Until fairly recently, the idea of listening to your gut was mostly metaphorical. The heart, lungs and liver are important to keep in good shape. But the stomach, intestines and colon? Surely they just keep chugging along, processing whatever you put into them, occasionally objecting, but basically doing their job.
Well, not quite. Over the last five years or so, evidence has been piling up that the huge community of microorganisms – bacteria, viruses and fungi – that live in the gut affect everything from the immune system to mental health. We have learned that there are roughly 500m neurons in the human gut, alongside the 100bn in the brain, and research around the “gut-brain axis” – the biochemical signalling system that links your gastrointestinal tract and your central nervous system – suggests that signals go both ways between the two. Professional athletes, for instance, have more diverse gut microbiota than regular people, but it is becoming increasingly clear that the relationship is bidirectional – they might be better runners because they have more efficient gut bacteria, but doing more exercise is probably helping to keep the little chaps happy.
