HOW TO IMPROVE YOUR GUT HEALTH

Episode 297:
Show Notes  

This episode dives deep into gut health, covering the two pillars of a healthy gut — the gut microbiome and the gut barrier — and how real food versus processed food impacts both.​

The Two Pillars of Gut Health

The Gut Microbiome

• A large, metabolically active ecosystem — not just a collection of bacteria — that interacts directly with the immune system, metabolism, and even the brain​
• A diverse microbiome promotes health; dysbiosis (low diversity) is a primary driver of autoimmune and other chronic diseases​
• Diet is the #1 driver of microbiome diversity and resilience​

The Gut Barrier

• The gut is technically a tube — everything inside it is outside the body, making the barrier crucial​
• The barrier consists of cells, a mucus layer, and a surrounding immune system; it selectively allows nutrients and water through while blocking harmful substances​
• There is also a sophisticated enteric nervous system ("the gut brain" or second brain) wrapped around the entire gut, which underpins expressions like "gut feeling" and "trust your gut"​

Why "Not All Fibre Is Created Equal"

A key theme is pushing back against the 2026 trend of "fibre maxing" and health-washed processed foods labelled high-fibre/high-protein.​

• Real food fibre (broccoli, salads, low-carb veggies, nuts, seeds) contains structurally complex fibres that feed a wide range of bacteria, producing diverse short-chain fatty acids (SCFAs)​
• SCFAs fuel colonocytes (colon cells), strengthen tight junctions, increase mucus production, and modulate gut immune responses​
• Isolated/processed fibres (e.g., inulin, cellulose powders) only feed a narrow range of bacteria and produce a limited SCFA range — a poor substitute for whole food fibre​
• Polyphenols and micronutrients found only in whole foods further support microbiome diversity​

Types of Fibre Explained

​

How Processed Food Damages the Gut

• Refined carbs and sugars feed unhelpful bacteria and reduce microbiome diversity​
• Emulsifiers (e.g., carboxymethylcellulose, polysorbate 80) found in ice cream, breads, and many packaged foods act like "soaps" — thinning the gut mucus layer and disrupting the epithelial barrier​
• Animal studies show direct evidence of gut barrier damage; human observational studies link emulsifier consumption to significantly increased risk of inflammatory bowel disease​
• The low-fat movement is partly to blame — removing fat from products led manufacturers to add more gums and emulsifiers to replicate texture, while gaining higher "health star ratings"​

Actionable Steps for Better Gut Health

• Eat a diverse range of real, whole foods — aim for ~30 different plant foods per week (vegetables, fruits, nuts, seeds, herbs, spices)​
• Add variety to every meal — different colours, textures, and types of vegetables and lower-starch fruits​
• Go slow when changing your diet — introducing too much fibre too quickly causes gas and discomfort​
• Drink plenty of water, especially with soluble fibres that swell and form gel​
• Read labels — look out for emulsifiers and ultra-processed ingredients​
• For those who are insulin resistant (like Dr. Mary and Dr. Lucy), limit legumes and grains due to their higher digestible carbohydrate content, and favour low-starch vegetables​
• Practical swaps: Add chia seeds to meals, use pre-mixed seed/nut blends on salads, buy pre-chopped salad mixes for convenience​

Coming Up Next

The doctors preview future episodes covering IBS, a deeper dive into specific fibre types, and fermented foods.
 

Episode 297: 
Transcript

Dr Mary Barson (0:04) Hello, my lovely friends. I am Dr Mary Barson.

Dr Lucy Burns (0:09) And I'm Dr Lucy Burns. We are doctors and weight management and metabolic health experts.

Both (0:16) And this is the Real Health and Weight Loss podcast! 

Dr Lucy Burns (00:21) Good morning, lovely friend. How are you today? Dr Lucy here, and I am joined by my spectacular colleague, Dr Mary. And you know we've had a gutful of all things guts, so we thought this month we might actually talk about the gut. And I am super excited because Dr Mary's, she's a bit of a gun on gut stuff. So let's get cracking on it. 

Dr Mary Barson (00:47) I do love the gut.

