Simple ways to improve your gut health with Dr. Karan Rajan

Your gut isn’t just in your stomach - it comprises 4 organs, all communicating with each other. The gut even has its own nervous system. When almost half of us suffer with gastrointestinal issues, learning how these organs interact is vital to improving symptoms.

Today, we explore how the gut and brain are connected, the lifestyle factors causing gut health issues and why it’s so hard for doctors to understand IBS.

Make smarter food choices. Become a member at zoe.com for 10% off with code PODCAST

Try our new plant-based wholefood supplement - Daily 30+

*Naturally high in copper which contributes to normal energy-yielding metabolism and the normal function of the immune system

Follow ZOE on Instagram.

Transcript

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

Your body has two brains and your second brain stretches from your mouth to your bum. It has more than a hundred million nerve cells. It can send messages to your other brain, the one that sits in your head. These messages impact your cravings, your mood, and your mental health. If you couldn't guess already, that second brain is your gut.

So what happens when you get a stomach ache? Even worse, when you get a stomach ache every day? Forty percent of people have some sort of gastrointestinal issue and Dr. Karan Rajan spends his days operating on those sick bowels. That is when he's not debunking myths about them for his 10 million online followers.

Dr. Karan Rajan is an NHS surgeon and a hugely successful health and science communicator. Karan is also a senior lecturer at Imperial College London, and his work influences the British government, the U.N., and the World Health Organization. His book, titled This Book Might Save Your Life, was a number one Sunday Times bestseller.

You'll finish today's episode with a deeper understanding of your gut, and some new ways to look after it, so it can look after you.

Karan, thank you for joining me today. 

[00:01:38] Dr. Karan Rajan: Thanks for having me. 

[00:01:39] Jonathan Wolf: So we have a tradition here at ZOE, where we always start with a quick-fire round of questions, which is really hard for a doctor or a scientist because we have this very strict rule; you can say yes or no, and if you absolutely have to, you can have a one-sentence answer.

Are you willing to give it a go? 

[00:01:56] Dr. Karan Rajan: Okay, let's do it. 

[00:01:57] Jonathan Wolf: Does the gut exist only for digestion? 

[00:02:00] Dr. Karan Rajan: No.

[00:02:02] Jonathan Wolf: Can my gut communicate with my brain? 

[00:02:05] Dr. Karan Rajan: Yes. 

[00:02:06] Jonathan Wolf: Could my sleep schedule improve my gut health? 

[00:02:10] Dr. Karan Rajan: Yes. 

[00:02:11] Jonathan Wolf: Will most probiotic supplements work for me? 

[00:02:15] Dr. Karan Rajan: No. 

[00:02:16] Jonathan Wolf: And this was our community's number one question, so I have to ask, could holding in a fart be harmful?

[00:02:24] Dr. Karan Rajan: No slash yes. 

[00:02:25] Jonathan Wolf: Okay, we'll definitely come back to that later. And finally, you have a whole sentence, what's the most common misconception when it comes to gut problems? 

[00:02:35] Dr. Karan Rajan: I think it's like with most facets of health in that a lot of people assume that it can be fixed easily or quickly or covered over with supplements or quick hacks. And whilst they can help, it's often a slow road to improve gut health, just like improving sleep health or physical health.

It takes repetition, chronically over a number of weeks.

[00:02:57] Jonathan Wolf: Our team always does a bit of research and comes up with some statistics before we record one of these podcasts. I was really shocked by one of these statistics, in which they said 40% of all people have some sort of gastrointestinal issue.

Now I had my own story of this. In my early 20s, I suffered from sort of mild IBS, which continued throughout my 20s and into my 30s.  I remember going to see a whole series of doctors who, after confirming that I didn't have something awful like cancer, basically said, yes, it's IBS. There's nothing we can do, and it's probably because of stress. 

Now to be fair, this was 25 years ago, before the gut microbiome was even known about. And I know you've really been pushing the needle about this with all of this amazing education that you've been doing to millions of people online. 

So I'd love to start, just simply right at the beginning, almost with the simplest of questions. When we talk about the gut, we're not just referring to the stomach, are we? 

[00:03:55] Dr. Karan Rajan: No, and in fact, if you're thinking about the gut, you think about digestion, and if you think about digestion, it would also be wrong to think about the stomach because no digestion actually really takes place in the stomach.

There's some mechanical and maybe some chemical digestion. It also happens in the mouth. But actually, digestion begins in the brain. 

So, when you're even thinking about an ice cream, a plate of food, the brain actually triggers that whole cascade of digestion. The signals get sent to the gut, to the salivary glands in your head, and all these juices are starting to be secreted. And that's all linked with also your circadian rhythm, that biological clock. 

You see, I like to think of the gut as this orchestra. And that orchestra, the maestro of that orchestra is the brain, the circadian rhythm, because it determines when you feel hungry, when you want to go to the toilet, so it really all starts in the brain.

And then the bulk of the digestion, the kind of real mechanical digestion and the chemical stuff that we think about, then occurs in the small intestine, that's where the bulk of it happens. 

So really the stomach is such a small player in the grand scheme of things of gut health and digestion. Even beyond the small intestine, where I've just said digestion occurs, it's really, if you want to dig down into the granular detail, the colon, where the bulk of the ecosystem of our digestive activities takes place, and that's where the microbiome live.

[00:05:22] Jonathan Wolf: I love the idea that digestion starts in the brain. It makes me think about that concept you always had about attraction, in fact, starts in the brain. And so I love this idea that we tend to think about food as it starts when you start to swallow it, but you're saying there's all this stuff that's happening beforehand.

Could you tell us a little bit more, about what is digestion and why is it so important? In fact, you’ve spent your life devoted to trying to make it work better for people.

[00:05:52] Dr. Karan Rajan: I'll be a bit biased when I'm talking about gut health, and if you ask any general surgeon or colorectal surgeon or any GI [gastrointestinal] surgeon, they'll tell you that guts are the most important system of organs there is, and if you speak to a cardiologist, they'll say it's the heart, naturally.

Really, when it comes to it, it's the foundation of everything. Actually, when microbiome research went from fringe hippie science into mainstream science, and that's probably the most popular health topic right now, that's opened our eyes into actually how powerful it is. Because we know your first question is, is our gut just there for digestion?

We know it's far more than that because we know the gut has its own nervous system, the enteric nervous system. The immune system is also very highly active in the gut as well. It has a role in building our immunity and it's interacting with the outside world. 

The gut itself, the 25 feet or so of the pipes that traverse through us, they're not really inside us. They're actually part of the external world. There's no part of the gut unless there's a hole in the gut, which actually connects us with the inside. 

We're basically, topologically or topographically even I should say, we're just basically a donut if you look at us from the top down.

