How The Food You Eat Affects Your Gut w/ Dr. Will Bulsiewicz & Ari Whitten

Content By: Ari Whitten & Will Bulsiewicz, MD

In this episode, I am speaking with Will Bulsiewicz, MD – a Board Certified gastroenterologist and the author of the book Fiber Fueled. We will talk about gut health, how to heal your gut, and the best foods for optimal gut health.

Table of Contents

In this Podcast, Dr. Bulsiewicz and I discuss:

  • What the latest science tells us of the role of the gut in overall health
  • Are farts good or bad?
  • How to overcome food intolerances
  • Dr. B’s top tips for gut health
  • The most common myths and misconceptions

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Ari: Hey there, everyone. This is Ari. Welcome back to the Energy Blueprint Podcast. With me now is Dr. Will Bulsiewicz, who is a Board Certified gastroenterologist and the author of the book Fiber Fueled, which I highly recommend. He’s a graduate of Georgetown University School of Medicine and was chief medical resident at Northwestern Memorial Hospital and chief gastroenterology fellow at the University of North Carolina hospitals. He’s authored more than 20 articles in the top American gastroenterology journals and has been featured by numerous media outlets.

He’s also a normal guy who loves fantasy football, improv comedy shows, and 90s’ hip hop. He lives in Charleston, South Carolina with his wife and two children. As I said, He’s the author of this book Fiber Fueled, which is excellent and he’s a gut expert. We are going to be digging in in this show all about gut health, all about the role of the gut and the microbiome in health more broadly, and we’re going to be talking a lot about fiber. With that said, welcome to the show. Such a pleasure to have you, Will.

Dr. Bulsiewicz: Ari, It’s my pleasure, my man. I am very happy to be here and to take a deep dive into fiber, into gut health, and to all these things and really help to separate the myth from reality and help people out.

The latest science on the role of the gut in human health

Ari: Beautiful. With that said, actually, that’s a nice segue into– Well, actually, I was going to maybe jump straight into myths, but I’m going to leave that for a second. Number one is talk to me about big picture of the latest science on the role of the gut in human health. We obviously know the gut’s important in human health. What are the latest findings as far as how it’s important and how it’s working? There’s the gut-brain axis and the gut-lung axis, the gut-immune axis, there’s the gut-mitochondria axis. There’s all these different aspects of how the gut relates to other systems of our body. What’s your take on the latest and greatest findings that have come out in the last few years?

Dr. Bulsiewicz: I think really what we’re doing is we are galvanizing the position of the gut as the central player in human health. It’s quite fascinating to imagine that the engine that drives human health isn’t even human. That we realize so much and have given so much responsibility to our gut microbes, that without them our physiology fails. With them, particularly when they’re with us in abundance and in diversity, we thrive and we are the best version of our human being self that we can possibly be.

When you’re asking the question, “Well, what’s the latest, greatest hottest thing in all of gut health?” What I would say to you is that we are just going down this path of unpacking so much information. With every single month that passes, you see new mind-blowing science fiction like studies that are changing the way that we think about medicine, changing the way we think about our body, and making it clear that this is not a fad. This is not a fad, that this is not fake. This is not just something that’s going to go away in the next three years. This is the future. I honestly believe that this is the future.

Take the gut-lung axis, for example. We did not really even consider that the lungs are connected to the gut until fairly recently. Now we have these studies showing the connections between the gut and the development of asthma. Let me give you an example. There’s a study that I cite in the book. This is right off the bat within the first 10 pages. You come to this study, where they actually analyzed poop from three-month-old children.

They’re taking the poop from a three-month-old, and they’re analyzing it and they’re able to predict who is going to develop asthma years later, not through blood testing, not through genetic testing, simply by looking at their poop. People are like, “Okay, that’s interesting but are the bacteria in the poop, are they actually the thing that’s going to cause the asthma?” That’s the million-dollar question.

To answer that question, they took this poop, and they transferred it into a germ-free mouse to see what would happen when you give the microbiome from this poop to a mouse. What they discovered is that these mice all developed asthma. This is the kind of stuff that we’re talking about. We’re in the era now, Ari, of COVID-19. People are wondering how can I optimize my lungs? How can I protect myself? How can I optimize my immune system? I’m seeing studies that are showing that a high fiber diet can potentially– Now, let me by the way, just to be completely clear that this is not a study of COVID-19. We don’t have those studies yet.

No matter what we talk about when it’s COVID-19 we’re always extrapolating at this time because we don’t have the studies yet. In the setting of respiratory viruses, I’m looking at studies that are showing that a high fiber diet protects against respiratory viruses. The reason why is because of the fiber interacting with our gut microbiome, which activates the gut-immune access and the gut-lung access at the same time. It’s crazy.

Ari: Fascinating stuff. If you were going to present a paradigm of all of the different mechanisms of how the microbiome interacts with our physiology in all the different systems of our body. The big picture of what the gut is doing and how it interacts with all these other different systems of the body. What are the mechanisms of how gut health impacts our health? Obviously, you just mentioned one there with the gut-immune, gut-lung axis, but what are some of the others?

Dr. Bulsiewicz: All right. There is a central part to the gut that is the key to all of the mechanisms. As you move further downstream, you will see there are different ways that the gut can affect the body but it all starts with one core simple idea. The gut is effectively a chemical factory, Ari. It has the ability to produce unique chemicals that we as humans are not capable of producing. When it does that, those chemicals are the parts that actually act as signaling molecules in multiple different ways throughout the body. Let me be more explicit than this even. Let’s talk about fiber for a moment. I know we’re going to take a deeper dive and we can talk more and more about fiber in whatever way you want. Let’s talk about the path of fiber. Most people don’t realize that fiber doesn’t just go into the mouth and come out the other end. Soluble fiber, and also resistant starch passes through the small intestine untouched, where it arrives in the colon, the large intestine, and that’s where the microbiome lives.

The microbes feast on fiber, soluble fiber, and resistant starch is food for the gut microbiome. They feast, they thrive, they multiply, and then here’s the key, they take that fiber and they transform it, it stops being fiber. It turns into something called short-chain fatty acids, butyrate, acetate, and propionate. Many people have heard of those, those are short-chain fatty acids. You get them when your gut microbes consume fiber. You can’t get them without the gut microbes, you can’t get them without the fiber, you need both.

When you pair those two together, the chemistry occurs, the magic ensues, out comes the short-chain fatty acids, and then what happens? This is the key, you have just created the signaling molecule that transforms human health. Short-chain fatty acids in the gut itself heal the lining of the gut, reverse dysbiosis or leaky gut, whatever we want to call it, it reverses that. They prevent colon cancer, they optimize diabetes, insulin resistance improves with short-chain fatty acids. They actually lower our cholesterol, they affect our weight, they affect our satiety, our ability to know when to stop eating. They actually cross the blood-brain barrier.

When I said a moment ago that the gut is able to activate both the gut-lung and the gut-immune access at the same time, let me expand on what I was talking about. The way that a high fiber diet can fight respiratory viruses is that the gut microbes take fiber, release short-chain fatty acids. The short-chain fatty acids get into the bloodstream and circulate to the lung. In the lung, help to recruit the right cells from the immune system called CD8 cells.

These are the cells that fight the virus. They’re getting the right fighters, the right soldiers on the battlefield. The crazy part is it’s almost too good to be true because it doesn’t just activate the immune system. What it does is it preferentially activates the right guy, the CD8 cell, meanwhile, the rest of the immune system rather than allowing it to go nuclear, it actually tells it to cool off.

