of it, it doesn’t disappear, but instead the fiber actually gets transformed in a very magical way. These microbes. It’s like a Harry Potter thing. And next thing you know, it’s not fiber. It’s short chain fatty acids.

Three Types of Prebiotics

So fiber is a prebiotic. But there’s two other forms of prebiotics that people need to know about. One is resistant starches. You actually find resistant starches in potatoes, sweet potatoes, starchy type foods. Well, resistant starches, they’re not fiber, but they actually behave exactly the same as fiber. So that’s the second type of prebiotic.

The third type are the polyphenols. Polyphenols are antioxidant compounds that are found in plants. Plants have the market cornered on polyphenols. And when you look at plants and you see colors, those colors are coming from these polyphenols and these chemicals, these phytochemicals, they actually don’t do anything for us unless they come into contact with our gut microbiome.

So David Sinclair talks about the benefits of resveratrol. Resveratrol is a polyphenol. Yes. You will find it in red wine. You don’t need to drink red wine. You’ll find it in red grapes, you’ll find it in peanuts. You’ll find it in a number of different plant foods. And resveratrol comes into contact with the gut microbiome and basically becomes activated by these gut microbes. And then it has these healing longevity benefits that he likes to talk about.

That’s true of all these different polyphenols. And every single plant has polyphenols of different varieties, different abundances. There’s literally, we believe, thousands of them.

The American Fiber Deficiency Crisis

All right, so the key is this. Our microbes, they want to eat. They need prebiotics. There are three types of prebiotics. Fiber, resistant starches, polyphenols. And what I’ve just told you is that you will find all three of these in one place: plants. The power is in the plants. If you want a microbiome that is as healthy as possible, this is where you need to turn.

And it’s problematic because in the US the average person is 10% plant based. Even in these studies where we set the mark, the Melanoma cancer research study, they set the mark, high fiber was 20 grams. Again, 20 grams is less than the minimal recommended amount. And 71% of the people, we’re not hitting that mark.

Right. So, Rich, you and I walk out on the street and assuming we are getting an average sample of the United States, like ignoring that we’re in Los Angeles, if we have an average sample of The United States, 19 out of 20 people that we come into contact with are deficient in fiber right now.

The Importance of Dietary Diversity

So what we need is fiber. But we don’t just need one type of fiber. We need all the different types of fiber, all the resistant starches, all the polyphenols that you will find in all these different types of plants. This is why eating a wide variety becomes the key. Because when you do that, you have this wide variety of types of fiber and polyphenols that feed a wide variety of microbes. Diversity in the plate translates into diversity in your personal gut microbiome.

And this goes beyond, you mentioned earlier, the American gut project. This goes beyond any sort of theory or idea on gut health. There’s a reason why the major gut health scientists of our time are stepping forward and talking about the importance of diversity in the diet. And that’s because in the American gut project, where they had 11,000 people and literally people from across the globe, and they were analyzing their diet and lifestyle and comparing it to the health of their gut microbiome.

They found that there was a single most powerful predictor of a healthy gut, which was the diversity of plants in their diet. Specifically in that study, the people who were consuming 30 or more different plants per week are the people who had the healthiest guts.

Now, why stop at 30? Why not go 35? Why not go 40? And so the point at the end of the day is make this a central dietary philosophy. And if you do this, you don’t need to count grams of fiber or macros or calories. You count plants. How many varieties of plants can you get into your diet?

The Plant Points Game

So to do this, I created a game, it’s called Plant Points, where basically we sit down at a meal and it could be, like, me, you, my family, your family, and let’s see who can get the most plant points. And we’re going to see how many plants each one of us can get. Every single plant counts, and you want to get as many different varieties of plants into this individual meal.

And so when we do this, it’s a simple way, like, yes, we’re gamifying it. We’re having a little bit of fun with it. Guess what? Kids love this. If your kids are struggling to eat fruits and vegetables, introduce the game and let’s see how they play.

RICH ROLL: It’s really powerful. And one of the things I love about it is just how simple it is. It’s not about eat this, don’t eat this, and overcomplicating everything and thinking about macros, et cetera. It’s just eat the largest diversity of plants as possible. And if you take away one thing from this podcast and begin to implement that into your life, I think that can have the biggest impact. And it’s something that you can just grok super easily, like, okay, how many plants have I eaten today? What is the extent of the diversity on my plate on a meal by meal basis throughout the day?

DR. WILL BULSIEWICZ: Yeah, you’re in the supermarket, you hear my voice, Dr. B is in your ear. “Diversity of plants,” right?

RICH ROLL: Don’t worry about polyphenols and phy. Just don’t worry about any of that. Just focus on that one thing, and it takes you pretty much to the goal line.

DR. WILL BULSIEWICZ: This is how we distill all this complexity of the gut microbiome into one place, and we make it so super simple. This is the golden rule. It’s the only thing that you need to improve the health of your gut is start with this.

RICH ROLL: But it’s funny because the human brain’s like, “Yeah, yeah, yeah, but come on, Dr. B, take me behind the velvet rope. What’s that one food? What is that one secret that no one else knows that’s going to solve my problem?”

The Power of Fermented Foods

DR. WILL BULSIEWICZ: Well, if it was a secret that no one else knew, I’d be making some crap up. So I like it. Here’s where I’ll go, though. Here’s where I’ll go with that. So let’s go beyond just the power of plants, and let’s dig into some of the research being done by Justin Sonnenberg at Stanford University in conjunction with my friends from the ZOE Scientific Advisory Board, Christopher Gardner.

And basically what they did, and it was published in the summer, I believe, July of 2021, is they were looking at different dietary patterns, different ways that they could intervene in a person’s diet, and ultimately what effect that has on the gut microbiome. And in their study, they introduced people to fermented foods.

Now, fermented foods are traditional foods. Every culture in human history has included fermented foods as a centerpiece of their diet, right?

RICH ROLL: Funny how that works, right? This evolutionary adaptation that becomes central to a culture, but serves this higher purpose without us even being consciously aware of why we love those foods.

DR. WILL BULSIEWICZ: And yet, when we look at other cultures that are not our culture, we often will point at their fermented foods and say, “Oh, that’s an acquired taste. I don’t think I can eat that.” But then they over there are saying, “This is my favorite food,” right?

So, well, we gave them up. We gave them up because basically, here in the States, we developed canning and ways for us to process our foods using preservatives and whatnot, where something is sitting on the shelf for two years and it literally has not changed. Now, like, think about that for a moment. That’s kind of weird. Like, food is meant to have a life cycle, right?

A plant starts as a seed. It germinates, it grows. At some point, it gets to a point where it’s in the right position for you to consume it. It’s edible, but if you don’t consume it during that window, you miss that opportunity. And then it starts to rot and decompose, and then it turns back in the soil. And that’s actually a beautiful thing. That’s the circle of life. The microbes are involved in every single step.

So if you want to disrupt that cycle, you disrupt those microbes, right? So these foods that are on these shelves that sit there for two years, and they never change from the day that you produce them. That’s because the microbes have been retarded.

RICH ROLL: Right? We’ve all seen those examples of people that put their McDonald’s Happy Meal in the closet for 10 years or whatever and take it out and looks exactly the same. So there’s no microbial life. It’s funny, these quote unquote “foods.”

Living Foods vs. Processed Foods

DR. WILL BULSIEWICZ: Yeah, it’s funny. But McDonald’s is not going out of business, right? People are still eating that food. And so now the flip side of that, the completely like diametrically opposed food is a fermented food, where that fermented food is literally an ecosystem. It’s alive, the microbes are transforming it.

Take sauerkraut for example. So sauerkraut is the simplest thing to make and so delicious when it’s made at home. Instead of getting it out of a can, you chop up some cabbage, you put it underwater in a sea salt and water solution and the microbes that already exist on the leaves of that cabbage will turn it into sauerkraut for you in seven to 10 days. You don’t have to do anything. You don’t have to add any probiotic.

So. Well, we gave up our opportunity to consume these fermented foods because we were seduced by our canning and processing and preservatives and we went towards that type of food. Now that’s 60% of the American diet. And it’s time for us to swing the pendulum back towards a more tradition based diet.

