Why Your Body's Microbes Hold the Key to Your Health and Happiness - An Interview With Alanna Collen

What follows is a transcript for the podcast Gut Health - Alanna Collen - Microbiome.

Topics within the interview include the following: 

• How quickly the gut microbiota shifts when we change what we eat
• How even one course of antibiotics impacts our microbes
• The importance of the microbiota and metabolites in learning and memory
• The role of the vagus nerve in regulation of body weight
• Why counting calories is complicated by the gut microbiota

Dr. Greg Kelly: Hello, this is Dr. Greg Kelly, the director of product Development at Qualia and today's host for Collective Insights Podcast. And with us today we have Alanna Collen, a science writer with a PhD in evolutionary biology from University College London, and the author of the Life-Changing Popular Science Book, 10% Human: How Your Body's Microbes Hold the Key to Health and Happiness. She's a well-traveled zoologist, an expert in bat echolocation, and an accidental collector of tropical diseases. Welcome to the show today, Alanna.

Alanna Collen: Thank you for having me.

Dr. Greg Kelly: Oh, it's my pleasure. I loved your book. I've read several books now related to health, The Gut Microbiome and yours was a five star.

Alanna Collen: That makes me happy.

Dr. Greg Kelly: Sure. So I wanted to just jump right in and just start with your background because at the beginning of your book, you talk a little bit of your own story and how you view things as an evolutionary biologist. So can you tell us a little bit about what led you to that profession and what an evolutionary biologist does?

Alanna Collen: Yeah, I've always been a biologist since I was in my teens, that was my thing, and I was very much into wildlife. I also loved human biology, but I loved wildlife. So I started studying bats when I was at university, and I then did a master's in bats and then a PhD in bats and many other trips for field work for other professors and so on. And my PhD was in the evolution of bats.

So an evolutionary biologist is someone who studies how evolutionary changes take place over time. So I was trying to work out how bats evolved echolocation, the way that they see the world through echoes through sound. And so looking back to 85 million years ago, what cool were they using? And basically, all this work took me to a lot of jungles and a lot of other very amazing habitats. And that's where my journey into this microbiome thing began.

Dr. Greg Kelly: I can imagine, well, I would think your background would give you a keen insight into the microbiota, microbiome because they're adapting all the time, and that a-

Alanna Collen: Absolutely.

Dr. Greg Kelly:... really quick rate.

Alanna Collen: Yeah. So it's one of the easy ways to see what's going on in evolution because for us it's really slow because our generations are 25, 30 years each. But when your generation time is 20 minutes like a bacterium and you're doubling your population all the time, then it's very easy for scientists to work out how evolution takes place. So yeah, they are like a literal Petri dish of studying evolution.

Dr. Greg Kelly: One of the things and this was right at the beginning of your book, when you tell a little bit about your time at... I know probably mispronouncing it, but Krau Wildlife Reserve in Malaysia.

Alanna Collen: Correct.

Dr. Greg Kelly: And having gotten infected with a tropical disease taking antibiotics. And this is from your book, I had a suspicion that antibiotics I had taken had not only eradicated the bacteria that plagued me, but also those that belonged in me. And I think that's such a profound realization for most people that these things that we've often been thought of as they're the villains, the bad guys in the story are actually doing these super important jobs.

How Even One Course of Antibotics Changes Our Microbiota

Alanna Collen: Absolutely. Yeah. At that time, I had no idea that... I knew that we had good microbes or good bacteria living in our guts, but I really was not aware of how much they did for us. In fact, really no one was aware of how much they did for us. I think there's something to do with being a evolutionary biologist. It struck me that if they were living there, they probably had a role to play and that if I'd taken so many antibiotics that maybe I had damaged them. And that was why I was feeling ill in new ways from my head before.

Dr. Greg Kelly: But I know I was shocked with some of the statistics you put in your book about antibiotic use and how many courses an average adult would have or by a certain age, how many a child would have. And I was thinking like, "Wow, I'm abnormal. I haven't had antibiotics." I think since 1987. But-

Alanna Collen: Wow, good for you-

Dr. Greg Kelly: Not-

Alanna Collen: ... wow, that's a really long time.

