How gut bacteria shape your health

You’d be forgiven for thinking that, when you sit down to a meal, you are the only ‘organism’ being fed. The nutrients released from the food simply make their way to where they are needed around the body, as building blocks, fuel, or even construction workers… right?

Well, not quite.

In fact, everything we eat is eagerly awaited by an army of bugs that inhabit our digestive tract (around 100 Trillion to be more precise). And most of these bacteria are friends. They have a symbiotic relationship with us, which means that they use us as their ‘host’, sharing our space and our food, and in exchange they perform certain jobs, which keep us alive and well.

Jobs for the bugs

Scientists are only just beginning to discover how extensively our microbiome (the community of bacteria in our body) shapes our health. Here are just a few of the items of its job description:

  • Regulating our metabolism, particularly our sensitivity to insulin (it turns out that cutting down on sugar is only part of the story!)
  • Training and modulating our immune system (so that it learns not to attack everything it comes across)
  • Keeping out invaders: occupying the space so that unwanted bugs can’t settle down and cause food poisoning for example.
  • Manufacturing neurotransmitters, like serotonin, the ‘feel good chemical’
  • Making enzymes, vitamins (particularly the Bs and Ks) and other essential nutrients
  • Metabolising nutrients (if the superheroes are not doing this job properly, then this could lead to malnutrition)
  • Creating signalling molecules that regulate our appetite, satiety and digestion (so the messengers that tell your brain you need food are sent by the bugs!)
  • It seems that some of the messengers which tell your brain you are stressed are also sent by the bugs… how much of your temperament is really yours?
  • Our bugs also play a big part in feeding  the protective lining of our gut wall – also known as mucosa. This surface area, large enough to cover a tennis court has to withstand more than 50 tons of food passing through it in a lifetime. When it gets damaged, unwanted particles can leak out and cause inflammation (again research is still in early stages, but some scientists warn that this could be a reason why metabolic syndrome develops)

So just a few then! And I’ve kept the most amazing till last: our gut bacteria have their own genome, which adapts much faster than our own, rigid genome. Whereas our genes evolve over thousands of years, our bacterial genes are constantly reacting to our changing environment. A new generation of gut bacteria can be born every 20 minutes in some cases.  And they can modify their DNA in order to handle a new toxin or food. For example, studies have shown that Japanese people are better at digesting seaweed than other communities, thanks to a common gut microbe cleverly acquiring a gene from a marine bacterium.


What does this mean?

Make no mistake: what these discoveries mean is that we are on our way to a totally new paradigm in how we approach our health. We’ve known for a few years (since the human genome project) that our genes hold very limited answers to the big questions about why diseases develop. We are also beginning to understand that the answer is not as straightforward as ‘eat healthy food’ – we need to make sure we cultivate a healthy microbiome too – an army of superheroes in our gut.

And how can we do this? Look out for my next blog post for some useful pointers.