And in this study, Justin Sonnenberg and Christopher Gardner from Stanford introduced people to progressively higher amounts of fermented foods over the course of weeks. People were not eating this prior to the start of the study. Like if they were, it was yogurt and that’s about it. But basically, over the course of weeks, what they discovered is that they actually were able to increase the diversity within their gut microbiome. And simultaneously there was a reduction in inflammation by simply consuming fermented foods.

So my message to everyone out there, don’t just eat a diversity of plants, but eat a diversity of plants and make sure that you’re introducing the fermented foods into your diet. I think that’s an important part of it.

The Bigger Picture

RICH ROLL: Yeah, yeah, yeah. But at the same time, eating sauerkraut or kimchi once in a while while also eating a predominantly Western industrialized diet, that sauerkraut is not going to overcome that.

DR. WILL BULSIEWICZ: No, not at all. I mean, at the end of the day, sorry, if you just.

RICH ROLL: Yeah, so if you’re just eating that’s a great study by the Sonnenbergs. And everybody should check out, the Sonic. Justin Sonnenberg did a recent podcast with Andrew Huberman. That’s great. He’s also, along with his wife, has been on our friend Simon Hill’s Plant Proof podcast.

DR. WILL BULSIEWICZ: And he supported my book. You can see the quote in the front of the book that he gave me.

RICH ROLL: So check those out. And I’m trying to get the Sonnenbergs on this show as well as Christopher Gardner. So anyway, I think what I’m trying to get at is people want to find that quick solution. They’re like, “Well, I’ll just eat sauerkraut once a week or something like that.” And what I’m trying to say is, like, that’s really not the way to think about this.

The Scale of Dietary Balance

DR. WILL BULSIEWICZ: I think of it like this. Our dietary pattern is this scale of balance where you can be putting stuff on the side that heals and nourishes your gut microbiome and your entire body, or you can be putting more stuff on the side that takes that health away, that disturbs the gut microbiome.

And so now look at the average American’s diet right now, and what we see is that their diet is 10% plants. It’s devoid of these fermented foods. It’s 60% ultra processed foods, which I don’t want to sit here and pretend that they are categorically automatically bad in all cases. But I have serious concerns about them. I don’t think that they’re good for our gut microbiome.

And the more studies that we do, for example, with dietary emulsifiers, we are finding that they disturb the gut microbiome. It’s impossible for me to believe that preservatives designed to destroy microbes are good for the gut microbiome. That’s impossible, right?

And then the last 30% of our diet is animal products: meat, dairy and eggs. Now, I can tell you what the fiber content of meat, dairy and eggs are. It’s zero. Literally zero. The polyphenol content actually may be more than zero. And it’s kind of like I get a little chuckle on the Internet when I see people talking about grass fed meat and how it’s high in polyphenols. I’m like, that is such a small amount of polyphenols relative to you eating one leaf of kale, right?

But the reason that there’s polyphenols in that grass fed meat is because the cow was eating grass. And then you slaughter the cow and whatever’s in its blood, you’re going to get some of that. So that may include polyphenols, but if the cow was pumped up with antibiotics, it’s going to be that too. Right?

The Rise of the Carnivore Diet

RICH ROLL: What’s amazing about all of this is the science is abundantly clear that eating a diversity of plant foods on your diet is key. We can talk about fermented foods, but in order to function optimally, we need to be focused on fiber. And so many people are walking around worried about being protein deficient. We talked about this last time. We should be thinking about our fiber intake.

And that ends up taking care of a lot of the problems that we’re worried about because we’re not protein deficient. We’re eating too much protein. Most people are fiber deficient.

And yet amidst this scientific certainty, or relative certainty, we have the rise of the carnivore diet. And this is sort of caught fire on social media. Lots of people are cottoning onto this. There are certain influencers who are promoting this and are holding sway over many, many people claiming that this is the solution for the chronic ailments that are unnecessarily debilitating people. This is a means to reduce your symptoms of your autoimmune disease. It reduces inflammation, blah, blah, blah, on and on and on.

In light of everything that you’ve just shared, it’s impossible for me to wrap my head around why adopting a carnivore diet would be a good idea. And yet here we are and this is what we’re seeing. I’m certain that you’ve thought about this, so please share with me your perspective.

Plant-Predominant Diets vs. Zero Fiber

DR. WILL BULSIEWICZ: Well, so first of all, if we’re talking about the scale of balance, I’m proposing that where I want people ultimately to be is a predominantly plant based diet in terms of their calories. And that is 70, 80, 90 or 100% plant based Rich. There are many forms of a healthy diet. It’s not just only a plant exclusive diet. A plant exclusive diet is when you align your desire for your best health with also ethical concerns about the environment and the animals. But that’s not the only healthy diet. There’s no denying the Mediterranean diet.

So the point from my perspective is that there are many forms of a healthy diet, but they are all plant predominant diets. And we have powerful research studies to back that up. But the problem is that the starting point is 10% plant based. That’s where people are right now. And that’s not me casting stones. I was 5% plant based 10 years ago. Right.

But 10% plant based is a heck of a lot closer to 0% plant based than it is to 90% plant based. And so it’s way easier for people to move in this direction. And many people want to hear that eating their bacon is actually going to be good for their health because they enjoy bacon. And I get that when I ate bacon, I used to enjoy bacon too. So I totally understand that.

But it’s an illusion and you’re being sucked into something that, first of all, there are no long term studies and there’s very close to no short term studies either. We have no data. The best that we can do is basically apply what we do know about science and say, well, what do we think is going to happen?

Now, I have told you that the single greatest predictor of a healthy gut microbiome is the diversity of plants in our diet. I’ve talked about how a low carb diet was disadvantageous when it comes to COVID-19. I’ve talked about how fiber actually saved people’s lives in melanoma when they were receiving immunotherapy. And we are talking about a carnivore diet that is zero grams of fiber. Zero grams of fiber. It’s impossible. The diversity of plants, I don’t even need to test you because I already know it’s zero.

It’s impossible for me to believe that in the long run this is good for the gut microbiome. But there’s a bit of a challenge that exists, which is that many of these people will claim that they healed their gut by going on a carnivore diet. Because, hey, I had problems. I did not feel well when I ate the way that you described, Dr. B. But when I do this, I feel really good. So how do we rectify this?

Well, it starts with actually understanding the way that our body works. You have to start there, right? Not everything that feels good is actually good for you. That’s completely absurd. If that were true, we’d all be doing cocaine.

Short-Term Relief vs. Long-Term Health

RICH ROLL: Well, yeah, we have to contextualize it in terms of short term and long term. I mean, if you’re having a short term positive experience, it’s likely due to the removal of all of these other things that were contributing to deleterious health outcomes. And sheerly, by reducing or removing them, you’re experiencing an uptick in how you feel and how your body is responding.

DR. WILL BULSIEWICZ: I think that there is value to removing ultra processed foods.

RICH ROLL: Sure.

DR. WILL BULSIEWICZ: And the carnivore diet, one of the things that it does really well is that it gives people a framework in order to actually accomplish that. And when people do see improvements of their autoimmune disease, and I am not saying that they’re like, there are people who do this diet and they say that it improves their autoimmune disease. I attribute that to the fact that you have removed ultra processed foods from your diet. That’s what I think you have done. I don’t think it’s that the meat heals. I think it’s that you’ve withdrawn these ultra processed foods that were negatively affected.

RICH ROLL: It’s interesting because that’s the same argument that’s used with respect to plant based, like, “oh, that’s why you feel better eating plant based, because you’ve removed all the processed stuff.”

The Illusion of Healing

DR. WILL BULSIEWICZ: Well, and I think that that’s a theme that brings together all these dietary tribes where we may be casting stones at one another, but that is one thing that we will all agree on, which I think at least we have that.

But the problem is, Rich, that you withdraw these foods, right? And you say, “well, my gut is healed.” Your gut is not healed because you have the absence of discomfort. Your gut is healed when you’re able to actually tolerate those foods. And a person who withdraws these foods on a carnivore diet, if they reintroduce these foods, their food intolerances are even worse than when they started.

