Episode Summary

**EP411: Gut Microbiome with Prof Talley Part 2** **Dr Warrick Bishop:** Welcome, my name's Dr Warrick Bishop. I'm a cardiologist, an author, and a keynote speaker. I'm the CEO of the Healthy Heart Network. I'm all about trying to help people live as well as possible for as long as possible. Heart disease is huge in Australia. Every 20 minutes, someone suffers a heart attack. Most of these could probably have been avoided if only we knew what to do. This podcast is all about helping you understand blood pressure, weight, and cholesterol for better health. If you enjoy this podcast, I would be honoured by a five-star review. You can share it with your family and friends. It may well save someone you love. Hi, it's Dr. Warwick here, and welcome to my podcast and videocast station. I have Professor Nicholas Talley with me. He is a gastroenterologist, an epidemiologist, a researcher, an educator, and an author. He actually will have done the podcast just before this one. So if you missed that, go back and have a listen. We're back for part two of Gut Microbiome. In the first episode, which I really do encourage you to go back and have a listen to, we recognized that the gut microbiome is incredibly complicated. We're talking millions to billions of organisms and an incredible interplay with how the body works, not just your gut, but beyond that, even to the brain. So welcome, Nick. Thank you so much for joining us again. **Prof. Nicholas Talley:** Thank you for having me. **Dr Warrick Bishop:** Look, some of the things that we were talking about previously were absolutely fascinating. And all I can do is encourage anyone who missed that last podcast to go back and have a listen. But we touched on the interplay between the gut and other systems, diabetes, Parkinson's disease, and obesity. Well, I'll share something with you really to try and get an understanding of your comments around the protective role of the gut microbiome. I was sitting in a presentation a year or two ago at a medical conference where they were talking about salt and high blood pressure. Now, for those listening, historically we've always thought if you eat too much salt, then water follows that salt. That increase in water increases the blood volume, and the increase in blood volume leads to greater pressures in the body. That greater pressure in the body drives wear and tear on the arteries, making them thickened, and therefore blood pressure becomes a self-fulfilling prophecy. I've been dealing with that for a long time. I have to say I was never completely sold on the salt story because it didn't seem to make sense. I always wondered why dolphins didn't have high blood pressure, but that's a different issue. As I sat there and listened to the presentation, they really outlined a series of experiments where they loaded salt into the diet of hypertensive-sensitive rats and demonstrated that the salt caused microbiome damage, which exposed the gut and created leaky gut. This allowed particles to get into the bloodstream, and those particles, which were inflammatory particles, ended up in the blood vessels and made them thicker, driving the high blood pressure from the inflammation of the blood vessel, not from the salt and water. They fixed or reversed this process or altered this process by adding fiber to the experiment. And I sat there, honestly, Nick, and I was blown away. I thought, this is just amazing. So speak to us about this concept of leaky gut, how the microbiome protects that leaky gut, and what other things leak in and what other conditions are impacted. Maybe Parkinson's is on that spectrum as well. **Prof. Nicholas Talley:** So we do think leaky gut is an important disease factor. We really do. I know alternative practitioners have been talking about this for a long time, but they haven't really understood what has been going on. But now we're starting to see evidence, the real science behind this, that there is leakiness of the gut that allows bacterial factors and other organisms to interact with the immune system. That's one way it drives change. It also allows food to interact with the immune system. So all of the foods we eat are potentially allergic, if you like, they're antigenic. And that can lead to interactions with the immune system, and then that can lead to disease. There are other mechanisms too because once the gut's leaky, there's no doubt anything in the lumen of the gut, anything in there that shouldn't normally get to the cells below will get in potentially. Little bits of it can lead to active inflammation. And inflammation is one of the key drivers of all chronic diseases virtually, from cancers to heart disease to most things that we worry about as chronic disease. We know inflammation is a key driver. What drives the leakiness? Probably there are lots of different factors. There can be genetic factors. There can be environmental factors. So if you take a medication like a non-steroidal anti-inflammatory drug like aspirin or ibuprofen, that can lead to the gut getting leaky because it damages the gut lumen, damages the gut wall. That allows things to get in, and that leads to problems down the track. The bacteria interacting with the food can lead to reactions as well. You can get kind of an allergic response to that interaction. And we've been studying that in a number of diseases because it seems highly relevant that if we can identify the factors that drive the leakiness, that might be a way to drive the inflammation. That might be a set of factors we can modify relatively easily. And you mentioned fiber. We've known for a long time that a high-fiber diet tends to produce a more diverse microbiome, which means a healthier microbiome. By the way, going and getting your microbiome