Dr. Greg Kelly: I'm not anti-antibiotics, I just haven't had the need. I think there was maybe 70 was an average adult's number of courses in a lifetime. And can you tell the audience a little bit about what happens, not just with one course, but when there's repeated courses of antibiotics over time?

Alanna Collen: Yeah, so even one course can have a really significant effect in the short term because it depends on the antibiotic, but very many antibiotics that were given in what's called broad-spectrum. And that's that they can kill a huge number of different kinds of bacteria in one go. And that's super useful if you are a doctor and you're trying to wipe out an infection, because you don't need to figure out what it is first. You just give someone this cluster bomb and it sorts it out.

But the downside of that is the collateral damage it does to all of your microbes that you do actually need. So yeah, in the short term, they're really very significantly affected. And if you are lucky, within two weeks you get a significant rebound effect and a lot come back. And probably particularly, if you have an appendix, which is like a little safe house for your microbes, where at the antibiotics don't get in there quite as much as they do the rest of the gut.

But over time, you will wear down the diversity of your microbiome by taking multiple courses of antibiotics. And on the flip side, you'll also increase your very own antibiotic resistance, which makes you less capable of responding to antibiotics in the future. But the most significant thing about taking antibiotics is when you do so or when your child does so.

When it's affecting particularly under three years old, it has a real impact and even later in childhood. Because at that stage, your microbes are communicating with your body to an incredible degree and they're teaching it how to be human. And so if you wipe those out or you even disturb them for a short period of time, you can have quite a big impact on how we develop and how our immune systems function.

Why Early Childhood Period Is a Critical Window for Both Brain and Gut Microbiome Development

Dr. Greg Kelly: Well, since you mentioned that early childhood period, the critical window for both their brain development but their gut microbiome, I loved how in the book you talked a little bit about the ecosystem idea and described how in a child, it's almost these sweeping changes one after another over those first few years. So could you maybe share a little bit about what those are? Because I know most people think of lactobacillus because it's in yogurt as an example, and you mentioned that, but that only sweeps in quickly and then gets swept out to an extent.

Alanna Collen: So typically, babies who are born vaginally will be inoculated with loads of lactobacillus because they are the vaginal microbiome. And that's what the child is encountering when it comes into the world. And lactobacillus is super helpful because they break down lactose and lactose is the major sugar in breast milk. So that's what you want them to be doing. But as time goes on, they get replaced like in waves just in the same way that you would if you left a patch of earth, bear or even a patch of rock bear, you'll start with getting some mosses and then some bigger plants will come in and then the soil level will build up.

And ultimately if you left a big enough area, you would get some kind of forest, what we call a climax community. And that's effectively what's happening in your gut. It starts out raw, like a patch of rock, and then it gets a nice coating of microbes to start it off when you're born. And then they get replaced by different sets of microbes until you have your climax community, your adult microbiome, and somewhere between the age of three and 18. And it can change throughout your life, but there's something about the age of three, which seems to be significantly more stable than the infant microbiome.

Dr. Greg Kelly: I don't remember which author, maybe it was Ed Yong, but the Thousand Days is what sticks in my head. As a general heuristic.

Alanna Collen: Exactly. Yeah.

The Role of the Vagus Nerve in Regulation of Body Weight

Dr. Greg Kelly: And then a big part of what your book then does is its I think you say I've learned to ask the questions, why, when, where, how. So you're trying to then sort out all these different modern diseases. What we could think of as things that have really become epidemics over the last four or five decades, obesity, metabolic health, neurodevelopment disorders. And I think I've had my eye on the weight obesity area for what feels like 20 years or more, actually, more going back to the Navy when I was asked to help the overweight people get in shape. And I just thought you did a fabulous job bringing all the different research together on the gut microbiome and obesity. So I'd love if you'd share a little bit of that with the audience.

Alanna Collen: Yeah. So it's more complex than you would think it would be is the first thing to say. So the thing that people first think is, "Oh, your microbes are consuming your food and therefore they can extract more calories from it and therefore you get fat because you've got calories." But it's more than that because of course your body actually should have a mechanism to decide how much weight you carry, how much stored energy, energy stored as fat that you have. So if your microbes are taking in more calories for you, then your body still should balance how much it is carrying.