[00:07:06] Jonathan Wolf: I love that. 

[00:07:07] Dr. Karan Rajan: And the food never touches our insides, the abdominal cavity. It just goes through this long pipe and it comes out the other end. And then things happen along the way, like a big factory line. 

Each person doing something in that manufacturing line, adding in some enzymes, churning it up a little bit more. The microbiome, bacteria, the viruses, and the yeast get involved and do something. 

It's basically like a big Willy Wonka factory and the Oompa Loompas are doing something at every step of the way. Digestion, it's a chemical and mechanical process. And actually, back in the day, in the early 19th century, people deliberated whether it was just mechanical or just chemical.

It was only later on, late 19th century, we figured out, thanks to William Beaumont, an army surgeon, that it's a combined process of both these things. So, our learnings of the digestive system have come quite late on in human history. 

[00:08:01] Jonathan Wolf: And you mentioned just there about how the gut has its own nervous system. And that's one of the examples of how it's more than digestion, which is definitely something we've talked about on the podcast and other shows. 

What does it mean to have its own nervous system? Why does it have a nervous system? And you also mentioned about this connection to the brain, what do we understand today is going on there? 

[00:08:23] Dr. Karan Rajan: So obviously you've got the central nervous system in the brain and you've got this enteric nervous system in the guts. These two are interlinked and they have this bi-directional feedback, the gut and the brain through this kind of super communication highway, the vagus nerve.

The vagus nerve is the largest nerve in the human body and a significant proportion of its root goes through the guts. And there's an obvious link between the gut and the brain that everybody experiences. Before an exam, you might feel nauseated or nervous and your stomach starts rumbling.

Even going back to William Beaumont, the army surgeon that I mentioned in the 19th century. In the very early 19th century, There was a fur trapper in Mackinac Island called Alexis St. Martin, who had his guts literally blown out by a musket that was fired accidentally at his guts. 

So he had this huge opening in his stomach. William Beaumont rescued him from the brink of death. But even though he survived, that hole in his stomach never fully healed. So it formed this gastric fistula connection to the outside world. 

And William Beaumont, I mean, in this day and age, we think this is completely abhorrent and unethical an experiment, but that was all okay back then. He used this literal window into the digestive system to learn things about digestion. And he saw, whenever Alexis Saint Martin was irritable, that would slow down the digestive process because he would put little pieces of meat inside and pull it out and just see how quickly it was digesting. So he could see his emotion was directly correlating with his local biology.

[00:09:55] Jonathan Wolf: That's amazing. I can also see that we would not get ethical approval for that study today. That's fascinating. 

So you're talking about the way that we know in our regular life, in fact, and you give this example of exams, which I remember very well, I'm pleased to say I haven't had to do any exams for a long time. You feel really nervous. You often get an upset stomach. 

And this is your example that has not just going from your gut to your brain, but your brain is also going to your gut. So there's a sort of two-way system here.

[00:10:21] Dr. Karan Rajan: And even linking the vagus nerve between the two, in the sort of early 2000s, vagus nerve stimulation was a sort of therapy for depression.

So you could see how, still in those days, there was some understanding that there was that link. 

[00:10:37] Jonathan Wolf: And you mentioned the microbiome. I'm sort of interested because you also mentioned what is clearly true, that this is very new science has been changing a lot. Has your understanding of that changed from the point at which you started to do your studies and your training and where you are today?

And how do you think about that today as you're thinking about your patients and also maybe the people you want to make sure don't end up on your operating table? 

[00:11:05] Dr. Karan Rajan: Yeah, absolutely. When I was in medical school, I understood the concept of the microbiome, uh, in very superficial terms, but I've never fully appreciated the depth of what we know now about the microbiome. 

It's not really the place of medical school to go into detail about that. It was more self-learning that I did. And the research we have now, as opposed to over 15 years ago when I was in medical school is just night and day, they wouldn't even have been close to the stuff that was clinically applicable back then.

Now we have a lot more clinically translatable science from the research table to our everyday lives. But we didn't 15 years ago in the way we do now. 

So I think it's an evolving science. And I think also the caveat there is a lot of the research and stuff we know about the microbiome, especially the juicy science is they're all relatively small studies and a bulk of them are in animal studies, rodent studies, and not all of them are directly translatable to humans.

So I think we can look at them with optimism, but also caution not to say You know, we can do this, and if you do this in humans, it works the same as rats, and we just need to be cautious of that. 

[00:12:15] Jonathan Wolf: Can you help us to understand what are the most common ways in which we are irritating our gut?

[00:12:24] Dr. Karan Rajan: I think it's worth bearing in mind that whilst for specific things like gallstones or cancers, there's a significant genetic component there we need to be mindful of. 

There's also, with any number of gut issues, there are lifestyle factors at play, which people can modify, which doesn't make them immune to these things, but can lower their risk of certain things. 

So for example, there are a number of irritants in our lifestyle that has a role to play unquestionably in our guts, some which we can't change. Environmentally, we cannot change. 

We know that air pollution can have an impact on our microbes. And if you're living in a polluted city, beyond moving from that city somewhere else, there's not really so much you can do about that.

Other things; we know that antibiotics, especially broad-spectrum antibiotics, and chronic use of those antibiotics can have a role to play. I think there was a recent study on about 14 and a half thousand NHS nurses. So the national healthcare system in the U.K., the healthcare system, they looked at 14 and a half thousand of those nurses and they found there was a clear correlation and association between chronic antibiotic use of over two months and lower scores on memory tests, cognitive tests, focus, reflex, etc.

Is it because of its impact on the microbiome or something else? We don't know. But clearly, it has some sort of detrimental effect there. And especially when the microbiome is evolving and growing in the early stages of life in the first few months and first few years, that's particularly when antibiotic use can have a role to play, impacting the good and bad bacteria. 

Other things like even the food we eat, a lot of them are enriched with antibiotics and pesticides. There's a lot of talk about ultra-processed foods. Again, the science is growing on that. I don't think it's right to say that ultra-processed food directly and causally affects your health directly. But we don't have enough consistent strong evidence to say that. There may be a role to play for sure because that's the change in the last few hundred years, one of the changes.

NSAIDs, nonsteroidal anti-inflammatory drugs, things like ibuprofen that can also have an impact on the guts. For example, I quite often operate on people who have got ulcers, burst ulcers because of chronic ibuprofen use, for example.

A lot of the other medications we can take can have an impact on the gut as well. Alcohol, that's another potent irritant for the guts. And we also need to bear in mind that all of these things can influence the microbiome in a way, especially in early stages, that influences the immune system.