tested commercially, don't bother. Don't waste your money because at the moment, most of those tests are just completely worthless. They just don't tell you anything that allows you to work out what to do. But having a high-fiber diet, a healthy diet—yes, lots of vegetables, lots of fruit—those simple things make your microbiome healthier, and that really helps. Look, while we're on those things that you can take, let's just break down probiotics, prebiotics, and the sort of supplements people may want to think about if they're wanting to maximize their gut health. What's a probiotic, first of all? **Prof. Nicholas Talley:** So a probiotic is, the theory of probiotics is you give a healthy group of organisms, or organisms that you find in healthy people. They're live organisms. They're supposed to be alive. And you take these to repopulate your gut microbiome bacteria. So that's the theory. We've known about this for 100 years. We've isolated these various organisms from many, many years ago often, and these are put into probiotics that you buy at the chemist for lots of money. What are the problems? Most times, the bugs have died in the capsules before you even get them in. So you're often eating dead bugs, not live bugs. And that's why, you know, if you're taking them off the shelf rather than from the fridge, you're going to wonder if they're really alive or not. Sometimes they are, but sometimes they're not. The other problem with them is they don't repopulate the gut microbiome. They just pass through mostly because the gut microbiome doesn't like new bugs coming in. It basically resists new bugs coming in; you have to displace the old bugs to get in new bugs often, and the probiotics alone don't do this very well. So probiotics can have health benefits in very small amounts, not large amounts, in terms of the studies that have been done. So you do see small benefit effects sometimes, but the data is all over the place. What I say is probiotics mostly don't help you very much; you're much better off with a healthy diet. Prebiotics are basically substances that help the good bacteria to grow and the bad bacteria don't grow as well. That's what a prebiotic is. You know, we're very interested in prebiotics, but fibers are prebiotic. You know, fibers, fibers, fibers. **Dr Warrick Bishop:** It's what you're doing with fiber when you eat a high-fiber diet. When we see medical headlines really discussing the problems with ultra-processed food, is that ultra-processed food having a detrimental effect on the gut microbiome as well? **Prof. Nicholas Talley:** Certainly, ultra-processed foods are everywhere in our diet. You look at the supermarket shelves; many of the things we buy, we all eat them, by the way. Many of the things we buy are ultra-processed, and basically, they're like chemicals we're eating in our food. There's more and more evidence, unfortunately, that these things can cause leaky gut, which we talked about earlier. So that's one issue. They can change the microbiome in ways that are unhealthy, not healthy. They've been linked to a number of chronic diseases, although whether they're really cause and effect, in other words, direct causes, is a little bit less certain from the data I've seen. So bottom line is, keeping ultra-processed foods—that's things like potato chips and all sorts of things that we buy in packets—almost everything in a packet is ultra-processed. The less we eat of that, the more we eat healthy foods that are, you know, fruits and vegetables, things that we know are not ultra-processed, the better off we will probably be in terms of our general health. But you can't avoid ultra-processed foods. It's impossible not to eat some. Certainly, from a cardiologist perspective, the salt and the trans fats are problematic just on their own, let alone their effect on the gut microbiome. **Dr Warrick Bishop:** Absolutely. Yeah, so try and avoid stuff with barcodes if you're listening. It's true, actually. And it's really interesting, you know, the gut bacteria also—the nutrients that we eat affect atherosclerosis risk as well, which, of course, is the ultimate factor driving heart disease. So some of the things like we eat in our foods, we eat certain chemicals, certain food products like choline and carnitine, and that gets sort of changed in the body by bacteria to a particular chemical that actually drives your atherosclerosis risk. So it's interesting; the gut microbiome and food are part of the atherosclerosis cycle probably. Look, I'll mention that; I'll come back to that inflammation very briefly for those listening, just to give an example. We're talking about the whole gut microbiome, which is really from the lips right through to the anus. I had a patient who I can clearly remember with recurrent problematic atrial fibrillation, so the irregular beating of the heart because the top chambers of the heart are playing up. This particular person had periodontitis and quite bad gums, and when they had that fixed, when they had it tended to, their atrial fibrillation disappeared. It disappeared, which for me was an incredible observation. I hadn't really seen it written. I hadn't seen it documented. It makes perfect sense. But you've got how many metres of gastrointestinal tract from one end to the other? **Prof. Nicholas Talley:** Oh, it's very, very long. The old 30 feet number comes to mind. It's incredibly long. Of course, we measure things differently, but it's incredibly long. There are patches everywhere that can be potentially at risk. So look after that gut microbiome. One of the questions I did want to ask, and it comes around from time to time, and I think of it myself if I'm caught in the situation, is if we have an intercurrent illness, a chest infection or an ear infection