Jeroen Raes, professor and group leader at VIB, Brusssels (and MetaCardis investigator) spoke at TEDx Brussels in November 2012. The topic was "Gut flora: You are your 100 trillion friends". He takes us on a guided tour of our body's microbial neighbourhood and reveals that only one in ten of the cells that make up the human body are in fact human. The rest? Microorganisms that live on and inside us. He introduces the idea of 'enterotypes' (groupings of bacteria) and reveals that there are just three distinct types that all humans appear to fit into. Such a finding, he  says, could be important as many diseases are linked to disturbances in gut flora. Moving on he describes how babies, which are born sterile, become inoculated at birth and that this can have important consequences for health later on. He also describes the effects of antibiotics on gut flora and describes some surprising outcomes when even low doses are used. Finally, he talks about a toe-curling but highly effective treatment for mending broken microbiotas - faecal transplants.

Watch the video above or read on for the transcript of his TEDx Brussels talk.


So, you think you are human?

There are 7 billion people on this planet. Do you know how many microbes there are? 5 nonillion (5,000,000,000,000,000,000,000,000,000,000).

That’s the number of stars in the universe multiplied by five million. That’s a lot of bacteria.

And they are everywhere. They’re on this floor. They are in your kitchen sink. They’re on your chair. They’re on your coffee cup. And yes, they are on you. You harbour 100 trillion bacteria in and on your body, right now.

That’s only a thousand times the number of individuals on the planet. And if you look at it in terms of cells, you are outnumbered ten to one. You are not human. You are a walking bacterial colony.

We have several commensual flora or commensal microbiotas, as we call them. You have your skin flora, you oral flora, your genital flora, and most famously, your gut flora.

These floras are numerous but good for you. They help you digest your food. They protect you against pathogens. They provide you with essential nutrients such as vitamins. They train your immune system and most importantly if something goes wrong with your flora, something is wrong with you.

So, we scientists, in the last few years, we’ve discovered new techniques to study the gut flora or gut microbiome at great resolution. We start off from a sample of your flora, we extract all the microbes, we extract all the DNA from these microbes, we throw that into one of those sequencing devices and we learn something about that ecosystem.

Because it is an ecosystem, we learn what microbes live there are we can learn about what these microbes can do, what genes they have in their collective genome.

And we have learnt that our microbiome, so the collective genome contains 100 times more genes than we have. We have a second genome active both in and on our bodies. And we have learnt that we can sort of classify the gut flora into three kinds, three corners of ecosystem space. We have called them “Enterotypes”.

To give you a better feeling about what these enterotypes are, I often make the comparison with types of forests. You have tropical forests, you have temperate forests, you have bamboe forests. They are all forests but you have different species living together and functioning as a unit. You have constellations that work optimally and that’s why I think you have constellations in your gut flora that work optimally.

And so, the environment that these bacteria live in, they determine these constellations it seems and the environment in the gut is the food that you eat. And so people have discovered that people who have more fat in their food or more protein in their food, or more carbohydrate in their food, they have different gut compositions.

And that is important, because more and more diseases are linked to disturbances of your gut flora. Diarrhoea, diabetes, obesity, atheroclerosis, ulcerative colitis, Crohn’s disease, even autism, all have been associated with disturbed gut floras.

It is not merely associations. Bad gut floras can actually cause disease. If you take the flora of an obese mouse and you put it into a germ-free mouse (so one that doesn’t have a flora), that germ-free mouse becomes obese.

So, we can learn something from this flora about your personal health. Moving towards diagnosing people on the contents of your gut. This is being done already for example for diabetes, or for colon cancer.

But, we can do this in everyday life. We can move towards life-long monitoring of your gut flora… from the obvious material. When I mean life-long, I mean life-long because your gut flora is seeded at birth. Babies are born sterile and it is only when they are born they are inoculated with the flora of the mother. The skin flora, the vaginal flora, the faecal flora. That’s when it happens, at that moment.

And so, messing with the flora in early life can have serious consequences. We are starting to understand more and more how serious these consequences can be.

Babies that are born by c-section have different floras than babies that are born normally. Babies that have been breast-fed have different floras than babies that have been formula-fed. We don’t really know which one is better. We just see the differences at the moment. But we do know that babies, using an example from mouse experiments, we know that mice that had low dosage of antibiotics at a very early age have a disturbed flora at adulthood and that they become obese. Low dosages of antibiotics at early age have been linked to asthma.

So, we have to start thinking and be very about the usage of antibiotics. I am not pleading against [the use of] antibiotics, but we should be very careful.

Also in adults this matters. If you get a normal dose of broad-spectrum antibiotics, some of you will recover, in terms of gut flora, after a few weeks. For some of you, it will take months. For some of you it can take over a year for your gut flora to become ‘normal’ or to return to what it was again. And for some people, they never recover. They have permanently altered their gut flora.

There are so many unknowns in this field. We don’t know what the effects of this are, we are just seeing the consequences and they are important.

We can also think about modulating flora. Resetting your flora. There is now a new approach. Well it is not new actually. It’s pretty old. Bedouins have used it for ages. Faecal transfer or transplanting a flora of a healthy individual into a diseased individual actually seems to work as a therapy in some diseases.

It is not only disease. The gut flora influences behaviour. It influences brain development. Experiments in mice are now showing that anxiety behaviour or explorative behaviour is determined by what flora they have. In Drosphelia (a type of fly) it has been shown to influence mating behaviour – sexual preference.

So, think about it. Or, is it you who is thinking?

Take home messages (I only have two):

One is take care of your friends

The second one is you never have to feel lonely ever again.

Thank you.

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