And so you’re not actually healing the gut. If anything, I believe that you’re making your gut health worse. In the process of doing this, you’re completely devoid of fiber, which is the key, from my perspective, for optimal gut health. And at the same time, you’re cranking up the saturated fat to a level that’s very deeply disturbing. And that this ultimately, saturated fat, has negative effects on the gut microbiome.

Now, going beyond gut health, talking about other health outcomes, for example, people will say, “well, I cured my diabetes.” You did not cure your diabetes. Because if you have a piece of fruit, your blood sugar is going to be off the charts. Saturated fat actually contributes to insulin resistance through a process called lipotoxicity. Anyone can look up research studies on lipotoxicity, and what you’re going to find is that it’s not that the fruit is the problem, it’s that the saturated fat is the problem. And then it’s affecting your insulin resistance. And then you spike your blood sugar after you eat the piece of fruit.

So this is what happens in this particular case. They say, “oh, well, I cured my diabetes?” No, because you’re not capable of eating normal food without your blood sugar going off the charts. Because your diet has made you insulin resistant, right?

RICH ROLL: Your insulin resistance is still there. It’s just not being tested. So you think that it’s resolved.

The Twisted Knee Analogy

DR. WILL BULSIEWICZ: Exactly. So this is the functional equivalent of like, if you are out running one day and you’re running on a trail and you step funny on a root of a tree and you twist your knee, right? And it’s like, okay, so, Rich, you could stop walking permanently and you will never feel pain in your knee, but your legs atrophy and now you’re sedentary and your metabolism gets out of whack and you gain weight and your blood pressure goes up and so does your cholesterol. And now you have cardiac risk factors and you give enough time, and this is how you get to coronary artery disease, right?

So the avoidance is not the solution. You twist your knee when you’re out running on the trail, and the solution is to heal the knee, to restore function. And that’s working through a process like perhaps with a physical therapist, where you work through this process with this physical therapist, restoring function to the knee. And yes, there may be some discomfort in that process, but when you emerge on the other side, you’re running again and you’re as strong as ever.

RICH ROLL: Right?

DR. WILL BULSIEWICZ: And this is the issue is that the avoidance that we see, whether it’s in terms of the gut or in terms of your blood glucose is not actually making you stronger, it’s making you weaker. But because you’re avoiding it, you can pretend that you have fixed your blood glucose level because it comes down.

The LDL Cholesterol Risk

I think the last thing I want to say real quick about this is that because about the carnivore diet is that because the consumption of saturated fat is so high, saturated fat drives up LDL cholesterol. LDL cholesterol is a widely accepted risk factor for coronary artery disease. This goes beyond epidemiology studies where we say, “oh, a person with higher cholesterol, LDL cholesterol, has higher risk of coronary artery disease.” Yes, that is true.

But then we have multiple different drug interventions of different classes that work in different ways to lower LDL cholesterol. And in these clinical trials, people are less likely to have a heart attack and die of heart attack disease. Any person who promotes a carnivore diet and tells you that the LDL cholesterol is not relevant is causing harm.

RICH ROLL: Well, that’s the party line. They’re very dismissive of this and say, “don’t worry about your elevated LDL, it’s not what you think it is.”

DR. WILL BULSIEWICZ: Do you want to be the guinea pig who has the crushing myocardial infarction at the age of 48 and you never get to see your grandkids? Do you want to be that guinea pig? We don’t have that data, but what we do know is this an LDL cholesterol that is off the charts. All I can say is show me a cardiologist that’s willing to come in here and tell you that that’s okay.

The Need for Long-Term Studies

RICH ROLL: You don’t have to convince me. It would be interesting to do a long term study on the microbiome of people who have persisted on a carnivore diet or a keto diet.

DR. WILL BULSIEWICZ: I would be very interested to see it. I’m very open to these things. I’m not here to attack people or be a zealot about this. Again, I’m here to tell people that there are many different forms of a healthy diet, but based upon everything that I’ve seen, these are plant predominant diets.

And so I think that all of us, if you are 10% plant based, that is more than I was. And you just take it one day, one meal at a time, moving in this direction and don’t put too much pressure on yourself.

Food Intolerances vs. Food Allergies: Understanding the Difference

RICH ROLL: Yeah, you mentioned food intolerances and allergies. I want to get into that. But before I do, I think just to put a cap on this portion of the discussion, I wanted to remark on how interesting and cool it’s been to see the popularity of a plant-based or plant-predominant plant-centric approach to diet is becoming in certain circles that have been traditionally resistant to this idea.

And by that I mean the kind of biohacking or longevity interested or obsessed space which has typically been populated with people who are more interested in a low-carb approach or a keto approach, because that’s more of a biohacking lens on health. But for example, I mentioned Justin Sonnenberg recently being on Andrew Huberman and he was very clear. Like if you want to basically take an insurance policy out on longevity and you want your metabolism to operate optimally, being as plant-predominant as possible is key.

And Andrew is a guy whose audience I would suspect is populated with a lot of kind of biohacking, low-carb, keto type of people. So I found that to be super interesting. And then in the longevity space you have David Sinclair who’s going plant-based. He’s influenced Peter Diamandis who was recently here, who’s plant-based. These are people who are obsessed with living as long as possible. And that is very much a biohacking thing that has Silicon Valley very focused on this.

And to the extent that a plant-predominant diet is contributing to this idea of human healthspan extension, I find to be super interesting. We both know Tom Bilyeu. I recently was over at his house, I did his show again and one of the reasons he invited me back on is he wanted to learn more about being plant-based because he too had Peter on and he had David on and he’s hearing about how moving in a plant-based direction is so important in terms of longevity, which is something that Tom is really interested in.

And the fact that people like this who traditionally, I wouldn’t, I don’t know if I would characterize them as resistant, but just not part of the plant-based kind of subculture, are now thinking about it and practicing it in a way that even I don’t think I would have predicted.

DR. WILL BULSIEWICZ: Yeah, well, I think that. So first of all, I think that that makes me respect them so much because that means that they haven’t just planted their flag and standing by their flag, which is far too common in our society these days. You have to use the brain that exists between your ears. You have to continue to evolve and strive to do better. And that’s a part of having the humility to say that what I believe today may change tomorrow. Right. As opposed to being rigid about your views and being unwilling to adapt to new information that becomes available to you. So it makes me have great respect for these people.

But now the flip side of this though, Rich, is look, I think that’s great and I want the most inclusive plant-based tent humanly possible. I want everyone to feel like they are welcome coming into this. This is not an elite type of thing and there should not be any holier than thou that exists in my tent, that’s for sure. But at the end of the day, if we look at meat consumption in the United States, it is not going down, it’s going up. So as good as I may feel about my book going out and touching 200,000 people, I have not accomplished my goal and we got a lot of work to do.

RICH ROLL: Yeah, amen to that. I can’t let you go without talking about food intolerances and allergies. This is something that a lot of people suffer from. So walk me through how you think about this and what kind of guidance you can give people who are dealing with this type of problem that continues to trip them up.

Understanding Food Allergies vs. Food Intolerances

DR. WILL BULSIEWICZ: Okay, so let’s separate these two things, because I think that it’s important for people to understand the difference between these two. Food allergies versus food intolerances. In both cases, it starts with the consumption of food. You put something into your mouth, and then there’s some sort of reaction that takes place that follows that. But it’s different things between these two.

A food allergy involves the activation of the immune system. Your immune system has decided that this food is the enemy. Any allergy. I mean, literally, the definition of the word allergy is the activation of the immune system in response to some sort of outside stimulus. So, like, asthma is an allergy in our lungs. We have seasonal allergies and allergic rhinitis in our sinuses, and this may be like dander that’s causing that. And in this case, we’re talking about food.

And there are specific foods that have been most clearly associated with the development of food allergies. About 90% of food allergies can be attributed to a limited group that includes dairy, eggs, fish, shellfish, soy, wheat, peanuts, nuts, and corn. I’m very proud of myself for getting through all that.

