Gut instinct – is it true or just your bugs talking?

What are your gut bacteria really saying?

Gut instinct – is it true or just your bugs talking?

Your gut is an organ of the body that is extremely vocal and very good at sending signals to the brain.

Have you noticed that when you are anxious or excited you get butterflies in your stomach? Or when something is about to go wrong your stomach does somersaults, lurches or feels tied in knots? Perhaps you've noticed after consuming certain foods or drinks your mood and energy levels alter, your stomach bloats or perhaps you get the shakes?

If you read the research you might just think that what you may have thought of as a saying – ‘gut instinct’ – is actually deeply rooted in scientific fact. For the past few decades, researchers have been studying the enteric nervous system, which is a part of the nervous system in the stomach. Their findings show how the enteric nervous system governs the bowel, but also how it controls our gut feelings, moods and some diseases.[1]

The enteric nervous system(ENS) is a part of the peripheral nervous system – the nerves that lie outside of the brain – and has been studied by Dr. Michael Gershon, Professor and Chairman of Anatomy and Cell Biology at Columbia University Medical Centre.[2] The ENS contains as many nerves as there are in the spinal cord and they regulate the behaviour of the bowel, gallbladder and pancreas. The vagus nerves connect the ENS to the brain and when stimulated, these control epilepsy, relieve depression and improve learning and memory.

What is fascinating is the ENS can operate without any input from the brain and research shows that the ENS actually signals the brain rather than the brain signalling it. As a result of these signals sent from the stomach to the brain, sadness, stress, memory, learning, and decision-making are affected.[3]

Research on the ENS has revealed a scientific link between food and feelings.[4] During studies of the interactions between signalling initiated in the gut and the emotions that they elicit, it was found that food impacts brain activity and the intake of fatty acids reduced sadness and hunger. So the saying "you are what you eat" could be rephrased as “your moods (to some extent) are because of what you eat!”

A study published in the Journal of Neurogastroenterology and Motility indicates that it is not simply the neurons and neurotransmitters in the stomach that play a role in signalling to the brain. In fact, a large part of the work may be done by the bugs in your stomach.[5] There are approximately 100 trillion bacteria living in your intestines. Researchers concluded; “That the presence or absence of conventional gut bacteria influences the development of behaviour and is accompanied by neurochemical changes in the brain.”

Thus the health and balance of the gut bacteria is essential to how our brain functions: so is it ‘gut instinct’ or your gut bugs that are speaking to your brain?

There are more bacteria in your gut than you have cells in your body and when you feed yourself you are feeding these bacteria first and it is these bacteria that are signalling the brain and giving you ‘food cravings’ and ‘emotions’ that need feeding.[6]

Too much sugar, alcohol, gluten and dairy can alter the balance of gut bacteria and gut function. One of the roles of gut bacteria is serotonin production: serotonin is one of our ‘feel good’ hormones and imbalances in its production are linked to issues with sleep and depression.[7]

These and numerous other studies suggest that what we eat alters our brain activity, body biochemistry and emotions. But also it could be that what we are eating is controlled to some extent by our feelings, stress levels and gut health. I know when I am tired I crave sugary foods or carbohydrates and that when I feel down I want comfort food. I'm sure many people can relate to that.

Can what you eat affect your mood? Can your diet be part of the equation to reduce stress and improve the way you feel? Take a moment to think about what you eat and how it makes you feel.

Do some foods lift you, comfort you, make you ‘hyper’ or lethargic? Do you feel bloated after meals or get constipation or diarrhoea? Do you eat differently when you are stressed or sleep deprived – gulping down caffeine and shovelling in fast food while on the run?

Stress leads to less and often poor quality sleep, which leads to reaching for caffeine and sugar for a fix, which is followed by a crash and need for another fix – this leads to a vicious cycle and if you add to that lack of exercise and maybe using alcohol to unwind then these too contribute to poor sleep. And so the cycle continues. We know that this way of eating and living doesn't make us feel good physically or mentally yet we continue repeating the same pattern, reaching for stimulants rather than looking at and addressing how we feel, our stress levels and sleeping patterns.

Foods like sugar, gluten and dairy, alcohol and caffeine all affect mood and behaviour and at the same time exert a negative impact on our gut bacteria. It is a well known fact that caffeine and alcohol are drugs, but did you know that so are gluten and the dairy protein casein? Both gluten and casein release opioid like chemicals that affect brain function and mood and have been implicated in autism,[8] ADHD, schizophrenia[9] and motor function.[10]

No wonder we crave foods and it can seem so hard to give up foods, even when our body is showing us they do not agree with it, when these foods actually release compounds that mimic addictive drugs and when we have altered our gut bacteria to be signalling our brain for more of the same.

It appears here that we have a chicken and egg scenario: which comes first, the gut sending messages for the food that alters our mood? Or is it how we feel and live that influences our gut and the type of bacteria that is present that then makes us more likely to crave and want certain foods when we feel certain ways, just like you get drawn to a sad song when you feel down?

We have been told so many times to rely on our gut, to listen to what our gut is telling us but, in essence, are we being given a bum steer when, in truth, our gut is acting based on our using food to alter how we feel, to be racy, dull, disconnected and less aware? A pattern that alters our gut bacteria that then crave and are seeking more of the same which just amplifies the underlying energy we are running in our body so we get a double feedback loop that feels so compelling it’s hard to ignore – to the point where we say this is gut instinct?

Food for thought perhaps?


  • [1]

    Forsythe, P. (2010) Mood and gut feelings Brain Behaviour and Immunity, V24(1) p9-16 Available from: [Accessed on 13.02.2018]

  • [2]

    Gershon, M. (2001) Organization and development of the enteric nervous system Anatomy and Cell Biology Available From: [Accessed on 13.02.2018]

  • [3]

    Hurley, D (2017) Psychology Your Backup Brain. [online] Available at: [Accessed 3 Oct. 2017].

  • [4]

    Oudenhove, L. McKie, S. (2011) Fatty acid-induced gut-brain signaling attenuates neural and behavioural effects of sad emotions in humans, The Journal of Clinical Investigation, 121(8): 3094-3099 Available from: [Accessed on: 13.02.2018]

  • [5]

    Jones, M., Dilley, J. (2005) Brain-gut connections in functional GI disorders: anatomic and physiologic relationships Journal of Neurogastroenterology and Motility, V18, p.91-103 available from: [Accessed on: 13.02.2018]

  • [6]

    Hadhazy, A. and Hadhazy, A. (2017). Think Twice: How the Gut's "Second Brain" Influences Mood and Well-Being. [online] Scientific American. Available at: [Accessed 3 Oct. 2017].

  • [7]

    Lorio, C. Berardi, J. Logan, A. (2009) A randomized, double-blind, placebo-controlled pilot study of a pro-biotiric in emotional symptoms of chronic fatigue syndrome Gut Pathogens V1(6) Available From: [Accessed on: 13.02.2018]

  • [8]

    Ferriter, M. (2004) Can a diet avoiding gluten and milk protein reduce autism? Medical News Today Available from: [Accessed on 13.02.2018]

  • [9]

    Medical News Today (2004) Schizophernia and gluten link, new study Medical News Today Available from: [Accessed on: 13.02.2018]

  • [10]

    Hadjivassilliou, M. (2008) Gluten ataxia Celerebellum 7(3) p494-498 Available from: [Accessed on: 13.02.2018]

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