4 foods that heal your gut and reduce inflammation (in as little as 24 hours!) with Dr. Will Bulsiewicz

Heart disease, dementia, depression, diabetes: what do these conditions have in common? Gastroenterologist and New York Times bestselling author Dr Will Bulsiewicz says the answer is inflammation.

In this episode, he explains 4 foods that heal your gut and reduce inflammation, and how you can start seeing changes in as little as 24 hours.

Dr Bulsiewicz explores the difference between helpful, short-term inflammation and chronic, low-grade inflammation that can linger in the background.

You’ll learn which symptoms that seem unrelated, such as fatigue, skin breakouts, bloating, headaches, and joint pain, all share a common driver. You’ll also hear why he believes the gut and the immune system rise and fall together, and how a weakened gut barrier may keep the immune system on constant alert.

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Transcript

Jonathan: Will, thank you so much for joining me today.

Will: My pleasure, thank you.

Jonathan: Well, it's very exciting because you've just released a new book and I'm sitting here in a studio in London and the heating has broken. It's absolutely freezing and I'm wearing my coat. So you are in South Carolina and I think you told me you might've been at the beach this weekend.

Will: It's wild this time of year how different the weather patterns could be depending on where you live. So I'm not quite, in Florida it's not that nice. But yes, over the weekend we did have some beautiful weather.

Jonathan: Alright, so I'm pretty jealous about that and I'm not going to even think about it for the rest of the show. Instead, let's jump into our quickfire round of questions from our listeners.

Will: Let's go.

Jonathan: Will, is inflammation always bad?

Will: No.

Jonathan: Can a regular sleep routine reduce inflammation?

Will: Yes.

Jonathan: Is your immune system most active during the day?

Will: No.

Jonathan: Can stress impact your gut microbiome?

Will: Definitely.

Jonathan: And finally, what new scientific discovery about the immune system has most surprised you as you're writing this book?

Will: After three years of research, Jonathan, I am completely convinced that you cannot separate the gut microbiome from the immune system, that they rise and they fall together. We see this in fecal transplant research that's emerging. We see this in cancer treatment where if you support the gut microbiome, it actually improves the response to cancer therapy. It is a wild time and it is exciting because we have opportunities to heal by healing the gut.

Jonathan: Well, I think that's super exciting. It's a brilliant start to the podcast and I was thinking about how inflammation has become sort of like a buzzword for people talking about wellness and on social media. And I think that has brought with it like a lot of confusion about what inflammation really is. A sense that maybe the whole thing is a bit hocus pocus and why it matters. And so maybe we should start with like, why did you decide to write a book about inflammation and the immune system?

Will: Well, just to contextualize. My first book, Fiber Fueled, came out in 2020. It was a surprise success. I was a full-time medical doctor. I did not expect to transition into a career as an author or working with ZOE. And that's set the stage for me where I have been blessed with a beautiful opportunity to write books that can impact the health of people that I've never met from across the globe. So as I sat there and considered, what do I want my next book to be, it actually was quite clear to me, Jonathan, that inflammation to me is the health related story of our time. I understand that we talk quite a bit about metabolism, obesity, or other health related conditions. I would actually make the argument that those fall under the umbrella of inflammation.

And as I was researching this topic over the course of three years, I asked a very basic question, how many health conditions can I identify where I could stand before you on the ZOE podcast, I could stand before Tim Specter and Sarah Berry and have them scientifically critique me. How many health conditions could I find where I have evidence to back me up and say, this health condition is associated with inflammation. And the answer was, I found more than 130.

Jonathan: 130.

Will: More than 130. And these are yes, autoimmune diseases. Yes, allergic diseases. These are things that we classically think of as being inflammatory, but these are also metabolic diseases, hormonal health conditions, mood disorders, cognitive health issues. So much of what we are struggling with in the modern world is tied to inflammation. That was shocking to me. So I followed up with a second question. How many of these, more than 130 health conditions, can I step forward with a study? And many of these studies are in the last five years, a study that shows that these health conditions are also tied to a damaged gut microbiome. And all of them were, every single one.

Now, the science has to be done right, the research has to be done. There are rare conditions that people are dealing with as they listen to this podcast that may in fact be inflammatory, may in fact be driven by dysbiosis or associated with dysbiosis, which is damage to the gut microbiome. In rare health conditions, it's harder to get the research done because you have to accumulate enough people with that specific disease. But with regard to the common health conditions, these health conditions are associated with inflammation and dysbiosis. And the evidence would suggest that three out of five deaths in the modern world, 60% are associated with inflammatory health conditions. These are the health related issues of our time. And from my perspective as a medical doctor with the opportunity to write books that can impact the health of people across the globe, I wanna talk about the serious most pressing issues, the greatest opportunities for healing. That's what I see here. Inflammation is it.

Jonathan: Well Will. It's a brilliant pitch for why we should definitely talk about inflammation. So why don't we just kick off with like what inflammation is?

Will: Well, first of all, inflammation is not bad. Inflammation keeps you alive. Inflammation makes you strong and resilient. We evolved to have inflammation for critical reasons. It protects us from infections. It helps us to heal wounds, to recover our body. So with that in mind, we can't sit here and pretend that it's inherently bad. Instead, we have to acknowledge that there's something different that has changed. We have gone from a place where the activation of the immune system, which is essentially what inflammation is, when the immune system identifies a threat, activates and attempts to eliminate that threat or to address some specific health related condition.

When the immune system gets activated to do that, that is inflammation. Acute inflammation is the time limited type of inflammation that occurs when your body is fighting an infection, when your body is recovering from some sort of injury, and that is good. But chronic inflammation, the term that we're using in medical papers is chronic low grade inflammation, is a different story because what's happening is that our immune system sits there. When well protected and kept safe, it should only be reacting to really serious threats. But with chronic low grade inflammation, what we have is an immune system that is perpetually turned on because it's being exposed to things that are basically saying, "Hey, as the immune cells, we need to go to war, and we need to fight to protect this body."