The key, Ari, is this, these short-chain fatty acids, I think they’re biggest secret in all of nutrition. They’re an entire chapter in my book, I could have written an entire book literally about just them. I could take that one chapter and turn it into 10 chapters. The key is that those are chemicals produced by our gut microbes. They are one example of what is called a postbiotic.

Many people have heard of probiotics. Some people have heard of prebiotics, which basically is fiber. These are the postbiotics and what really matters are the postbiotics. It’s not just short term fatty acids, when you talk about resveratrol and other polyphenols, everyone hears, “Red wine is good for you because it has resveratrol.” People don’t realize that these polyphenols, 99% of them do nothing until they come into contact with our gut microbes.

How the modern diet affect gut health

Ari: Actually, that’s something that I have on my list here too to ask you and that’s a topic that in my experience very, very, very few people even gut experts know a whole lot about is the interaction of different phytochemicals with gut microbes and how they get metabolized into other chemicals which then have their bioactive effects. I’m very curious to dig more into that with you.

Before we get to that, let me ask you another kind of big picture question, which is, why is there so much focus on gut health right now? Why do we even need to worry so much specifically about the health of our gut? Is it that there is something just wrong in our modern lifestyle and our modern diet and our modern environment that is wrecking our gut health and that’s feeding into all of these other health problems? What what’s the fundamental reason why we should focus on the gut?

Dr. Bulsiewicz: I think the gut health matters for every single person listening to this podcast right now, whether you are healthy or not. The reason why is the more that we learn, the more that we realize how central this is to most human physiology. If you want to be healthy, you need to protect this. You don’t want to wake up one day with a disease and realize that it could have been preventable if we had just taken care of our gut health. The reason that I think it’s so trendy or hot right now is it’s almost like a perfect storm.

When people use that expression, the perfect storm, what they’re referring to is multiple conditions being in the right spot at the right time, all at once, to lead to some sort of effect. What we have is we have this tidal wave of clinical research that started in 2006. There was a laboratory discovery that allowed us for the first time to start to study these microbes,. Prior to that, we really didn’t have a way to study them. We now see thousands of papers coming out per year on this topic of the gut microbes, on this topic of the gut microbiome.

At the same time, we as a society are getting sicker. We have more people suffering with autoimmune issues, more people suffering with metabolic problems, obesity through the roof, Type 2 diabetes ratcheting up very quickly. Food sensitivities, way more than it was 10 years ago, way more than it was 15 years ago. People are starting to ask questions, why is this happening? At the same time that they ask the question, why is this happening, studies are coming out that are saying the reason this is happening is damage to your gut.

Ari: What are these factors in the modern environment and modern lifestyle or modern diet that are leading to such widespread gut problems?

Dr. Bulsiewicz: I feel like it’s almost like recall bias. Recall bias suggests that you remember short term something and that’s what forms your ideas and thoughts. It’s almost like we as a culture have recall bias because we’re forgetting what it was like for our great grandparents. Go back 100 years, what do you think life was like in the United States when television didn’t exist? When most people didn’t have a car, or if they did, they were certainly weren’t cruising around in their car all the time. They would go to the restaurant maybe once or twice a month.

There was virtually no processed food. They knew the farmer. Everything was locally sourced. Everything was seasonal. These herbicides and pesticides didn’t even exist and antibiotics– Let me first start with the caveat that it’s probably the greatest breakthrough in modern healthcare, added more years to our life expectancy than anything was the discovery of penicillin. The problem is anything that’s that good, you’re going to over-utilize it and the next thing you know, you exit World War II, and life is rapidly changing for us. We have these medications we never used before. We have widespread use of antibiotics. 100 years ago, the plate wasn’t dominated by meat.

People were predominantly plant-based back then. Now here we have a scenario where Americans eat more meat than anywhere in the world. 220 pounds a year, and some people will tell you that you should triple down on that and double down on that. 80% of our antibiotics go into animal agriculture. Our food supply, here’s what’s happening with our food supply, 60% of our diet is processed food. There are 10,000 food additives approved by the Food and Drug Administration that virtually all of them did not exist 100 years ago. Very, very few of them have had human testing.

Meanwhile, the actual, real food that you would grow in the soil, we have forced the farmers to abandon any idea of biodiversity because the economic pressures have forced them into growing whatever crop will produce the highest yield at any cost. I feel like there’s all of these trends of diet and that’s just, honestly part of the story what about our lifestyle? We’re more sedentary. We watch more TV, video games didn’t exist. We have checked out our brain. How addicted are we to our phone?

Then the blue light sitting up late at night, nine o’clock, 10 o’clock at night, and you’re exposing your eye to bright light from your computer or from your phone or your tablet or your television. It affects your body’s natural hormones like melatonin, and you don’t realize it, but then you have insomnia and you can’t get a good night’s rest. Then you can’t get a good night’s rest, which affects your microbiome. All of these things start feeding into it. What’s interesting, Ari, is that our gut microbiome is actually really, basically an imprint of our diet and lifestyle.

The choices that you make, the food that you eat, your sleep, your exercise, how you socialize, all these different choices, ultimately get reflected in your gut microbiome. You either reap the benefit or suffer the consequence in the long-term.

The most common myths and misconception on gut health

Ari: Well said. What are some of the biggest misconceptions out there on gut health? Are there any myths or is there any misinformation you feel is out there that’s widely prevalent among people talking about gut health. That is just not true from your perspective.

Dr. Bulsiewicz: Let me start with ones that I consider to be smaller and work my way towards the ones that really actually disturbed me the most. There’s this idea that bone broth is the solution to gut health. Do how many studies exist showing that bone broth is beneficial for gut health? Zero.

Ari: Bone broth specifically, probably zero.

Dr. Bulsiewicz: There’s zero. There’s not even one. There’s not even a bad one. Give me three people who drink bone broth and said that it healed their gut. At least give me that.

Ari: It’s more extrapolation from glycine and collagen and the potential beneficial properties of those two compounds.

Dr. Bulsiewicz: Even with collagen, the data are so weak. This is turning into a billion-dollar industry, the collagen supplements. I can’t find a study that clearly shows me that a human being consuming collagen supplements has any health benefit other than there are some industry-funded studies for skin. Even those are quite debatable, whether or not you really want to buy in being that a small study with just a few people and its industry-funded.

My concern is this; we have so much that we know that works when it comes to gut health. Why would we emphasize things that we don’t know whether they work or don’t work? If you’re a billion-dollar industry, I expect more of you. If you’re a billion-dollar industry and you are selling something and you don’t have a study to back it up, because if you are a billion-dollar industry, you are making a lot of money. If your product is good, take some of that money and show me that it actually works. The problem for me as a doctor is that they’re not going to do that. Why? Because that would threaten their industry. It’s not about integrity.

It’s not about integrity, it’s about selling the product and making profit. That’s driven by marketing because they got something that’s rolling right now. People are buying it. Why would you stop? Those are minor ones. All right. I wouldn’t sit here and say, I think that people are actually hurting themselves with bone broth. Whether or not people are hurting themselves with collagen is debatable. I don’t have evidence to say they’re hurting themselves.

The biggest concern that I have, Ari, is that I see these books that come out under the guise of gut health and oftentimes written by someone who they’re not– like what’s a cardiothoracic surgeon doing calling himself a gut health expert. What is the psychiatrist doing calling himself a gut health expert? It’s hard for me to understand that because I’m a gastroenterologist and I spent years of my life and this is what I do full time.

