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The gut-brain axis: Are the gut and brain really connected?
Written byChloe Gray
Reviewed byJasmine Bliss
Could mood, focus and sustained energy be linked to your gut health? Or what if your brain could be connected to bloating and discomfort? We’re unpicking this gut-brain connection with expert insight
Summary
1What is the gut-brain axis?
Think of it as a phone line between the gut and your brain, meaning the gut sends signals to the brain and vice versa...
2Why is the gut-brain axis important?
It’s changing how we think about health and disease and in some cases, messages from the gut can affect how we feel..
3How does gut health affect overall wellbeing?
The gut is linked to immunity, with about 70% of the immune system being housed in the gut...
Have you heard about the gut-brain axis? For a lot of people, the idea that these body parts share a connection makes instant sense. After all, we often turn to ‘gut feelings’ to get through some of life’s biggest decisions, from breakups to career choices. Indeed, you may even have seen the gut being referred to on your social feeds as the ‘second brain. You might also understand it on an innate level, having tapped into your own ‘gut feelings’ to get through some of life’s biggest decisions, from breakups to career choices.
You would’ve been right to listen and you might have seen the gut being referred to on your social feeds as the ‘second brain’. Of course, your gut doesn’t think or make decisions like your brain but it does have its own nervous system. The gut-brain axis refers to this communication system between the gut and the brain, which according to studies, may influence everything from mood to pain.1
So what really is the gut-brain axis and what could it mean for health? We asked Jasmine Bliss, a registered nutritionist and gut health specialist, to share her insight.
What is the gut-brain axis?
The gut-brain axis can be thought of as a phone line between the gut and your brain. “It means they are constantly ‘talking’ to each other,” explains Jasmine. That conversation happens through nerves, hormones, immune signals and ‘messengers’ produced by gut microbes, she adds.2
The talk is also bidirectional, meaning the gut sends signals to the brain and vice versa. “What happens in your gut could potentially influence your mood, energy and stress response, while your brain can directly affect digestion, motility (muscle movements that dictate the speed at which food moves through our digestive systems) and sensitivity to pain,” explains Jasmine.2
The vagus nerve plays the biggest role in maintaining this contact. “This runs all the way from our brain to our gut and is part of our parasympathetic nervous system, which dictates our stress response,” she continues.3 The vagus nerve helps your body relax and digest food. It supports things like saliva production, stomach acid and movement in your gut. In contrast, the ‘fight-or-flight’ system takes over when you’re stressed and slows down digestion.
“Feeling ‘butterflies’ is the perfect example of our gut-brain connection causing physical symptoms from something that’s making us nervous, and is why short-term anxiety from things like stressful work presentations or job interviews may trigger gut symptoms like bloating and diarrhoea,” adds Jasmine. If this is common however, it’s worth speaking to your GP.
Why is the gut-brain axis important?
“Our gut-brain axis could potentially affect a huge amount of body functions shown by emerging research,4 including helping to regulate appetite, digestion, gut motility, metabolism, mood, stress resilience and sensitivity to pain. Other emerging evidence5 also suggests it might also affect what we crave and choose to eat and could play a role in how sensitive some people are to certain foods, though many factors are involved,’ says Jasmine.
The gut-brain axis is also changing how we think about health and disease. In some cases, messages from the gut can affect how we feel and the brain can also influence how the gut works. For example, certain gut bacteria have been linked to depression and studies6 show that transferring gut bacteria from people with depression to mice can make the mice act depressed. This suggests the gut can affect the brain, although scientists are still studying how this works in humans.
“We also used to think irritable bowel syndrome (IBS) was solely a gastrointestinal disorder, but some people refer to it as a ‘disorder of the gut-brain axis’7 because of how heavily involved our brain and vagus nerve are,” says Jasmine. “When we’re stressed or anxious, the brain can trigger changes in how the gut perceives signals. This could be why IBS symptoms often flare with stress, even if your diet hasn’t changed.”
Meanwhile, about 90% of serotonin (our ‘happy’ hormone) is made in the gut,8 and “gut microbes also produce dopamine and GABA, which are neurotransmitters that regulate mood and motivation”.