When the immune system is turned on, when we have inflammation, there is always, unfortunately, a price to pay. You can't have your army going to war and not simultaneously create damage in the process of that occurring. Chronic low-grade inflammation is the ongoing activation of the immune system. That's unremitting, and that buildup of damage and injury to bodily tissues is what explains the connection between inflammation and these more than 130 health conditions.

Jonathan: This thing that you're describing, this chronic low grade inflammation, just means it's on and on and on instead of being switched on for a period of time and then being switched right back off again.

Will: Yeah, exactly. And when you think about that idea of like this acute, where it's getting switched on for a period of time, inflammation, there's symptoms that we classically associate with that. And every listener knows what I'm talking about. We're talking about fevers, we're talking about like redness and warmth of bodily tissues or swelling of tissues. Right? You know when there's an infection because you get those specific symptoms where your throat gets sore, your nose gets clogged up, you get fatigued powerfully, right? And that's self-limited while your body is fighting the infection. Chronic low grade inflammation is not as intense. You're not necessarily going to get those intense symptoms that make you go, whoa, something is totally different right now. Instead it becomes and blends into your daily normal. You start to accept that fatigue is just the way that you feel. You see skin breakouts and you think, oh, well I just have bad skin. You may have sinus issues or ongoing congestion or seasonal allergies and think, oh, well I just have seasonal allergies. This is just what happens. My nose gets clogged up. You may get gas, bloating, digestive symptoms, struggle with food. Just think this is the way it is in the modern world. And what I'm saying to you is that as you look out across the body, these sort of smoldering low grade symptoms can be manifestations of chronic low-grade inflammation.

Jonathan: And so were all those things you're describing, which sound to me completely different because you mentioned like fatigue, you mentioned skin breakouts, you mentioned then like my gut symptoms with like bloating and things. Those are all potentially symptoms of this low-grade inflammation.

Will: A hundred percent. And we could keep going. Headaches, migraine headaches, joint discomfort, joint pain, body aches, difficulty with recovery, menopausal type symptoms, the worsening of those irregular menstrual cycles, erectile dysfunction in men. Jonathan, there's a very long list. We could sit here and do an hour podcast on the 80 plus symptoms that can be the manifestations. Just to be totally clear, I'm not arguing that inflammation is the only thing that explains fatigue. Certainly any medical doctor would say there are many things that can explain. But what I'm saying is that when inflammation is present, it creates fatigue. And we see this when we get an infection, but we also are living in a world where the energy drink industry is blowing up. People are looking for solutions for fatigue. And I'm saying to you, the solution is not in a can. The solution is in your gut.

Jonathan: How legitimate is this?

Will: My book, which is just out, I share all of the studies to back up everything that I say and what we discussed a moment ago, 130 plus health conditions associated with chronic inflammation. In that particular section of the book, which is literally just a table, there's over 300 references.

Jonathan: So if you're like an academic scientist, what you're saying actually is sort of well known and understood, even if, to me, as sort of a regular person, it sort of seems extraordinary that these things might be caused by like the same underlying inflammation.

Will: So here is what I say, first of all, with total clarity, this is legitimate. And unfortunately, the system that we have in place in which we study the body, the system that we have in place in which we administer healthcare creates challenges in terms of us focusing on something that can be the driving force within your health that's affecting you in a mild way throughout your entire body. So what I'm saying is that you could go to five different medical doctors for five different health conditions and none of them are going to turn to you and say, "Hey, there's this one thing I believe is at the root of all five of these health conditions, and that is inflammation." I wish that we lived in a world where they would, and the reason why they don't is because we have basically put doctors into a vacuum where they have a specialization on some particular part of the body, and they're not looking at the whole system. But the reality is your health doesn't care that the healthcare system is going to separate into cardiologists, gastroenterologists, nephrologists, etc. Your body doesn't care. Your body is dictated in total in some, and inflammation is a driving force behind these health conditions. That ultimately may be manifesting with what are subtle symptoms in different parts of the body and different health conditions that you go and you say, well, there's a skin issue and there's a mood issue and there's a gut issue. But what we should be saying is all three of these things, they're kind of coming from the same place, which is inflammation. That is the driving force behind them.

Jonathan: That's fascinating. Will, so what you're saying, I think, is that it's not such a surprise that in the modern world, often we might feel that we've got a set of different symptoms that in our mind feel very different. You said like, I've got a skin problem and I've got fatigue and maybe I've got a gut issue. Those aren't like three completely separate issues in many cases. There's actually this sort of underlying thing going on in my body, and these are just symptoms coming from the same thing, which is like this inflammation being turned on sort of across all parts of my body, sort of higher and longer than it should.

Will: Yes. And as a medical doctor, I believe that most of my colleagues feel the same way that I do, which is that both in the UK and the US we have a healthcare system that is designed to treat symptoms. And there's nothing that goes beyond that. Unfortunately. There is no incentive to continue with: "Okay, but what was the root of the issue? What is the driving force behind the genesis, the development of disease?" And if we had a system that was designed to do that, where we didn't just stop by patching the symptoms, where we actually continued into a better and deeper place, which is I wanna address how we got here and make this person truly healthy. If we did that, this word, inflammation would be showing up all over the place. And I believe that if we had a lineup of a thousand medical doctors and we said to them: "What is the most pervasive problem in the modern world?" And they could be of many different specialties. I believe that what we would hear is inflammation is the most common answer by far.

Jonathan: So there are pills that I can buy that are anti-inflammatory, right? And I think about like ibuprofen or something like this. So does this mean that we should all be taking anti-inflammatory pills every day in order to reduce this level of inflammation that we're living with?

Will: No, and that's a great question actually, but the answer is no, and here's why. Our goal is not to artificially suppress the immune system. Every time that we do that, we end up with some sort of consequence. There are massive side effects to non-steroidal anti-inflammatory drugs. There are massive side effects to anti-inflammatory drugs like prednisone, and there are massive side effects to the drugs that we use to treat chronic inflammatory health conditions, which may include biologics like anti TNF drugs. So we would prefer to not get there if we could avoid it. It's not to say that we don't use those drugs, we use them when we need them. That's what they're there for, but we would prefer to not get there. Jonathan, what we want is an immune system that is strong, it is precise, and it is targeted. It is only being turned on when it is needed. And when it is needed, it will do its job and do it highly effectively. But in the meantime, when it is not needed, we would far rather that immune system relax and chill, and that's not what's happening. So the point from my perspective is let's build a stronger immune system. Let's not try to just suppress it.