RICH ROLL: Yeah. Why do you distinguish between peanuts and nuts?

DR. WILL BULSIEWICZ: Peanuts are legumes. Peanuts are actually legumes. Most people don’t realize that. So, yeah, peanuts are actually closer to a bean than they are to a nut.

RICH ROLL: Wow. Why so much peanut allergy out there?

DR. WILL BULSIEWICZ: They’re very common. And actually, there’s interesting research looking at development of the infant microbiome and the belief that food allergies in children come from disturbances of the gut microbiome in these children.

So anyway, a food allergy is the activation of the immune system, and it may manifest in a number of different ways. That could include GI symptoms. Like, it could include bloating, gas pain, diarrhea, or constipation. But classically, we’re going to see other stuff. So we’re going to see, like, hives or a rash or. The thing that we really worry about as doctors is, like, difficulty breathing, labored breathing, throat swelling. That’s the stuff that we freak out as doctors.

Now, with an allergy, one of the important points is that the amount that it takes to activate the immune system is very small. So if I had a dairy allergy, you could potentially put one drop of milk on my tongue, and that would be enough for me to have an allergic reaction.

Flip side, let’s talk about food intolerances. They’re different, and people need to understand the difference. But food intolerances are always manifest with symptoms. You don’t have a food intolerance, and be symptoms free. Usually they’re digestive symptoms. So gas, bloating, abdominal discomfort, cramping, diarrhea, constipation. And by definition, a food intolerance does not involve activation of the immune system.

RICH ROLL: So if you have hives or some kind of other skin manifestation or other condition, that’s more like an allergy than an intolerance. What is an allergy?

DR. WILL BULSIEWICZ: Generally speaking. But we will talk about histamine intolerance in a brief moment here. And that’s an exception to that rule that needs to be clarified so that people understand that. But a food intolerance is not the immune system, so it is not inflammation. It is generally sloppy digestion. Your gut microbiome, which we talked about in the very beginning of the show, is critical to our digestive process, is struggling to keep up with the demands of the diet that you’re consuming. And so when this takes place, this is why we get these types of symptoms. So we have to separate these two.

Testing for Food Allergies vs. Food Intolerances

Now, when we test for these things, if you were to do food allergy testing, you would typically go to an allergist, and there’s a couple of different tests that they would do, and they would talk you through it. You allow a health professional to guide you through that process. It may involve a skin prick test where they basically will inject very small amounts of the proteins from specific foods underneath your skin. And they look to see if you get an allergic reaction to it. It may involve a blood test where they look at antibody levels, specifically IgE antibody levels, to see what’s going on. These tests are not perfect, but in the hands of a trained health professional, they can guide you towards figuring out what the problem is.

But on the flip side, food intolerances, there’s poop tests, there’s blood tests, there’s antibody tests, there’s saliva tests, there’s hair tests, and none of them have ever been proven. And because of that, they can create confusion, and you can receive information that makes you not really know what you’re supposed to do, Right? So I’ve seen a bazillion patients, Rich, who their food intolerance tests that they ordered off the Internet and they did at home, it says, “You have a food intolerance to these foods.” And I say, “Well, do you get any symptoms?” They go, “No, I never get any symptoms with those foods.” You don’t have a food intolerance, and we didn’t need the test.

RICH ROLL: So what is contributing to that test result?

DR. WILL BULSIEWICZ: Well, many. So it depends on which test you’re doing. But in many cases, it’s the IgG antibody that they’re looking at. And IgG is basically the immune system being shaped by something that it gets exposed to. So quite simply, exposure of the immune system to regular consumption of certain foods could show up on one of these tests. And that doesn’t mean that it’s a food intolerance.

Again, going back to the definition of a food intolerance, a food intolerance does not involve the immune system. So if it does not involve the immune system, why are we checking IgG antibodies? And if it had been proven, I would say it. But it has not been proven. We don’t have any clinical study that I would describe as powerful enough to validate the use of these tools and actually guide people towards good results.

The GROWTH Strategy for Food Intolerances

So what do you do if you’re the patient that’s confusing? What am I supposed to do? The answer is this. You need a methodology. You need a stepwise approach that allows you to have information that you can lean on with confidence and know that you’re making the right choice with your dietary pattern. That ultimately is what led me to create what I call the GROWTH strategy. And you’ll find this in my new book, the Fiber Fueled Cookbook.

Now, GROWTH is a very big word in my community because I talked about, in Fiber Fueled, the growth mindset, which came from Carol Dweck. She wrote a book about it. So the growth mindset is about ignoring winning versus losing, and instead is about valuing the challenge and valuing the process and enjoying and celebrating progress and letting go of perfection. In this case, I’m not talking about the word growth. I’m instead using this as an acronym to describe the stepwise approach that I take to food intolerances with my patients to identify and ultimately heal them.

So the first step is G. G stands for genesis. What is the root of our problem? So, as a medical doctor, the first question is, what am I treating? Because if I start delivering treatments and I don’t even know what I’m treating, then what am I doing? Am I just throwing mud up against the wall and hoping something sticks? At the end of the day, we are empowered when we know and have the right information to know exactly what we’re going after. You have to start there.

In my book, I introduce something called “the big three of food sensitivity.” And these are not the three things that are the most common causes of food intolerances, but what they are, are the three things that I, as a gastroenterologist, as I ponder what is the root cause of my patient’s problems, I want to make sure that these three things are not present. So they are constipation, celiac disease, and gallbladder dysfunction.

There’s a process that I go through every single patient that comes in and says, “I’m having a problem with food. Dr. B.” This is what I’m thinking about, these three things, because if they are there, I can fix them. And when I fix them, most of the time, the food intolerances go away entirely. And you save yourself from having to go through any sort of process because you’re done, you’re good.

RICH ROLL: Right. The decision tree ends there.

Identifying and Addressing Food Intolerances

DR. WILL BULSIEWICZ: Exactly. But once we get past that, let’s pretend that we identify that this is irritable bowel syndrome and we’re trying to fix these food intolerances. Well, we have to know what foods we’re actually intolerant of. This is where I get back to these tests that are commercially available at home. They don’t get the job done. So we need something that’s more reliable than that.

And the way that we approach this is with R, O, W. These three letters in combination that are almost like doing a dance together. They’re not 1, 2, 3, but instead, it’s the three of them in a waltz. Restrict. Observe. Work it back in.

When we are observing throughout the entire process, keeping notes on how we feel, and we take the food that we’re worried about and we withdraw and then reintroduce off, on, off, on. You flip the switch, and in doing that, you are creating flows of the current. And those flows allow you to determine whether or not it’s causing issues, and you can figure out how much. So not only what foods, but also how much of that food is causing trouble.

So in this process, you have to first identify what foods you want to fix. But then once you get past that, it’s time to train your gut. Train your gut is the process that you go through rebuilding and restoring function to your gut. Your gut can grow stronger. You can restore function. You are capable of tolerating foods that you don’t think that you can eat.

Training Your Gut Like Exercise

The way that we do this is the same way that we exercise. Our body is adaptable. You become a runner in your 40s, and you progressively ratchet up the distances that you run. Your legs grow stronger, you become more efficient with oxygen, your heart chambers grow larger. It actually is able to more efficiently squeeze blood, so it can slow down and your lungs actually expand and you’re able to mobilize more oxygen.

RICH ROLL: Yeah, you’re not exercise intolerant. You’re just exercise maladapted if you’re out of shape.

DR. WILL BULSIEWICZ: Right, exactly. And so when we go through that process of introducing exercise, there’s a process that we all are familiar with, that we go through to basically build up that strength or build up that endurance that we’re looking for. You can apply the exact same approach to your gut.

These microbes can be trained. When you don’t use them, you lose them, they grow weaker, they atrophy. That’s what restrictive diets do. But on the flip side, when we take the foods that we struggle with and we go low and we introduce them slowly increasing over time, then that is conceptually the same as the person who’s training for the marathon and starting off with a short run, or the person who’s going to the gym and wants to be ripped, but they’re starting off with the five pound dumbbells.