We know a bulk of GI conditions are autoimmune in nature. Things like Crohn's, ulcerative colitis, and beyond. So there's a number of irritants, some in our control, some out of our control. One of those things in our control could be things like smoking habits, alcohol, the diet, the fiber, as we mentioned, we know that has a role beyond just roughage as you suggested was the kind of dogma a few years back.  

So yeah, there's a number of things modifiable and non-modifiable. 

[00:15:32] Jonathan Wolf: That’s an impressive list of things we might worry about. I wanted to maybe dive into the antibiotics for a minute because I had a personal experience of this last year that was sort of shocking and eye-opening.

So I managed incredibly stupidly to drop a very heavy bench on my big toe at the beginning of last year and I ended up on an operating table with a surgeon sewing it together, who then prescribed a whole bunch of antibiotics and he prescribed a very broad spectrum intense antibiotic. 

Because I'm at ZOE, I've been measuring my gut microbiome regularly now for about five years and I had actually done a test literally a couple of weeks before this test and after a great deal of work, I'd managed to get to the point where I had about 30 of the 50 good microbes that we discovered that were in a Nature Medicine paper that we published a couple of years ago. I was feeling very good about this because I'd grown that from about half that level a few years before. 

So I did this test a week later and I was absolutely shocked that I was down to two of these good microbes. I had basically wiped out every single one of the good microbes and it did not bounce straight back two or three weeks later.

Actually it has been a slow hard climb over the last 18 months and I am getting significantly better. But even now I'm not back to the point that I was 18 months ago. 

And partly we see this because we now have this new ability to do these tests and actually understand what's going on in the microbiome, so you can really say, I know which are the good bugs, I can really measure it in a way that wasn't possible.

It seems to me that potentially we have really not understood that there's more going on than we previously realized. 

[00:17:11] Dr. Karan Rajan: Yeah, I think it's a flaw of human nature that we identify the problem once it's looming right in front of our face. You know, climate change, pollution. over usage of antibiotics and more.

And I think as we understand more about the microbiome, we realize how everyday things that we were taking for granted. Whether it's not paying attention to the amount of fiber we're eating, or even antibiotic use willy-nilly.

I think, 10, 20 years ago, if someone has a cold, more often than not, their family has a cupboard full of amoxicillin, some antibiotics and usually potent broad-spectrum antibiotics, which isn't necessarily tailored to target any one specific bacteria.

It has a wide-reaching effect into multiple potential strains. And one of the ways to at least mitigate or counter this antibiotic apocalypse or crisis we're facing is if we are using antibiotics, it needs to be used judiciously and also selecting highly specific antibiotics. 

So if someone has a bug that has streptococcus or an E coli strain, trying to find an antibiotic that is narrow spectrum and can target that specific strain, not a bunch of other bacteria, which could be collateral damage. 

[00:18:23] Jonathan Wolf: And so does that mean that you could deal with, for example, an infection without having a really big impact on these microbes in your guts?

[00:18:32] Dr. Karan Rajan: That would be the aim, because, essentially, when you give this broad-spectrum antibiotic to someone, you give that antibiotic carte blanche to just nuke everything in sight. 

If you drop a nuclear bomb on a city, you're not just targeting the building, you're targeting the collateral damage of all the residential homes nearby who don't need to be involved.

And the same instance with antibiotics, all the good bacteria are wiped out as well. 

Join the community

Be the first to know about ZOE’s breakthrough research, content from the world’s leading scientists, and more.

[00:18:57] Jonathan Wolf: That's a very powerful mental metaphor like a nuclear bomb is like the worst thing that you can imagine and you're describing these broad-spectrum antibiotics is potentially like that. If you could have had a more targeted antibiotic to deal with that particular thing rather than sort of wipe everything out and say, well, I killed the bad guy, but I sort of killed all the good guys at the same time.

[00:19:16] Dr. Karan Rajan: I mean just taking the example from your own anecdotes, essentially, you've had 18 months of nuclear winter where you've been struggling to get back. The soil has been poisoned as it were. 

Listen, I think antibiotics are life-saving. Don't get me wrong. They are probably one of humanity's greatest inventions. There's no two ways about that. 

And you know, a common cut could have been lethal without antibiotics, but we have overused them and that is a state of play right now. And we know that if someone is dying from sepsis, a bloodstream infection, and they need antibiotics, no doctor even now is going to think, Oh, it's going to impact their microbiome long-term. 

We need to save them. We need antibiotics and we can worry about the microbiome later because we also have strategies that can help to recuperate and regenerate that destroyed habitat as it were.

[00:20:06] Jonathan Wolf:  And does that mean, because obviously you're doing a lot of operations on people, so presumably you're generally saying that they should take antibiotics after these operations?

Do you feel you're more thoughtful about that than you might be if you were a foot surgeon, thinking about the antibiotics afterwards? 

[00:20:23] Dr. Karan Rajan: I would say far more. I mean, there are certain guidelines, for better or for worse that we have to stick to. So if we're doing an emergency operation, a bowel operation, bowel operations as opposed to other areas, because there's a high risk of contamination. Things from the inside coming out. You don't want fecal matter from the inside getting out. 

So there is an increased index of us using antibiotics to prevent those, you know, really deleterious infections. So we need to be mindful of those things, but we can go from, let's just give them a 10-day course of antibiotics to wipe everything else out. To then thinking, do they need antibiotics? 

Every day on the ward round, we see the patient. The infection markers are improving, they're improving, do they need antibiotics anymore? No, they don't. Let's speak to the microbial pharmacist, let's get a sort of a team decision, can we stop them early? So I think that's something which has come more into play now and maybe 10 years ago, 15 years ago, that wasn't a thought.

[00:21:18] Jonathan Wolf: That's really interesting. So definitely something that you're now seeing with these sort of pros and cons. I think also really interesting what you said before, I was really struck you talked about us as being a doughnut. 

I never really thought about myself being a doughnut, although I am aware from from talking to other scientists about this idea that actually my gut is still sort of like the outside and you're describing that we have all those bacteria as long as they're in our gut, that's a good thing for us.

But I think what if I understood right, I just want to make sure that I'm playing this back right, when you're operating, then you have this high risk that some of these bacteria that are sitting in our colon doing good stuff for us, they suddenly get inside our body, into our bloodstream and suddenly they could switch from being nicely managed by our body and doing good things, they could suddenly become really dangerous. 

[00:22:05] Dr. Karan Rajan: Yeah, absolutely. And I think the environment in which they're in provides them a habitat in which to continue their normal functions. And it seems while we're alive, our immune system also keeps them in check by preventing them from overpopulating and overgrowing because there are certain conditions where bacteria can overgrow.

For example, SIBO, small intestinal bacterial overgrowth, where there's an overgrowth of bacteria in the wrong place in the small intestine where it shouldn't be. And I think there's a delicate peace being kept between us and these microbial tenants we have when we're alive. 