Jonathan: That's really interesting. How does the gut microbiome fit into this story about sort of inflammation being switched on all the time and the immune system being switched on with it?

Will: Again, I discovered that all of these health conditions are associated with dysbiosis, which means damage to the gut microbiome. And as I dove deeper into understanding what was going on there, I began to realize that the gut microbiome plays an essential role in the health of your immune system and the ability for your immune system to do its job properly. So to unpack this for a moment, first of all, 70% of our immune system is in the lining of our gut. If you were to ask the question, where does your immune system live with total clarity, the answer is your gut. This is its home base. It may get trained in the bone marrow. That's basic training, but these little soldiers that are there to defend your body, they get deployed to the front lines in your gut. That's where most of them live, and in that location, they are so close.

If you were watching this on YouTube, you would zoom in and see my fingers that are saying they are so close to 38 trillion microbes living inside of you. The only thing that separates them is a paper thin single layer of cells called the gut barrier. This is our epithelial layer that lines the entirety of your intestine and it keeps the gut microbiome on one side, and it keeps your immune system on the other. And what I've discovered, Jonathan, when I graduated medical school, I thought as a practicing internal medicine doctor and as a practicing gastroenterologist, that your immune system is your defense system. That's your first line of defense. I was wrong. It's your third. The first is your gut microbiome. Your gut microbiome, by being healthy, strong, diverse, it crowds out and reduces the inflammatory pathogenic bacteria. We know this because if you wipe out the gut microbiome, you expose yourself to risk of an infection.

The gut microbiome also is training your immune system. We get the benefit from birth where the gut microbes that are basically coming into and becoming a part of our body are actually teaching your immune system: who are the good guys and who are the bad guys? When the gut microbiome is doing its job properly in that role, your immune system will know who the good guys and bad guys are as a result of that, but also the gut microbes, they are producing really important chemicals. The short chain fatty acids, these are the most anti-inflammatory chemicals that I've come across. I've been saying this for five years, it continues to be true and I have, again, 1700 references in my brand new book. So these are the most anti-inflammatory chemicals.

And part of what they do, these short chain fatty acids, is they help us to repair and restore the gut barrier. And they also allow the immune system to be precise because we don't want the immune system to be overactive, but we also don't want it to be underactive. We want it to be in the sweet spot where it's able to do its job effectively and our short chain fatty acids produced by gut microbes allow us to do that. The gut microbes are the stewards of the gut barrier. They're the ones that are working hard to help us to insert high quality cells, keep them there, and seal them together through proteins called tight junctions, which are like the cement that hold the bricks of the wall together. And when the gut barrier is strong, Jonathan, it plays an essential role in protecting the immune system because the entire job of the gut barrier is to allow the good stuff in and keep the bad stuff out. And so when you keep the bad stuff out, you never actually have to activate the immune system. The immune system will only become activated when it's being exposed to things that it's not supposed to be coming across, and that's what occurs when the gut barrier is weak, which we call increase intestinal permeability. People used language like leaky gut, and I don't think it's wrong because leaky gut is actually what's occurring when the gut barrier is weak. So the point is that we actually have three layers to our defense system. The first are the gut microbes, the second is the gut barrier, and the third is actually our immune system. And we would prefer to allow the first two to do the work for us.

Jonathan: I love this idea, which I hadn't heard before, that the first line of defense of my immune system is a healthy microbiome. I think that's really lovely. I love thinking about it. I think it's really interesting what you describe then about saying that the gut barrier itself, which is incredibly thin, is like this second line of defense. And I think you are saying that for most of us in the modern world, that gut barrier is not in as good shape as it should be.

Will: So we've seen from our own research at ZOE that if you look at the state of the gut microbiome in America, the state of the gut microbiome in the UK, and you were to compare that to, for example, the third world, you see radical differences. Our gut is not as diverse in the industrialized world. Actually in the United States we're worse off than in the UK and that's an entire different conversation. But the point is that we are dealing with mass scale epidemic dysbiosis, and when the gut microbiome is not strong, it's not able to do its job, which is to repair and restore the gut barrier, which leads to a weakened gut barrier, that then allows the immune system to become perpetually triggered by things that are sneaking across. Every doctor who is listening to this episode right now has heard the language, the terms lipopolysaccharide or bacterial endotoxin, and we hear this and we immediately think: this is a patient with an infection who's probably going to need to be in the ICU because this is basically the armor that coats bacteria like E. coli.

But it turns out that you can have a low grade amount of these E. coli or other bacteria covered in this armor lipopolysaccharide that gets to sneak across. It's not supposed to be there, but because the gut barrier is weak, it gets to sneak across. And this leads to an ongoing chronic activation of the immune system, which is another way of saying chronic low grade inflammation. And so this bacterial endotoxin is basically what the immune system has been trained since before our birth to identify. That's the target. If I see that I need to take it out. And so what we need is we need to repair and restore that gut barrier because if we do, we would actually keep that contained within the gut microbiome where it doesn't actually cause any harm, any inflammation, and our good guys are able to suppress it.

Jonathan: You've worked closely with ZOE for I think probably over five years now, and in your latest book, when I read it, I noticed you talked about a number of pieces of ZOE's research that actually sort of helped fuel your interest in how inflammation and gut health were linked. And since there can be a number of listeners who've been involved in some of that research, I thought it would be really fun for them to understand how like their participation in their science has actually almost helped to shape some of your thinking. Can you tell me a bit about that?

