Instant Genius - Gut health, with Dr Megan Rossi

Episode Date: January 3, 2022

Dietician and nutritionist Dr Megan Rossi explains why your gut health is important, and how you can improve it without cutting out your favourite foods.Once you’ve mastered the basics with Instant Genius, dive deeper with Instant Genius Extra, where you’ll find longer, richer discussions about the most exciting ideas in the world of science and technology. Only available on Apple Podcasts.Produced by the team behind BBC Science Focus Magazine. Visit our website: sciencefocus.com Hosted on Acast. See acast.com/privacy for more information. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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so you can experience exceptional sound at home. Music just as the artist intended. Visit namea audio.com to learn more. Hello and welcome to Instant Genius, a bite-sized masterclass in podcast form. I'm Sarah Rigby, online staff writer at BBC Science Focus magazine. In this week's episode, I talk to Dr. Megan Rossi, also known as the gut health doctor, who is the author of The New Book, Eat More, Live Well. In the book, she explains the diversity diet, a way to improve your gut health without cutting out your favorite foods.

She tells me everything I need to know about gut health and what I can eat to improve it. First off, could you please just tell us a bit about yourself? So my name is Dr. Megan Rossi and I'm a dietitian by trade with a PhD in gut health. But, you know, if we rewind 10 or so years when I was studying nutrition dietetics, I certainly didn't ever think I'd be going into gut health because it wasn't really that much of a hot topic. But actually, sadly, I lost my grandma to bowel cancer. And that was really my conscious, my first conscious encounter with the gut. And then I started working as a dietitian.

and I started to find that so many of my patients and clients, whether they're in the hospital settings, so I had different types of cancers or diabetes, or actually some elite athletes that I was working with, what I found they're all coming to me complaining of the gut. And I thought, gosh, what is it about this organ? And that was 2010, so there hadn't been a whole lot of gut health research really at that stage coming out. And I thought to myself, you know what, I owe it to my grandma and to my patients to find out more about this, you know, somewhat misunderstood organ. And that's when I decided to embark on a PhD in the area and try to understand more about it. And it completely changed my outlook. It became so clear that actually the gut was just very misunderstood it and

had so much power and potential. If we understood how to look after it, we really could improve our lives in very real and often surprising ways. So that's when, yeah, I decided I really wanted to dedicate the rest of my career to gut health. So I did all of that background research in Australia, so you may pick that by my accent, and moved over to the UK to continue working as a research fellow at King's looking at all different types of nutrition interventions and how they impact our gut health. So when we're talking about gut health, are we specifically talking about the gut microbiome or is there something else that contributes to it as well? It's a really great question because I think gut health is a word now most people have heard about, but what it is

exactly is not very accurately communicated. So gut health relates to functioning of our entire digestive tract. So we've got this nine meter long tube coiled up in each and every one of us. And that nine meters is so, so important for three main reasons. One is, you know, digestion of food. So the good old saying you are what you eat is kind of not that correct. It's more you are what you digest. And in order to have that, you need to have a really good gut lining to extract that nutrition from your food for it to get from your gut into your blood to feed your other organs. So really to make the most out of our food, we need to have good gut health. The second element of gut health is really around our immune system. And that comes down to the fact that

70% of our immune cells actually live along that nine-meter digestive tract. And that's why we see the gut health and immune health really do go hand in hand. And like you said, this third element, the gut microbiomes, those trillions of microorganisms, is certainly an area that's made, I think, gut health more of a hot topic. It's brought the fame to the area. And it really is a landmark scientific discovery and we're discovering, you know, things that we thought human cells were doing for us like hormone production, vitamin production. Actually, a lot of that is done by these microorganisms living within us, again, in that nine-meter digestive track. Why is gut health so important? What parts of your body can it affect? Yeah, this is where the gut microbiome is, you know,