Because we know once we die, they begin to feast on us and decompose us. That's part of what they do. They're broken free from their jails in our intestines. They literally, our intestines burst and they go everywhere and start to, you know, decompose and putrefy things. 

[00:22:51] Jonathan Wolf: I think it's really interesting. I know that this is a big area of research in the way that our immune system, a big part of it’s job seems to be managing all of these bacteria inside us to do something good.

And then those bacteria themselves are somehow also managing our immune system. So there's a sort of complex interplay. And maybe I want to come back to that thing you mentioned early on about our early life. 

Because I understand that there's a lot of research suggesting that one of the really important things that's going on inside children in the first couple of years is actually sort of developing their microbiome and managing it and a sort of two-way system. 

[00:23:30] Dr. Karan Rajan: I mean, in terms of microbiome, building it and building it the right way, as though it were a neatly curated bonsai tree.

I think there are certain things we can do to guide it in the right way. But it's not always possible for everyone. 

For example, we generally have to assume these days that when you're a fetus, as far as we're aware, essentially that fetus is sterile in terms of there is no existing microbiome and it's populated throughout life and there are certain paths that microbiome can take.

So for example, vaginal birth versus cesarean section, there'll be a different set of microbes either way. So through the mother's vaginal canal, there'll be some microbes that come onto the skin, onto the mouth, which is then swallowed, and then that populates it. And C-section, there'll be bacteria from the mother's skin, potentially, or from the surgeon themselves touching the baby.

And then the next stage would be interacting with the environment, whether the child is breastfed, so the bacteria from the breast milk, or if it's via formula or infant formula or something like that. Whether the child at an early stage is in an urban or nonurban environment, exposure to animals at a young age, whether it's an only child or it's the youngest child or the eldest child, that also has a role to play. 

[00:24:49] Jonathan Wolf: As an eldest child, I want to know what's best because I know I have a younger brother and a younger sister. They would each argue that being the youngest or the middle is best. So I'm going to put you on the spot now and find out what is the best. 

[00:25:01] Dr. Karan Rajan: So based on some of the research that's been done on this allergy risk and autoimmune disease risk, it suggests that the youngest child is probably the best as it were in terms of having the lowest risk for these things.

Because it's getting these infections from their older siblings and interactions from these people. There's more diversity in their environment because the elders just had themselves. 

[00:25:24] Jonathan Wolf: That's fascinating. So it's another example where it's the exact opposite of the way that I understood things when I grew up, which is you want to keep the environment completely clean.

You're basically saying the youngest child is surrounded by all these older children who are like bringing in dirt and mess and actually they are therefore having less of issues than their eldest child who is sort of wrapped up in cotton wool by their adoring mum and dad? 

[00:25:48] Dr. Karan Rajan: Yeah, supposedly. And I think actually you mentioned there about the sort of sterile environment and this hygiene hypothesis. That's one of the things which we've changed in terms of the scientific community, we've changed our idea on a lot over the last few decades. 

There was this idea that the hygiene hypothesis, that the sterile environments are leading to increased rates of allergies, et cetera. But that hygiene hypothesis is not quite right. And it's more called almost the new friends hypothesis. 

You don't want a super sterile environment. You also don't want to introduce unnecessary pathogens to children. So if a child drops a chocolate bar on a dog poo, you don't want them to consume that chocolate because you think, oh yes, low-grade bacteria is good. No, pathogenic bacteria will always be pathogenic no matter how strong your immune system. 

All it suggests is that. It's okay for kids to play in the mud and then make sure they're washed afterwards. Wash your hands, get your vaccines, all the basic things, but a little bit of dirt in the environment and diversity isn't a bad thing and it probably could be a good thing.

[00:26:55] Jonathan Wolf: That's fascinating. I want to sort of bring us back, I guess, to the place we started with this amazing statistic of like 40% of people having these gastrointestinal issues. 

I understand that IBS is sort of the most common disorder within that group. Could you maybe help us to understand simply what it is, what's going on and maybe what the difference is between that and some of the other diseases that you describe like a Crohn's or something like that?

[00:27:25] Dr. Karan Rajan: The thing is with IBS, irritable bowel syndrome, we don't really understand, in most of the cases, why it happens. There are some cases of IBS which can be secondary to things we do to the body. 

For example, you can get post-infectious IBS. If you have a particularly bad bout of gastroenteritis, or a stomach bug, or food poisoning, you can actually develop some sort of irritable bowel syndrome, which is not the sort of primary cause, but that is a thing.

If someone's undergoing chemotherapy after bowel cancer surgery or radiotherapy, you can get some sort of pseudo-irritable bowel syndrome. And there are lots of diseases that mimic IBS, but there's so many different subtypes of IBS. You can run constipated, you can run more loose, you can run mixed, and we don't have one specific cause.

It's very likely that lifestyle factors maybe have a role to play, to at least worsen symptoms, the microbiome and the immune system have a role to play, genetics, but we haven't put it all together. We have different parts of the puzzle, but we haven't put it all together. 

And really, it's dissimilar to other things, like, for example, autoimmune conditions, which, again, the similarities probably stop at the microbiome and the immune system, which is heavily involved in autoimmune diseases like Crohn's or ulcerative colitis. 

But those are lifelong and there are no real cures as far as we know, for many of these things, IBS included, Crohn's, ulcerative colitis, we have medications, surgery and management options which can limit symptoms, but there's no cure. 

Even for bowel cancer, we remove the cancer macroscopically. And then the patients might have chemotherapy, radiotherapy, and they have surveillance, but it's not an instant cure once we remove the bowel cancer. There's a period of observation where we need to make sure there's no disease recurrence. 

And that's the problem with the gut. It's because we know so little, it's hard to have definitive cures like in many other conditions. 

[00:29:22] Jonathan Wolf: It sounds like you're saying, though, that actually our understanding of what is going on inside the gut is not as well developed as in many other systems.

[00:29:32] Dr. Karan Rajan: I mean, we know a lot about the gut. For example, colorectal cancer, the treatments for colorectal cancer have improved dramatically over the decades. And for all intents and purposes, in most cases, like it was maybe decades ago, it's not really a death sentence. We have amazing technology diagnostics and operative and other management options to deal with it.

And even now we've got novel monoclonal antibody treatments for various things, which we didn't have years ago. For example, someone could essentially be virtually asymptomatic with Crohn's or ulcerative colitis in specific cases, just using these monoclonal next-generation antibody treatments.

[00:30:10] Jonathan Wolf: What is the difference between irritable bowel syndrome I.B.S. and Crohn's, and then can you help us understand for a minute what you're describing, which sounds very exciting? 