Will: The PREDICT studies of which there are three are what have set the stage for many of the things that we are discussing here today. How I came across ZOE was a publication in Nature Medicine in June of 2020 where in essence what happened is that ZOE showed—Professor Tim Specter and Professor Sarah Barry showed—that our triglycerides, our blood fat, our blood sugar, and our insulin levels after a meal are informed powerfully by our gut microbiome, that the way in which we respond to food is unique and individual to us and our gut microbiome is an important part of that story. For example, with blood fat after a meal, your gut microbiome is more predictive of what's going to happen than your age, than your gender, than your genetics, than even what you ate. In terms of your insulin after a meal, your gut microbiome is the second most important factor, which is fascinating because we know the ties between the gut microbiome and insulin resistance.

So now, Jonathan, where I am today is a medical doctor who is out there pounding the drum and trying to let the world know that I believe the opportunity for healing exists in our gut. This is not something that I was taught. This is not something that I came up with as an idea out of nowhere, I was led by the science and the ZOE study in June of 2020 is one of the powerful studies that helped me to inform the way that I think about these things, how essential the gut microbiome is to these different factors. The following year, Jonathan, in 2021 from these PREDICT studies, once again, ZOE scientists published a paper and they looked at inflammation that occurs after a meal. So in essence, they were zooming in: what happens in your body the hours after you eat? And what they discovered is that actually eating our food does create some inflammation in our body. This isn't necessarily a bad thing. Exercise is inflammatory too. This can be how we build resilience, how we get stronger, but at the same time, we don't want excessive amounts of that. We want it to be in the sweet spot. And what this study in 2021 showed us, Jonathan, was the way in which specifically our blood fat levels after a meal are associated with inflammation. What I'm saying is that ZOE research has shown us that there is inflammation that occurs after a meal and that it is worse if your triglycerides are spiking out of control, that it will stay elevated for six to eight hours. That your gut microbiome plays a really, really important role in explaining where that is coming from.

Jonathan: That's amazing. And it's really cool hearing you talk about that. Will, was there anything else on your journey that the science has been unlocking over the last few years that has, I guess, means that it's a story that we can talk about today that wasn't really obvious even five years ago?

Will: Some of the things that I discuss in the new book are the levers that we can pull, which are actionable opportunities to repair and restore the gut microbiome. And in doing so, strengthen and fortify the gut barrier and to create a healthy immune system. And so some of the research that we've done during the last five, six years together at ZOE has contributed to that because, for example, one of the chapters in my book is entirely about circadian rhythm, and we conducted the world's largest fasting study. I'm incredibly proud of the fact that we at ZOE, managed to get close to 40,000 people participating in a research study where they're adding time restricted eating into their daily habit, into their daily lifestyle. And those people felt significant benefits: more energy, less bloating, their mood was improved, and in a fascinating twist, their hunger was less. Each of these things fits so nicely as a piece of the puzzle into this conversation that we're having around inflammation. That explains—that is the real world manifestation of what we are learning about the power of the circadian rhythm. That if you do simple things like address the regularity of your meal times and maintain consistent eating windows, you can achieve these types of effects. Energy, mood, hunger, bloating, all improved.

Jonathan: And Will, just to make sure that I'm following that, are you saying that by eating your meals sort of in more of a pattern, so you're saying eating your food for 10 or 12 hours a day and not in the middle of the night that that actually reduces your inflammation and that's why you're getting these benefits?

Will: Well, we can't say that from the ZOE trial itself because unfortunately this was a remote study. You can't get to 40,000 people and simultaneously get detailed elements like blood work, so we don't have anti-inflammatory or inflammatory measures in this particular study. We have other work that supports the idea that mealtime regularity and time-restricted eating can be contributory factors to weight loss and ultimately reduced inflammation. So we do have other studies, Jonathan, separate from the one that we're discussing, but it fits nicely into an entire conversation that we're having around inflammation being associated with fatigue, impulsive eating and increased appetite, bloating, changes in mood, right? These are four of the elements that we've already discussed as being associated with inflammation and what we're seeing in a real world study. Again, we don't have blood work, but in a real world study, when people follow this pattern, this is the payout. And I would argue that if we were to zoom in on their body, we would discover that on a microscopic level there was an anti-inflammatory effect that's contributing to these factors.

Jonathan: So, Will, if I listen to all of this, I think what you're saying is there's an amazing number of symptoms that we just live with now in the modern western world, and they range from like my mood to weight gain to symptoms in my gut to bad skin, fatigue and bad sleep. All of these things. And they seem like they're completely different, but you are saying actually this like long term sort of low level inflammation that's just switched on across my body is sort of causing all of this stuff to go wrong. And that if you want to understand why that inflammation is turned on high, you have to go and look at like our gut microbiome and the food that we're eating because it's supposed to be providing all of this sort of anti-inflammatory support and keep us in good shape, but actually it's going wrong and it's turning on this inflammation and if we could fix it, therefore we can all feel better.

Will: So yes, and I think that the proof for the individual person who's listening to this and what they appreciate—the value that comes from research and clinical trials—they appreciate that, but ultimately they just wanna feel better. And to me, that is ultimately where the proof does exist. But you know, just to go back to the idea of like meal timings being important, there was one study, Jonathan—this was not a ZOE study—but there was one study where they took a group of people and they just had them do a simple thing: shift your food from late in the day to early in the day. And people who did this were rewarded with a drop in inflammation. And by the way, what's quite fascinating: a drop in their triglyceride levels by just eating their food earlier in the day. And those who maintained a late dominant eating pattern, most of their food late in the day, actually had their triglyceride levels going up. And once again, this ties back to this concept of like postprandial inflammation. So when we're digging into the specifics of the science, you can get lost. It is so complex. But what I'm here to say is this affects all of us. We should be paying attention to this. And the opportunity for healing is actually rather simple, which is we just need to repair and restore our gut. And if we do that, the rest takes care of itself because basically we can elevate these systems together.

Jonathan: So I love that. I think the argument you're laying out seems pretty clear now. In which case, I'd love to talk about practical advice. So listeners saying: "Okay, I buy it. I believe that this inflammation is a problem. I'd like to reduce it." And then the question is, what can they do about it?

