The Secrets of the Bacteria in Your Gut

Today we are talking about guts and the bacteria inside them. Sounds disgusting. Well, it appears that bacteria play a crucial part in our health. In this healthlab episode, you'll discover how that works.


Discover the book: The Good Gut

23-09-2015 -  by Kevin Van der Straeten

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Today we are talking about guts and the bacteria inside them. Sounds disgusting. Well, it appears that bacteria play a crucial part in our health. In this healthlab episode, you'll discover how that works.


Hi Justin, hi Erica, welcome in our studio.  


Great to be with you. Yeah, thanks for having us.  


You are both the authors of the book 'The Good Gut'. Why are the guts so important that you have to write a book on the subject?  


Well the gut is really central to our biology. We've known that for a long time. We have even known for over a hundred years that we have all of these these micro-organisms living in our intestines, known as the gut microbiota. But really it's only recently over the past 10 years or so that we've really begun to map this community of microbes really carefully, and started to understand its biology, and it has become incredibly clear that it is very fundamental to all aspects of our biology. And so over the course of our research of these microbiota we have realized that we're changing our lifestyle, as we live it: we eat different things, we raise our children in different ways... And we just really thought this is an important piece of science to communicate to people, so that it wasn't just us the scientists that have this information, but everybody could have this information and act on it. 


And what exactly is then that kind of information you act on? What is so different from what you thought before?  


The thing that we need to understand is that humans are in fact a composite organism. We actually have over a hundred trillion bacterial cells that live in our gut. So we actually have ten times more bacteria associated with us than human cells. And so this new way of thinking about ourselves as composite organisms that are mostly microbial, I think is influencing not only the way we view ourselves as humans but also the way we take care ourselves. And it's becoming clear that this community of microbes is incredibly important for our health. So we need to do things like: take care of them, feed them, make sure that we don't harm them by taking antibiotics too often, and these were the kinds of things we started incorporating into our lives and our children's lives. And the other thing that became apparent... And you know, this is just over the past few years, is that those of us that live in the modern world and an industrialist country, have what appears to be a deteriorated microbiota. So right at the same moment that we're learning all these fundamental important things about the microbiota; how important it is to so many aspects of our health. And it's not just an interesting little part of our biology, It's really a control center for our metabolism, for our immune function. And there's really good evidence that the gut microbes even speak to and control in some way our central nervous function. And so our central nervous system function. And so I think, at the same time we're realizing this, we're also realizing that in the Western world we're not taking care of our gut microbiota, That it's deteriorated and that we need to change how we live as a society, the choices we make, the foods we eat, to nurture it back and perhaps have a positive impact on some of these modern plagues that are causing problems for our society. 


Okay, but let's make an example. What can you do to improve the health of all those bacteria and yourself?  


So most of these microbes live in the very distal part of our large intestine. And so we need to make sure that we eat food that gets all the way to our large intestine. So for the most part this is the dietary fibre that is found in plant materials, like: fruits, vegetables, nuts, whole grains... These things contain dietary fibre; the carbohydrates that our microbes really need to live off of. This is the main fuel that drives them. And what we're finding in our research is: When you provide lots of dietary fibre to these bacteria, they metabolize this dietary fibre and produce chemicals within our gut, and those chemicals can influence how our immune functions. They can influence our metabolism; so whether or not we're gaining or losing weight. And it's becoming clear that they're even communicating with our brain so potentially affecting our mood and behaviour. All through the bacteria that are living in our gut. 


You were mentioning plant materials. Does that mean that we are not built to eat meat? Because that's always a big discussion.  