[00:30:20] Dr. Karan Rajan: So Irritable Bowel Syndrome is different to Inflammatory Bowel Disease, where one is autoimmune and one is, we think it's a gut-brain-driven functional disorder.

Inflammatory Bowel Disease is not a functional disorder. It's an autoimmune disease where there is the body's immune system is attacking its own cells, its own self. It doesn't recognize self as self, sees it as foreign and attacks it. 

That inflammation can cause symptoms like bleeding from the rectum, pain, and bloating. It can increase that chronic inflammation, can increase the risk of bowel cancers as well in many of these cases of ulcerative colitis and Crohn's disease.

Really these novel treatments, I mentioned these monoclonal antibody treatments, they're essentially immunosuppressants, which suppresses the immune system and thus would help to suppress and manage the symptoms that would be experienced by that inflammation. Anti-inflammatory treatments essentially, which are fantastic. And that's just a testament to how much we've progressed in the gut space. 

But equally, I see the gut space as this sort of reverse Dunning-Kruger effect, where the more we know, the more we realize we really don't know.

Because it's within the last couple of decades, people, I think a lot of it is in Holland, have pioneered these fecal microbiota transplant therapies, poo transplants, and seen remissions in cases of gut disorders, clostridium difficile infection. Clostridium difficile is a bacteria, and C. diff and Diarrhoea happen after prolonged antibiotic use, and that's awful. That can be life-threatening. 

Someone pioneered a treatment where you get poo from a healthy person, put it into the gut of an unhealthy person with this disease, and you see a disease remission. And this poo transplant is pretty widespread even in the U.K. And that's fascinating for me to think that, wow, such a DIY type therapy actually has some potent effects.

So it shows me that we're rapidly progressing in our understanding. But also, wow, it's like an abyss. There's so much to uncover. 

[00:32:22] Jonathan Wolf: I was really struck as you mentioned the fact that these inflammatory bowel diseases is autoimmune disease where your body is attacking yourself. 

Because we had a fascinating podcast recently about childhood allergies and the growth in peanut allergies where our guest was explaining that now about 1 in 10 children in the U.S. and the U.K. have a peanut allergy. And 50 years ago, it was 1%. 

So there's been this enormous increase in this situation, which is an allergy, which is again, as I understood it, your own body basically attacking this thing that is actually healthy food and thinking it's a pathogen.

Is there an increase also in these sorts of inflammatory bowel diseases in comparison to 50 years ago? Is that the same as it used to be or has that increased also? 

[00:33:07] Dr. Karan Rajan: Yeah, I mean, as far as the data concerns, increase in irritable bowel syndrome, increase in other digestive conditions, including inflammatory bowel disease, even colorectal cancers as well.

And as to why that is I don't think there is one singular answer. There may be something to do with the diet, almost certainly. It's changed significantly, whether there's some effect there. 

Climate and environment, that is certainly a factor as well. And you could also argue that our lifestyles and behaviors have changed significantly from how we sleep to how we interact with other people.

We have far more isolated lives these days than maybe 50 years ago, where maybe you could say we're a bit more asocial now. Particularly post-pandemic, there's been increasing isolation. 

So there's a number of factors and they all probably have a role to play. Epigenetic factors as well, so not just genetic. But environmentally, how the environment has changed our genetics. 

So I don't really know, is the honest answer. And it's an evolving space as we understand why it's all changing. Because if you look at certain populations around the world, and if you compare, yourself and myself, who are living in the U.K., the Western world, and you compare our gut microbiomes. 

We'll be relatively healthy guts, and you compare them to the most similar we can find to our ancestors, maybe a few hundred years ago, who didn't have access to the vices of modern life. Something like that would be the hunter-gatherers in Sub-Saharan Africa, the Tanzania, for example, the Hadza tribe. Their microbiomes have species of bacteria that are nonexistent in other populations, Italy, U.K., U.S. Why? 

So we've got the extinction of certain bacteria that are essentially endangered and only found in some of these hunter-gatherer tribes or sort of more isolated tribes. Why? So clearly the vices of modern life have a role to play.

[00:35:03] Jonathan Wolf:  Before we move on to what can we do about this, I just want to pick on one other thing you said because I think you mentioned a couple of times that we're actually seeing a rise in bowel cancer cases, and this came up on a podcast specifically, but I'm fascinated in if that's true, is this what you're seeing?

[00:35:20] Dr. Karan Rajan: Yeah, I mean, it's certainly more visible and certainly in younger people. You could argue is it a true increase in actual prevalence or are we just picking it up more because of better diagnostics? That's the real answer there. 

And it might be both. It might be that we are seeing an increase because of changing lifestyle factors, lower fiber, which is a risk factor for bowel cancer, et cetera. But also because we are more health conscious in 2024 than we were in 1924, for example. 

We have high-resolution CT scans, we've got access to these services, certainly in the Western world, far easier. I think even 20 years ago, 30 years ago, when someone comes to hospital with abdominal pain. As opposed to now in 2024 where we would get a CT scan within a couple of hours of that patient entering the hospital and we could pick up something serious. 

Decades ago, it was more a clinical diagnosis, it could be this and they'd be sent home potentially with a diagnosis of IBS without having a scan and that could have been a IBS masquerading as a bowel cancer potentially.

So it's that increase in diagnostics and, you know, clinical efficacy maybe now. But also, yes, there may be an increased actual prevalence as well. It's hard to unpick both.  

[00:36:44] Jonathan Wolf: You're saying we'd probably catch a lot more than we would have done 20 or 30 years ago because we got better technology for actually picking this up.

[00:36:49] Dr. Karan Rajan: And bowel cancer screening programs and all of these things and people engaging with them a lot more. So certainly, yeah, the pickup rate is much higher, I think. 

[00:36:56] Jonathan Wolf: Well, our listeners have been very patient while we sort of talk about what's going on. 

I definitely want to transition now to something I know you talk a lot about in all your different social media, which is when you're thinking about advising people about what they can do to make their guts happy, what do you say?

And maybe we should start with food, which obviously we spend a lot of time talking about in ZOE, and I'd love to discuss a bit with you, but then I'd love to discuss some of the other things that you talk about as well. 

[00:37:19] Dr. Karan Rajan: Yeah, I think it does start with food, a lot of the at least easy options. That someone can make a change from right now, listening to this podcast from tomorrow, from today, even making that change.

We know the gut microbiome is quite adaptable. It bounces back, relatively well, and it's very responsive to change. So even within 24 hours of eating a certain food, you can begin to see some changes in the microbiome. 

If you look at most of the literature that's out there, the meta-analyses and the systematic reviews when it comes to eating for better gut health, it's nothing very complicated.