Will: Well, the beautiful thing is that there are small, simple choices that if you do them with consistency, they can have a massive effect. And that includes the food on our plate and the choices that you make in that regard, which is what ZOE is all about. But it also includes our lifestyle, includes our daily patterns, your morning routine, your evening routine, how you eat and your meal timings during the day, which we've sort of already touched on. It also includes things that we don't talk about enough, but I actually think are quite important in the modern world, which are our connection to other people, our connection to purpose and how we're living our life. What is driving and fueling our days? What are we trying to achieve? And things from our past, things like trauma. So one of the essential takeaways for the listeners is that healing comes in many forms. And when I write a book, I can only write one book. I can't write a personalized book, but the way in which a person receives the information is personalized. Because as you flip through the pages, you're gonna have an aha moment. You're gonna have hopefully several aha moments. That moment where the light bulb goes off and you go: "That's me. That explains it. That's what I was looking for." And it's gonna be different for you than it is for other people. So from my perspective, Jonathan, we can start to dig into some of the tactical elements, some of the opportunities that people have within these realms of nutrition, circadian rhythm, connection, and emerge with some takeaways for the listeners today.

Jonathan: So let's do it. And I think maybe we could use something that you've coined in this book, which is the four nutrition workhorses. I think that would be great. I really liked that phrase, the first of which was fiber. So what's so magical about that?

Will: I mean, I kind of like the stuff. I'm not sure if anyone realizes this, but am I allowed to feel proud that kids on TikTok are making fiber a thing right now? And granted it took five to six years after my book coming out for this to occur. But am I allowed to feel like I contributed to this?

Jonathan: Of course.

Will: Because to me, fiber is the conversation that's been missing. Fiber is the most important nutritional deficiency that we see both in the UK and the US. Fiber to me is the key hinge point. If we're going to, for example, recently the US dietary guidelines were re-released. Look, there's an entire conversation that can be had around what was good, what was bad. But to me, if I were to summarize what was really not emphasized nearly as much as it should have been, it's fiber. And the reason why is because this is the gut health nutrient. This is ultimately the fuel for our gut microbes. This is what they're starving for. They need this. And when they receive it, not only do we repair and restore that first layer, the gut microbes, they grow stronger. We empower the good guys, the anti-inflammatory microbes. They thrive, they grow up. The bad ones we're actually suppressing.

Not only do we achieve that. Fiber actually stops being fiber and is converted into these short chain fatty acids: acetate, propionate, and butyrate. And we mentioned a few moments ago, these are the most anti-inflammatory nutrients that exist. And they play an essential role, particularly butyrate, in the restoration of the gut barrier. Those tight junction proteins that hold the cells together, basically the cement to our bricks, are prepared from butyrate. We need that energy source in order to achieve what we're looking for there.

Jonathan: And so Will, does that mean that if you're not eating fiber, then basically your microbes can't create those short-chain fatty acids and therefore I can't have this really healthy gut barrier that you were describing before as so critical for the health of my immune system?

Will: I sincerely believe that what we view as being sicker than ever, and the stress that's placed on the healthcare systems in our countries, is directly related—not in isolation, these are complex issues—but is directly related to the longstanding fiber deficiency that we've had in our cultures where 95% of Americans and about 90% of people in the UK are deficient in this essential nutrient that we need in order to restore these systems. The microbiome, the barrier, and the immune system are all elevated and improved. And as we sit here today, we have a fiber deficiency epidemic. And Jonathan, my favorite fiber study of all time, Professor Andrew Reynolds from New Zealand, showed us that fiber is strongly, definitively associated with protection from heart disease, from heart attacks, from death, from heart disease; protection against three different forms of cancer: breast cancer, colorectal cancer, esophageal cancer; protection from death from cancer, protection against stroke, protection against diabetes and more. And we look out and we see what's getting us. I just named four of the top 10 causes of death in America, four of the top 10 causes of death in the UK. I really believe that fiber needs to be addressed, and this to me is not just like a passive: "Hey, we could use more vitamin D" type of thing. No, no, no. This is way too important for us to be passive. We need to get this right.

Jonathan: And so if we eat more fiber, does that reduce this sort of low grade chronic inflammation that you were talking about? And therefore if I'm living with any of those 130 symptoms that you were talking about like can it reduce them?

Will: So the answer is globally yes. Zoomed out. Simple answer, yes. Fiber is what we need to start to address this issue. Not the only thing that we need, but it is a—to me, when we think about opportunities, we should be focusing on two factors. How big of a payoff will we get? Fiber, it's massive. Number two, how bad is the deficiency? Fiber, it's massive. So those are the opportunities for you to do something that could really change the outcome. Yes. To address those issues, we need fiber. Now, is fiber nuanced? Is fiber a bit complex at times for people to introduce into their diet? Yes, and there's ways that we can go about that.

Jonathan: And is fiber just one thing? So can I go and buy a packet of fiber and eat it and just solve this problem in the way that I might think about taking, as you described it a minute ago, a vitamin D tablet?

Will: Fiber is far more complicated than that. So the word fiber, you shouldn't think of it as being this one thing. You should think of it as being a broad category in the way that we think about protein. Fiber is very much like protein. Protein, you would never argue that the protein in a fish is exactly the same as the protein in a bean. So we shouldn't argue that the fiber in one type of plant is the same as the fiber in another because it's not. This is part of the argument in favor of 30 different plants or more. In essence, variety. When we focus on variety, the various forms of plants that we consume provide various forms of fiber that feed various families of microbes. The result is enriching the diversity of your microbiome and supporting as many of them as possible so they can do their job effectively.

Jonathan: Amazing. I think we can spend the rest of the podcast talking about this, but I need to get onto the second nutrition workhorse, which was polyphenols. And Will, you write this brilliant phrase in the book where the rainbow intersects with the pot of gold, which is more poetic than I'm used to from you, so I loved it. Can you explain what it means?