RICH ROLL: Sure. So essentially the idea being that if you have a “food intolerance,” you’re not really intolerant to it. You just have a microbiome that is out of sync with being able to live symbiotically with the introduction of that food. And by seeding it very slowly, you are seeding a new ecology that can metabolize that and ultimately acclimate to it to your advantage.

And you hear this all the time, somebody who goes plant based out of the blue and maybe had a terrible diet beforehand and just says, “I’m just bloated all the time. It’s terrible. I can’t do this.” You know, if you eat beans or whatever, and I always just say, “Well, you just stick with it, eventually your gut will adapt.” You know, I’m just like, suck it up and do it. I mean, this is a much more gentle approach of starting small, which is smarter, obviously.

But this trainability of your gut, which goes to the malleability we were talking about earlier, I think is really powerful and just more broadly understanding that these intolerances are not concrete. They’re just a window into kind of where you’re at now. And that is something that can shift if you take advantage of this kind of growth protocol that you’re talking about.

DR. WILL BULSIEWICZ: Your gut has strengths and weaknesses, and every single one of us has a certain threshold at which it is becoming excessive. And that would be true for you and I as well.

Understanding Histamine Intolerance

RICH ROLL: You mentioned histamines, though. How are histamines different? This is something that a lot of people are concerned about and talking about.

DR. WILL BULSIEWICZ: Yeah. So histamine is an interesting topic. And one of the things that I’m super excited about with the new book is that I feel like I’m bringing forward something that’s going to change people’s lives and give them a solution.

So, first of all, histamine is a signaling molecule that’s a part of our body. And when we are healthy, we have histamine. It’s a part of us, literally right now. And it can contact receptors throughout different parts of our body, in our brain, in our vascular system, in our heart, in our stomach, in our gut, all these different locations.

But if you consume an excess of histamine, because food ends up containing histamine, because of the life cycle of the food, the microbes produce histamine. And so when you consume food that contains histamine, it’s possible to overwhelm your body’s ability to handle the histamine load. And that starts to stimulate these histamine receptors and activate symptoms.

And the number one symptom. So you can have any of a number of different symptoms with histamine intolerance, the number one symptom that people need to know is gas and bloating. If you have gas and bloating that is unexplained and you’re not really sure what’s going on, you need to try a low histamine diet and see if it improves. And by simply doing this for two weeks, it could potentially change your life.

RICH ROLL: And what would be an example of foods that would find their way onto a low histamine diet?

DR. WILL BULSIEWICZ: Well, let me describe the foods that are high in histamine. And then there’s sort of the counterpoint.

So the high histamine foods, the most high histamine foods, are fermented foods, comes back to the microbes are producing the histamine. So now, fermented foods goes a little more broad than many people perhaps even realize, because I’m not just talking about sauerkraut and kimchi here. I’m also referring to things like vinegar and chocolate and alcohol. So all of these things are high in histamine.

Many different animal products are high in histamine. The most classic is fish. Fish can be very high in histamine and activate these types of issues. And then on the plant side of things, there are sort of four classic plants that we think about, and those are spinach, tomatoes, eggplant. And then finally, it breaks my heart, but it’s avocados. It’s a tough one.

So nonetheless, the point from my perspective is that if a person has histamine intolerance, so let me just kind of say real quick that going beyond gas and bloating with histamine intolerance, it could be hives, it could be flushing, runny nose, headache, rapid heart rate, lightheadedness. So many of these are nonspecific symptoms that you wouldn’t necessarily equate to a food intolerance.

RICH ROLL: What about puffiness in your face or under your eyes?

DR. WILL BULSIEWICZ: So some puffiness in your face or under the eyes is possible, but throat swelling in the way that we see with a true food allergy, you’re not going to have with histamine intolerance. Histamine intolerance as an intolerance is not a life threatening issue, not in the way that a food allergy would be.

So nonetheless, the challenge that we’ve had, Rich, is that there’s no blood test, there’s no CAT scan, there’s no way to really prove who has or doesn’t have histamine intolerance, which limits our ability to diagnose it, because a doctor is never going to turn to you and hand you a packet full of recipes.

The way that we have to diagnose histamine intolerance is with food. You have to eat a low histamine diet for two weeks. Now, that’s an overwhelming and complicated thing if you don’t have someone guiding you and holding your hand. That’s where my new book comes in. I saw the opportunity to help these people, number one, identify whether or not they have histamine intolerance. Number two, once you realize you have it, let me show you how to fix it.

But in order to get there, you have to do a low histamine diet first. And so we give you 25 recipes that you can follow as a protocol. And you just basically, quite simply cook the food that I give you for two weeks and see how you feel. And if you feel better, then we have identified the issue.

Retraining Your Gut for Histamine Tolerance

RICH ROLL: But then this growth protocol would be equally applicable in the histamine context in that if you feel better in that two week period of getting off of all these foods, you can start to reintroduce them very slowly and develop a robust response so that they’re not giving you all these symptoms.

DR. WILL BULSIEWICZ: There’s two things. Number one, people who have a histamine intolerance, it’s not just food. It’s that they have a damaged gut. And we see this, that because there’s a breakdown in the barrier of the gut, they have increased intestinal permeability, which makes them more vulnerable to histamine intolerance because of the histamine that’s in their food. So we’re going to heal that part.

RICH ROLL: So resolve the dysbiosis with non histamine plant foods.

DR. WILL BULSIEWICZ: That’s part one. But the second part is that there is a process to training your gut and reintroducing these foods, and we have to be systematic about it. So if you just literally started throwing sauerkraut into a bowl, you would have a problem. But if you work through the process one step at a time, starting with the lower histamine foods and working your way back up towards the top, you ultimately can get there.

RICH ROLL: Right? That’s amazing. But how aware are people if they have a histamine problem?

DR. WILL BULSIEWICZ: They’re not.

RICH ROLL: And that’s the thing, right?

DR. WILL BULSIEWICZ: That’s what I’m trying to bring attention to. I’m trying to shine a light on this because I know that there are people who are listening to you and I right now, and they’re saying, “Holy cow, I have gas and bloating. And when I eat foods, I see that when I eat fermented food, I don’t feel well, and I can get hives or a little bit of a rash or flushing or a runny nose or a headache.” And that person should be doing this low histamine protocol to identify whether or not they have histamine intolerance.

RICH ROLL: Right? Yeah. I would suspect this is going to be news for a lot of people, and they’re going to try it and be like, “Oh, my God, this was right underneath me the whole time, and I didn’t realize.”

DR. WILL BULSIEWICZ: I pray that that’s the case, because that, to me, is. This is where I am basically using my opportunity to write a book to create tools that can improve people’s health. And that’s what I’m here for.

What Your Bowel Movements Tell You

RICH ROLL: What about bowel movements? We talked about this before, but I think we should touch on it a little bit. What can we infer from taking a look at what’s happening down there?

DR. WILL BULSIEWICZ: You can infer a lot. It’s incredible.

RICH ROLL: I have a thing with this because mine don’t really measure up based upon what you’re telling me they should look like.

DR. WILL BULSIEWICZ: Well, so I think at the end of the day, how do you feel?

RICH ROLL: I feel fine, but it’s pretty runny down there.

DR. WILL BULSIEWICZ: Yeah, it may be very runny because you are so high in fiber that you’re producing a ton of short chain fatty acids that ultimately are making it a little bit more on the loose side.

RICH ROLL: Although when I really ramp up the fiber and I’m kind of crushing super dense high fiber smoothies and the like, there tends to be a little bit more form. I found that it’s runnier when I’m off my perfect game.

DR. WILL BULSIEWICZ: Yeah, well, so I think that looking into. I think that the key here is this. We have stigmatized bowel movements. And that’s kind of silly from my perspective.

RICH ROLL: Yeah, I feel bad. I’m like, I’m supposed to know how to do this, and I’m not. I’m not getting that optimal form.

The Importance of Gut Rhythm

DR. WILL BULSIEWICZ: Our body thrives on rhythm, right? So if I take you, you are a runner and you rely on the rhythm of your heart in order to facilitate your ability to run. If I throw you into an abnormal heart rhythm, I could literally make it so you can’t even walk up a flight of stairs, despite the fact that you’re training for a marathon.