If you break it down into, we talk about fiber and prebiotics, they're essentially the fertilizer for the bacteria, allowing them to thrive. So plant-based foods. Now, it doesn't mean you need to have a plant-based diet full stop and cut out every single piece of meat or fish. That's not the case, you can have a perfectly thriving microbiome, with meat, but the majority of the diet, if it is plant-based, that's good.

And I think even a lot of the ZOE data, which published a few years back, suggested that magic number to be around 30 grams of fiber a day. And I think getting not just that target in mind as that number, but also an abundance of variety as well. 

A lot of the studies suggest that the diversity comes from the colors, because the colors are linked to varying levels of polyphenols, which are antioxidants, natural phytonutrients, plant chemicals, which provide this sort of anti-cancer anti-inflammation effect.

That's what antioxidants and polyphenols are and that helps your gut ultimately. And all of these fiber-rich foods, apart from providing various nutrients, vitamin C, vitamin A, et cetera. Also provide that basics of the fiber, the solubles and insoluble fibers, which we can't deal with, with our normal digestive enzymes, but the bacteria, which we host in our colon. 

Their enzymes, the bacteria enzymes can deal with that. And then ferment those fibers which we can't process to then churn out other beneficial nutrients like vitamin K, B12, and much, much more. 

And a lot of these chemicals, particularly things like butyric acid, butyric acid is a short-chain fatty acid, which is very beneficial for the gut lining and the gut health in general.

So, all of these sort of basic things, colorful foods, diversity, and fiber. Those are the kind of very, very basics. 

[00:39:44] Jonathan Wolf: And all of that interestingly is basically about feeding your microbes to then support your health. So it's interesting that all of the things you've described so far, when you're saying, how do I have a healthy gut and hopefully reduce my risk of these symptoms, it's interesting you're very focused, in fact, on supporting your microbiome.

Is that a fair playback?

[00:40:01] Dr. Karan Rajan: Yeah, I think more so than worrying about adding more good stuff to your garden and adding more flowers to your garden, that's not sustainable unless you actually tend to the existing wildlife and flora and fauna that exists right there, right now.

And that's the best strategy you can do. So if you've planted all of these wonderful flowers, you need to take care of those instead of just adding more good flowers and forgetting to water the ones that are there.

[00:40:24] Jonathan Wolf: I love to hear you talk like this because I am reminded, as I said, about 25 years ago, my experience seeing quite a lot of doctors in the U.K. with the symptoms I have and just really no thinking at all about this idea that you have the microbiome, that you need to feed it.

And what's interesting is that I've been on a long journey with my own health and my symptoms got much better through my 20s and 30s. And interestingly, were triggered by an illness at the very beginning, which is something you mentioned could possibly happen.

But one of the things that I've been really struck is since I started ZOE and started working with all these different nutritional scientists, my diet has changed a great deal and it's made an immense difference to how I feel.

I never would've believed that that was possible. So I find there's something really wonderful that there are there. doctors now sort of talking about this. I do want to ask a bit because I think you were just switching there to contrast, I think, eating food with sort of probiotic supplements, right?

Eating something which says it has bacteria in it. And I want to come back to that question right at the very beginning. What are your thoughts on probiotic supplements?

[00:41:33] Dr. Karan Rajan: So I’ve prescribed probiotics to patients, limited over my career, but these are medical grade probiotics, have specific strains, lactobacillus usually, which is one of the most highly studied strains of bacteria when it comes to probiotic research. They have the right number of colony-forming units, so the right concentration, dosage, et cetera.

And again, when we prescribe them, we don't prescribe them with the absolute guarantee and belligerent confidence that they will absolutely work. They might work for a specific subset of people with conditions. 

So certain infection-associated, you know, antibiotic-associated infections, maybe certain subtypes of IBS and certain post bowel cancer or bowel surgery states, they may have some effect. We don't really know, but there is some evidence they may have some effect. 

So when you then contrast that with consumer-grade probiotics that's available for the public in your local supermarket, there is no way to guarantee that has an effect for a multiple number of reasons.

One being that our microbiomes are so unique, as unique or more unique than our fingerprints. So how can we expect an over-the-counter one-size-fits-all supplement to work for every single person? That is one argument. The second argument is in the U.K. and in the U.S. as well, these are regulated as foods and supplements, not medicines. 

They don't have to go through the rigorous medical testing and trial testing. So actually, these probiotic supplements and juices and drinks don't have to actually back up any evidence that they purportedly claim in their bottles. 

Do they actually have live strains of any of these? Do they have the right number of units? They can claim all these wonderful things like immune boosting, clarity, and focus. None of that has to be backed up at all. 

[00:43:25] Jonathan Wolf: That's rather depressing. 

[00:43:26] Dr. Karan Rajan: It's very depressing. And what's even more worrying is that I was of the opinion that, you know what, it's harmless. It probably won't work, but it's harmless. So if you want to take it, you're just wasting money. Go ahead. 

But actually, I was wrong. It's not necessarily harmless, because there is actually a few research papers out there suggesting that if you add in all these probiotics, if they are alive, what if they overcrowd existing good ones if they do end up colonizing? 

What if they end up colonizing in the wrong place and causing small intestinal bacterial overgrowth? What if they do cause more harm? And what if they contain contaminants? So actually, more so than money, there is published evidence suggesting there could be a risk as well.

And one final thing I will just say on that as well, there's one interesting study I read. which suggested that a lot of these bacterial strains put into so-called probiotic supplements are genetically engineered. And they could be harmful in a way that it contributes to antibiotic resistance.

Because these are, again, genetically modified and bacteria transfer their genetic information by a horizontal transfer. That's one way, apart from mutating. So they could transfer some of the genetically modified genes to bacteria that already are inside us, that we host, which could increase the risk of antibiotic resistance. That's definitely a concern. 

[00:44:49] Jonathan Wolf: I can tell you're definitely not very keen on people going down to the local grocery store and popping a probiotic. 

[00:44:57] Dr. Karan Rajan: I wouldn't be. I'm optimistic in that we will get to that point in science where actually that's a viable option, where we have tailored probiotics and we have, or even generic probiotics which actually do work.

But I don't think we can actually say, just like we recommend vitamin D in winter months, actually, yeah, we recommend probiotics for general health. I think we could get there in the next few years, maybe, but right now I don't think it's worth it because there are so many other low-hanging fruits.

[00:45:26] Jonathan Wolf: I think there have been two things that have been quite eye-opening for me. The first is because we can now do this sort of shotgun sequencing of the microbiome, so we can actually understand the individual microbes that are inside your gut, and then from that figure out which are really the good ones, and I described that we now have this panel of sort of 50 microbes that we've identified as good microbes.