Will: Yes. Well, in my mind I did have this vision of a leprechaun who's friendly and smiling and rewarding us with a beautiful life. And that pot of gold, in my childhood, I remember the dreams of wanting to see the end of the rainbow and find that pot of gold. And perhaps it's possible as adults for us, because polyphenols are the parts of plant-based foods—sometimes we refer to them as antioxidants—and they're responsible for the colors that you see as you walk into your supermarket. So it's not a coincidence that you walk through the doors of your supermarket and in every single one of them, they put the colorful, fresh produce right out front. Why? Because we are naturally attracted to all those different colors.

Jonathan: And they're all polyphenols?

Will: Yes. This expression of like eat the rainbow to find your pot of gold. In essence, what I'm saying is if you focus on different colorful foods, it's another way of arguing in favor of plant diversity. If you focus on getting many different colors of your foods, you are going to fulfill all of these different polyphenols, and this is gonna lift your health. This is gonna improve your gut microbiome. This is going to help your immune system be strong.

Jonathan: And Will, how do these polyphenols reduce this inflammation that we've been talking about today?

Will: So it's a little more complex than fiber in the sense that there are, thus far, we've identified at least 8,000 polyphenols. The listeners of this show will recognize many of the names. I'm gonna list a few: quercetin, resveratrol, curcumin from turmeric. These are just a few examples of the 8,000. So now to fully understand this, we would have to conduct studies on all 8,000 and we're not even close. But what we're seeing, Jonathan, is that these polyphenols, they're big molecules, they're highly complex. And what that means is that we can't absorb them easily. So we—they may be in our nutrition, you eat plant-based food, they have polyphenols, but they actually, much like fiber, make their way down to the gut microbiome in the large intestine. And that's where they get activated because it's the microbes that have specialized enzymes that allow us to basically unlock the polyphenols and give them access to them. So 90 to 95% of polyphenols require our gut microbiome. And when this occurs, very similar to the fiber story, the microbiome is changed. It becomes healthier. It shifts in a direction that actually is allowing the microbiome to produce more short chain fatty acids. Now, to be clear, the polyphenol is not the precursor to short chain fatty acids. The polyphenol is its own thing. Resveratrol gets activated and enters your body and has anti-inflammatory, anti-aging benefits after entering your body. But what I'm saying though is that you could eat the same amount of fiber and when you sprinkle in some polyphenols, you will get even more short chain fatty acids from that fiber without changing anything else. So this is the payout.

Jonathan: And Will, are you saying that I need my microbes to sort of unlock these chemicals in these polyphenols, and if they unlock them, it's almost like taking medicine? It's like they're these complex molecules that are creating health benefits in my body, but I need the microbes to sort of take them out of their wrapper.

Will: We sit here and we celebrate these things. We celebrate quercetin as being anti-aging and resveratrol and curcumin as being anti-inflammatory, right? We celebrate these things, and what I'm saying to you, Jonathan, is that if you had no microbiome, you would not get access to hardly any of these polyphenols. Five to 10% is what you would receive. It's the microbiome that gives us the vast majority of what we get.

Jonathan: And I guess that's just another example of the way that I understand it's sort of every other animal. We are just meant to have all these microbes inside us. And so naturally they're just part of the process of breaking down the sorts of foods that we evolved to eat and evolve to have support us.

Will: To me, it's evidence of a symbiotic relationship that we have. Symbiotic means mutual benefit with our microbes, and it also to me is evidence of our connection out to the broader world, which is that we as humans, without interaction with our environment, without these microbes that come in and reside inside of us that we weren't born with—they come and they become a part of us. We receive the benefit of this. So to me, it's a beautiful story.

Jonathan: Amazing. Alright, let's get on to number three, which is healthy fats. And I think a lot of us were brought up believing that fats are just bad. So tell us about healthy fats.

Will: Yeah, so we were brought up with the belief that fats are bad. In fact, there were campaigns that were occurring to lead us to believe that that is true. And now we see that fat is not inherently bad, it's the choice. So to me, really our goal is to enhance the quality of our diet. We can enhance our carbohydrates by consuming more fiber. Fiber is a carbohydrate, and we can enhance our fats by making the proper choices. The types of fats that we want to prioritize are monounsaturated fats, which you will find in extra virgin olive oil, avocados, many nuts. And the second type of fat that we wanna prioritize are the Omega-3 polyunsaturated fats. These Omega-3 fats are what we call essential. And what that means is much like essential protein, our body is not capable of producing this type of fat. So we are required to get this in our diet. And you can find these Omega-3 polyunsaturated fats in many seeds: chia seeds, flax seeds, hemp seeds, basil seeds. You'll find them in walnuts, but you'll also find them in fish and shellfish. And once again, it's important that we get this in our diet. And if we're not gonna get it in our diet, then that's an argument in favor of getting it through a supplement.

Jonathan: And Will, do we understand how these healthy fats reduce the inflammation that you're talking about and support our immune system?

Will: We need more research. Jonathan, there's so much more. If you gave me an unlimited budget, I could do so much with it to answer the question that you just asked me. And unfortunately there's not enough money going into the understanding of how food can be medicine. But that being said, there's these specific studies that give us some insight. So here's a few. Number one, the biggest nutrition study was called PREDIMED, funded by the Spanish government. And they had 7,500 people in three specific dietary approaches, 2,500 people each. And they were either doing a low fat diet or they were doing a high-fat Mediterranean diet, including added nuts, or they did a high-fat Mediterranean diet, which included extra virgin olive oil, lots of extra virgin olive oil, four tablespoons per day. And in this study it was quite fascinating because they were looking at cardiovascular outcomes as their main outcomes. The high fat diets were consistently better.high-fat

Jonathan: So the people who took more fat in their diet, it was actually better for their heart health?