I actually am board certified as in internal medicine, but I wouldn’t go and call myself a neurologist. I want to go and call myself a brain expert. I wouldn’t call myself a heart expert. There’s cardiologists for that. There’s neurologist for that. You know what I mean? We have these people–

Ari: What’s interesting though, is you’re not a typical gastroenterologist. What I mean by that is how many of your gastroenterology colleagues, specialists in gastroenterology have spent a lot of time educating themselves on nutrition and how nutrition and lifestyle factors impact on microbiome health. I would imagine that most of them are more entrenched in an allopathic mode of if symptoms indicate symptoms and tests indicate this disease, prescribe this drug, not do deep dives on nutrition lifestyle with people.

Dr. Bulsiewicz: No, it’s definitely a fair point. I feel like there’s a younger generation of doctors who are emerging that are saying, “Look, I didn’t get into medicine to pretend that pills and procedures are the long-term solution for people.” There’s a younger generation that’s coming out and saying, “We need to be getting to the root cause of people’s issues and we need to change how we’re taking care of people.”

Ari: I hope that’s true.

Dr. Bulsiewicz: What you can see in the American College of Lifestyle Medicine, which has been like exponentially growing and it’s predominantly younger doctors and they are excited and interested in doing this, even though the system is not really supporting us right now. Ari, the biggest thing that I worry about with regard to gut health is the pervasive idea over the last 20 years, that the solution is restriction. That every diet that comes out, it’s progressively more restriction. That first it was, “Oh, well we should be fearful of phytates.” Then it was gluten. Then it was whole grains and lectins. You go down the line and you give people an unhealthy relationship with their food.

You put people in a situation and they deserve better than this. You put people in a situation where food that nourishes their body, they start second-guessing it, and it provokes anxiety. That anxiety actually manifests with further symptoms. You make their symptoms worse. You make their food sensitivity worse. In some cases, and I’ve seen many cases of this, people end up going down a path that leads to an eating disorder, like full-blown anorexia, bulimia. The larger problem is not only are we giving people an unhealthy relationship with our food, but more importantly, when you look at the science, the clear-cut, number one, predictor of a healthy gut microbiome is the diversity of plants in our diet.

The broader and more diverse our diet is when it comes to plants, when it comes to fiber, the healthier our microbiome becomes. When people ask you to eliminate categories, the problem is when you take a black bean, for example, you eat a black bean. There are certain types of bacteria that thrive, multiply and release short-chain, fatty acids, because you just ate that black bean. Unfortunately, the counterpoint is also true.

If you eliminate that black bean, if you eliminate beans as a category, those microbes, they recede, they starve, they grow weak and at some point they just die. The solution that we’ve been fed of restriction to accomplish gut health, I see it in my clinic every day. It doesn’t work. These people end up just as bad, if not worse, and their gut gets weaker, but their gets more and more narrow to the point where eventually all they’re eating is like literally chicken and potatoes and that’s it. That’s a terrifying place for these people. How do I get out of this problem? I don’t even know what to do.

Ari: It’s a case right now that there’s so much conflicting information as you were just alluding to there. There’s so much conflicting information on all these different diet books that have been put out over the last several years that have demonized so many different plant foods for so many different reasons. “Oh, they’re carbs, carbs make you secrete insulin. Insulin makes you fat.” Of course, get rid of the processed carbs, but also starch too makes you secrete lots of insulin and grains are also bad for you for various reasons. There’s gluten. Then there’s other compounds in grains that are bad for you.

There’s fruit, which is nothing but just bags of sugar and it has fructose and fructose has even worse negative metabolic effects and it gives you a fatty liver and all this kind of stuff and then there’s lectins, and then there’s phytates as you said. There’s all these different layers of reasons that have come out that have– Essentially, the bottom line is they’ve given us some rationale for demonizing almost every plant food imaginable and even some perspectives now, the Dr. Gundry’s work with the demonizing of lectins and the plant paradox.

It’s like all these different foods, tomatoes and beans and all these things that are rich and lectins, even though you think they’re healthy, they’re actually the things that are killing you. Then now the extreme is the carnivore diet, which is like the complete exclusion of plant foods. People who are listening to this, many people are confused by all this conflicting information. Why should they trust– Just to be clear, I’m aligned with your perspective. I believe the science is aligned with your perspective on this. Why should people trust your view over Dr. Gundry’s or the carnivore diet people or the keto people, or whoever else?

Dr. Bulsiewicz: Ari, I completely understand, and literally I hear from these people every day and I feel for them because they’re completely confused. They’re getting jerked all over the place and it’s the layperson. They’re not a medical doctor. When a medical doctor says, “I have the science on my side,” and they start citing studies, it’s hard for them to know whether or not that’s high-quality research, not high-quality research. That’s like me if I talk to finance people or me when I’m talking to attorneys. There’s a language that they can use and I’m just like, “Okay, whoa, I have no clue what you’re talking about. I’m an educated person. I still have no clue what you’re talking about.”

That is part of the problem. It’s that a medical doctor can come forward and write a book and there is no peer review. There’s no peer review in writing a book. That includes me, I was not subjected to peer review. When I wrote my papers that were published in the GI journals, I had to go through peer review people challenged me and I had to prove my points. What I actually did, Ari, it’s funny that you’re asking me about this because I literally finished writing this morning.

I sympathize with these people and I’m over it in the sense that I feel like people deserve better. I wrote a research guide, call it research 101 if you want to. My book has 600 references and I couldn’t put the 600 references into the book because it would add like literally 60 pages to the back of the book. I’m putting them on my website completely for free. I decided, you know what, I’m going to give people like the basic fundamental education that they need to help to guide them when these situations come up where you have two doctors who are both saying, “I have the science on my side, how do you figure out what is the true and where is it just noise?”

I think the solution is really this, number one you need to understand the fundamentals of research, which my research guide will walk you through. The most basic thing is this, there is a hierarchy to research. There are higher quality studies and there are low-quality studies. At the top of the hierarchy, and this is completely agreed upon by scientists. These are the rules of engagement.

Ari: Just for reference, if somebody is interested, you can do a Google image search for the hierarchy of evidence and you can actually see an image of what he’s describing here.

Dr. Bulsiewicz: Yes, you can see the image and the image is also in this downloadable research guide that I’m putting on my website for free,, by the way, for people who are wondering. At the top of the hierarchy are systematic reviews and meta-analysis. This is a study where they ask question first and then they go through all of the literature and they comb through in a systematic way, identify the pertinent studies, bring forward the information from those studies and if they do a meta-analysis, they compile the data and they analyze it for you. Many times they’ll review several 10,000 studies and they’ll bring forward 50 or 60 and they’ll give you all the information.

Basically, they’re summarizing the entire body of research. That’s why it’s at the top and below that are randomized controlled trials where you have two groups, one that gets the actual treatment and one that gets something else like a placebo and you do those two things and you see what happens at the end. Then third below that are cohort studies where you have a large population of people, many times, thousands if not hundreds of thousands of people that you follow and you track them and you have specific things that you’re looking at. Here’s why these are at the top.

The reason why these are the top is that you are seeing statistical power. You are seeing trends among a large group of people and because these are human studies at the end of the day we care what happens when real people do real things. That’s what we care about. At the bottom of the hierarchy, the very, very bottom, are test-tube studies. You should never take a test tube study without human validation. A test-tube study basically means– Let’s take gluten for example, because there’s a lot of studies like this. In a test tube or a beaker or something like that, you put some random concentration of gluten in there with some human cells and you shake it up and then you see what happens. Now is that like a real representation of what happens when I eat a piece of bread?