really this landmark discovery in terms of these microbes have been linked to the health of pretty much every organ in the human body. So things like our brain health, our kidney health, our heart health, etc. We think the microorganisms living within us are actually really important in the communication and the health and disease risk of these different organs. And what different organs does it affect? Literally, the research has linked our gut microbes are pretty much the health of every organ in our body. I mean, there's fascinating research out they're connecting our gut health and our brain health. We call it the gut brain access, which people may have heard about. And the research, you know, one of the landmark studies was

called the Smiles trial. And what they did was fascinating in terms of their, of their type, to show that actually nourishing the gut through the right nutrition can actually have, you know, clinically meaningful improvements in people's mental health. And for me, you know, as a dietitian, And we're always got taught that, yes, diet may have some sort of role in mental health. But that study really gave me, I guess, the confidence to say, actually, it's not just an add-on benefit. It can have a hugely and clinically relevant improvement in people's mental health. So certainly when I'm seeing patients in gut health clinic, I do look at how I can really nourish

their gut bacteria and improve their mental health. In many cases, with the support of patient psychiatrists, if they're on, antidepressant medications, we've been able to lower them via really nourish. people's gut bacteria. And if we wanted to improve our own gut health, I've often heard that changing your diet is a big one, but are there any other things we can do? This is an important topic because I think a lot of people, certainly are the ones that I see in clinic, they are all very much fixated on their diet. And like you said, absolutely we know diet is crucial in delivering good gut health results. But you can have the most perfect gut-boasting diet. But if you're super

stressed, not getting enough sleep and not moving your body, actually you're not going to have ideal gut health because those three other areas independent of diet are known to have important impacts on our gut health. Right, I see. And so let's talk about diet for a bit. So in your book, you talk a lot about how a plant-based diet can improve your gut health. So why is it that a plant-based diet in particular is good for your gut? Yeah, I mean, this is the whole point of, of me writing my new book, Eat More, Live Well, because I think there is just so much confusion out there in terms of how we should be eating to really maximize

not just our human body cells, but also our gut bacteria. You know, the myths out there essentially have suggested that we need to follow a very restrictive diet in order to have good gut health. But the science doesn't support that at all. What it's suggesting is that we need to really maximize the types of plants that we're eating in our diet

in order to get ultimate gut health. And whatever we add on top of those plants, if we want to add a little bit of animal foods, then that's completely fine. So I talk a lot about this concept of plant-based diversity in Eat More Live Well, where I think the concept of being plant-based has been slightly misunderstood.

So if we think of the definition of plant-based, it means the base of your diet is plants. And like I said, whatever you decide to add on top of that is up to you. So plant-based doesn't mean plants only. Like I said, according to the research, it shows that people who we eat at least 30 different types of plants in their diet each and every week seem to have better gut health than those who eat the same 10 on repeat. And the research, I think, was really interesting in that actually compared vegan, so those who were 100% plant-based and omnivores, those who eat plenty of plants, but also ate animal products. And what they showed is actually being vegan, 100% plant-based didn't mean they had better gut health.

it really came down to the concept of plant-based diversity. So that's what I'm really about in terms of helping people with the practical strategies, the really easy ways in to get as many different types of plants in their diet without extra cost, extra effort. And yeah, that's essentially the reason why I wrote this new book, because it's really frustrating to see in clinic people who really want to make the most out of their gut health. And they're following these crazy fatty diets because they've read it's beneficial on a blog. and I'm seeing like this organ that has so much power and potential being destroyed and

mistreated by following very restrictive diets. So is it just a case of getting more fibre? That's an easy in to, I guess, the concept of how we nourish our gut bacteria because fibre, which essentially is a backbone of all our plant-based food groups, is really important to nourish the bacteria. So interestingly, humans actually don't have the enzymes needed to digest fiber. So when we eat plant-based foods with all the fiber, and actually most of that gets melabsorbed through that 9-meter digested tract.