Will: It was better for their heart health. It was better for many other measures, including inflammation. They measured inflammation in the study and the people who had the best anti-inflammatory outcomes were doing the high fat diet. And it's important to understand that when we say a low fat diet, we're not talking about low fat junk food. They were recommended to consume the same amount of fruits and vegetables. And the extra virgin olive oil group did amazing, better than the nut group in the vast majority of factors, which was very surprising to me. And I've since come across new research where they had people consuming extra virgin olive oil on a daily basis for eight weeks, and it increased the diversity in their microbiome. Why is that? It may be the polyphenols. The polyphenols are what make good extra virgin olive oil bitter, spicy, but it also may be the healthy fats which are contributing to our gut microbiome. So this is the first sort of wave of research to show this. And on the flip side, Omega-3s, there's now discussion in the scientific community that Omega-3s may be prebiotic. Prebiotic is the term that we use to say something that feeds and nourishes the gut microbiome. Fiber, resistant starches, polyphenols—these are widely accepted prebiotics. And now we may need to start to talk about Omega-3 fats as being prebiotic because they impact the gut microbiome and then they have a beneficial effect on our health.

Jonathan: Amazing. Will, let's talk about the fourth and final nutrition workhorse, which is fermented food. And at ZOE, that's definitely something that we're a fan of. I think regular listeners will have heard Tim Specter talk about this a number of times, but how does that help tackle inflammation?

Will: Tim wrote an entire book on the subject. So of course anyone who's listening, particularly in the UK, you should grab a copy of this book for sure. There's some listeners out there right now who they're health conscious. They've been eating a healthy diet for many years, and this is the one of the four that they're probably not doing. The vast majority of us are not, because you have to make a conscious decision that you're going to prioritize fermented food in order to get this done. But research out of Stanford University conducted by Professor Christopher Gardner showed us that on a matter of 10 to 12 weeks, by increasing the fermented food in your diet, you can actually increase the diversity within your gut microbiome and simultaneously reduce the measures of inflammation. This is partially proof of what we've been discussing this entire time, Jonathan, but also it's exciting because this is a human study showing us that we have something that we can add to our plate and have profound healing effects, both in our gut microbiome and immune system. At the same time, there was research that we did similar to the time-restricted eating study. We activated the ZOE community to start adding fermented food to their plate, and they went from generally having very close to none to about two serves per day. And these people who were adding two serves per day, once again, they had improvements in their energy, they had improvements in their mood, they had improvements in their bloating, and they had improvements in their appetite, like their hunger was reduced. So once again, it's like you start with the Christopher Gardner study, which is more mechanistic, and then you land with this ZOE Research, which was a large group of people, and you see the impact.

Jonathan: As well as talking about food, you also talk about modern life and daily stress. How does that fit into this story and what can you do?

Will: Yeah, so there are these things, Jonathan, that if you asked me when I was in medical school 20 years ago, I would've said: "That's woo woo. What is that?" Now the pieces are starting to fill in where actually there's a very clear physiology, things that are occurring in the body that explain how stress can manifest in our gut. And this is actually the story of the brain-gut connection. Our gut and our brain are inseparable. They're communicating with each other right now as we sit here. There are many ways in which your gut can send signals to your brain. Your brain will respond to them. There are many ways in which your brain can send signals to your gut. Your gut will respond to them, and there are things that can occur.

A quick example, Jonathan. Imagine—and I want the listeners at home to create a vision in their mind of what I'm gonna say. Imagine that you are out driving your car one day and you come so close to a horrible car accident. What happens before you even processed, before you even know what just occurred? Your heart rate is pumping, your blood pressure is up, your eyes are bugging outta your head. You're hypervigilant, right? You can feel your muscles shaking. You could literally go and jump to the top of a tree. That is the activation of your sympathetic nervous system. That is your adrenaline, right? That is your react and respond to a threat, and that is the activation of your brain. And ultimately, there are manifestations that occur in the gut because when we do all these things in the context of the sympathetic nervous system, we ultimately have to sacrifice our gut in the process. And this is why when you are stressed, you get bloated, you feel a little bit queasy, or you may get cramps and they can come from mild all the way up to big, horrible waves of cramps that rip through you. Stress can do that to us. That is through the activation of the sympathetic nervous system. And if we were to zoom in on what's occurring, I promised you that the physiology is there to back it up. What's happening is the brain releases a hormone called corticotropin releasing hormone, which sets off an entire cascade throughout your body. That is your stress response, and the stress response was meant to keep you alive. If you were to come under attack by a foreign tribe or by an animal, or whatever it might be, the stress response was there to give you a quick response. That burst of energy that you need to save your life and protect yourself. But unfortunately, it negatively affects our gut, and we live in a world where we are in sympathetic overdrive with excessive stress. And so ultimately, that—which can by the way, include trauma—that trauma to me is like this is just going nonstop 24 hours a day. Ultimately, those things, we need to balance them out. We need to recalibrate them by taking our foot off of the gas and applying it to the brake. That is our parasympathetic nervous system that occurs through the vagus nerve and the ways in which we do that are the things that we think of in terms of being wellness. We think about massage, we think about acupuncture, we think about sauna. But there's other things too: connection to other people. Right? Our relationships, quiet time, meditation—these are opportunities that we have to basically get out of the sympathetic cycle and put ourselves into a place of safety and comfort, which is what our body needs to heal and restore itself.

Jonathan: And Will, you talked about how there's this like direct link to the gut and the symptoms you have in the gut from sort of being stressed and having a higher level of stress all the time. Is there evidence that this stress is also linked to this chronic long-term inflammation that you're describing has all of these health harms or is that just a sort of wild leap that you're making here?

Will: So it's an extra layer of evidence that's required in order to get there, Jonathan. And unfortunately there haven't been enough pioneers in the academic world out there examining this, the question of how the mind affects the body. But there are some. So one of the things that I discuss in my book is my relationship with one of my mentors, Professor Douglas Drossman, out of the University of North Carolina, and he's been studying this stuff since the 1980s. He was way ahead of the curve and what he's shown us is that stress or exposure to trauma is clearly associated with the manifestation of disease, including irritable bowel syndrome, including inflammatory bowel disease and others. But the problem is like, again, if you have 130 health conditions, we don't have research on the vast majority of them to examine the connection between stress levels and that.

Jonathan: But this is real. This isn't just a sort of woo woo theory, like long-term, continued stress really can affect you physically over time in a way that's really harmful.