Ari: Probably not, no.

Dr. Bulsiewicz: Probably not, that’s the law. It’s that these test-tube studies or even animal studies, they can give us insights into mechanisms that can help to form our understanding, but they should always, 100% of the time be validated with human research. The lowest human research that exists is the anecdote. It’s basically saying, “Hey look, my uncle drank a 12 pack every day and he smoked two packs every day and he lived until he was 95 and because of that, I think that I should drink a 12 pack every day and smoke two packs a day.”

Well, that’s one person and that’s not likely to happen for most people who live that way. I think we all can agree on that. I guess the point from my perspective is there’s this hierarchy and when you see people who are exclusively picking from the lowest parts of that, if they’re exclusively talking about test-tube studies, they’re exclusively talking about anecdotes. They are not using high-quality research. I want to know what actually happens when real people eat real food.

Take beans and take whole grains, for example. In my book I walk you through these particularly “controversial foods.” Lectins, are they bad for the gut? Actually, when you see what happens when real people eat beans, they’re not. Gluten, does it destroy the gut? If you have celiac disease, which is a genetic condition, yes, it does if you have celiac disease but that’s not what most people have. That’s less than 1% of people.

Ari: Another gut expert I interviewed recently suggest that even people who are not celiac will react to gluten with– even if they feel no symptoms, they’ll have at least a transient increase in gut permeability. Do you think that’s accurate or not accurate or has little, if any, clinical relevance to actually health outcomes?

Dr. Bulsiewicz: This is a perfect example because you’re posing a scientific question to me and the people who are listening at home are going to hear that there’s two different studies on this. Let me unpack this a little bit. The people who say that gluten causes a transient increase in-gut permeability are basing that on these preclinical studies. Those are not human studies where real people are eating a piece of bread. Those are studies where they look at a tube or they look at an animal model and they see that. There’s no disputing that, they see that in these studies, but you need to validate it.

When you study humans, real humans, eating gluten-containing foods who do not have celiac disease, you do not see an increase in gut permeability. It’s actually very well described in, I believe it’s chapter five of my book, that when you look at the gut microbiome, there is not inflammation. There’s less inflammation because the foods that contain gluten– Let me say, I feel compelled to say this.

I’m not telling people that gluten should be like 50% of your diet or that you should reach for more white bread. What I’m saying is that the idea that we should live in some absolute world where we go completely gluten-free, and if there’s no redeeming value to any wheat product at all is dangerous. We’re throwing the baby out with the bathwater because people who go gluten-free, we have studies that say they’re at increased risk for heart disease. That’s the number one killer in the United States. Does gluten, does wheat destroy your gut? When they study and they look at the microbiome, they look at inflammation, they look at intestinal permeability, they don’t see that in humans. I opt for the higher quality evidence which is a real human study when they’re eating real food as opposed to the preclinical stuff that gives us ideas, but they always should be validated in a real study.

Ari: I love that you answered with the hierarchy of evidence as the center of how you should educate people on what to believe, how to decipher what’s good information and not so good information, and assess the strength of the evidence they’re being presented with. Just to complete that idea, are there a large amount of randomized controlled studies and systematic reviews on the carnivore diet comparing it to the Mediterranean diet where these randomized controlled studies have shown superior outcomes for the carnivore diet?

The same question for a low lectin diet versus a Mediterranean diet or a paleo diet or a vegan diet or something like that. Do those studies even exist that would allow one to make a claim that the carnivore diet or the keto diet or whatever diet is superior or low lectin diet is the best one for disease prevention and longevity? Do those studies exist?

Dr. Bulsiewicz: The important point here is to separate theses, like hypothesis which is an idea that warrants testing versus actual clinical findings that you can take to the bank. We have clinical studies that show the value of the Mediterranean diet. We do not have any long-term studies at all with the carnivore diet, at all. We have little to no data long term with the ketogenic diet. The vast majority of studies look at metabolic parameters in the short term and ignore the potential threat over the long term. A ketogenic diet, number one killer in the United States is heart disease.

Are you telling me that there’s less risk of heart disease in the ketogenic diet or are you actually putting yourself in harm’s way if you were to engage in this diet over the course of decades? A low lectin diet we have literally no data. We have literally no data. We have almost no data on the carnivore diet, almost none at all.

Ari: This point is worth emphasizing and just drawing people’s attention to it. There are people writing books with a perspective, for example, such as yours the role of the fiber in gut health and there’s literally thousands of studies and all the different layers of the hierarchy of evidence from randomized controlled studies to epidemiological studies on populations that consume more or less diverse plant foods more or less fiber for an entire lifetime, long-term health outcomes, real-world disease outcomes. There are no such studies for low lectin diets or carnivore diets. Is that accurate?

Dr. Bulsiewicz: Yes, that’s accurate. Really those diets are based on idea. They come into the public conscious because people can bypass the need for peer review by publishing books or by starting social media accounts or having a blog. You can create whatever you want on the internet. That’s the problem is that you have this information that’s available that just muddies the water and confuses you because it’s not good information and there’s no one checking it to stop it because anyone can say whatever they want on the internet.

Let me just say another thing that I put into this research guide is that I felt compelled to share ideas of how you can identify a person who has a valuable perspective versus someone who just wants to sell you something. There’s a lot of people that you read their book and the entire point is come buy my supplement. You should be alarmed by that. There’s a lot of people who always no matter what you throw their way, no matter what study you show them, will always find some way to tear that study down if it doesn’t fit their agenda. They always come to the same conclusion no matter what. They’re not using science. They’re agenda-driven.

Ari: Yes, there’s, unfortunately, way too many people and I’ve experienced a whole lot of them. It’s extremely common to find people who will ignore or as you said, try to attack and debunk any study which conflicts with their views and then they’ll go selectively cite only the research that supports their views and no matter how much evidence they encounter that contradicts their views, they remain preaching the same dogma instead of adjusting and correcting stances where they’re wrong and aligning themselves with the best evidence.

Dr. Bulsiewicz: The problem is that there is no separation between the economics of what these people are doing and the messaging or the integrity. There’s no separation between those things. If a person makes their living off of promoting an idea– For example, if someone makes their living often with supplements, guess what they’re going to do? They’re going to drive you to buy the supplements and anyone who challenges the value of those supplements, they’re going to want to protect their honeypot.

This same is true, “Hey, go to this service that will deliver meat to your house every two weeks. Go to this thing. Use my code and I make tens of thousands of dollars off the people doing that.” Those things are problematic. Those things are serious issues. Because at the end of the day, if that’s how they make their living, they’re going to want to protect that. Me, I’m a gastroenterologist. That’s what I do for a living. I’m a GI doctor. I go to my clinic. Writing this book is not going to put my kids through college. I’m going to tell you that right now.

If I was trying to sell as many books as possible, I sure as hell wouldn’t write a book about fiber. The problem is 97% of Americans are getting the minimal daily amount of fiber. I see a huge problem. I deal with it every single day in my clinic. I’m grappling with all these medical issues that come through my door because people are not having enough fiber in their diet. I see study after study after study showing us that there’re these health benefits yet it’s being ignored and that’s why I had to get the word out.

The key role of fiber in gut health

Ari: Going back to the beginning, gut health is massively important with our overall health disease prevention longevity. Fiber is would you say the central key to gut health?

