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The gut and the brain

Sophie Medlin and Laura Tilt cover the impact of gut function on brain function and vice versa.

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February 25, 2021
6 min read


Sophie Medlin: Head of nutritional research for Heights ,registered dietitian, chair of the British Dietetic Association for London and expertise in gastrointestinal and colorectal health. You can check out Sophie on the Braincare podcast here.

Laura Tillet: Registered dietitian, health writer, working with patients with gut disorders.

What is the gut-brain axis?

  • The gut-brain axis (GBA) is the connection between the gut and the brain. Demonstrated by the “nervy-tummy” feelings you might get before a first date or interview with the sudden urge to go to the toilet. Due to this “gut-brain axis” which explains the relationship that exists between your brain and the little brain that lives in your guts known as the “enteric nervous system”.

  • The Gut is connected physically and chemically:

    • Physically: the gut and brain are connected physically by millions of nerves, and most importantly the Vagus nerve which is the longest nerve in the body.

    • Chemically: Our gut microbiomes can also communicate with our brains. They produce various compounds that can cross the blood-brain barrier and can influence how we feel. This means our gut health can impact our mental health, and vice versa.

Impact of chronic stress on gut function & how it manifests in terms of symptoms

  • The effects of acute stress on our gut could manifest as those stomach churning feelings you get before a meeting, presentation, etc. 

  • The muscles in the gut start squeezing and relaxing more, resulting in the need to go to the bathroom. 

  • Examples of stress can include the pandemic, work pressures, relationships under pressure, overall stress going on in the background. 

  • Elevated stress hormones can potentially reduce or suppress the growth of beneficial microbes. Over time, this could disrupt the balance of microbes in the gut and affect how we digest food. As a result, nerves in the gut become hyper-activated and can be switched on all the time. This can become a vicious cycle. 

  • It is theorised that when we are more stressed, we produce more digestive enzymes, more stomach acid, and so things move more rapidly through our digestive system. As a result, the bacteria that live in our colons have more substrates & food to ferment, creating more of these symptoms and perhaps allowing a bit more breeding ground for the less beneficial bacteria in our bodies.

What stress management strategies do you advise? What sort of things can benefit gut function in terms of stress management?

This is very individualised, which means different things work for different people.

  • Gut-directed hypnotherapy: Research shows gut-directed hypnotherapy is helpful for patients with IBS symptoms. Created by gastroenterologist Dr. Peter Whorwell (Manchester) 1980. Originally used it with his patients as he thought it would be a way to improve their quality of life by reducing stress levels. Results show it did do that, but also found a huge improvement in their symptoms.

  • Low FODMAP diet: a dietary therapy which involves eliminating certain types of carbs that can aggravate symptoms and IBS sensitive tummies.

  • Cognitive Behavioural Therapy (CBT): Type of talking therapy which looks at how certain thoughts affect feelings and symptoms in the body. For example, people with IBS may feel pain in their stomach, and the brain will start to catastrophize it by asking “is that my IBS, will I need to run to the toilet?” This sets up a negative feedback loop. Once they’ve had that thought, it triggers a wave of movement in their tummy, resulting in them actually needing to go to the toilet. This is about breaking the cycle, and finding more helpful thought patterns around that process.

  • Breathing exercises

  • Yoga: Yoga has been compared to the low FODMAP diet in that it was found to be similarly effective by helping to activate the calm side of our nervous system.

Ultimately this is an individual thing. Key is to find the correct tools to help yourself based on what works for you.

Food as symptom triggers

Foods can be symptom triggers, so naturally people seek to cut foods out of their diet. Although this may help in the short-term, it’s preferred not to limit foods in your diet in the long-term, especially if its not necessary.


What do you think about having a “gut mind” and the idea that our guts hold intuition?

  • Medicine has lost the connection between the gut and mind- we don’t like to link them (has to do with the stigmatisation of mental health). 

  • Stress has a huge impact on gut function. 

  • Interesting: the reintroduction diets for IBS (people who have been on treatment diets)

  • Can be helpful to blind the reintroduction of foods because people can convince themselves that gluten, for example, triggers their symptoms. It’s not the food, it’s the anxiety of the food that triggers symptoms. 

  • Hopefully all practitioners are much more open to recognising the impact of our mental function on our gut function (and vice versa).

  • From a personal perspective, I think we neglect the instinct of things we recognise in our gut. As humans, we’ve moved away from listening to our bodies/instincts. 

  • Dietetic perspective: Perhaps moving out of the realms of solid evidence-based medicine. 

  • Historically would have been essential to go to different places and pick up on things in the surrounding areas that would be triggering neurotransmitters in our brains to understand whether or not where we were settling was safe. We’ve moved away from this as a species. We carry a lot more information within us that we don’t tap into.

Can we talk about depression and the gut-brain connection?

  • This is a relatively new area of research. Scientists have looked at the gut bacteria of patients who are anxious and depressed and it looks different to “healthy control patients” who don’t have anxiety or depression. 

  • Data tells us that when people are diagnosed as being anxious, they have a different profile of gut bacteria that lives in their colon. 

  • Currently trying to unpick whether the bacteria existing there drives the depression, or whether the feelings of depression and anxiety affect our diet. 

  • Important to note is that nothing you eat, drink, or do should be used as a stand-in for having the treatment that’s been prescribed to you by a medical practitioner. It is important that we don’t blame people's mental health on things they did/don’t do with their diet. 

  • Neurotransmitters produced by the brain (e.g serotonin, dopamine) do not pass the blood-brain barrier. But they do produce certain compounds.

You can use the code "clubhouse10" for 10% off to give your brain the love it deserves.

Find out more


  1. Laura’s Podcast: “The Gut Loving Podcast: All about IBS & the low FODMAP diet” 

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