And in the lower part of the digester tract, where we actually have most of our microorganisms, and that's where the digestion begins because they've got the enzymes to break that fiber down, produce all these really beneficial chemicals, which then feed and nourish the rest of our body, some of which communicate to things like our brain and our liver, et cetera. So they're really, really important.

So fiber is absolutely crucial. However, what we're discovering is, you know, it's not just about fiber. And this is why just having a fibre supplement's never going to get you the wide range of benefits that following a plant-based diet will. And that's because, you know, we have tens of thousands of other plant chemicals, and we call them phytochemicals in food, which do so much to support our body. And, you know, the pharmaceutical world hasn't actually discovered how to manufacture a lot of these chemicals, again, which is why trying to get in as many,

different types of plants in your diet is going to be the optimal way to maximize your health and also the health, those trillions of microbes living within you. Fiber, yeah, as you say, it's not the only one, but it is the one that a lot of people are most familiar with that you need to get from plants. But what exactly does fibre do in your body? Yeah, so historically, you know, from all the research, it was known that people who ate more fibre had better gut health. And the mechanism thought to attribute that was because fiber essentially helped you poop. But now we've appreciated that actually there's so much more to fiber. Yes, fiber helps with bowel regulation. And let's be honest, we all feel better once we've

had a regular bowel habit. But actually, we're discovering about these microorganisms. And it's only, I guess, been the last 10 or so years where we've appreciated the in-depth nature of how important these microbes are for the wealth of different functions in the body. And the fiber is their favorite nutrient. So if we have a very low fibre diet, essentially we starve these bacteria and therefore we don't possess all of the skills that we need to function at our optimal because these microbes are doing so much for us, including, you know, like I said, producing a range of different vitamins are also really important in different hormone regulation. So without a really well-fed community of microbes, we think that is why people are high risk of a range of chronic conditions like type

to diabetes, mental health conditions, autoimmune conditions, etc. I think a lot of us would be keen to find some foods we can eat that are really good for our guts. So are there any foods in particular that are especially good for our gut health? A lot of you have asked me, you know, what are the fire foods I need to be having more of? You know, what's the superfood? And you know what? According to the science, there is no such things as superfood because it comes back to that concept of diversity. like I said with Eat More Live Well, and that's why, you know, this is what we should be trying to do.

Instead of just having broccoli, you know, you get the steam mix of vegetables because you each different type of plant have a range of different types of chemicals which actually do different things in the body and also feed different types of bacteria. So instead of thinking, you know, what are my five types of food? Try where you can think of diversity. So instead of just having almonds, get the mixed nuts. Instead of just getting sesame seeds, get the meat. mixed pack of different seeds. Same with the fruit and the berries, etc. Because we see people who eat the different types of plant-based foods have the better

gut health. And that's because each different bacteria like human cells actually have different taste preferences. So if we're only feeding our bacteria, you know, broccoli types of fibres and plant chemicals, we're only going to be really harvesting the growth of the broccoli-likeing bacteria. We're not going to get the bacteria that lacks chemo or the bacteria that lacks wheat. And all of these different bacteria have their own skill set. So we really like a sporting team.

We want to get as much different variety and skills within us. And how we do that is through a plant-based diverse diet. And what about those probiotic yoghuts and things like that you can get? How much of an effect do they have on your gut health? Yeah. So we certainly do see this world of fermented foods coming to the. forefront. And that's where we get things like live yoghets, um, kaffirs, which is type of fermented dairy, kimbucha, um, kimchi, which is like a fermented type of cabbage. There's many different

types of fermented foods out there. And actually my team at King's College in London did a review of the science to have a look at how strong the evidence was for having these fermented foods on our gut health. And although there's, you know, many, many studies out there highlighting potential benefits through test tube studies, actually there's a real lack of translation into human clinical trials. So I guess with my scientific hat on, I am not going to say you have to have these fermented foods in order to have good gut health. However, we certainly are seeing that potentially they could have mechanisms where they are linked to overall better gut health and mental health, etc. So my philosophy is dabble in them, dabble in fermented food,