What's interesting is these probiotics you buy, don't have a single one of those 50 good microbes, which was shocking to me. And what I've understood now is it's really hard to grow the microbes that are inside your gut because they like to live in a place with no air and they're managed by your immune system like it's a very special environment.

Whereas the probiotics that you can easily grow and therefore sell well they just live in the air and so you end up with these things that tend to colonize a yogurt well, but it's not necessarily the thing that's best for your gut. 

The other thing that was really interesting to me is that when I broke my toe, I called up two scientists and doctors who are associated with ZOE, Tim Spector and Will Bulsiewicz.

And basically, after all of this, they said, well, there's one probiotic that I think in this particular situation you might try, which is actually yeast. And Tim was like, oh, I actually wouldn't take any. I would just go all out on fermented food. 

And I was fascinated that like the cutting-edge insight was so far away from what I had started with, which is this assumption that, well, you know, just pop these probiotics. So there is like a really big gap, I think, between what's been sold today and it seems to be where the scientific evidence is today. 

[00:47:00] Dr. Karan Rajan: Yeah, I think so. And even when we recommend fermented foods, that's with the best intention of saying, listen, they contain probiotics. They also may be prone to not surviving the hostile environment of your stomach acids and digestive enzymes.

And they might also not take root and colonize, but they're cheaper. It's far more safe in terms of risk profile, there is a chance they can take root, but also more than that, they have a host of other benefits beyond just the probiotic nature. 

So yogurts and kimchi, for example, you're eating it for the protein or the fiber or the other spices, not just the probiotic value.

When you buy a probiotic, there's no other value in the probiotic. There's no extra protein. There's no other vitamins or minerals. It's just a probiotic. But with food, you get all these other benefits as well.

[00:47:45] Jonathan Wolf: Now Karan, I can't wrap up without picking up on something you've talked about a bit, which is foods that boost your mental health, and I know that there are a bunch of foods that say things like serotonin-boosting on the label.

What's your view about that? 

[00:48:02] Dr. Karan Rajan: I never really understood that. Actually my first instance with this sort of food mood thing was they say that cheese gives you nightmares and things like that. And I never really understood where's this coming from. Or Turkey makes you sleepy.

And I looked into it and then you look at all these generic websites. It's usually news headlines and they talk about the tryptophan and that causes the drowsiness and this and that. But often whatever's broken down in our guts. A lot of these molecules cannot cross the blood-brain barrier and have brain impacts.

So really, when food affects mood, I think it has an indirect role potentially. So if you eat more fiber and your gut microbes are healthier, they may produce metabolites and byproducts, which may influence your mood. 

But also not accounting for the fact that if you're eating more fiber, you'll probably poo better and you'll feel better as well. There's loads of indirect links, but directly I would be very hesitant to say there's a singular food that can either improve or ruin your mood. 

[00:49:09] Jonathan Wolf: With possibly the exception of alcohol that can do both in a short period of time. 

[00:49:14] Dr. Karan Rajan: And well, and then wipe out your microbes.  Yeah, exactly. 

[00:49:17] Jonathan Wolf: Now we talked a lot about digestion. I feel we should sort of come to the end of the line because I know that this is important for everyone who's a gastroenterologist or a surgeon. 

What's the criteria for an excellent daily poo? 

[00:49:30] Dr. Karan Rajan: I like to refer to it as the Goldilocks zone. You know, everyone's different. So, if you're outside the sort of threshold of three times a week to three times a day, that spectrum, you're probably running constipated. 

But your bowels are more than just frequency and number. It's also about how you feel afterwards, how you feel before, how you feel during, are you straining, how it looks, how it smells, how it feels. 

There's a number of variables here, but essentially, if you have some sort of regularity and even for example, you're going once a day, and you feel incredible after you've gone, and it's a huge evacuation. That even could be that you're constipated. You could well be constipated going once a day. It's a fallacy to think that you can't be constipated. 

So, there are things though that you can do to ensure that you have the highest chance of having a good motion. Beyond hydration and eating more fiber, there are things you can do in terms of, I mentioned at the start of this chat we had, that the gut is intrinsically linked to our circadian rhythm, that biological clock, and there are certain hormones which are released at certain times, which make us have the urge to go in the morning.

So if you keep going to the toilet for a number two every day at seven o'clock in the morning, your body releases hormones and enzymes and cues your digestive system to think, we need to make sure this happens at 7 a.m. every single day. 

So the day you're jet-lagged or you're traveling and you delay that by a few hours, that can disrupt everything, your whole digestive system and your appetite and beyond.

So actually keeping a rhythm, just like your sleep-wake cycle, trying to keep the sleep-wake times aligned, trying to keep your bowel motion timing aligned as well. 

When you have the urge, that is a cue, that's a signal to go, okay, go as soon as you can once you feel that urge. Once you feel the walls of the rectum stretching, that's a cue. You need to get there now.

Because if you ignore the cue, in the stool, the feces actually retro traverses inside your colon a little bit more, it goes backwards, it reverse parks slightly, and once it's in there, you missed the signal, and then you might have to strain, which then signals this kind of chronic constipation cycle

There's things which you can do in terms of your physical manoeuvres and habits in the toilet, trying to get your knees higher than your hips, maybe leaning forwards, putting your feet on your tiptoes to get more of that angle.

There's so many things you can do and even not spending an overly large amount of time on the toilet as well and straining. So there are certain habits we can suggest, but again, everyone is wired and plumbed so differently it's difficult to give sweeping recommendations for every single disease, state, and person.

[00:52:25] Jonathan Wolf: Do you know someone who gets frequent gut issues, cramps, indigestion, or can't eat certain foods? Why not share this episode with them right now? Empower them to feel better with the latest science-backed information. I'm sure they'll thank you.

It sounds like you’re saying it does matter. Having a regular movement ideally at the same time going when you want to go. This is going to affect sort of everything that is upstream if that isn't working right. 

[00:52:57] Dr. Karan Rajan: Yeah, I think really, you know, we're governed by so many hormones and clocks and rhythms our bodies basically that suggests they crave routines. Just like sleep, just like food, mood, everything, it's just routine.

When you're in a good routine, you feel good because everything runs on autopilot. And once there's even a slight variation or disruption of that routine, you almost feel ripped out of time and space almost. 

And it's the same thing with bowels, even if you're away from your usual toilet, psychologically, we know the gut and brain is linked, that can have a huge impact. If you're in a different country and you don't used to your own throne, it can be chaos. 

[00:53:35] Jonathan Wolf: I love that and I love that you're talking about it because I think this is one of those things where there's particularly like in the Anglo-Saxon world like you know America or the U.K., people don't like to talk about it.

I'm always really struck that you know if you go to Germany they have a completely different toilet bowl where afterwards you can really examine what's happened. Whereas in the States or the U.K., it's all designed to hide it away completely as fast as possible which tells you there's a very different mindset around this activity.

