But

also, yes, there may be an increased actual prevalence as well. It's hard to unpick both. You're saying we'd probably catch a lot more than we would have done 20 or 30 years ago because we've got better

technology for actually picking this up. And bowel cancer screening programs and all of these things and people are engaging with them a lot more. So certainly, pick-up rate is much higher, I think. 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 I've always spent a lot of time talking about, and 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. Yeah,

I think it does start with the 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. And 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. So 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, you know, 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, you know, 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. And 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, etc., also provides that basics of the fiber, the solubles and insoluble fibers, which we can't deal with with our normal digestive enzymes. 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.

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? I think, you know, more so than worrying about, you know, 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, you know, 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. 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 UK with the centers 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, you know, I've been on a long journey with my own health and my symptoms got much better through my 20s and 30s. And interestingly, we're triggered by an illness at the very beginning, which is something you mentioned could possibly happen. But one of the things I've been really struck is since I started Zoe and started working with all these different nutritional scientists, you know, my diet has changed a great deal. And it's made an immense difference to how I feel. And I never would have believed that that was possible. So I find there's something really wonderful that, you know, there are 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 the question right at the very beginning. What are your thoughts on probiotic supplements? So I've prescribed probiotics to patients, limited over my

career, but these are medical-grade probiotics, have specific strains, you know, lactobacillus usually, which is one of the most highly studied strains of bacteria when it comes to probiotic research. And they have the right number of colony-forming units, so the right concentration, dosage, etc. 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, 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, you know, as unique or more unique than our fingerprints. So how can we expect an over-the one-size supplement to work for every single person? That's one argument. The second argument is in the UK and in the US 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, 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 and claritine focus. None of that has to be backed up at all. That's rather depressing. 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, you know, 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? What if they contain contaminants? So actually, more so than money, there is published evidence suggesting there could be risk as well. And one final thing I will just say on that as well, there was 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, you know, harmful in a way that it contributes to antibiotic resistance. Because, you know, these are, again, genetically modified, and bacteria transfer their genetic information via horizontal transfer. That's one way, apart from mutating. So they could transfer some of the genetically modified genes to bacteria which already are inside us that we host, could increase the risk of antibiotic resistance. That's definitely a concern. I

can tell you're definitely not very keen on people going down to the local grocery store and popping a probiotic. I wouldn't be. I think I

would, 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 with there in the science where 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. 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, you know, 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, they 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 like 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, like, well, they just live in the air. And so you end up with these things that tend to, you know, colonize a yogurt well, but it's not necessarily the thing that's best for your gut. And 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 Bolsiewicz. And basically after all of this, Will 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 the cutting edge insight was so far away from what I had started with, which is this assumption that, well, just pop these probiotics. So there is a really big gap, I think, between, I guess, what's been sold today and it seems to be where the scientific evidence is today?

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. Now, Karen,

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? I

never really understood that. Actually, my first instance with this sort of food mood thing was, you know, they say that cheese gives you nightmares and things like that. And I never really understood where's this coming from. And then, or turkey makes you sleepy. And I looked into it. And then you look at all these generic websites, they talk about, it's usually news headlines, and they talk about, you know, 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. With possibly the exception of alcohol that can do both in a short period of time. And

then wipe out your microbes. Yeah, exactly. 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? I

like to refer to it as the Goldilocks zone. 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, you know, 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. You know, 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 7am 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 those, you know, 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, you know, 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, you know, traverses inside your colon a little bit more. It goes backwards. It reverse parks slightly. And once it's in there, you miss the signal and then you might have to strain, which then, you know, signals this kind of chronic constipation cycle. You know, there's things which you can do in terms of your physical maneuvers and habits in the toilets, trying to get your knees higher than your hips, maybe even leaning forwards, putting your, you know, 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, you know, large amount of time on the toilet as well, and straining. So it's really, you know, there are certain habits we can suggest, but again, everyone is wired and plumbed so differently. is difficult to give sweeping recommendations for every single disease state and person. 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. But it sounds like saying it does matter, having like a regular movement, ideally sort of, you know, at the same time going when you want to go like this matters, is going to affect sort of everything that is upstream if that isn't working right?

Yeah, I think really, you know, we're governed by so many hormones and clocks and rhythms, our bodies basically, that suggests it craves routine. Just like sleep, just like food, mood, everything, it's just routine. You know, 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 you know, ripped out of time and space almost. And it's the same thing with bowels. You know, 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're not used to your own throne, that can be chaos. 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 UK, 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 like really examine what's happened. Whereas in the States or the UK, it's all designed to like hide it away completely as fast as possible, which

tells you there's a very different mindset around this activity. I think so. There are inbuilt inherent cultural taboos. We're obsessed with deodorizing the toilets with the potpourries. 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, you know, 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. 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? I mean, ideally, no, because it's a gas that needs to escape and

it'll just prove very uncomfortable and it can be worse than 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 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. You know, we look after our physical health in so many ways, it'd be a shame not to pay heed to these sort of more, you know, the ugly duckling of the health world, the farts and the poos. I

can see you feel, this is part of the light feeling that this whole thing is just not as glamorous as the heart surgeon is that this is the fight back. I'm trying to, you know, start a revolution in poo. 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 right. And then will you just 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 donut, both of which I love and I'm going to stick in my mind. And that's because actually like I got it 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 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 sort of gut-related issues, whether that's IBS or like these serious diseases like IBD, and that likely DART is playing a big part in that. But you said not only DART, it might also be an 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 UK, like a big one, I think you said like 14,000 nurses, where the nurses who had had sort of very heavy antibiotic use actually had sort of lower scores on memory tests than the rest. Did I get that right? And so this idea that somehow this regular loose of these antibiotics over and over again might be having these unexpected negative impact with the microbiome somewhere else. But you also said really clearly, it can be life-saving. So you absolutely shouldn't feel 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 improve. And you said like food is the number one thing about better gut health. Fiber is your first thing you wanted to talk about. You said 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 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 like, 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, you know, better to take fermented food because even if the, you know, 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 like, you totally see the impact of food overall being able to improve your mood, but you're very skeptical about like an individual food being like 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 sort of respect your natural gut demands. So you said like your gut also has a circadian rhythm. So if you're used to having a bowel movement at 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. This is stuff. And I would note if you're on audio that I managed to make Karan smile a bit 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. Yeah, we need to make number two is number one. 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.

Thank you for having me and giving a platform for bowel-related stuff.