Dr Lucy Burns (00:48) How are you, lovely? 

Dr Mary Barson (00:49) I'm good. I've got a good feeling about this. Maybe I have a good gut feeling about this particular podcast, and I may have to stop the puns there because it's getting a bit cringy. But I am well. I'm well. Good. And I love this topic. I do love gut health. I think that gut health is extremely important and interesting, and I can nerd out on it. And I also think that there's a lot of misinformation, misunderstanding, a lot of woo out there when people talk about gut health, and also a lot of health washing. A lot of the processed food industry has jumped in on this and is trying to health wash their processed food products by saying that they're high fibre, high protein, high fibre. And though that may sound good, when it comes to looking after our gut, food quality really, really matters, and not all fibre is created equal. So yeah, I'm happy to dive into this.

Dr Lucy Burns (01:49) Yes. As you know, I am always scathing of the processed food industry, and the term that is currently being used for 2026 is fibre maxing. So there's a lot of content on social media about fibre, and at the guts of it, fibre is usually good. But not all fibres, as you've said, are created equal. And slapping a label of high fibre, high protein on a processed food product doesn't make it healthy. And to use a very old-fashioned term, you can't polish a turd, but that's what they're trying to do.

Dr Mary Barson (02:24) That's right. That's right. So these processed food turds are still a bit turdy, unfortunately. When it comes to gut health, there's two main components that we need to think about. One is the gut microbiome, and the other is the gut barrier. So our gut microbiome has got a lot of press lately. We know it's just not a collection of bacteria. It's a really large, metabolically active ecosystem that directly interacts with us, directly interacts with our immune system, our gut lining, our metabolism, our brain even. And when our gut microbiome is nice and diverse and healthy and functioning well, it helps us function well. But when it is not diverse, when we've got dysbiosis, which means just not a particularly healthy inner garden, then that can be a primary driver for all kinds of illnesses, including autoimmune illnesses, but lots of others as well. And what we eat, the foods that we eat, is the primary driver of how diverse our gut microbiome is and how resilient it is. So it's not simply just about adding fibre. It is about the overall quality of the food and processed dietary habits. Even processed dietary food that is high in protein can have a really detrimental effect on our gut microbiome. And the other one is the barrier. So gut protects us. And our gut is like, it's really like a tube. It starts in our mouth, ends in our anus, and technically everything that's inside our gut is actually outside our body. It's a little bit of a mind bend, but it is kind of true. 

Dr Lucy Burns (04:10) I know it is weird to think about that. 

Dr Mary Barson (04:11) It's like this little tube. We are elaborate tubes. And this is a really important point because the stuff that's inside our gut, even when we've got a healthy gut, all of that microbiome, that poop, all of that stuff, it's good for it to be there, but we do not want it to get into our bodies. So the gut barrier is incredibly important, but it's also incredibly sophisticated because we need to get some things through. Like we have to get our water and our fluid and our nutrients through. That's extremely important. But we don't want to get the other stuff through. So it's a very, very sophisticated, selective barrier that's made up of our cells and a mucus layer. Our immune system is lining all around there. And also our gut, we've got a gut brain, this incredibly complex nervous system that is wrapped around the entire gut. People actually call that our second brain or our gut brain. Really, really complex, metabolically important, vital structures that are literally at the center of us and at the center of our health. And we do need to look after them.

Dr Lucy Burns (05:19) You know, I just love this because I love language. I'm a language, a bit of a language nerd. And so all of the puns that we've been doing, when you think about it — gut feelings, trust your gut — like that's all based in physiology. So, you know, there's nerve cells, and the anxious feeling that we get is often related to the nerve cells around the gut. You know, you've got an instinct, that like — I just think it's amazing. 

Dr Mary Barson (05:45)Follow your gut. 

Dr Lucy Burns (05:46) Follow your gut. Yeah. It's so incredible.