So yes, if you have a microbiome, you can take in more calories than if you don't like really significant amount actually maybe 30% additional calories from... I'm talking about mice here. So you can make mice germ-free where they're born in a sterile environment, and they have no microbes at all. And if you then add microbes, then they have to eat 30% more to stay the same weight. So in humans, that is part of it, but then the much more significant part is what they're doing to your immune system.

So there's a couple of things. One is that your microbes, when they consume fiber in particular, they produce little chemicals metabolites, which then stimulate your nervous system through the vagus nerve, which I think people are becoming much more aware of these days. So the vagus nerve travels actually collects information from all over your body, but very much from your guts and it takes that information back to your brain to let the brain know what's happening in the body. And it is stimulated by the compounds that your microbes make when they eat, when they consume fiber. And that tells your brain that you are not hungry anymore.

It's even more complicated than that, however, because the other thing that microbes do is they control your immune system, and they stop your body from being inflamed. So there's an example in my book of one quite exciting microbe called Akkermansia muciniphila, which means mucus loving muciniphila. And this microbe, it lives in the mucus layer on the edge of your gut, and it eats fiber. And when it eats fiber, it then stimulates a particular cell called a goblet cell in the lining of your gut to make more mucus.

So it's providing itself with a home and it's providing itself also actually with something to eat it, much it prefers to eat the mucus. So when the other microbes are producing compounds from fiber, then that enables this mucus loving microbe to stimulate the gut to produce mucus for it to eat. And that mucus provides a barrier between your guts and your blood.

Essentially your gut is outside, it's like your skin, it's inside, but it's outside. It's exposed to the rest of the world. And so it has to have some pretty tight security policies to work out what should get through and what shouldn't. And obviously we want food to go through, but we don't want pathogenic microbes that could harm us. We don't want things like pollen to get into the bloodstream, all things that aren't helpful to us if they go across the bloodstream. So we have this mucus layer, and we also have a set of cells that are really clever chemically, and they can work out whether they should let something through or not.

And they're a bit like bricks, so bricks that can move, they can move apart and allow things through, or they can tighten up and stop things from coming through. So when you have a good microbiome and you are eating fiber, those things stimulate a nice mucus layer and they make your gut lining stick together really nicely and tightly, and that prevents things that shouldn't be going into the bloodstream from going into the bloodstream.

If you have a poor microbiome, you have a thin mucus layer, your gut lining isn't being told that it needs to tighten those defenses, then all sorts can get through including compounds that the gut microbiome itself makes which are inflammatory. And it is that inflammation that process then creates in your body where the immune system goes, "Oh my God, what is this stuff? I don't want any of this in my blood." And it has a little panic. It sets the immune system on high alert and that then changes your brain and changes the regulation of your appetite, the regulation of how much weight your body wants to carry.

And enables you, makes your body want to carry more weight and makes you want to eat more, makes you be more restful and want to exercise less. So there's an awful lot more control that is nothing to do with consciousness, nothing to do with greed, laziness, someone's personality. It's just about what's happening biologically in your gut and in your brain that determines how much weight you're carrying.

Akkermansia: A Next Generation Probiotic

Dr. Greg Kelly: I want to just touch on Akkermansia for a second. I know the Biohacker Community in general here in the States and I know when I described it to our marketing team and some of the people at Qualia, it's like, "Oh, think of this. This is a next generation bacteria that's also thought of as a keystone species." So having more of it in its niche, it just controls that niche reshaping it to make that whole gut healthier.

And you've also mentioned phaco bacterium as another important one of the organisms in your book as well, which is another of the keystone species. And so I think what I've seen is most of us think of probiotics as the old generation or I think of it as 1.0 probiotics, the lactobacillus, bifidobacteria, which is nothing wrong with those, but when I hear or see things written about Akkermansia, it's like, "Oh, cool, they're talking about the next generation." Like the updated.

Alanna Collen: Yes. Absolutely. And it really is the next generation, because one of the reasons why the traditional are the probiotics that we have are that they're easy to grow in an oxygenated environment. We can do stuff outside the body, we can make yogurt from lactobacillus and yeah, they're easy to make. The trouble with Akkermansia is not... I've seen online Google searches like suggested searches. "Where can I buy Akkermansia?" You can't. I'm afraid because it's anaerobic, which means it exists solely in environments with no oxygen.