taste them, explore with them, you know, many of them, you can. You can, can easily make it home. In fact, and eat more live well, I talk about how you can make some of them really low cost at home. And it's a fun thing to do to get the kids involved in science as well. But yeah, you don't need to have them essentially to get good gut health. And a lot of the marketing claims out there are really, I think, are surrounded by a lot of myths and just trying to make people buy things when evidence isn't there. And as well as probiotics, I've also seen advertised prebiotics. So what's the difference between a probiotic and a prebiotic? Well, despite one letter difference, so PRE biotic versus PRO biotic, the prebiotic, essentially most of them are types of

dietary fibers that are found in a wide range of plant-based foods where they essentially feed the good bacteria. Now, in terms of supplementation, there are a few cases in my clinical practice where I would recommend a prebiotic supplement, but the vast majority of people, can be getting their pre-biotics from eating that plant-based diet. So, again, you don't need to necessarily fixate and knowing that garlic and onion and chickpeas and lentils have loads of these pre-bikes, isn't it? If you're getting in your 30 different types of plant-based foods per week, which is my challenge for everyone listening, then you're going to be getting in plenty of prebiotics.

Now, the probiotics, so we did mention the live yogurts, so you mentioned, and also, you know, the fermented foods. Now, there's also another realm of probiotic out there, the capsule form, the supplementation form. And I talk a lot about this in my first book, Eat Yourself Healthy, where the probiotic world has very much been misunderstood, I believe, in terms of, you know, one day the media is saying they're super beneficial, everyone should be taking a supplement, and the next week they're saying they're a waste of your money. Whereas kind of the evidence is very much in between where each different type of probiotic actually can do slightly different things. So you need to be very savvy with, I guess, your selection of a probiotic. And if you're generally healthy, actually, the evidence supports that you don't need to take a probate capsule.

However, there is around seven areas where there's good scientific evidence to take a very specific probiotic. And I talk about these probate prescriptions and eat yourself healthy. But as an example, one is if you have to go on antibiotics for whatever reason, there's really good evidence to take one of two probiotics. One is called Saccharomycese Pallardi. and the other one is called Lacta Pesos Raminus Gigi. So you would take either of them at 5 billion units twice a day throughout your antibiotic period

and for a week after. Now, see how prescripted that is? Now, you know, I lot of people like, oh my God, that sounds really painful. But you know what? If we want the benefit of probiotics, that's actually how we need to treat them. There's no point describing any off the shelf and just taking it. You need to be very specific if you want that therapeutic benefit. it. Otherwise, you know, just get all of your nutrition and your life cultures from the food

that you're having versus taking supplements. Are there any foods that are really bad for your gut health? One of the concepts that I talk a lot about in Eat More Live Well is about, it's more about what we're adding into our diet versus cutting out. So think inclusion, not exclusion. And that is really based on the science where it shows that, you know, things like added sugar. A lot of people think added sugar. It's a toxin and it's bad for your gut health. But actually, the science reinforces that sugar, so table sugar, gets absorbed very high up our digestive tract. So actually doesn't reach the bulk of our gut bacteria. So having loads of added sugar is definitely not great for our overall health. But that's not because sugar is a toxin. It's because if we're filling up

on these added sugar foods, then actually we're not going to be getting in all that plant-based diversity that our gut bacteria need. So it's more of an indirect reason of why it's not not great to include. So if we're focusing on adding in plenty of different plant-based foods into our diet, but then, hey, we have, you know, some treats here and there. That's absolutely fine. You can still have, you know, fantastic gut health. So think about what you're adding in, first what you're kind of cutting out is a really important concept and also really important for your relationship with food. I think a lot of people are starting to get a little bit fixated on their diet and it can really ruin how people enjoy food.