Dr. Bulsiewicz: Completely. Just real quick, we have all levels of evidence, all levels of evidence pointing in this direction. Let me tell you about one that’s interesting that I have to share. This is published by Justin Sonnenberg who’s one of the top microbiome expert researchers in the entire planet. This is the guy at the podium who’s basically giving the talks at the meetings. He actually is a supporter of my book. One of his studies was looking at generational differences in the microbiome of mice. Now, here’s the key.

I just said a minute ago, microbiome studies or mouse studies are not worth much, but they can provide insights when you can’t do things in humans. You can’t do generational studies in humans. It takes us 30 years to procreate a new generation. With mice, you can do three-four generations very easily. What he showed is that when you put mice on a low fiber diet, they start losing diversity within their gut that compounds over generations. If grandma had a thousand species, but by the time she has mom, she only has 700 species because she’s on a low fiber diet.

Mom starts with 700 but then mom drops onto 400 because she’s on a low fiber diet so then by the time I’m born, I start off with 400, I’m down 60% compared to grandma. What was fascinating is that through these generations, if you reintroduce fiber early enough, you can get it back, but if you continue down the low fiber path, there was a point where it became irreversible. That’s just another study that proved the strength of fiber with the gut microbiome.

Ari: Fiber is central key to gut health. Without mincing words, what is your take on the carnivore diet? Because I have to imagine if fiber is the central key to gut health and no fiber all-meat diet has to be pretty horrific in your mind.

Dr. Bulsiewicz: The biggest short-term consequence of following that diet is the damage that you’re doing to your gut microbiome. With every week that passes, you’re going to make it more and more difficult for yourself to come out of that diet because of what you’re doing to your gut. To reintroduce food later on, you will find that you have even more food sensitivity than you’ve ever had. Just to be clear, that is not the food has changed. That is the consequence of the changes to your microbiome because you have engaged in this diet. That is the biggest short term consequence. Big picture, as a medical doctor the idea of doing a 100% new diet, we have no data but if I were a betting man people consuming that diet, I would be shocked if they could live to 60 without having a heart attack. I would be shocked. Colon cancer, I can’t imagine what the rates would be. It’d be through the roof. Why would you engage in a diet that can’t help you live longer and healthier? Why would you do that? For what? For short term metabolic benefits? It doesn’t make sense to me.

Ari: Do you think there are short term metabolic benefits?

Dr. Bulsiewicz: If you were to unpack this diet in terms of what happens in the short term, let’s talk for a moment about what happens if you have Type 2 diabetes. If you take away 100% of carbs then your blood sugar is not going to spike because you’ve taken away 100% of carbs. So you can’t show that your insulin resistance is actually getting worse. We have to separate out the blood sugar improving from the insulin resistance, which is the actual disease state. That person is going to have much worse insulin resistance on a diet because of the mechanism by which insulin resistance takes place.

You’re basically creating more insulin resistance, but here’s the thing, because you don’t eat carbs you don’t see it. The minute you reintroduce any carbs no matter what they are, it could be whole plant food. The minute you reintroduce them your diabetes can be off the charts and worse than it’s ever been. When people say, my hemoglobin A1c went down, they say I fixed my diabetes. You didn’t fix your diabetes.

Diabetes is the presence of insulin resistance. If you create a situation where your hemoglobin A1c goes down because you’re not eating any carbs at all it’s an artificial victory. That’s the point. It’s an artificial victory because your diabetes is still there and it’s worse than ever. You just aren’t eating any carbs so you’re not exposing it.

Ari: There are species in the gut of bacteria that change very rapidly. As you pointed out earlier they change very rapidly within days, maybe even arguably hours in terms of their population densities in response to our nutrition and lifestyle habits, especially our nutrition habits, what foods we are or are not eating. If you put somebody on an all fast food diet and then switch them to a whole foods diet, you’re going to see massive changes in microbiome diversity and what bacteria are there.

Is there a risk of with something like a carnivore diet a certain species actually dying out completely? Like certain species of bacteria that feed on different types of fiber and those types of fiber are no longer present. They’ve now, not only dwindled the numbers but actually completely died out such that even if you reintroduce fiber they wouldn’t regrow. Is that a thing or not so much?

Dr. Bulsiewicz: We don’t have the long term data to clearly answer this question in humans. What we have is the study that I referenced earlier, where there’s mouse data with Dr. Sonnenberg that show that if you put a mouse on a low fiber diet, which obviously the carnivore diet is a zero fiber diet. If you put a mouse on the low fiber diet, then you see the dwindling of the microbiome. There’s lots of diversity, it progresses over time, and at some point it reaches a critical point where it’s irreversible.

We do know that if you look at native tribal people that eat a high fiber diet, for example, go to Tanzania, and there’s this fascinating tribe called the Hadza. They live a pre-agrarian lifestyle, meaning that they’re living like paleolithic times. They don’t have any like fields that they farm, they’re hunters and gatherers. These people are eating more than a 100 grams of fiber per day. You compare their microbiome to our microbiome in the US and they have 40% more microbes than we do.

Ari: In terms of number of species?

Dr. Bulsiewicz: In terms of number of species, in terms of alpha diversity. When you ask what happens with the carnivore diet I can’t give you long term data. We know that it’s a zero fiber diet. I have what I think would happen, which is that its the way that you described it. There would be a loss of biodiversity within the gut, and depending on how long you engage in this diet at some point, it’s likely that you would lose that diversity and not be able to get it back.

In regard to the initial part of what happens in the very beginning, we actually do have data for that. We actually do have data. There was a study published in Nature in 2014. By the way, this is one of the studies that completely changed my perspective published by Peter Turnbaugh. 2014, they did five days of a 100% whole food plant-based diet versus five days of a 100% meat, dairy, and eggs diet and they’d check their microbiome every day.

Here’s what they found. Number one, within 24 hours, massive changes in the microbiome regardless of whatever diet you did. If you change your diet you will change your microbiome. I honestly think that change is in your [unintelligible]. The plant-based diet led to, no surprise, enrichment of the type of bacteria that thrive on fiber. These are universally accepted as anti-inflammatory microbes. The plant-based diet was associated with higher levels of short-chain fatty acids. No surprise. If you’re not using fiber, how could you have enough short-chain fatty acids?

The completely animal-based diet when they watched what happened over five days, I personally when I interpreted, and I would encourage anyone who’s listening to this who’s interested, please go and check out this study and read it. What I see disturbs me. That five days of meat, dairy, and eggs leads to the emergence of multiple strains of bacteria that are universally accepted as being inflammatory. I mean they are universally associated with the development of disease. Just to give you an example, there’s this one called [unintelligible] has been associated with inflammatory bowel disease Crohn’s disease and ulcerative colitis in numerous studies.

The bacteria that thrive with this type of diet are what we call bio tolerant. The reason why is because the high fat from the animal products leads to the liver producing more bile. Bile is how your body absorbs the fat, but there’s a dark side to bio. Bio is our digestive juice but you don’t want an excessive amount of it because what happens is when you have too much bile these microbes that consume bile, they thrive in an environment with bile. They become very strong and they produce what are called secondary bile salts. Secondary bile salts have been clearly associated with colon cancer.

In this study with five days on a plant-based diet, you already see the foundation for inflammatory bowel disease emerging. You already see the foundation for the development of colon cancer emerging. Then the third thing is that they actually saw that there was antibiotic resistance. It’s like, “Wait, how do you get antibiotic resistance in the gut by eating meat?” The answer is that they think. This is their theory, and by the way there have been other studies that can verify these findings.