Dr Mary Barson (05:50) It is. Yep. Yep. Our gut brain is wise, and we should be able to tune into its wisdom whilst also nurturing it very, very, very well. So let's talk about how real food protects and repairs our gut. And I think a great place to start is fibre, which we touched on before. So fibre is incredibly important. fibre is what scientists like to call Microbiota Accessible Carbohydrates, or MACs. And essentially, it's carbohydrates that we eat that are not digested by our body. So instead, it stays in the gut. And as it's staying in the gut, it can feed the bacteria in our gut. And when these bacteria in our gut, they feed on the fibre, it's called fermentation. They ferment the fibre. And as part of this process, they create this fuel, this short chain fatty acid, which is the by-product of their fermentation. But then those short chain acids act like a fuel for our gut cells, particularly the cells in our colon. They love it. And then this fuel for our gut cells strengthens the junctions, like how well the gut cells stay together. It's what they call the tight junction. So it improves the barrier of the gut, increases the mucus production, which is another important part of the barrier, but also helps promote the way that the immune system is modulated within the gut and can help prevent further inflammation. So we really want to have this fibre in there to help feed our bacteria. But not all fibre is created equal, which I think is really important. The processed fibres, like fibre isolates, are things like inulin, cellulose. And although they can provide some benefit, they certainly can, they only feed a narrow sort of set of bacteria. And then those bacteria will then only create a limited range of short chain fatty acids. Whereas structurally complex fibres that are in whole foods, like your broccoli, your salads, all your low carb veggies, low carb fruits, your nuts and seeds, there's all different types and lengths of fibres in there, which feed all different types of bacteria, which then create different types of short chain fatty acids, which then nurture the whole spectrum of our gut. But it's also, it's not just fibre, it's also the polyphenols, like the plant nutrients that are in there, and other micronutrients, which are naturally found in whole foods, that nurture and support the whole microbiome. Because we want our microbiome to be diverse. It's not necessarily that certain bacteria are bad and others are good, although there is an aspect of that. It's more that we want it to be nice, to have great diversity within our gut, lots of different bacterial populations all working in there. And the way that we get those diverse bacterial populations is by eating a diverse range of fibres from real foods. So relying solely on processed fibres is nowhere near the same as eating a variety of intact plant foods. 

Dr Lucy Burns (08:58) Yes, absolutely. And I'm looking forward to one of our upcoming episodes where we do dive a little bit deeper into the types of fibres, because people will be asking, oh, well, what's the difference between soluble and insoluble? And what about sugar alcohols, which are technically a type of fibre, and pectins and all of these things? And we're going to go into that more. But I love what you've said, Miss, because, I mean, it just makes sense. But the structure and the delivery, or the matrix in which real food exists, is really important. And there are natural pairings that happen that don't necessarily happen when you get your fibre from a powdered supplement. Which is not to say that, you know, they're terrible. They're not terrible, but they're kind of like should be the second option. Absolutely. For people that can't access real food for whatever reason — whether they're, you know, they've had some anatomical issues, structural issues, financial issues — for whatever reason, it is definitely, you know, the second tier option.

Dr Mary Barson (10:05) And it's about that — how food interacts with all the different components of food, interacts with the other components of food. And I think we should talk about the damages of processed diets. So there are processed diets — you can get that fibre deprivation if you're eating a low fibre diet. Processed fibre is only going to make up for that a little bit. Not really, not completely. No, not at all. But beyond that, there's actually components within processed food that actively damage our gut. And they're things like really refined carbohydrates and refined sugars. They can feed unhelpful bacteria. They can promote a lower diversity within our gut microbiome, especially if we're relying heavily on those, which is not good. But also the things like emulsifiers that are put inside our food — and these are common food additives, like the carboxymethylcellulose and polysorbate 80. They're often in lots of foods — ice creams, processed breads, just heaps of foods. It improves the shelf life and the mouth feel of a whole lot of processed foods. And they're essentially kind of like soaps that we eat, these emulsifiers. And we've got good evidence — like good direct evidence in animal studies — that they thin the mucous layer and disrupt that epithelial barrier, that gut barrier that we need. And also we've got quite strong observational studies in humans that consumption of these foods is linked to a significantly increased risk of inflammatory bowel disease.

