Prof. Simon Carding, Leader of the Gut Health and Food Safety Research Programme, Institute of Food Research and Norwich Medical School at the University of East Anglia, describes our current understanding of the human gut and its relationship with its human host and introduce the provocative proposal that gut microbes influence when, what and how often we eat and whether we stay healthy or succumb to disease.
Prof. Simon Carding:
Right, well. Thank you Rich for the introduction. So as Rich said, I’m going to try and inform you a little bit about:
- What goes on in your gut and in particular about all the microbes that live in your gut,
- Why they’re so important for your health, and
- Why under some conditions, they can actually cause quite severe disease
So there’s been a significant shift in our understanding of what causes disease. I think, you know, traditionally we’ve always thought of it to do with who we are – our genes, and then the things we do as we go through life – so lifestyle, and what we eat and what we get exposed to in the environment. It’s those two that come together, to either keep us healthy or to cause disease.
But what’s apparent now is that in the middle of this and that, may be involved in interpreting a lot of these things that we do and eat, our gut microbes. They’re a direct link to our genetic material and they can in turn influence how we react, and respond to things in the environment and how they can keep us healthy or not.
Really, the understanding of gut microbes has really taken a fantastic leap since around 2000. This graph here shows the number of scientific articles that have been published about gut microbes. You see they really started to take off here around 2002 and that’s because of technology.
So before 2002, the only way we could really identify and characterize our gut microbes was by what we could culture on a petri dish. And since we now know that about 80 percent of our gut microbes can’t be cultured that really isn’t a good representation of what’s in our gut.
But then with the advent of gene sequencing technology we can now identify microbes according to their genetic blueprint. What’s apparent is that different types of bacteria have a unique genetic fingerprint. So if we can identify the fingerprint we can say whether or not they’re present or absent.
And this, as I said, has led to this huge explosion in this area of research. We can now identify microbes we can culture. So this has led to massive interest in gut microbes and some of these are very recent.
So the Daily Mail thinks that healthy gut bacteria might be linked to anxiety and then we’ve got others that are linking gut-brain connection – Autism, probiotics as a means of treating diseases and then a couple of books.
This one has just come out and those of you in the Institute will notice the significance of broccoli on the front as the Institute is responsible for generating strains of broccoli that have lots of nutrients — good beneficial nutrients in them. But really the message here is that what we eat influences our microbes which in turn can influence our brain function, and keep it normal.
But as always we have to be aware of the hype, okay. So whenever we read these articles we need to have a couple of things in mind that allow us to determine whether or not, you know, there’s some factual basis to it or whether it’s hype. And these are some of the questions that I would say you need to ask.
So the obvious one is, well, “So what do these differences they’re detected do they really matter are the changes, a cause or a consequence of the disease?” And of course we want to know — “How it works? What’s the mechanism?” So is there anything in this article that allows us to understand how it actually works?
Then a lot of experiments are carried out on animals because we can’t do many interventions in humans for ethical reasons. So another obvious question is well – “Is a mouse – a small human?” No it isn’t. So we’ve got to bear that in mind.
And then obviously we’ve got to think “All is there something else they haven’t looked at which could explain what they’re describing?” So behavior and lifestyle are two important things.
So I’m going to try and sort of touch on some of these things in the rest of my talk. So this is what I’m going to cover. I think I need to introduce the gut to you. I’ll talk a little bit about microbes, some interesting facts, a little bit of trivia and then how gut microbes may play a role in determining what we eat and what the consequences of what we are for our health, well being, and then how we actually might manipulate they’ve got microbes to improve or restore our health.
So that’s what I call LawnCare, right start with so did the guts mouth to the anus, it’s a long tube. Here’s a picture taken with an endoscope and you can see it’s not a smooth tube. It’s got these ridges to it, the muscles. This is what allows food to be propelled through the guts. But it’s not a smooth chew. It has lots of finger-like projections that we call villi that stick into the lumen to capture nutrients and absorb them.
So the tube is quite long — it’s like nine meters from mouth to anus. And somebody has taken the trouble trying to calculate what the surface area of all these villi are. And the outcome of that is it’s probably about the size of a badminton court. So it’s an incredibly large area and it has to be large in order to take up the nutrients that are in your diet to keep you healthy.
Gut – the Bioreactor:
And then we also consider the process of digestion. And the gut is in fact a massive bioreactor. so we take in food plant material, for examples, and they’ve broken down first of all in the small intestine.
Here’s where the small simple sugars are absorbed, and then the larger more complex plant material that we eat in our diet passes through into the large bowel or the colon where it’s fermented. And it’s fermented by the bacteria that live in the colon. And the end product of all of this is something called short chain fatty acids which are very important because they can provide about 5 to 15 percent of our daily energy requirements. In some animals it’s up to 30%. So this has to be a very efficient process to keep us alive basically.
And the enzymes that are responsible — the proteins that digest these food materials and the polysaccharides. Now we only have about 20 genes in our whole genome that will allow that encode proteins will break down these carbohydrates.
But one bacterial species – this one in particular – Bacteroides has 260. And you think there are a thousand species. So that’s a vast number of proteins that can digest our food. So the bacteria that live in our colon are ideally suited for processing our food and extracting the maximum level of nutrients from them.So it’s a bioreactor.
A little bit about the microbes. So the gut is packed full of microbes. There is no space that endoscope image I showed you. They’ve displaced and rinsed out all the bacteria. Normally that will be jam-packed with bacteria – most of them are floating free in lumen.