They think that the consumption of meat contains antibiotic residues because the animals and livestock are being treated with antibiotics. Then it comes down in your gut and it basically breeds antibiotic resistance within your gut. Well, that’s bad. That’s a bad formula for long term health. From my perspective the changes that you’ve seen literally five days are dramatic. They’re radically different. To me, they speak to a choice in terms of what you want to do with your diet. You can choose one side, you can choose the other. You can blend the two together, but to me I see advantages to the one side of and then it’s hard for me to find the advantages on the other side.

Are farts good or bad?

Ari: One of the things I’ve heard people mention on carnivore diets is the absence of bloating and flatulence. It’s interesting to me that a lot of people have almost pathologized a bloat after a meal or having gas as signs of disease processes of something is terribly wrong with you if you have that going on. My take is influenced by the fact that I have two healthy beautiful little kids. I have a three-year-old son and an eight-month-old daughter. They’ve gotten as perfect of nutrition and lifestyle as a kid could possibly ask for. Very healthy parents, very healthy diet, very healthy environment. It’s pretty much as good as it gets in the modern world. You know what, my kids fart sometimes. [chuckles].

It’s funny to me when people are so worried that they’re farting a little bit that everything’s terribly wrong. I’m like, based on my kids I’m pretty sure it’s normal. I wouldn’t worry too much about it. I’m interested in your take as a gastroenterologist what’s your take on bloating and flatulence?

Dr. Bulsiewicz: Well, first of all, we all fart. We all poop. Those are [inaudible]

Ari: Even you as a gastroenterologist?

Dr. Bulsiewicz: Do I?

Ari: Even you as a gastroenterologist?

Dr. Bulsiewicz: Multiple times during this podcast already I [inaudible]. We all do that. That’s normal human bodily function. The problem is how we are framing these challenges that are very real for people. These are the people that I see in my practice that have food sensitivities. They eat food and they go, “Oh my gosh, I feel horrible. I get gas, bloating, my stomach gets distended.” The question is what’s happening there? They’ve been told that this is inflammation but it’s not. There’s no evidence of that.

What the evidence suggests is that this is sloppy digestion, sloppy processing. The reason that is happening, I want people to understand that this doesn’t randomly happen to any person. This is evidence of a damaged gut. The reason why you’re struggling with these foods is because there’s been damage to the gut and because we need to rebuild the gut. The important thing is that the gut can be rebuilt. We can heal it. We can make it strong and then you can thrive.

The reason comes back to digestive enzymes. What’s fascinating is that we big strong humans lack the enzymes necessary to process it and digest fiber and many of the polysaccharides that exist in plants. We weren’t born that way. The reason why is because if you think about human evolution, we started in Africa, we radiated out across the globe. There is no ancestral diet. We ate off the ecosystem. Wherever we lived we ate what was available to us. We lived during a time of famine and starvation so we were just trying to eat to survive. Then your diet would look like whatever a diet looks like based upon what the land provides. We needed a gut that was adaptable, like highly adaptable.

Because most people don’t realize that fiber is incredibly complicated. Fiber is not just fiber, there are millions, potentially billions of types of fiber that exist in nature. We need something that allows us to adapt and process and break down and digest all these different types of fiber. That’s where the gut microbiome comes in. We are not readily adaptable as humans. Our gut microbes are turning over every 20 minutes. 50 generations of microbes go through in a 24-hour basis. That’s an evolution on par– if we were humans that’s the same number of generations as us going back to the pyramids on a daily basis, 24 hours.

The point is the gut microbiome is highly adaptable. We lack the enzymes to process and digest our plant polysaccharides and fiber because we outsourced it to our gut. We need like I said hydrolysis to break down our fiber, our plant polysaccharides. Us big strong humans only have 17 of them. Our gut microbes may have 60,000. A single cellular bacteria, one cell could have hundreds of these enzymes and we, our entire human body, only have 17. We rely on our gut microbes to break down and process our fiber and our plant’s polysaccharides.

When there’s damage to the gut you may struggle in the processing and unpacking of that food. It’s not inflammation, it’s just sloppy digestion. What you need to do is– the key is this. The gut is like a muscle. It can be strengthened, it can be fortified. The way that you fortify and strengthen it is by exercising it. For example, if you’re a person who’s sensitive to black beans here’s the thing, if you eliminate black beans entirely the microbes that thrive off of the black beans will grow weaker, and weaker, and weaker and potentially recede to the point that they die.

If you acknowledge that you’re sensitive to black beans all that means is that it’s a point of vulnerability, you need to build up strength when it comes to black beans. You moderate. You reduce the amount of black beans that you eat, you don’t opt for the four-bean chili. By reducing it it’s like when you exercise and you’re in the sweet spot. The sweet spot of exercise is when you do just enough to test your body without doing so much that you hurt yourself, and without doing so little that it’s worthless.

How to build tolerance to foods you are intolerant to

Ari: This is a really interesting reframe of something. This idea of food sensitivities that from your perspective it sounds like a lot of people, almost everybody out there is just getting this wrong. It’s like the equivalent of somebody doing a really hard workout and feeling really tired afterward and sore for a couple of days and then thinking, “Man, I should just stop exercising because exercise is clearly bad for you.”

You’re saying you should lower the amount of exercise because exercise is great for you. Keep doing exercise but find the right dose for you that you can tolerate and slowly build up from there. In the context of foods maybe that means, hey eat three black beans or a teaspoon of black beans a day and then build up to two teaspoons the next week or something like that. Is that accurate?

Dr. Bulsiewicz: That’s completely accurate. Take it a step further; life is easy when you are in a state of fitness. Going to the gym is easy when you’ve been going to the gym for months, you’re in great shape. You know and you thrive and you are addicted to the feeling of just cranking out those workouts. It’s a totally different story. What happens to the guy who’s in great shape but then he breaks his arm. He breaks his arm, he goes on a cast, and then let’s just call it six months later the cast comes off and his arm is shriveled up. Because he hasn’t been using it.

Now this guy who’s used to being in great shape and grabbing 45-pound dumbbells and doing curls, he goes to the gym and you’re not doing 45 pounds, you’re not doing 20 pounds. You have to go and grab 2.5 pounds off the rack and you need to start there. You recognize this is a rehabilitation process. You’re not in the phase of taking something that’s already humming along and top shape and just making it better. You’re taking something that’s been damaged and you’re getting it back to baseline before you get back to getting it above baseline.

There’s this rehab process that you have to do with your arm where you start the exercise with light weights and then you build up. Go to 2.5, you go to 5 next week, and then you go to 7.5. It might take time and there’s probably going to be some discomfort that comes with it because you’re rehabilitating the damaged arm, but eventually, you’re going to get there. Next thing you have your arm back and you’re thriving again. That’s the best state of health as opposed to saying, “Look, I got the cast-off. I can’t lift 45 pounds anymore so I give up. I’m never going to work out again. I’m just not going to use this arm.” That doesn’t make sense.

Ari: Very, very interesting refrain. Just to wrap that idea up I’m wondering if do you really believe there’s a place at all for someone to say, “I have food sensitivities to this, this, and this so I’m going to eliminate those foods?”Is that something you ever advocate or is it just wrong almost every time?

Dr. Bulsiewicz: If you have a food allergy, you get hives; you get swelling of the lips or something of that variety that’s a different situation.

Ari: Like a true food allergy, IgE food allergy as opposed to a food sensitivity or intolerance?

Dr. Bulsiewicz: A true IgE food allergy that is symptomatic and manifests with those types of symptoms, I completely understand food elimination in that setting. By the way, there are ways, not that you should be doing at home but there are ways under the guidance of a trained professional to actually reverse the food allergy. It just is more; it’s an even more challenging form of rehabilitation. In that setting absolutely.