Dr Lucy Burns (11:42) Absolutely. And as we always say, the poison is in the dose. It doesn't mean if you have a small amount of some sort of emulsifier in some product, like a sauce or something, that your gut's going to disintegrate overnight. It's years and years over time of increasing quantities. And that's what we're seeing in the change of our food environment. So 50 years ago, there weren't a lot of processed products out there. There was cake mix or something and not much else. And now it's everywhere. And as you said, it's not always obvious as to what is ultra processed food. And again, there's some controversy over it. And not everything you buy in the supermarket that's in a packet is actually ultra processed either. So it's harder. It is hard for people to discover the nuance around it. But I just think that it's learning to read labels. And I know most of us are busy and we haven't got time. And again, it's reading a label, working out what's helpful, what's unhelpful. How much of that have we had this week in our trolley, for example? Oh, well, that's not very much. We'll have that because I'm not making, in my case, tomato sauce from scratch. I will buy some. And again, this is not a sponsored ad, but I will buy Mingle tomato sauce because I look at it and go, right, it has some processed products in it, but it's the least damaging of all the things out there. The trickiest bit is that a lot of these emulsifiers have been added because of the low fat movement. So low fat, well, it's been around for a very long time. And even though there is a shift towards the concept of healthy fats, healthy fats are still not even defined. And in the processed food world, the health star ratings are based on low saturated fats. So if companies want to get a higher health star rating, they take out the fat, add in some gums and emulsifiers to sort of bulk it up and make it feel like you're having fat. And then you get extra stars. Bang in a bit of fibre and some protein and whoop, suddenly it's five stars and looks as healthy as hell. Yes, absolutely. I just wanted to talk about the types of fibre that we've got. So it's broadly classified into soluble and insoluble fibre. So the way to remember it is soluble, as the name on the box says, it dissolves in water. So these dissolve, they form a gel sort of substance, and are then easily fermented by gut bacteria. So they can be helpful for improving our gut microbiome. The other one is the insoluble fibre. So it doesn't dissolve in water, and it is less fermented, adds to the bulk of your stool. And so for some people that can be helpful for gut motility and improving peristalsis. For some people, though, it can actually make constipation worse. So it's always important to, again, we'll mention this, but when you're changing your diet or what you eat, to do it slowly. Now, interestingly, there's actually some subtypes of soluble fibre, which I'm sort of starting to become a fibre nerd. So if we want to think about the subtypes, we've got pectin. So pectin's found on the skins of fruits, and it's the thing that forms gel and is used in, you know, things like jams. And it is very fermentable. We've also got something called beta-glucan, and that's the one that is found in oats. And as you know, as low-carbitarians, we're not big oats fans, but there is potentially some role in lowering cholesterol if that is one of your goals. Again, we've got our own thoughts on cholesterol and where we need to be in that sphere. It is potentially important in secondary prevention of cardiovascular disease, but the jury is still a little bit out on primary prevention. So we'll just move on from there. But then the other types of soluble fibre are what's called gums and mucolages. So that's like psyllium. And again, they form a gel. We use psyllium, again, for constipation. It's used a lot in cooking, which is rather helpful. And then these are the ones that are the tricky ones. So the tricky ones are things like fructans and inulin. So these are found in, they're found in normal foods. So they are found in cereals. They're also high in onions and leeks and garlics and Jerusalem artichokes. Not that I'm chowing down on those. Don't think you are, Miss, either. And they do act as prebiotics. So they can be helpful, but they can also really ferment. And the inulins in particular, which are derived from chicory root, are prolific in ultra processed food. And so for people getting gut issues and gut pain, it may well be the quantity of ultra processed food that you're having. The last ones are called galacto-oligosaccharides, or GOS, and they're found in the beans and lentils. And this is why, again, when people over consume, they can get a lot of gas, they can get a lot of gut pain. So like lots of things, a small amount can be useful, too much unhelpful. And some people are really intolerant. And then the insoluble fibres. So these are the things that are found often in vegetables, but these are the things that we don't digest. So, you know, when you see undigested bits of food in your poop, that's this stuff. So it's high in nuts and grains, some vegetables, things like corns and stuff like that, certainly vegetable skins, and it can be useful. It's cellulose. It's certainly not a terrible product. Hemicellulose is another type of insoluble fibre, also found in grains, which again, we're not eating a whole heap of those, little bit fermentable. And then the last one is something called lignin. And it's a polyphenol compound found in really woody plant materials and seeds. So the outside, you know, the outside of your linseed, it's that. Now, the other thing I just want to have a quick mention for is something that is getting a lot of press is something called resistant starch. So resistant starch is carbohydrates, and they are technically not a fibre, but we can take some carbs and make it behave a bit like a fibre. So this is where the whole cooked and cooled foods that you may have heard about are coming. So things in particular, like potato and rice. Now, this doesn't turn them into a no carb, free for all potato, rice, bread, but if you were going to have them as part of your diet, then the way for them to have the least amount of carbohydrate in them is to cook them, cool them and reheat them. So again, that might be something that's useful. When you have increased resistant starch, that's also, they also produce short term fatty acids, again, good for the colonocytes. The other place where you can get resistant starch is green bananas. And I don't know anyone who is going to eat those, you know, voluntarily, because they're pretty gross. So the key with this is, again, as you mentioned, Miss, is getting a variety. So this is what is lacking in ultra processed foods. It is the cheapest variety. They can slap fibre on it. It doesn't tell you anything about the type. But if, again, having a diverse range of foods in your diet can be helpful, and thinking now about where you're getting your fibre from.