food and food, you know, it should be enjoyed. It's a very pleasurable thing. In terms of, I guess, you know, like you said, that the foods that are really bad, now the science is currently looking at specific food additives. Now, there's close to 400 food additives that have been approved as safe in our food supply, but those additives were tested, you know, back many years before we really appreciated the importance of our gut bacteria. So they're all tested on human metabolism, so to speak. But now we're appreciating, actually, we want to make sure we're not harming these gut bacteria within us by having food additives. So there's this re-evaluation process currently underway. And at King's, we're actually looking at a certain group of food

additives called emulsifiers. And we're looking at, based on some pilot study, some early stage studies, suggesting some of them may not be very good for our gut health. So I think where you can, trying to reduce the number of processed foods and really, you know, map. maximize the whole fresh foods that you're having. But again, the research is too early stage for me to say completely cut them out of your diet. So I don't want to scare people. But that's just where the research is currently investigating. So we can improve our gut health a lot, as you've said, by eating a lot of plant-based foods. But given that we evolved as omnivores, why is it that our gut microbiome seems not to like meat and animal products as much as it likes plants? I love this. This is a great question. And, you know, the truth is it doesn't necessarily hate all animal product. We certainly know that things like omega-3, which is found in oily fish, actually, people who eat more of that seem to have better gut health. So some microorganisms really do like things like your omega-3s. So again, that's why I'm certainly not anti-meat, but I am very passionately pro-plants, because that's what the evidence is suggesting. You don't need to cut out all of these animal products. But we do know that we should be having the base of our diet on plants. And the reason for that is because of the nutrients within plants is the foods that our microorganisms prefer.

If we eat loads of animal products which are high in protein, what that does is overwhelms the higher part of our digestive tract's ability to actually digest and absorb that protein so it gets from our gut into our blood. And if we get too much protein getting into the low part of our digestive tract, the bacteria, when they cement it, produce a range of different chemicals that are thought to be linked with things like colon cancer risk. So our bacteria, when they eat too much protein, it's not very preferable for overall health outcomes. However, if you're having the protein with plenty of dietary fiber from the plants, actually that overrides any sort of detrimental effect.

So again, it's all coming down to diversifying your diet, adding the base. of it coming from plants and adding, you know, some animal products on there if you enjoy them, then that's completely fine in terms of overall health. Brilliant. Thank you. And finally, what three things do you think we all should know about gut health? I think the first one comes down to it's not about following a restrictive diet for optimal gut health. People who've got a more broad and diverse diet seem to have the best gut health. So thinking about what you can add in in terms of plants versus what you can cut out. The second one,

I would say is that it's not just about diet. So don't just fixate on diet and ignore your stress levels, your sleep levels and your exercise because they all can impact the gut bacteria. And the third one, I would have to say it's not just about what you're eating, but also how you're eating. So keeping in mind that digestion actually begins in your mouth, not only do we start to physically break down the food, but we have the enzymes in our saliva which start to chemically break down the food. So we should be chewing our food, you know, at least 20 or so times to really get optimum digestion to really help nourish our gut bacteria in that way. So I think they would be my top three things for people to take away from what we've chatted about. Diversity all the way, chewing your food well

and, you know, thinking about the other domains, not just diet. Thank you for listening to this episode of Instant Genius. That was Dr. Megan Rossi. If you want to know more about the diversity diet, Check out her book, Eat More, Live Well, or head over to Instant Genius Extra, available only on Apple Podcasts. The New Year issue of BBC Science Focus magazine is out now. Pick up a copy in store or visit ScienceFocus.com. This podcast is sponsored by Name, Audio and Focal. The texture and emotional depth of music can be lost through digital sources or poor signal. Name Audio believes you can have digital precision,

with analog warmth. Alongside French acoustic specialist vocal, Name creates high-end audio systems combining innovation with craftsmanship so you can listen to music, just as the artist intended. Discover more at name audio.com. Ambition comes in all shapes and sizes.

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