A person who has celiac disease, if a person has celiac disease which by the way manifests in the gut with inflammation because they consume gluten, that person I will look them in my eye and tell them you’re not having gluten for the rest of your life. I don’t want you to have one cookie. Not even one. Not at Christmas either. Those are specific scenarios. How about dairy? The person who says I want to eliminate dairy. Well, from my perspective when did it become the idea that we are adapted to cow’s milk and we need that to survive and thrive?

That’s really again a part of our modern lifestyle that we have accepted as normal that was never really normal. I don’t see the advantages of dairy. So a person who has symptoms with dairy and they want to eliminate it, be my guest. When it comes to plants, and specific categories of plants, I’m not going to stand there and advocate for the complete elimination of categories of plants.

If you get rid of black beans because you don’t like black beans and you’re like, “They’re icky. I don’t like them.” You can compensate with lentils and garbanzo beans and go down the line, pinto beans. There are so many choices. There are other beans. When you get rid of all beans there’s no way to replace that with kale. You can’t do it.

How glyphosate, herbicides, and other toxins affect gut health

Ari: I have another maybe slightly more controversial question for you. That is, within the scientific community there are certain topics that are just hot button topics that are very, very polarized where there is a climate that is not conducive to discussion and debate. It’s like you’re either with us or against us sort of thing. Vaccine is a good example of that topic. I’m sure you know if you’re an MD, I have no idea what your position on vaccines is but probably no one does.

Even anybody who might have any question is afraid to say anything because there’s a climate that’s like, “Hey, if you’re an MD and you say anything that even remotely questions the safety or efficacy of a vaccine it’s like, “He’s a quack. Get him. Let’s get his credentials taken away from him and his license taken away from him.” There are certain topics that are just like, hey, you’re either in the scientific position or you’re a quack.

The herbicides and pesticides, it’s not as extreme as vaccines, but it’s like that. In the sense anybody talking about glyphosate and how it’s damaging human health, “You’re quack. You’re one of the pseudo-scientific soccer moms that’s scientifically illiterate who thinks glyphosate and GMOs and vaccines are bad.” You mentioned herbicides and pesticides earlier so I’m curious what you think of glyphosate and any other pesticides and herbicides and their role in gut health?

Dr. Bulsiewicz: Let me just say before we jump into this topic already that I regret in our 21st Century life where we’re all on the internet and social media the tribalism that has resulted from it. What makes me really sad is what’s happening in our country now. Where you see people getting into tribes about how they feel. Everyone has an opinion about COVID-19.

It’s become so politically charged based upon your personal beliefs that we can’t even have a conversation where we try to actually– navigating this process where you have competing interests between human life and the economy. There will be sacrifices on both sides, and it’s a question of how we choose to navigate that. Navigating a process like that requires us to come together not to punch each other in the face. You know?

Ari: Yes. 100%

Dr. Bulsiewicz: I just wish that we could be better.

Ari: I mentioned this in another interview with my mentor John Ashraf recently. There’s this famous cliche of, hey, if we were all attacked by aliens that came here to take over the planet, all of humanity would overcome our differences and all of our conflicts. We’d unite and become one. It’s interesting that now that’s happening. We’re all being attacked by this virus and yet we’re more fractured than ever instead of [inaudible].

Dr. Bulsiewicz: It breaks my heart because I feel there are conversations that are real and then there’s stuff that’s being presented as fact that’s just certainly not a fact, that’s for sure. I think we need to be delicate. The reason I bring that up, Ari is because whether we’re talking about COVID-19 or we’re talking about vaccines, whatever we are choosing to talk about the solution or the answer is always in the details. It’s always somewhere in the middle when you peel apart the layers. It’s like people who vilify entire categories of food like, “Carbs are bad.” “What? Fiber is a carb.” “Fat is bad.” What? Avocados, they’re bad?”

You can’t take on the whole category of cool macro and take it out all at once. That’s so lazy. Now, when it comes to herbicides and glyphosate let me say that there is a camp that believes very, very, very strongly that this is the entire story and there are people who are dismissive of the entire idea. I let the science do the talking. Which is that the number one when they study people who consume foods containing glyphosate there is an increased risk of lymphoma.

When they study a population in a different country, France, and they looked at the consumption of organic fruits, vegetables like organic food, people who consumed organic food had a decreased risk of lymphoma. It was literally almost parallel in terms of the effect. Of course, organic means that the glyphosate is not a part of it. I think that there’s a lot that we don’t know.

I worry that the glyphosate is causing harm to our soil. That’s what I worry about. I worry that we are accepting a short term boost in productivity at the expense of potentially degrading the most important thing in human nutrition, which is soil. The nutrition of our food is directly proportional to the nutrition of our soil. Our soil has a microbiome. If these herbicides destroy the bacteria then they’re destroying the soil microbiome and that I don’t know how long it would take for us to get that back.

From my perspective can anyone provide me an argument that suggests that this is better for human health? I suppose the only angle that you can make is that we live on a planet with 7 billion people, and I will accept this argument. We live in a planet with 7 billion people. We were 1 billion in 1800. We’re going to be 10 billion in 30 years. From 1800 to 2050, 250 years, 10 times the population on this planet. I could see where you say, “Well, we have more productivity of food with glyphosate.”

If we’re talking about the efficiency of our food then why are we eating 220 pounds of meat per person per year in the United States? That’s wildly inefficient. Most of the glyphosate is going towards corn and soy that’s used to feed animal agriculture. The point from my perspective is that I don’t see an advantage to it. I see that there certainly are studies to suggest disadvantages or potential for threat. I personally, in my family I raised my children with a predominantly organic whole foods diet. There are specific foods that I feel less compelled to make organic in the interest of saving a dime like bananas. If you peel the skin off then I’m less concerned about it.

I also feel like, and I said this in the book, when I spend $1 on casting a vote and I want to cast the vote for the farmer who’s got an organic farm that’s trying to basically do their best to give us highly nutritious food that doesn’t compromise the soil or the surrounding ecosystems. That’s the way that I feel about it. I don’t know how do you feel about all that or do you.

Ari: I feel exactly the same way that you feel. I don’t have a super-strong opinion on glyphosate, but I’m inclined to think hey, that there’s no potential for benefit here and there’s definitely some research suggesting harm. When there’s that scenario it’s zero possible benefit, lots of potential harm, though there’s a need for stronger evidence. To me, it’s just a no brainer that’s the thing I’m going to avoid. Unless you can show me an equal potential for amazing benefits it’s a clear avoid for me just based on the precautionary principle.

As I said before there’s this macho scientific climate of the only people who are bad mouthing glyphosate must be scientifically illiterate quacks. There’s almost this pressure to either not say anything negative about glyphosate lest you be labeled a quack or to at least downplay it and not let people know your actual position. Do you know what I mean?

Dr. Bulsiewicz: I think that the important point from my perspective, this is the way that I’ve always felt about the glyphosate thing, there’s some people that it seems they take their shifts and they go all in like, glyphosate is the problem. What about the fact that only 10% of our diet is real food, fruits, vegetables, whole grains, seeds, and nuts? What about the antibiotics that we’re giving to the animals? What about the hormones that we’re injecting into them?

What about the fact that we live a sedentary lifestyle? What about the fact that we are up all night with our electronic devices? What about the fact that we’re not sleeping well? There’s just so many other things that all feedback into our gut microbiome. We can’t put it on one thing. I think that a low fiber diet is a glaring problem. I think it’s a glaring problem. I wouldn’t sit here and say it’s the only problem.