Dr Mary Barson (19:52) It is genuinely confusing when we have these processed food products masquerading as health foods. It is a genuinely confusing world out there. I think it could be helpful if we sum up with some like, what are like a few actionable steps that you could take? You know, listening to this, what are the few things that you could do to help improve your gut health? Starting with your next shop?

Dr Lucy Burns (20:18) Yeah, so certainly, I mean, what you know, we are loud, proud omnivores. I know that there is a carnivore community out there and we'll probably shunned for them, that's fine. There are a few people that can't tolerate vegetables. And there are people that can't tolerate, interestingly, some of the fibres that are found in, you know, FODMAP foods. They're just hypersensitive or sensitive to some of these, these fibre products.

So the key is to, if you're changing your diet, and it really is to go slow. So if you haven't been eating lots of vegetables and you go out and eat a whole cauliflower, well, nobody's going to be loving you for that, least of all your, and certainly not your gut. But adding a diversity of vegetables, and dare I say some fruits, again, lower starch fruits for us, is going to be helpful to your gut. It will like it.

Dr Mary Barson (21:13) Yes, absolutely. I'd say as much as possible, just choose a variety. You don't need to be, I think, obsessional over it. There are quite a few famous studies saying that people who eat 30 different plant fibres — like plant products, sorry, plant foods, 30 different plant foods throughout the course of the week — had the healthiest gut microbiome. It's like that might be a bit hard, aiming for 30 different. And so that's all across your plant seeds, nuts, herb spices, all of those — aiming for 30. It's a lot. I think it's totally doable, but it might be a bit hard to go straight off. But just think about variety: a mixture of colors and textures. And that way, you're going to be getting different types of those phytonutrients, and those different types of polyphenols, and definitely different types of the plant fibres, which are going to help maximise that microbiome diversity.

Dr Lucy Burns (22:02) Yeah, absolutely. And this is, as you all know as well, just to clarify, we are still pro-meat, like pro-meat and fish. Totally. Pro-meat, fish, to eggs and dairy — that's our protein sources. And legumes, well, this is the tricky bit. Legumes are very high in fibre. They really are. They're also quite high in digestible carbohydrates. So when we're talking about carbohydrates, there's the total carbs, which includes technically fibre. And then we've got net carbs, which is the glucose that will be absorbed. And then the leftover is the fibre that is not absorbed. So legumes are higher in starches. They're higher in glucose than many of the other products, you know, then things like meat, for example, in your protein, and as our grains, which is why, you know, for us being women who are insulin resistant, we — Mary and I — choose not to eat grains usually, and certainly not a lot of legumes. If, you know, a chickpea snuck in or a bit of hummus, I'm not going to worry about it, but it's not something I would actively choose. But it does have a good source of fibre. So it is about balancing it all up. So it might be good for people who are not insulin resistant, or who are, you know, kids and stuff like that, who are not insulin resistant. But for people like you and me, Miss, it's something we probably don't eat a lot of.