And the same is true with our gut. Our gut thrives on rhythm. And rhythm means that we are having good, regular, complete, and dare I say it, satisfying bowel movements. Like, they’re supposed to feel good. You’re supposed to look forward to bathroom time, and the best way to start your day is a great bowel movement.

And so the problem that we run into is that there are a lot of people out there who – this is not what they experience. It’s not in rhythm. They struggle with it. It doesn’t come regularly. They fear bowel movements because they have to strain just to have, like a little nugget. These are people who are out of rhythm. And ultimately they manifest symptoms as a result of that.

Understanding Your Bowel Movements

Our stool is not the excrement of our food. Our stool is predominantly made up of our gut microbes. Your bowel movement is a window into the health of your gut microbiome.

And what we look at is not just how often you go. That to me, is in itself usually not super helpful. Now I will say if you tell me, “Hey, Dr. B, I haven’t pooped in seven days,” okay, you’re constipated. I can say that for sure.

But the problem is that there are a ton of people who poop every day – they are constipated. They poop a couple times a day – they are constipated. There are people who have diarrhea that are actually constipated. And it’s kind of mind blowing.

But what’s happening there is that we’re missing the second part of the story, which is really critical, which is, do you have a complete evacuation? So when you go, do you feel like you’re really completely going?

The Hidden Signs of Constipation

Because if the answer is no and you’re simultaneously suffering with digestive symptoms, the number one symptom of constipation is gas and bloating. The number one cause of gas and bloating in my clinic is not histamine intolerance, even though I’ve been hyping this up. The number one cause of gas and bloating is constipation.

So if you are someone who has incomplete bowel movements, even if it’s every day, and you’re suffering with gas and bloating, I am guessing you are probably constipated. And if you strain to have these little nugget turds and you do that four times a day, you go into my office and you say, “Dr. B, I’m having four bowel movements a day.” Yeah, but what do they look like?

RICH ROLL: Right.

DR. WILL BULSIEWICZ: Are you completely evacuating? “I’m not really evacuating, Dr. B. They’re these little chicken nuggets.”

RICH ROLL: But is it a kind of, you know it when you feel it thing? Like that satisfaction that you get where you’re like, “Yeah, man, that thing. I emptied it out.”

DR. WILL BULSIEWICZ: When you whip this door open and you strut out in slow motion. That is proof in an illustration.

RICH ROLL: And there’s that weird pride, you know, you’re like, “Yeah, man, I crushed that one.”

DR. WILL BULSIEWICZ: Oh, 100%.

RICH ROLL: What about – sorry, go ahead.

Overflow Diarrhea: A Hidden Form of Constipation

DR. WILL BULSIEWICZ: Well, but the problem is there’s a lot of people out there that aren’t experiencing that. And, you know, the last thing that I want people to hear about, because I really hope that there are people who benefit from this, is that there is a group of people that have what is called overflow diarrhea.

And these are people who chronically suffer with constipation. And one day the poop gets impacted and you have a column of solid stool that is not moving. And the only thing that can get through, sneaking through the cracks and the…

RICH ROLL: Crevices, is the liquid.

DR. WILL BULSIEWICZ: Is the liquid.

RICH ROLL: Yeah.

DR. WILL BULSIEWICZ: And it comes down to the bottom. And our bottom is not designed to stop liquid from coming out. And so you get urgency and you rush to the restroom and it explodes out as diarrhea. And you go into your doctor and you say, “I’m having diarrhea.” And they say, “Take Imodium.” And Imodium slows down your motility even more and your problem gets worse. It gets worse.

RICH ROLL: Yeah.

DR. WILL BULSIEWICZ: The paradoxical solution in this particular case, with a person who has this overflow diarrhea, the paradoxical solution is to flush it out. You got to get it out and then start over.

Frequent Bowel Movements: When Is It Normal?

RICH ROLL: I want to get to colon cleanses in a second. I want to touch on that. But first I – I’m going to take advantage of the fact that you’re here. Like, I think I’m on the opposite end of this spectrum because I do a number two, like six times a day. And I’m thinking, this can’t be – like, it’s so much more often or frequent than most people that I know. And Julie’s just – my wife’s like, “Yeah, but you’re like a furnace. Like, everything, you know, everything down there is churning, like, so hot all the time.” But what would a gastroenterologist say about this?

DR. WILL BULSIEWICZ: How do you feel?

RICH ROLL: Like, am I – am I unhealthy in the other direction?

DR. WILL BULSIEWICZ: How do you feel?

RICH ROLL: I feel fine.

DR. WILL BULSIEWICZ: Yeah. You know, so from my perspective, a guy who’s consuming a super high fiber diet, we know that, right? We know you’re consuming a high fiber diet and you’re a runner, and that actually stimulates motility and it keeps things moving along. Like, we know that there’s this common pattern among runners called the runner’s trots.

RICH ROLL: Yeah. I mean, I’ll do a full blown bowel movement in the morning and think I’m totally empty, and then I’ll go running. And 30 minutes into the run, I got to pull over to the side of the trail.

DR. WILL BULSIEWICZ: 100%. So when you move, this is important for people to know at home, like, independent of talking about what’s happening with you, is that when you move, your intestines move, you are stimulating motility. Our sedentary lifestyle is part of what’s contributing to the epidemic constipation that we see out there these days. Constipation is far more common of a problem than diarrhea is.

But when you move, your intestines move. People who run quite frequently will have more frequent bowel movements because they’re a runner. So you take a gentleman yourself who’s on a high fiber diet. A high fiber diet by itself, you were not a runner, Rich. If you were a sedentary man, you would still probably be having three or four bowel movements a day. But then you add in the fact that you are going on these runs and you were accelerating that motility a little bit, and that’s probably what’s contributing to not only the frequency, but the form.

Colon Cleanses: Are They Necessary?

RICH ROLL: Right. But if you’re somebody who is constipated and perhaps not even aware of it for the reasons you mentioned, but you’ve got this skyscraper stuck inside of you, would that be somebody who would be a candidate for a colon cleanse? Like, I’m sure you’re not in favor of these kind of, you know, cleaning out the colon from the rear side.

DR. WILL BULSIEWICZ: Sure.

RICH ROLL: For – because it’s going to, you know, take out a lot of that microbiome that you want in there.

DR. WILL BULSIEWICZ: Right.

RICH ROLL: But would that be a scenario in which maybe that would be a good idea for that person, or would you just amp up their fiber until the motility enhances and it all gets cleaned up?

DR. WILL BULSIEWICZ: Well, I think you’re bringing up a very important point that I’m glad that we get to address and bring out to the…

RICH ROLL: Well, that’s what I’m going to talk about this with.

When Fiber Isn’t the Solution

DR. WILL BULSIEWICZ: Yeah. So I think the important point that I want to touch on real quick, and then we’ll talk more about the cleanse part, is that fiber isn’t always the solution to constipation.

So in people who have mild constipation, meaning not every day and not going on for days at a time, but instead, like a touch and go here and there, maybe twice a month – in that person, you turn up the fiber, you increase your water consumption, you get some exercise, maybe you literally take a walk after dinner or something like that. Those people will poop and they will be good. So lucky them.

The people that I’ve seen in my clinic, that’s not them. You know, people with moderate to severe constipation – that’s not going to work.

RICH ROLL: And there’s a problem even if they do like psyllium, you know, those psyllium husks that you can put in water that are supposed to enhance your ability? Get it out.

The Fiber Paradox in Constipation

DR. WILL BULSIEWICZ: You can try. But here’s – here’s my word of warning. I just want people to be empowered with understanding what potentially could happen so that they can react and respond to what they experience in terms of their symptoms.

So when fiber is moving through, fiber is your friend. But when fiber gets locked up, it turns into cement. And your gut microbes are given unlimited access to ferment that fiber. And what we see is that people who are constipated, they at baseline, produce more gas.