Will: There's no doubt, there's no doubt that this is real and that this affects you long term. And again, what's occurring is the activation of that stress response that's unremitting. And when we do that, it negatively impacts the gut microbiome. It negatively impacts the gut barrier and it actively increases inflammation.

Jonathan: So, Will, as we're coming towards the end of summarizing this, I'm just wondering if there's any really common mistakes that people make that might be sort of sabotaging their immune health and their inflammation, but perhaps they're not really aware of it, right? Like we all know that if you eat a whole bunch of cake and processed food, it's probably not very good for us. But are there common mistakes that people are making that maybe aren't really obvious?

Will: I think that there are a number of opportunities for healing, and what I would say is that, first and foremost, before I get specific to your question, we cannot allow modern culture to dictate and negatively affect our health. And the problem that we have is that modern culture in both of our countries has created a normal that is not the way that our body was designed. And I'm not saying that we need to go back to living in a cave. That is not what I'm saying. But what I am saying is that we need to take control of our environment, which includes our home and our day-to-day rhythms and patterns. We need to take control of these things to restore this natural relationship between our body, the way that it works, our environment, and ultimately that trickles down to our gut and our immune system. That is the opportunity that we have. So an example of this, what I'm referring to, is that we live in these homes. They have controlled air, controlled temperature that is like continuous exactly where we want it to be 24 hours a day. We have these windows. We see some sunlight that trickles into the home through that window. But we don't step outside. We don't step outside nearly as much as we used to. Think about a hundred years ago. I don't know if my family, meaning my grandparents, I don't know if they had a car. I do know that my grandfather, he had to walk to school. That's what he did. They spent so much more time, even in my childhood in the 1980s, I played outside. I had no reason to be inside. There were no devices, there were no video games. The TV was very basic and wasn't really on that much. Right? And here we are. And the evidence would say that we spend 93% of our time indoors and we never step outside and get exposure to the sunlight, which has healing effects. And depending on the time of the day, provides different nutrients that our body is starving for. And these nutrients, they're not the same as like fiber and polyphenols, but I want you to think of them as nutrients because blue light in the morning is how our body knows that the day has started. And if you don't get outside in the morning, your body will not know when the day starts and when it ends. And we shouldn't be surprised that it's confused and outta rhythm and not really doing the things that we want it to do. But if you do that, if you step outside in the morning, get that exposure to light, or this time of year you can get a lamp that provides 10,000 lux. If you do that, then you will notice from the very beginning, increased energy, you will notice that you have better focus, that you're able to get more work done, more cognitive endurance. You can continue this for a matter of time and you're gonna notice it improves your mood. And the other thing that you're gonna notice is that it gets to the evening and you're ready to go to bed and you're gonna sleep well. Why? Beause of that simple signal of getting light in the morning that your body really needs in order to know that the day begins. So that would be my argument is that we're missing these opportunities to basically make our body work the way that it's supposed to because of the modern world.

Jonathan: It's a beautiful picture, Will. Just to conclude, if someone starts to make the changes that you describing, how fast can they lower their chronic inflammation and feel better?

Will: There are things that you can do that I'm of the belief you will start to feel the difference in the very first day. What I just described with the sunlight exposure, I really believe that on the very first day, you will notice more energy. That being said, this is a message of hope and optimism. The choices that we make with our food will start to impact our microbiome by tomorrow. Now, that doesn't mean an entire microbiome overhaul in one day. For many people that have chronic inflammatory conditions like inflammatory bowel disease, it could take months. It could take over a year. But I'm saying that what you choose today will impact your microbiome by tomorrow. And your gut barrier is the area of the greatest cellular turnover in your entire body. Every three to five days we install a brand new gut barrier. What I'm saying to the listeners is that in the next five days, the choices that you make can install a healthier, stronger, more formidable gut barrier that is going to protect your immune system and make it strong.

Jonathan: Love it Will. I'm gonna try and do a quick summary here of what is a whole new book. So. I first struck with this idea that there are 130 health conditions associated with inflammation, which is an enormous number. And also they're so different. You said fatigue to skin breakouts, to gut symptoms like bloating to headaches, to joint pain. So it's an amazing number of different things. And then the doctors are super specialized, so they look at one part of you. They don't look at the whole system because of the way that our medical system is set up. Then I think the other thing is amazing is that 70% of our immune system is in our gut, which just tells you how deep the link is between our gut and this immune system. The first line of defense of our immune system actually is a healthy microbiome. So you want to have that protect you and then the second line of defense is your gut barrier. But for most of us in the western world, it is not in good shape at all because of the foods that we eat. But amazingly, in five days, I could replace it completely with a new gut barrier. So I think that's an amazing positive idea about how rapidly you can improve things. There's a lot of factors in our modern life that are leading to this chronic inflammation. And we were talking at the end about sort of the stress and the environment that we're in and how that affects our inflammation, the fact that we never go outside. But I think the bulk of what we're talking about is these four nutrition workhorses. And just to remind us what they were: the first was fiber. And you were saying about how that protects us from heart disease and cancer and deaths—just this amazing thing—and yet we're all so deficient in it and we don't really talk about that deficiency anything like as much as we should versus other factors of food. The second is polyphenols. These are like the colors in the plants we eat. These are antioxidants and interesting. We need our microbes to unlock the benefits. So you're saying like we're not even gonna get 10% of the benefits unless we've got these microbes inside us to sort of unwrap them is what I took away. The third one is healthy fats. You said there's a whole range of healthy fats, but we're talking particularly about the magic of extra virgin olive oil and sort of the proof of what happens if you start to take quite a lot of olive oil. Amazingly all that fat doesn't give you a heart attack. It actually reduces your chance of getting a heart attack. And then finally, you talked about something that I think for many of us is still really quite new, which is fermented food and this discovery that it has these anti-inflammatory properties and our ancestors tended to eat this as part of our diet. It sort of disappeared, but we should be bringing it back because it's an important part of that story of transforming our guts and through this, transforming our inflammation, and therefore just suddenly feeling better. You said potentially in just a few days.

Will: That's a beautiful summary. Thank you, Jonathan made that very easy for me.