And so it's not actually that easy to make into a probiotic that you can just sell on the shelves. It is though being worked on in that way. I'm not sure where they're up to, but there were various patents when I was writing the book that even making compounds metabolites from the Akkermansia, even dead Akkermansia seems to work to some degree. And so I'm sure one day it will be a commercially available probiotic. It's not the be all and end all. It's not like you've got that you're thin, you don't have it, you're overweight. It's not nearly that simple. And there are so many that potential bacteria and interactions as well that can play into it.

And of course, there's what you do with your microbes. It's not just take some and then you're sorted. You've got to feed them. And there's also a lot of, I'm actually writing my next book on obesity and on the underlying causes of obesity. So not diet and exercise, but what makes us eat too much, what makes us move too little? Why does that happen? What's happening in our guts? What's happening in our brains for that to happen? And I'm not talking about psychology here, I'm talking about the real nitty-gritty biology of it. And there are many, many things that play into it. But yeah, Akkermansia is a beautiful example.

Dr. Greg Kelly: And in the States, there is a company Pendulum would be the product that makes an Akkermansia that's alive probiotic. And I think EFSA in Europe has only improved. You mentioned the inactivated, so a postbiotic version of Akkermansia, but I'm not sure if there's a company selling that in Europe. And then just my role, I get spoken to a lot by probiotic companies and companies selling into the dietary supplement space, and there's at least two I know of that are-

Alanna Collen: Oh, really?... working.

Dr. Greg Kelly: On-

Alanna Collen: Oh my God.

Dr. Greg Kelly: ... stabilizing Akkermansia. So I think it'll become much more available. But like you mentioned, it's a piece of the puzzle, but this is a crazy complicated puzzle.

Alanna Collen: It is. Really is the complexity it's an absolute web of... We're not just talking about the microbes themselves and how they interact with each other, but how they interact with our genes and how they interact with our food. And just, there are so many variables here that it is really difficult to pull it all apart. And there are of course many, many pieces that are acting simultaneously as well.

Genetic Manipulation of Gut Microbes

Dr. Greg Kelly: Well, you mentioned genes. So let's touch on genes because one of the cool things that you highlight in your book is that our genes are fixed, at least what we got for genes. The expression of those is modifiable. But tell us a little bit about the microbe genes and how they're like that is a different tool or something that resource we could tap into.

Alanna Collen: Yeah. So we have about 23,000 genes as humans. And like you say, the genes themselves are fixed. They're not going to change over your lifetime. That's what you got the expression of those genes. You can change to some degree, and it varies from generation to generation, which isn't the same as evolution. There's the expression of them, it's called epigenetics, but there are limits to what you can do, whereas your microbiome, it's got far more genes than your own genome.

So there's an awful lot to play with there. And you do have some control over it, not complete control. And your control it takes time to make significant changes and to make them last. We don't really understand a whole lot about what is coming from your body to control your microbiome. We do understand more about what's coming externally that controls your microbiome, i.e., diet, antibiotics, breast milk, that thing. But we don't really know how your body determines what microbes you can or can't carry.

But yeah, you've got freedom to at least try and metal with your microbiome and try and improve your health via that, and through what you eat. And through the medications you take, which is again, much more complicated than just antibiotics. Other medications affect your microbiome like antidepressants and all sorts. And then if you are planning to be a parent in particular, you have a unique opportunity to do the best for your child's microbiome.

It's a tricky one because of course people don't always have the choice for various different reasons, but babies who are born naturally vaginally rather than by C-section, get a more healthy microbiome than those who come out by C-section because they get skin and hospital microbes typically instead of vaginal and fecal microbes. And then breastfeeding is extraordinary in the way it develops the microbiome because it's evolved to do it perfectly.

And again, I'm not down on formula or C-sections, they're like lifesaving. Just as I'm not down on antibiotics, they're lifesaving things that we need, but when you have a choice, it's great to be able to do things the natural way because it makes such a difference to how your child's microbiome evolves.

How Our Modern Lifestyle Shapes Microbial Ecosystems

Dr. Greg Kelly: I've heard that some scientists use the word extinct. Again, you mentioned in your book the differences between some hunter-gatherer or people living a more natural environment and the diversity of their gut microbiomes versus there was the study where they looked at the Italian children. I've seen a few things like that, and I think the key thing is once the species goes extinct, your ecosystem's just not going to be designed or adapted to allow it to thrive, even if you did try to reintroduce it.