And there’s this interesting vicious cycle that exists, Rich, where we have discovered that methane gas, which is the product of fermentation of fiber, methane gas actually slows bowel motility. So you get constipated, you produce more gas. That gas makes you more constipated.

Now you pour fiber into this equation and it’s effectively pouring gasoline on the fire. And now if you pour the fiber in there and all of a sudden, boom, here we go, we’re moving again, we’re back in business. You’re good right now. Fiber is your friend again.

But if you’re staying locked up and you’re not getting it moving through, that’s a problem. And you’re going to have worsening of your gas and bloating. And I’ve had a number of people who come to see me and they’re like, “Doc, I was inspired by your book. I started doing your four week plan and I felt like crap.” Really? What symptoms? Gas bloating, a little bit of nausea, tons of fatigue. I’m describing constant constipation right now. This is what people feel like.

And I know instantly your issue is constipation. And it goes back to the very beginning of the growth strategy.

The Connection Between Constipation and Other Symptoms

RICH ROLL: Fatigue goes hand in hand with constipation.

DR. WILL BULSIEWICZ: 100%. 100%. And so does food intolerance. And so does food intolerance. And the food intolerances are very nonspecific, meaning that you feel like everything causes trouble. It’s not just like one thing or two things. It’s like everything’s causing trouble because you get gassy.

So what do we do? It goes back to the very beginning of the growth strategy. G stands for genesis. What is the root of the issue? And when I identify that it’s constipation, treat the constipation, fix that – the food intolerances go away. You introduce the fiber. Now, after you’ve already got things moving through, now you introduce the fiber, and the fiber is rolling through, and the fiber stays your friend.

RICH ROLL: But how do you fix the constipation?

DR. WILL BULSIEWICZ: Well, there’s a number of ways. So it depends a little bit. I mean, we could do an entire podcast on constipation. I’m not kidding. I taught a course and I did a 90 minute lecture on constipation.

RICH ROLL: Well, let’s just drill it down to make it digestible for the person who’s listening who does have that problem and is looking for some things that they can do.

Natural Approaches to Constipation

DR. WILL BULSIEWICZ: Yeah, totally. So just to be clear with everyone, please talk to your medical doctor. I am not giving you medical advice right now. I’m just telling you the way that I approach my patients and I’m trying to empower you with information.

So one of the classic ways that I will approach constipation in the very beginning, because many of the people who come to me, they’re like, “Doc, I want a natural approach. I don’t want to take medication.” Well, I don’t want you to take medication either, if I can avoid it.

So what I will do is I will use magnesium. And magnesium is a beautiful thing because it can be taken before bedtime, helps with sleep, helps with mood, reduces headaches, and by the way, it’s great for bowel movements. But there are many forms of magnesium. It’s not just any form of magnesium. You go out and you buy magnesium glycinate or something like that. It’s not going to help you in terms of having a bowel movement.

We need a form of magnesium that’s not easily absorbed. And so there’s a few specific magnesium oxide, magnesium citrate, magnesium sulfate. And you start off at around 500 milligrams, depends on what brand you get and stuff like that. It could be 400 milligrams, but you start around 500 milligrams. You take it before bedtime and you do this consistently and you give it four days and you see how you feel.

And if you’re pooping, cool, we just won. And if you’re not, turn it up another 250mg. And if you keep doing this, you can eventually again do this with your medical doctor, but you can keep turning it up until you achieve the effect. And you don’t want to go overboard on the magnesium.

But here’s the beauty of it. If you’re doing this in collaboration with your healthcare provider, you can check your magnesium level before you start, and you can check your magnesium level once you get on a steady dose. And when I do this, what I typically will find is that the magnesium level before we start is too low. My patient is missing magnesium, our diet is deficient. And when I supplement them and they start pooping and they’re getting these health benefits, I repeat their magnesium level and all of a sudden I discover it’s exactly where it needs to be.

RICH ROLL: So it’s a function of both a deficiency and making sure that you’re replenishing your requirements. But also this idea of it not being overly absorbable so that it stays in the gut. And there’s something about the chemical composition of magnesium that helps push all this stuff through.

DR. WILL BULSIEWICZ: Yes. So magnesium, what it will do is it gets into sort of college level chemistry type stuff where water wants to basically flow towards where the electrolytes are. So when you have this magnesium, the water starts to flow towards the magnesium and you’re basically introducing some additional water into the colon that helps to float the log down the river.

RICH ROLL: I see.

DR. WILL BULSIEWICZ: Yeah.

RICH ROLL: I think the citrate version is the one that is most, that finds its way into most of these products.

DR. WILL BULSIEWICZ: Yeah, it can be, but there’s like.

RICH ROLL: Calm is one, I think that’s magnesium citrate.

DR. WILL BULSIEWICZ: It can be, but also magnesium oxide has randomized controlled trials that show that this is placebo controlled trials showing that this works as well as many drugs for constipation. So I think it’s a great approach that people can start with. And then there’s other things downstream, permutations of possibilities that are running through my mind as a gastroenterologist.

Top Line Advice for Gut Health

RICH ROLL: Right, right, right. All right. Well, it’s almost closing hour at this saloon, but I’m not going to let you out of here without kind of taking us out with just some top line advice for people. We talked about plant diversity. We talked about trying to get 30 different varietals of plants in our diet every day. We talked about fermentation, bowel movements, et cetera. What are some other just kind of really practical, actionable things that people should be thinking about and practicing to enhance the health of their gut.

DR. WILL BULSIEWICZ: We want to move the scale of balance. We want to move the scale of balance and start to put the weight on the side of healthy foods. And so yes, this does involve eating more plants in variety, in abundance. It does involve eating fermented foods.

But it also means that the substitution that we’re making is withdrawing these ultra processed foods, withdrawing the animal products that are devoid of fiber and very high in saturated fat. So we’re making substitutions that are leveling up our gut microbiome, leveling up our health.

But we would be remiss because there’s so much more that we could talk about and we haven’t even touched on the topic of how you can heal your gut without even lifting a fork. There are ways in which you can heal your gut without even lifting a fork.

RICH ROLL: Rolling in the mud, letting your dog lick your cheek, hugging other human beings, being out in the world.

Exercise and the Gut Microbiome

DR. WILL BULSIEWICZ: So that’s a great place to start, but let’s think about movement. So I actually was a part of a recent study that was published from people from the University of Nottingham where we did an exercise intervention. And it was literally 15 minutes of exercise. That’s it. And we did not change people’s diets.

And in doing this, 15 minutes of exercise, who can’t do that? Come on, you can do that. In doing the 15 minute exercise intervention, we saw a shift in their gut microbiome and the result was that we had more butyrate producing microbes.

So going full circle all the way back to the beginning, we were talking about in COVID-19, severe COVID-19, the absence of butyrate producing microbes in people that have severe disease. There are so many examples where this is good for us. And what I’m saying to you is, yes, dietary fiber will increase the representation of butyrate producing microbes, but so will exercise.

RICH ROLL: What is the mechanism for that?

DR. WILL BULSIEWICZ: It’s very interesting. So we think that there’s a couple of different ways that it could potentially be doing this. But one of the ways is that we have this system called the endocannabinoid system. And people probably recognize this cannabinoid, like cannabis, they’re conceptually similar. It’s not the same, but conceptually similar to the active chemicals that you will find in marijuana.

And this endocannabinoid system is involved in our gut microbiome. And it’s also involved in, for example, our perception of pain. So in this study that we did, it was people who had arthritis. And when people do exercise and they have arthritis, they have improvement of their pain because we’re activating the endocannabinoid system.

But it turns out that the endocannabinoid system also has the downstream effect of affecting the gut microbiome, which leads to the emphasis on the butyrate producing microbes. And so it also has a mood.

RICH ROLL: Altering aspect to it as well, doesn’t it?

DR. WILL BULSIEWICZ: Well, there may be a mood altering aspect to it in the sense that.

RICH ROLL: Just in terms of enhanced well-being, you know, the runner’s high.

DR. WILL BULSIEWICZ: Right, right. So where is the runner’s high? Where does it come from? And we believe that this actually comes from the endocannabinoid system. So, yeah, so it’s quite fascinating to consider this. And it’s you’re not even changing your diet, but yet when you do consume fiber, you will get more short chain fatty acids from that fiber because the exercise. So basically what I’m saying is we’re synergizing.