or whatever it might be, and we need antibiotics, what impact does that have on the gut microbiome and how do you guide someone through that process? **Prof. Nicholas Talley:** So antibiotics have a huge negative effect on the gut microbiome. In fact, it has a negative effect on all the microbiomes in the body, we believe. And that effect is not just necessarily short-lived. There are data which show that if you follow an individual for a reasonably long time, I'm talking several months or even longer, and people have done these experiments, the microbiome diversity really gets impacted very badly by a general antibiotic. Most antibiotics seem to do this, although it varies by how broad-spectrum the antibiotic is, of course. But regardless, it has a negative effect. And that effect then leads to changes in the microbiome that occur in like almost a zigzag shape. You know, it will go up, it'll go down and change over several months. Eventually, it may get back into more of a normal pattern for that individual, but not always. So sometimes it can be very long disturbances. So what we're really saying here is if you don't need an antibiotic, don't take one. That's really important. Of course, if you do need one because you have an acute infection that must be treated, then that's absolutely fine. Some people suggest trying to give probiotics or other approaches to help maintain the microbiome, but the evidence that’s really beneficial is incredibly limited, so I don't think that really helps. But again, the healthy diet story is probably critically important if you can maintain that. So look, you know, for most people, it doesn't lead to any long-term health negative effects, but theoretically, multiple courses of antibiotics may predispose you to new disease. One of the risk factors for inflammatory bowel disease is having had multiple courses of antibiotics. So, you know, it's certainly potentially a risk for chronic disease down the track. **Dr Warrick Bishop:** Wow. So eating your yogurt and making sure you've got plenty of fiber are useful things if you're being prescribed antibiotics? **Prof. Nicholas Talley:** Well, yogurt certainly has bacteria in it that are thought to be relatively healthy. How many survive through the stomach acid and down into the small intestine where they need it varies very much. But I guess it's certainly unlikely to hurt you and probably could have some benefit. But I think the high-fiber diet, the healthy diet—what's called the Mediterranean diet—is often thought to be the healthiest diet in terms of not just cardiovascular health, but general health as well. All of those things can be useful. I also tell my patients, because we underestimate the importance of this, exercise helps shape the microbiome in a positive way as well. You know, getting exercise is good for your health regardless. Make sure that that's part of your active health promotion going forward. Look, we're going to come towards the end. I just, because we've again blown another 15 minutes effortlessly, what I would like to try and finish off with is what are some practical tips? You said that it's not worth testing the gut microbiome, but is there a way that people listening might be able to get a handle on whether their gut microbiome is healthy or unhealthy or any comments on that? **Prof. Nicholas Talley:** I guess it's not an easy question to answer. Certainly, if you've got a healthy microbiome, normally you have a normal bowel habit. So if you've got constipation or you've got loose bowel motions, it might suggest that microbiome is not as healthy as it could be. And that may be an indicator of that, a very simple one. The amount of times we open our bowels actually correlates very well with how fast things move through our gut. So that's another indicator of health, I suppose. But unfortunately, we don't have any easy ways of doing this. And we don't have any great tests that we can say, "Oh, this will help you work out what to do and tell you to eat a healthier diet." It's really the other way around. Measuring what you eat, looking at what you eat, and then deciding if it's healthy and then going towards a more healthy diet going forward. But I guess my biggest message is this: We are only half human. I really want to emphasize this. There are 30 trillion human cells. There are 39 trillion microbial cells in every single one of us. There are 20,000 human genes. There are up to 20 million microbial genes. We're 43% human in terms of cells and 1% human in terms of genes. Think about it. **Dr Warrick Bishop:** Wow. That's an insane statistic. Look, with that, which is a bit of a mind-boggling concept, I think we might wrap it up for fear of going down a black hole of uncertainty. For those listening, thank you so much for giving me your time, and I really hope you found this chat with Professor Nicholas Talley as informative as I have. I'm sure you will have. If you've got any queries or questions or suggestions for future podcasts, hit us up at info@drorichbishop.online. Nick, again, I'd like to thank you once more for finding the time to share. **Prof. Nicholas Talley:** Thank you very much for having me. **Dr Warrick Bishop:** And for those listening, until next time, I hope you live as well as possible for as long as possible. Take care and bye for now. Hi. Ever wondered what your risk of heart attack is? You should. It's the single biggest killer in the western world. We're talking one death less than every 30 minutes in Australia. One death less than every 60 seconds in the United States. Nine million deaths globally per annum. Well, how do you check your risk? You can go to www.virtualheartcheck.com.au. You'll find out about your risk and what can be done beyond that to be even more precise.