Alanna Collen: Absolutely. Yeah, it's really tricky. I'm sure there'll be a lot more research on in the future, but that's it. If you take antibiotics again and again, you're going to kill off some of your species and how are you going to get them back? Maybe you will, maybe you'll encounter again on some food or from kissing someone or from even nasty sources like sharing toilets. You might get those microbes back, but you can't guarantee it.

And it's pretty hard work for your microbiome to recover that kind of diversity after it's been lost. It's like chopping down a rainforest and then wanting it to be a rainforest again is going to take a lot of time and a lot of chance, and probably some intentional reintroductions to make that happen. So as much as you can avoid damaging it in the first place. That's great.

Dr. Greg Kelly: You've mentioned a few of the things in the modern world that impact the stability, diversity, evolution of an individual's microbiome. So you touched on the antibiotics about what we eat. You mentioned just in passing that other drugs as well. Is there other things in the modern world that have a profound effect on our gut microbiomes?

Alanna Collen: Those are certainly by far the biggest players. Your diet is just completely fundamental, and you can change your microbiome within two or three days by changing your diet, but it will go back again if you change your diet back again. So that's not ideal. There is also probably some role for exercise in what your microbiome looks like. The studies on exercise have been a bit... They're not easy to interpret because often people have studied athletes and saying that someone who does a lot of exercises has a different microbiome from someone who doesn't when they're an athlete.

And there may be so many other things that they do. Special diet, all sorts, it's not really clear, but we know exercise, the role of exercise in longevity and health is huge, and in reducing inflammation. So once again, going back to the obesity thing, exercise doesn't seem to help people lose weight. There's really very poor evidence that it makes a significant dent in people's weight. Even though it burns calories, it just means your body balances out, makes you eat more, makes you save more if you can't eat more.

But it reduces inflammation and that's more fundamental than reducing calories because it's making your body healthier from the root rather than just trying to cut out a few calories. So that's a big one. And then, yeah, I think there's likely to be so many medications that play a really significant role that we just don't. We haven't even touched on what they do to the microbiome and I'm sure we'll discover some horrifying things. And maybe even we'll discover some good things about what they do.

Dr. Greg Kelly: But my intuition is almost anything that we would put in our mouth and swallow is going to have some impact, maybe lesser, maybe more. I know even a lot of vitamins or there's different forms of B3 sold in the US and at least in animal studies, they all have slightly different effects on the gut microbiome in animal studies because as an example, the fleshing nice and versus the non-fleshing versus something like nicotinamide riboside, which is a bigger molecule, which now these things that can cleave and eat that part of the molecule have some food. So it's like you said, it's a really complicated area.

Alanna Collen: Yeah. Another one, thinking of vitamins and so on is ultra processed foods. The compounds that we are eating that are not even food and we eat a shocking amount of it. I think about 50% of the British and American diet is ultra processed food and something so simple as sweeteners, non-sugar sweeteners, they change your microbiome and there's increasing evidence that they are not good for you. And there's also very poor evidence that they help you lose weight.

In fact, they may even do the opposite. So they seem to help you lose weight for a couple of weeks, which might be related to water weight because sugars help you might store a little bit of water, but over the long term they seem to change your microbiome and increase inflammation, which leads to your body wanting to store more weight and store more energy as fat again.

So yeah, I think we're going to be horrified in the next 10 years when we realize all these compounds that we're eating that aren't really food that are being sold to us as if they're completely acceptable things to eat when it turns out that they massively shift our microbiome and change our immunity and change the way we think. And everything that they potentially do to us, that we have not evolved with these non-food foods. So the body is not used to them and it's not surprising that it reacts badly.

Dr. Greg Kelly: Well, since you're talking about what you eat, both foods and the non-food things in food, one of my favorite quotes in your book was, "You are what you eat, what's more you are what they eat." With each meal you make spirit thought for your microbes. What would they like you to put in your mouth today? So I know, honestly, I keep that in mind now when I eat.