RICH ROLL: With just a 15 minute minimum dose.

DR. WILL BULSIEWICZ: That was a 15 minute minimum dose. Now, of course, we want to strive to do even more than that if we can. I mean, as humans, we were not designed to only do 15 minutes of movement per day. Right. But in this study, just 15 minutes made a difference for these people.

Sleep, Relationships, and Microbiome Sharing

So sleep becomes very important. We know that people who get more sleep, more restful sleep, have more diversity within their gut microbiome. If you wake up in the middle of the night at four in the morning and you’re having those racing thoughts, this phenomenon of waking up in the middle of the night has been associated with decreased microbial diversity. So sleep is something, the people that we surround ourselves with.

Very interesting study, Rich, where they looked at spouses and they discovered that you share more microbes with your spouse than you do with your siblings who share your genetic code. Right. And come from the same place. And what was really interesting about this is that they showed that it was not their diet that was the explanation. There was something else going on.

But here’s my favorite part in this study. The amount of love and affinity that you had for your spouse was associated with the beneficial response that you received. So the person who felt most connected to their spouse actually shared the most microbes with their spouse. Now, I don’t know if that’s kissing, touching, if that’s sex, but at the end of the day, the people who felt closest to their spouse were sharing the most microbes. The people who felt most distant from their spouse were not.

RICH ROLL: That’s super interesting. That’s super interesting. And also, I couldn’t help but think about the way we started this podcast, which was talking about how the micro mimics the macro and vice versa. And in creating this list of things to enhance your microbiome, it goes back to the same things you hear about when we’re talking about weight loss, longevity, it doesn’t matter, right? Get a good night’s sleep, increase the amount of plant foods that you’re eating, get outside and exercise, connect with nature, connect with other human beings, all of these things.

Holistic Healing and Trauma

DR. WILL BULSIEWICZ: And there’s one more thing I want to add, if I could. When we talked about the growth strategy, I missed out on talking about the last letter, which is H. H stands for holistic healing. We are so much more complicated than simple biochemistry, where fats, proteins and carbohydrates meet enzymes. We are complete humans, and the way that we feel affects our gut microbiome.

And trauma becomes critically important. And I have seen a number of different patients, Rich, where these are the people who bounce from doctor to doctor to doctor, and they never get anywhere. And they will come in and they will say, “Dr. B, I have done everything that you have asked me to do. I eat a diversity of plants, I sleep, I exercise, blah, blah, blah, blah, blah.”

The issue is that these people oftentimes have something in their subconscious that is holding them back. Trauma can continue to echo throughout our gut microbiome and ultimately manifest with digestive health issues. I want to share a quick story, if it’s okay just to close this out.

RICH ROLL: Yeah.

DR. WILL BULSIEWICZ: I had a patient who I’d been taking care of for years. She has ulcerative colitis, and I was pulling out all my tricks. So, I mean, I had her on what I thought was the right medicine. I was working on her diet, lifestyle, all these different things. It was not working. It was a humble moment.

And then one day recently, she comes in, she goes, “Dr. B, I’m so excited to tell you this. I’m back. I’m all the way back, back to feeling like myself. I’m 100%.” This is a person whose quality of life was destroyed. She’s young, couldn’t go on a date because of how sick she was, waking up in the middle of the night to poop.

So when she came in and she told me this, I was so pumped. But I needed to know, so what happened? What changed? And she says to me, “Well, I finally had the audacity to change my job.” She was working in an environment where she dreaded going to work on a daily basis, where her boss would publicly belittle her in front of her work colleagues. It was a hostile environment, and she ultimately decided that she needed a change.

She left. She entered into a new work environment where people treat her with respect and just this simple shift completely fixed her health issues.

RICH ROLL: Incredible and beautiful.

DR. WILL BULSIEWICZ: It’s powerful.

RICH ROLL: Yeah, it’s really powerful. The holistic way of looking at it, how interrelated all of these things are. And to treat things in isolation is to be blind to the greater play.

DR. WILL BULSIEWICZ: This is why we always have to, again, remain humbled to the possibility that there’s so much more going on with the body than we could possibly understand. So we do the best with our clinical tools, with our research, but at the same time, we have to look at the whole human and understand how do we help this whole human.

The Future of Microbiome Research

RICH ROLL: More will be revealed. We’re just at the start of this amazing adventure into the microbiome revolution. I think what we’re going to be learning and discovering over the next five to 10 years is going to blow people’s minds. And you’re right there, man, on the cutting edge of it, doing the thing.

Thank you. That was amazing. I think people are going to get a lot of value out of what we just talked about. And I appreciate you sharing so openly over the course of these past couple of hours. You are doing fantastic work. I’m at your service, my friend.

So everybody who is listening and watching, if you have not yet checked out Dr. B’s first book, “Fiber Fueled,” it’s a must read. That’s sort of the why behind all of this, right? And your new book, “The Fiber Fueled Cookbook,” is the how. It’s all about the practical things that you can do, consistent with the many things that we talked about here today.

The Fiber Fueled Cookbook: A Personalized Toolkit

DR. WILL BULSIEWICZ: My new book is a toolkit for people to figure out how to create gut health in their own individual way. No matter who you are, if you don’t have digestive health issues, guess what? I have 125 absolutely delicious recipes. And the plant points are listed on every single recipe. You can turn it up.

But if you do have digestive health issues, if you have food intolerances, I’m going to walk you through the growth strategy in great detail. And I’m going to give you two food protocols. One of them is the histamine protocol, 25 recipes. The other is a FODMAP protocol, 30 recipes.

You want to ferment food? I teach you how to make sourdough. I teach you how to make delicious fermented foods. You want to sprout like me and Doug Evans? You can join the party. I teach you how to sprout.

The point is that you can implement this and introduce this in your own life in whatever way you feel works best for you. And it doesn’t have to be a 100% plant based thing if you don’t want it to be. I want you to walk that path in a way that feels right for you. At the end of the day, I just want you to be thriving, be enjoying your food and having great joy in your life. That’s what this is really about.

Free Research References Available

DR. WILL BULSIEWICZ: And Rich, one last thing I just want to mention real quick. We’ve talked about a lot of research studies during our episode today. We talked about a lot of research studies during our first episode. So in order to engage with everyone who’s been listening to these two episodes, I want to be completely transparent with my science and provide that to everyone.

So I’m actually going to prepare a PDF that’s going to be available for download. And if you quite simply go to my website, www.theplantfedgut.com/richroll – if you go to my website, theplantfedgut.com/RichRoll I will give you the references both for this episode and the last episode. If you haven’t listened to the first episode, go back and check it out. You’ll have the references.

And at the end of the day, this is about trying to empower you with knowledge that you can apply to your own life in a way that transforms your health. That’s what I’m about.

Wrapping Up and Looking Forward

RICH ROLL: I love it. That’s fantastic. Our friend Simon Hill did that for the episodes that he did on the show, and the audience loved it. So that’s very generous of you to do. And of course, I’ll link all that up in the show notes if you can’t remember the website or any of that stuff.

In the meantime, pick up Will’s new book, “The Fiber Fueled Cookbook,” available everywhere. And you can find out more information about it on his website, ThePlantFedGut.com and there are so many more. I made this outline, I shared it with you, and there were all these other topics that I wanted to explore that we didn’t even come close to getting to.

DR. WILL BULSIEWICZ: So cool topics.

RICH ROLL: Open invite to come back and dive deeper into all of this.

DR. WILL BULSIEWICZ: Absolutely, man. I would love to. It’s always a privilege to. This is – I mean, going back to the first episode, you know that this was a dream come true for me. To be a part of this and to be here with you today for the first time in person is really – it’s just crazy for me.

RICH ROLL: Well, the pleasure and the honor is all mine, and we’ll see you back here soon, my friend.

DR. WILL BULSIEWICZ: Thank you, man.

RICH ROLL: All right. Peace. Plants microbiome.

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