[00:54:01] Dr. Karan Rajan: I think so. There are inbuilt, inherent cultural taboos. We're obsessed with deodorizing the toilets with the potpourris. We don't like to talk about the smells. 

Interestingly in Japan, they have toilets that have white noise in public toilets because they don't want people to be ashamed of the noises they make when they're in the toilet.

So for those shy poopers, for shy pooping syndrome, they've got constant flushing white noise to drown that out, and I think that is a wonderful cultural example of how taboo toilet habits are. 

[00:54:34] Jonathan Wolf: It's brilliant and I have been to Japan, and they have these extraordinary toilets. We should do a whole mini-episode on that, but I know I'm running out of time.

So, my producer said I had to make sure I asked this last question, given it was so popular, and you picked it up a little bit in the short answer questions at the very beginning. Should we be holding in our farts? 

[00:54:54] Dr. Karan Rajan: I mean, ideally, no. because it's a gas that needs to escape and it'll just prove very uncomfortable and it can worsen any bloating that you might have.

So there's no harm to your life if you're holding in your farts, but it'll be a very uncomfortable. And I think the more you hold in your farts, it's essentially contributing to this taboo we have that it's wrong. 

I'm not saying that if you're in a busy meeting that you need to let one rip right there in front of everyone, but it's something which we need to take more account of. We look after our physical health in so many ways, it'd be a shame not to pay heed to the ugly duckling of the health world, the farts and the poos. 

[00:55:39] Jonathan Wolf: I can see you feel this is part of the feeling that this whole thing is just not as glamorous as the heart surgeon. Is that this is the fight back? 

[00:55:46] Dr. Karan Rajan: I'm trying to start a revolution in poo. 

[00:55:49] Jonathan Wolf: I love it. I think we are partly doing that as well. 

I'm going to try and do a quick summary if that's alright. And then correct me if I get anything wrong. 

So we started with this brilliant idea that digestion starts in the brain, and then you told us we are a doughnut, both of which I love and are going to stick in my mind.

And that's because, actually, it's sort of on the outside even though it's inside us, that it's much more than digestion. In fact, it's deeply intertwined with this nervous system, which is why our gut and our brain are linked in, in both directions. 

And you also talked a lot, I think, about how we now understand the microbiome is really important and that even when you were studying 15 years ago, it was sort of much less of a focus. There's been that big change. 

You talked about the fact that there's really been a rise in gut-related issues, whether that's IBS or like these serious diseases, like IBD and that likely diet is playing a big part in that.

But you said not only diet, it might also be our environment. And you talk quite a lot about antibiotics and you shared this study that I'd not heard of before. You said there was a nurse's study in the U.K., like a big one, I think you said 14, 000 nurses where the nurses who had had very heavy antibiotic use actually has lower scores on, on memory tests than the rest. Did I get that right? 

And so this idea that somehow this regular use of these antibiotics over and over again might be having these unexpected negative impact with the microbiome somewhere else. 

We also said really clearly, it can be life-saving, so you absolutely shouldn't feel that you should never have antibiotics.

And again, you gave me yet another brilliant vision, which is don't create a nuclear winter in our guts. So if you are taking the antibiotics, you want to try and make sure that they are focused for the problem, not just kill all the bugs because we understand now they're good. 

Then I think we talked about what can you do to to improve and you said food is the number one thing about better gut health.

Fiber is the first thing you wanted to talk about. You said it's a it's a prebiotic, it's like the fertilizer for our bacteria. Ideally you'd be getting at least 30 grams a day, which we know is not what most people are. 

But then you also talked about variety, diversity of colors, all these sorts of things.

Interestingly, you're a doctor, but you were not very keen on probiotics, at least for what people can buy themselves. You said there's no real guarantee this is going to work. Our microbiome is unique. You haven't really seen the data that supports it. And indeed given a choice, better to take fermented food, because even if the bugs didn't work, the rest of this is going to be valuable.

I asked you about the foods that will magically improve my mood. And what you said is that you totally see the impact of food overall being able to improve your mood, but you're very skeptical about an individual food being the magic thing that will improve us. So maybe like if you change your whole diet and your microbiome, but you don't buy that.

And then finally, I think we wrapped up with this idea that you should respect your natural gut's demands. So you said your gut also has a circadian rhythm. So if you're used to having a bowel movement seven in the morning, your body's expecting that and you really want to make that happen.

And indeed, if your body is saying it's time to have a poo, then you should go for it rather than hold it in. And actually you have the same view about, the fart. And I would note if you're on audio that I managed to make Karan smile a bit by just by saying the word fart. So even you find the word slightly embarrassing. 

But your point being that these are sort of natural bodily functions and resisting it all is part of what also potentially sort of backs everything up further up in the system. Okay. 

[00:59:36] Dr. Karan Rajan: Yeah, we need to make number twos number one. 

[00:59:39] Jonathan Wolf: I think that is a brilliant place to finish.

Karan, thank you so much for joining us. I really enjoyed it. I think I totally understand why you have this amazing ability to communicate these ideas in a powerful and memorable way. 

[00:59:52] Dr Karan Rajan: Thank you for having me and giving a platform for bowel related stuff.

[00:59:56] Jonathan Wolf: It's a pleasure. I hope we can convince you to come back again in the future.

[00:59:58] Dr. Karan Rajan: Absolutely. 

[01:00:00] Jonathan Wolf: I really enjoyed having Dr. Karan on the podcast today. My biggest takeaway is that if we look after our gut by feeding our microbiome with the right foods, it will look after us in return. 

Now, if you'd like to start taking better care of your microbiome, then listening to the show is the perfect place to start, but you can only do so much with general advice from a weekly podcast.

If you want to feel much better now and hopefully live many more healthy years, you need something more. And that's why more than 100,000 members trust ZOE each day to help them make smarter food choices. Combining our world-leading science with your ZOE test results, ZOE is your daily companion to better health for life.

So how does it work? ZOE membership starts with at-home testing to understand your unique body. Then ZOE's app is your health coach. Using weekly check-ins and daily guidance to help you shift your food choices to steadily improve your health. I rely on ZOE's advice every day, and truly, it has transformed how I feel.

Will you give ZOE a try? The first step is easy. Take our free quiz to find out what ZOE membership could do for you. Simply go to zoe.com/podcast, where as a podcast listener, you'll get 10% off. 

As always, I'm your host, Jonathan Wolf. ZOE Science and Nutrition is produced by Julie Pinero, Sam Durham, and Rich Willan. The ZOE Science and Nutrition podcast is not medical advice, and if you have any medical concerns, please consult your doctor. See you next time.