Alanna Collen: Yeah, me too. Yeah, I do think that a lot. And I'm not like, "I'm no angel when it comes to my diet." I could definitely still make improvements, but I do definitely think about my microbes. I can't help it. And it is an incentive, I think, to think about what you're eating and to... I really like fermented foods these days and I probably wouldn't have even bothered trying had I not known about the microbiome.

Dr. Greg Kelly: Can you tell us a few of the fermented foods at your favorites?

Alanna Collen: Kimchi, kimchi, kimchi and kefir as well. I love kefir and I buy it. I don't have enough time to make it, sadly. My mom makes it every single day. But yeah, I buy it and I add different fruits to it. I love adding rhubarb. I don't subscribe to the whole superfood thing, but if I was was going to say one thing, rhubarb it's amazing and it is got really unique fibers. It tastes delicious. Yeah. So I add that to kefir quite a lot. And then kimchi, for me, it's some toast with melted cheese on top and kimchi on top of that. That's just perfection. I also eat some of the other ones, but not nearly so regularly as... I eat yogurt all the time as well. I eat yogurt daily. But yeah, kimchi.

Dr. Greg Kelly: You are the second person in the last week that's raved about kimchi to me.

Alanna Collen: Well, do you know what? I honestly think it's addictive and I've talked this about this with friends who are fermentors and it makes an awful lot of sense, and I think even I wrote about this in the book as well, that your microbes have some control over your brain. They have some control over what you eat and what you feel like eating. So I think if you eat kefir or kimchi, then you are contributing to a different shaped microbiome.

And then some elements of that microbiome are sending messages saying, "More please." Because it's in their interest. If you've got a species that loves something within kimchi, then in order for that species to grow, it needs more of that foodstuff that's sustaining it. So if it can tell you that you want more, so much, the better. I think the example I gave in my book is of seasonality and memory related to where particular fruit trees might be.

For example, for let's say a nomadic tribe who are moving around following their food sources throughout the seasons, if their microbes can help them to form a spatial memory of what they've had where, then the microbes can get more of that thing. So if you go to a fruit tree, you eat that fruit, it increases the population of a particular strain of microbes.

That strain of microbes then sends messages to your brain saying, "Remember this place." Then you'll come back the following year and it will get another boost. So that thing is remarkable, and you see it in various studies, things to do with autism, for example, about how people remember and how they forget. And conditions where you over remember things and you can't let go of what you've remembered. So there's no space for new things that can all be microbe influenced as well.

How Our Gut Microbes Influence Behavior

Dr. Greg Kelly: Yeah, I love that. In the book, when you pointed out the importance of forgetting and it was mouse models of autism and that what it seems like their microbiota are doing is they're preventing them from forgetting, which then creates some of the patterns of behavior you would see in both those mice. But then in that model, would it be expected in humans as well.

Alanna Collen: Exactly. Yeah. It's all about pruning synapses in your brain, these connections that enable you to form a memory. I think I spoke about there's some American twins who are autistic savant twins, and they have an incredible memory for something like record, like what song or what was on TV or what song was released on a particular day. They also remember what they ate on that day. Interestingly, given the connection with microbes and they remember the weather on that day, but they can't remember new things. They can't remember how to dress themselves and so on.

But those traits have been reinforced again and again. And the microbiome in autistic people seems to be different from it is in neurotypical people. So again, we've got this idea that their synapses have reinforced these same memory roots again and again, and again. Whereas in someone who's neurotypical, you don't need to know what the weather was in 1999 because what does it do for you now? So that's an important thing that the brain needs to be able to do is forget the stuff that's not going to help you to survive in the future and remember the stuff that is. And so these synapses are either reinforced because it helps you or they're pruned because it's pointless. And yeah, microbes are involved in that.

Dr. Greg Kelly: I think of my memory, I've always thought of my memory as not gifted, not that type of memory, but solid. It does a good job for me, but I always thought like, "Oh, more would be better. Who wouldn't want even better memory?" And it has to be at least 20, 25 years ago and I don't remember the book, but in it, they were talking about this one case of... I believe it was a gentleman that was thought of as having one of the best memories on record. So they studied him quite a bit. And the thing I remember taking away from that book is like, "Oh, there's a cost to having this crazy good memory." There was certain things I take for granted that I can do that he wasn't unable to do because he couldn't forget as he's going.