Dr. B’s top tips for gut health

Ari: I would agree with you 100% on everything you said there. I want to get into your– the last thing is just your practical tips. This is something that could take up a large portion of time. Maybe you could just list off your top three or four big takeaways for improving gut health.

Dr. Bulsiewicz: All right. It’s actually so much more simple than people realize. We don’t need to make this complicated. Number one, embrace the idea of diversity of plants. No matter who you are, no matter what dietary tribe or religion you’re a part of this is something that is so simple for you to do. Is add more plant diversity to your meal. Add those fresh herbs and spices. Add a couple of plants into the tomato sauce. So easy. That’s number one.

Number two, I want to transition into talking about lifestyle. Sleep is completely free. Sleep is completely free and we should be like, there’s no evidence to suggest that we need less of it as we age, we just choose to live that way. We should be striving towards eight hours whenever possible. The other thing to keep in mind is that we have a circadian rhythm. I’m transitioning into number three now. We have a circadian rhythm. We have a 24-hour biorhythm and it’s actually all timed to the rise and fall of the sun. Going to bed at 1:00 in the morning and waking up at 9:00 in the morning is not the same as going to bed at ten o’clock and waking up at 6:00.

We should be timing our sleep to our circadian rhythm. We should also be timing our meals to our circadian rhythm. People love the idea of intermittent fasting. Everyone gets the idea of like, 12 hours, 14 hours, 16 hours without food. That’s great but what you’re missing, the most important thing is how you time it. Early dinner. Early dinner. If you want to have dessert be my guest and then boom start the clock and you’re water fasting for a couple of hours before you go to bed. That way by the time you wake up the next morning you’ve already done 12 hours. You’re doing a pretty good job.

I feel when it comes to gut health it’s so simple. Right there [unintelligible 01:23:36] for diversity of plants when you go to the supermarket. Diversity of plants at the salad bar. Diversity of plants when you sit down at dinner. Get yourself a good night’s rest. Make sure that you’re optimizing your circadian rhythm and have a nice water fast after dinner and carry it into the next morning.

Ari: I love that you went the sleep and circadian rhythm angle there. That’s my saver. One of my favorite topics and obviously it relates very strongly to energy and the fatigue story as well. I have maybe one last little layer, which is are there any specific foods, and granted there’s a diversity. Diveristy is huge, but are there any specific foods like your top three let’s say superfoods for gut health?

Dr. Bulsiewicz: I say in the book that I want you to have a lot of best friends. I’m sorry, I want you to have a lot of friends. I want you to have a lot of friends, but it’s okay to have best friends. Rather than over-emphasizing the superfoods let’s focus on diversity, but it’s okay to build your foundation around the superfoods. I brought forward an acronym, F Goals. It’s hard for me to separate out from F Goals.

I will give you my top three, but just so you know, F Goals stands for real quick, fruit and fermented. Greens and grains. Omega-3 super seeds like chia, flax, and hemp. Aromatics like onions, garlic, leeks, shallots. Legumes for L, beans, lentils. Then S, I will list sulforaphane referring to cruciferous vegetables like broccoli sprouts. I also give two bonuses, which are seaweed and also shrooms. That’s my list of my foundational foods that you should be striving to have a couple of times a week, at least. In some cases, daily.

For me, I truly believe the foundational foods for gut health are actually the ones that have been villainized the worst. I’m not just trying to be provocative, I’m really am not. I think the whole grains and legumes are the foods for gut health. I lay out in chapters four and five of the book my argument for why. If I were to pick a third I’m going with broccoli sprouts. Sulforaphane, the power of this phytochemical. Sulforaphane is the phytochemical, a plant-based chemical. It is cancer crushing. It is the most powerful anticancer chemical that I’ve ever come across, but it also works and has healing effects throughout the body beyond just preventing cancer.

Again, I could have written a whole chapter about broccoli sprouts, I’m obsessed with them. They’re easy to grow at home, in your own house. Instead of a whole chapter, I just gave you five pages in the book, and that’s the best I could do. I just summarize it with bullet points of boom, boom, boom, here’s all the things it does. They’re amazing.

Ari: I’m obsessed with them myself. I have trays of them growing 20 feet away from me. This has been awesome, thank you so much. I’d love to have you back again at some point. I might even turn this into a two-part interview. It has gone so long, it’s just been so fascinating and I can’t stop asking you questions. I can’t help myself here. It would be great to have you back and maybe do a deep dive on even all the details of the practical tips and stuff like that. This has been amazing. Thank you so much for sharing your wisdom with my audience. I really appreciate it.

Dr. Bulsiewicz: Oh my gosh, it’s such a pleasure to come on your show. I love the questions. There’s a lot of questions that you asked me that I haven’t had on other podcasts. I appreciate the angle that you come from. It’s interesting, I honestly didn’t know whether or not we were on the same page in terms of a lot of these ideas, but it appears that we are. That’s really cool.

Ari: I try to play devil’s advocate a little bit too sometimes, but also be kind and respectful and not antagonistic. I try to not be too buddy-buddy and be like, this is how I also think. I want viewers to hear a little bit of challenging of perspectives.

Dr. Bulsiewicz: I like that. I think that’s the way that it needs to be done is to have these conversations. At the end of the day let the science do the talking. As I said earlier when I was referring to the science of fiber fuels, which is like research 101 guide, I want to empower people with the right way to approach these issues. I would encourage people a couple of things. Number one, check that out. It’s totally free at you can download it.

For your listeners, if you guys enjoyed this conversation and you found it to be useful and helpful– we live in a time with so much misinformation. If you guys found this conversation to be helpful, lift it up. Let people know. Tell your friends, hey, I listened to this really cool podcast, you got to check it out. Put it on your social media; share it on your stories, whatever it may be. That’s true for this podcast. That’s true for my book Fiber Fueled. When you find high-quality information we need to lift it up because we live in this era of confusion and misinformation. When we find real legitimate sources let’s celebrate them and let people know.

Ari: 100%. For people who are interested in getting your work or following your work, obviously they can get the book on Amazon, Fiber Fueled. Is there anywhere you want to direct them to your website or social media or anything like that?

Dr. Bulsiewicz: Beyond my website, the Plant Fed Gut, which by the way in addition to my research guide, I also have a COVID-19 guide. I have an email list that’s very active and people get regular emails that they enjoy. Beyond that find me on social media at the @GutHealthMD, the Gut Health MD, that’s my social media. I am juggling the Plant Fed Gut and the Gut Health MD at the same time.

The other thing I was going to say is that I have a course that I developed. I’ve done two beta versions of the course with amazing results, and it’s effectively a much deeper dive into gut health and reversing a damaged gut or reversing dysbiosis. I’m hoping to launch that this summer. If that’s something that interests you, if you read the book and you want more that would be the opportunity. That hopefully will be coming this summer.

Ari: Well, thank you again so much. Really a pleasure. Hope to chat again with you very soon.

Dr. Bulsiewicz: Thanks, Ari. I appreciate it, man.

Show Notes

The latest science on the role of the gut in human health (4:22)
How the modern diet affect gut health (13:55)
The most common myths and misconception on gut health (21:09)
The key role of fiber in gut health (47:02)
Are farts good or bad? (59:13)
How to build a tolerance to foods you are intolerant to (1:05:35)
How glyphosate, herbicides, and other toxins affect gut health (1:11:00)
Dr. B’s top tips for gut health (1:21:00) 


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