Laura Tilt, registered dietitian, takes us through the basics of the intricate connection between your gut and brain.
What is your gut?
Unless you struggle with digestive problems, you probably don’t spend much time thinking about the ecosystem in your belly. But research shows that the microbes in your gut influence everything from digestion to immunity and even your mood.
Stretching an impressive nine metres in length, your gut (or digestive tract) is the long muscular tube that stretches from your mouth to bottom.
Your gut is home to trillions of microbes (bacteria, fungi, and viruses) — collectively called your microbiome. Most of these are housed in your large intestine, where they help digest food and turn dietary fibre (from wholegrain foods, fruits and veggies) into anti-inflammatory compounds.
As well as digesting food and removing waste, your gut and microbiome form a crucial part of your immune system. In fact, around 70% of your body’s immune tissues are located in your gut. Together with the bacteria lining your gut, these tissues form a physical barrier and prevent harmful bacteria from the external environment entering your body.
Your gut-brain connection
Your gut is also intricately connected to your brain — you’ve probably heard the expression ‘gut-brain axis’. This describes the mesh-like network of nerves that spider their way from your brain into the depths of your gut. This network is a sort of information superhighway, which allows messages to be pinged back and forth between your brain and gut.
Not only does this help coordinate digestion and the movement of waste through your gut, but it also links the emotional centres in your brain with your digestion. So when you experience stress, your gut feels it too. This explains why a job interview or a stressful situation can leave you running for the loo!
This is a two-way thing, your gut also influences your brain. Gut microbes are in charge of churning out various neurotransmitters like serotonin — a hormone which regulates mood, appetite, and sleep. It makes sense then, that changes in your gut microbes might have a knock-on effect on your mental health.
Scientists are now looking at whether changes in your microbiome can contribute to anxiety and depression. And whether specific types of bacteria (dubbed psychobiotics) can have a positive effect on your mood and reduce anxious behaviour.
Taking care of your gut
Knowing this, what can you do to nurture a good relationship between the two?
Diet remains one of the most important factors. Getting enough dietary fibre is key. Current guidelines suggest aiming for 30g of fibre a day. Most of us fall short of this — average intakes are roughly 20g for men and 17g for women. Including more whole grains, fruit, veggies, nuts, seeds, and pulses will help.
Pre and probiotics
Prebiotics are a type of fibre. These non-digestible parts of food promote the healthy microbes in your gut to grow. These are found in various foods like beans, pulses, onions, garlic, leek, artichokes, oats, and under-ripe bananas.
Probiotics, on the other hand, are types of live bacteria and yeast (similar to the ones already living in your gut). These are found in certain foods like some yoghurts and other fermented foods like kimchi, sauerkraut, and kefir. Or you can also get probiotic supplements — although it’s not clear yet which microbes and doses are the most helpful.
Including both pre and probiotics in your diet is a helpful move towards maintaining a beneficial balance in your microbial garden.
As mentioned, your mind can impact your gut health. So beyond diet, learning to balance emotional stress is important too. Practices like yoga and mindfulness are great ways to manage stress, which might have a positive effect on your gut. In fact, yoga and mindfulness training has been shown to improve symptoms of irritable bowel syndrome (IBS) — supporting the benefits of stress-management for good gut health.
Cryan, J. F., & O’mahony, S. M. (2011). The microbiome‐gut‐brain axis: From bowel to behavior. Neurogastroenterology & Motility, 23(3), 187-192.
Dinan, T. G., Stanton, C., & Cryan, J. F. (2013). Psychobiotics: a novel class of psychotropic. Biological Psychiatry, 74(10), 720-726.
Foster, J. A., & Neufeld, K. A. M. (2013). Gut–brain axis: How the microbiome influences anxiety and depression. Trends in Neurosciences, 36(5), 305-312.