Alanna Collen: Yeah, we actually need adaptability. We need to be able to alter things as our environment changes. So it'd be fabulous to have an amazing memory and it not affect your ability to process other things. But I don't know, maybe there's an analogy with a computer that's got a really full hard drive and it can't work as quickly as it should be able to because it's got no space, it's got no working capacity left because its memory is so full. And in biology, there are always trade-offs, that's what evolution is all about. You can't have everything. You can't simultaneously, you can't have eyes in the back of your head and in the front because there's not enough energy to make that justifiable.

Dr. Greg Kelly: One thing I do want to get back to because you're not the first person that's brought it up was that idea of maybe our microbiota because of us feeding something that's helped one species or many species thrive are nudging us towards, "Oh, more, I want more of this." So you're of the three different people I've spoken to that have spent a lot of time in the gut microbiome space, they all believe that to be true.

The research is preliminary, but they all think of it as something and we call it quality, symbiotic, it's one of our products, but it's prebiotics, some fermented foods and probiotics. And at the beginning was very regimented. I took it the first thing every day for two months and then decided, "Okay, I'll just take it whenever." And there was days because it's whenever I'll forget and all of a sudden at 8:30 at night, it's like, "Take this." I'll be watching Netflix or something. And it's just like, "Oh." Flashes into my mind like, "I haven't taken this yet." I don't know if that's them [inaudible 00:36:30].

Alanna Collen: Your microbes are giving you a little hints. Yeah. Well, I find that with kefir, if I drink it daily, then I really look forward to drinking it. If for some reason I don't have it, if I go away for a few days, the first three days or so, I'll be thinking about kefir a lot. And then if I stay away for longer, then I'll steadily stop thinking about kefir. But then as soon as I start drinking it again, I become obsessed again and I just really want it.

So yeah, I'm sure that there is a communication there that's reinforcing what we... I think the same to some degree is true of things like sugar that initially if you try to cut down on your sugar intake, it's really hard and your body screams for it. And then after a while you get used to it. And then you're just not craving anymore, which again, could be the microbes telling you what populations are there. If that population that's craving sugar has died away, then you haven't got those same messages coming to you to remind you that you want sugar.

Dr. Greg Kelly: Yeah, I always think of that sustaining something for a bit. I know for me with movement, I used to do a lot of bicycle riding, but anything with movement, it seems like for my body, if I do it routinely for a while, then all of a sudden, I'll get an itch to do it if I don't do it on a certain day. And I always think of that, "Oh, that's like I finally got to... Wow. Now it's more work not to do it than to keep doing it."

Alanna Collen: Yeah, definitely.

Dr. Greg Kelly: Well, since your book, because it's been a few years now, has there been anything new that's come out that's really either cemented what you wrote about, but were stretching maybe where the science was or that's caused you like, "Oh, this is super cool."

Alanna Collen: Well, I think the most amazing thing is how many things I left out of the book because I just felt like I can't say that microbes cause everything. And in fact, one of my earliest... I remember getting a three-star review and I was horrified. When your book first comes out, you're like, it affects you all the reviews. And I read this three-star review, and it said something like, "She hammers everything that looks like a nail and basically blames everything on microbes." And the thing that's really become noticeable in the... Now, eight years since I wrote it, is how many more things I could have written about.

So I left out cancer, basically I left out dementia, I left out Parkinson's because all of them had the evidence was tenuous. There wasn't anything particularly big or bold that I could talk about. And at the time I thought they're all immune related. It's completely plausible that they are going to be significantly influenced by the microbiome. But that's what's really struck me over the last eight years, that there is a role for the microbiome in everything.

And that's not because microbes cause everything, but rather because they are fundamental to everything. Just like our genetics and our environment, they're just part of the web of what makes a human body tick. So them being involved in everything doesn't mean that there's some crazy magical thing going on. It's just it's inevitable that they're involved in everything. So yeah, that's been intriguing. What else? I've seen a lot more backup for various different elements of the story in terms of neurodiversity and mental health.

I think I touched on depression and anxiety. And I touched on some more neuropsychiatric disorders that you wouldn't necessarily refer to as mental health. And those links have been considerably strengthened. There's some really significant, I think the idea that depression and anxiety are inflammation linked or have a significant part of them or a significant proportion of the people who suffer from them have inflammation as part of the basis that's really well accepted now.