If you look at people today that live a hunter gatherer-lifestyle, so how our ancestors lived about a 100,000 years ago, they do eat meat. and that meat was clearly a part of the human diet, but what you see is that most of their diet, the majority of what they were eating, was plant material. So I think we just need to be mindful of the fact that most of what these microbes require are plants. For instance vegetables, these types of things. So we need to make sure that that forms the majority of our diet. And nowadays it's the other way around. In most situations we eat more meat than we eat plants. Exactly, and if you look at these modern day hunter-gatherers... They're mostly eating plants and on many days when they are not successful in their hunting excursions they are vegetarian for that entire day. And they eat on the order of 100 to 150 grams of dietary fiber per day. That's about 10 times more than the average westerner. In the United States the average American gets about 15 grams of dietary fiber per day. So it really comes down to the fact that we're starving these microbes that live in our distal gut. And amazingly, when we starve these microbes, they have no other choice than to turn and start eating us. They actually start eating the mucus lining of our intestine if we don't feed them enough dietary fiber. And this is probably the case for most westerners. 


And this leads to diseases and things like that?  


Yeah exactly, the fact that this microbiota is being deteriorated and neglected... Erica has mentioned dietary fibers. I think fermented foods are a really important part of the diet for supplementing microbes, environmental microbes and beneficial food bore microbes into our digestive tract. I think avoiding antibiotics is incredibly important. And even with our kids we've really tried to be less crazy about being totally sterile and sanitized everywhere we go. We let them pet the family dog and then eat without washing their hands, just as a way of introducing more microbes. Because there's good evidence that we're basically being too hygienic and this is having a negative impact on our microbiota and on our health.  


That's an interesting thing to think about. Another thing you mentioned earlier in our interview: antibiotics. That doesn't sound very good for your bacteria inside you.  


Yeah, antibiotics have a pretty devastating effect on the microbes in our gut. I mean, antibiotics were designed to kill all bacteria without really any thought about the microbes that live in our gut. So every time you take a round of antibiotics, you're not only killing the bad bacteria that are causing the infection, but you're also killing many of the good bacteria that are associated with us, and I think we really just need to reframe the way we think of microbes. For so long these were just terrible things that we want to get rid of. And we need to understand that most bacteria are in fact good and good for us. And so when we are feeling sick and going to see a doctor, we should make sure that if we... And antibiotics really are something that we need, and not something that is just like a automatic response when you don't feel good. And then be aware that if you do need antibiotics and take them, that your gut microbiota has sustained damage, and you want to make sure that you try to nurture it back to health, so that would be increasing your dietary fiber consumption, eating things like yogurt or kefir, to provide environmental bacteria from fermented foods. To help the gut bacteria heal after a course of antibiotics. 


And what's your opinion on probiotics?  


I think that probiotics are probably a really important part of what we eat. There are multiple ways that you can get probiotic organisms. You can get them through supplements or you can get them in fermented food. The bacteria that you actually find in the supplement aisle of the store, that are labelled as probiotics are actually bacteria that have largely been isolated from fermented foods, like yogurts or kefir, and you can get those same organisms by just eating a variety of fermented foods. Like: yogurt, kefir, sauerkraut, kimchi. All these foods are teeming with microbes. And there's really good evidence that they have many beneficial effects on human health. It's important to realize that these microbes don't take up permanent residence in the digestive tract. They just pass through. And so it's important to have these as a daily part of your diet. So that you continually have these microbes passing through your system.  


Okay, we were talking about what is good to eat for the guts. Are there also things we should better not eat?  


I think there's not really great evidence of things that are an absolute must to avoid. I think that when it comes to medication, certainly antibiotics is as we've discussed. But I think that beyond that there's good evidence that there are compounds in red meat, that can be turned into harmful compounds by the gut microbiota that contribute to cardiovascular disease. There's evidence that limiting meat consumption is probably a good idea from the standpoint of your own health, and it just happens to be the microbiota that's an intermediate and contributing to that problem. So probably... If you limit red meat, that's one thing, but besides that all evidence is pointing towards just a really diverse diet. Trying to eat as many different plants as you can, to encourage a diverse microbiota. A microbiota made up of many different bacterial species. This appears to be something that's linked with positive health.  


Okay, thank you both for this new view on bacteria. We will put the link to buy the book below your video, because there is a lot more to discover in there. Thank you so much for your time.  


Great to be with you. Thank you.  


And you at home: thank you for watching our show. I hope to see you next week.