Dr Mary Barson (23:27) No, and there's still lots of delicious, you know, veggies and fruits that you can — that do fit in with that lower sugar, lower starch that is helpful for us.

Dr Lucy Burns (23:39) Yeah. Yeah, absolutely. So, um, you know, and again, we've been experimenting with recipes in our new program, the Metabolic Action Plan. You know, there's particularly chia, which I know is, again, it's having another revolution. We've been talking about chia for a long time — chia puddings — but you can add chia to lots of things, and it's a good fibre source. And the other thing I've started doing is I've just made up — well, I've made up, I have not made it up. I bought it at a shop. It is a mixture of nuts and seeds. So it's got sunflower seeds and pepitas, which are pumpkin seeds, and some pine nuts. And basically I just sprinkle that into my salad. So I've already got salad, I've got leaves. Delicious. Yeah. And I will now try and buy leaves — like I try and buy, I still like spinach leaves, but I also buy rocket. I'm not a big fan of some of the others; they have the bittery ones. Rocket's peppery, but the others are a bit bitter. Your radicchio. Yeah, yeah, yeah, yeah, absolutely. And the butter one, it's, I don't know what it is about the texture or the size or something. It just drives me nuts. Um, but then, you know, I think like I was looking at my salad last night, which did have rocket and spinach, and then it had some cherry tomatoes, and I had some cucumber. I had a little bit of pumpkin, and I have my three seed mix. I had some herbs in the dressing. I don't know if it's enough to count, but I sort of thought, right, well, that's pretty good. Plus, you know, I just then had my air fryer — it's quite diverse. Yeah. Yeah. I had my air fryer chicken on it. Olive oil was bloody beautiful. I eat that all the time. It's so delicious.

Dr Mary Barson (25:17) Yeah, it's good. I like to get the, um, pre-chopped salad mixes from the supermarkets because I'm, you know, time poor — aren't we all? I tend to ignore, if it comes with a little sausage, I usually ignore that, but, um, yes, just like pre-made. And I'll get the ones that have got, like, you know, bits of beetroot and carrot in them as well, because, you know, a little bit of beetroot and carrot is not going to make the world end. And it's good. Yeah. Get a nice, it's an easy way to get, uh, basically just to get a delicious salad without much effort, which is a full plus for me.

Dr Lucy Burns (25:46) Yeah, absolutely. Um, so again, if you're going to add to your foods, the key is start slow and go and titrate up. This is the same for anything — fermented foods, anything that we do that is changing what we're delivering to our gut. And like always, you know, plenty of water is also useful, particularly for some of the soluble fibres that swell up. Again, we'll talk a bit more about that next week, but they swell and create this gel sort of consistency. But if you don't provide enough water for them, they actually suck water out and can increase, um, constipation and things like that. So, you know, again, it sounds so boring, doesn't it? Plenty of water — but plenty of water. It's good.

Dr Mary Barson (26:28) Yeah. We've only thought this is just like a small snippet of, like, the actions you can take to help your gut. But I actually think it's probably the most powerful one by far — is the real food versus processed food. And just getting that sorted in, in your mind, getting it sorted with the actions you take means your gut will be very grateful. 

Dr Lucy Burns (26:47) Absolutely. Good friends. All right. We will be back next week with more gut stuff. We're looking forward to it and helping you get lovely, healthy, pain-free guts as well. 'Cause you know, IBS — we can talk about that. Um, another modern-day disease, and, uh, go from there. 

Dr Mary Barson (26:05) Bye guys.

Dr Lucy Burns (26:06) Bye.

Dr Lucy Burns (27:10) The information shared on the Real Health and Weight Loss Podcast, including show notes and links, provides general information only. It is not a substitute, nor is it intended to provide individualised medical advice, diagnosis or treatment, nor can it be construed as such. Please consult your doctor for any medical concerns.

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