The one other thing I'd say is that it's just extraordinary to go within 10 years from people saying microbiome. What's that to? It's everywhere. It's in adverts looking after your gut is completely accepted as both scientifically and by the population as a whole. I think the only people who haven't accepted it are doctors controversial, sorry. But yeah, it's very much in terms of the impact it's had on our culture in such a short time. I think that's amazing.

Dr. Greg Kelly: I know recently, I would say in the last three or four years I've seen just an explosion in the gut-joint axis if I look on PubMed for your arthritis type of thing. So gut-skin axis now is fairly well established. So I think it's pretty safe to say you started earlier that it's inside of us, but outside of us. But it's a part that connects to all the other parts.

Alanna Collen: Yeah, it is almost like the interface, isn't it, between our genes and our environment. And as an evolutionary biologist in particular, you are constantly seeing this phrase GxE, which means gene by environment interaction that equals what something is. Is the genes plus what the environment is. That's how a trait becomes. But the bit that's missing from that is the microbiome. That's how you get from environment to genes in so many cases. And that's how you create the phenotype, the type, the trait, the physical trait that you see or that you experience is via the microbiome.

Dr. Greg Kelly: And we touched a little bit about what you like fermented foods, but in your book, you mentioned fiber a lot and how writing your book caused you to really go out of your way to drastically increase your fiber. Has that persisted?

Alanna Collen: Absolutely. Yeah. And I think I probably made a big deal about my breakfast. I still make a big deal about breakfast because I just think it's your best opportunity in the day to get a whole host of nutrients and fiber that are harder to get in the rest of the day or less reliable. Most people eat pretty much the same thing for breakfast every day. So if you can have a high fiber breakfast with loads of different grain types, nuts, seeds, something fermented like yogurt or kefir, some dairy, if you are tolerant of dairy.

And some fruits, especially if you can get in some highly colored fruits because the polyphenols in those interact with the microbiome and generally appear to keep us healthy, then you are after a really good start. You could probably eat, if you're not a fiber lover already, you could probably eat the quantity of fiber that you are having in your entire day just at breakfast by working on your breakfast. And then you've got a bit of freedom the rest of the day to not be so well-behaved.

Dr. Greg Kelly: You mentioned polyphenols and colorful fruits, but I always think of the fruit polyphenols as prebiotic or prebiotics with the twist. They're not quite classified as prebiotics, but there's certainly some of the microbiota that thrive when they get enough polyphenols in our diet, which is their diet.

Alanna Collen: Once again, it's via the microbiome thing, isn't it? They're the ones, ones who are encountering it first. So those things are like that. I have a seven-year-old daughter and I say, "Is your tummy colorful today? What did you have?" And she says, "I had orange, I had green." And then I go, "Okay, so you need some yellow, so have some sweet corn." And that's part of my thinking about what they eat.

Dr. Greg Kelly: That's so wonderful. I'll keep that. Hopefully our audience eat a rainbow.

Alanna Collen: Yeah. And that's part of what I try to do with my breakfast. I love having raspberries and blueberries, because I'm like, "That's red and purple TikTok." Brilliant.

Dr. Greg Kelly: Well, we're just about out of time. So I wanted to get back to something you teased earlier, which is you've been working on another book. Is there anything you can share with the listeners about when that might be available or too early to tell?

Alanna Collen: It should be published in probably February 2024. It's going to be published by Grand Central Publishing, which is an imprint of Hachette. And yeah, I'm working on it now. And as I said before, it goes into the underlying reasons of how your body manages the weight it carries. So I see the diet and exercise is how you gain weight or lose weight, and what I want to know is why, what is happening underneath? What's the mechanism that makes your body want to gain weight or lose weight? I personally think that the diet and exercise thing is completely secondary.

Dr. Greg Kelly: Well, I'm definitely going to be looking forward to reading it. That's an area I love learning more about and can't wait for your contribution. So again, for anyone Alanna's first book, 10% Human, I highly recommended. I gave it five stars and I'm not an easy grader.

Alanna Collen: That's very flattering. Thank you.

Dr. Greg Kelly: Well, thank you for joining us today on Collective Insights.

Alanna Collen: Thank you for having me. It's been really fun.