However, none of this is a perfect science and researchers are only just scratching the surface of the deep link between the complex organs. “Research9 is also still ongoing into links between the gut and neurodegenerative conditions (like Parkinson’s and Alzheimer’s), as early evidence suggests that gut changes may be an early symptom of these diseases. Other studies are also investigating whether certain probiotic strains can impact mental health conditions like anxiety or depression10 but at the moment the research is still in its infancy,” adds Jasmine.
How does gut health affect overall wellbeing?
Your gut isn’t only linked to your mind – it’s also connected to many other aspects of the body that impact your health and wellbeing.
In particular, the gut is linked with immunity, with about 70% of the immune system being housed in the gut.11 “This means our gut health could be linked to whether we catch the cold from the person next to us on the tube and even how well we respond to vaccines,” says Jasmine.
“Our gut microbiome also regulates inflammation in the body, metabolic health and nutrient absorption, meaning two people can eat identical diets but absorb different levels of nutrients from them.” That’s because certain microbes are better at breaking down foods to release minerals like iron, calcium and magnesium, while a healthy gut also has a strong lining that means nutrients don’t ‘leak’ through it without being absorbed properly.12
However, some of the hype around gut health has gotten ahead of the science, Jasmine warns. “Anything that promises to ‘detox your gut’ isn’t backed by science – your liver and kidneys are all the detoxification you need.
“Another red flag is ‘gut microbiome’ stool testing and food intolerance testing kits. Unfortunately, we don’t fully know what a ‘healthy’ microbiome looks like yet, and it’s not just about whether certain strains of ‘good’ or ‘bad’ bacteria are present but also overall diversity, fungi, archaea and viruses. In addition, we need to know how different microbes interact with each other, the waste products they produce, how healthy our gut lining is, stomach acid levels, bile flow, pancreatic enzymes and how our microbiome actually behaves. It’s impossible to capture this in a poo test!”
How to support your gut health
Jasmine has shared the following tips for supporting your gut and overall health.
- Eat at least 30 different plant foods per week for fibre and polyphenols. Research from the American Gut Project found that those who ate 30 or more different plants per week (including fruits, vegetables, legumes, nuts, seeds and grains) were more likely to have certain ‘good’ gut bugs than those who ate just ten4
- Include fermented foods like kefir, yoghurt, sauerkraut or kimchi. These foods contain live bacteria that research13 suggests can infiltrate the gut, as well as providing nutrients for the bacteria that already live there
- Reduce high-fat, sugar and salt intake, particularly biscuits, supermarket ready meals and convenience foods that contain additives and emulsifiers and a low fibre content. These foods have been linked to a less diverse microbiome, lower levels of beneficial bacteria and an increase in pro-inflammatory microorganisms, according to a 2025 study14
- Manage stress with tools like breathwork, yoga, walking and mindfulness. Stress directly impacts gut motility and sensitivity and can reshape the gut bacteria through stress hormones, inflammation and changes to the nervous system, according to researchers15 from Ohio State University College of Medicine
- Prioritise movement. Even walking supports digestion, with a study16 in elderly women reporting that a one-hour daily walk led to increased levels of beneficial bacteria
- Stay hydrated, as fibre needs water to move through the gut. In one study,17 researchers had two groups eat 25g of fibre a day, but one group drank two litres of water while the other drank just 1.1 litres. The former group reported 50% more bowel movements per week. Plus, based on recent data, 96% of the UK don’t get enough fibre18
The final say
Better digestion isn’t the only reason to support your gut health. The gut-brain connection means that looking after your stomach may support your mood and help you manage stress, while potentially protecting your mind for the future.
Getting on top of any stress may also support our gut health and remember to take extra care of your digestive health during unavoidable anxious times. If you have continuous gut issues, it’s important to speak to your GP as well.
If you want to learn more about how the gut impacts your wellness, read our guides on the gut-skin connection and how stress impacts your gut.
Disclaimer – This article provides informational advice and is not a substitute for medical care. Working with experts for accuracy, we take great care to ensure the information is up-to-date and relevant. However, you should always consult your GP or healthcare professional before using supplements or alternative products, particularly if you have medical conditions or are under supervision.
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2. Carabotti M, Scirocco A, Maselli MA, Severi C. The gut-brain axis: interactions between enteric microbiota, central and enteric nervous systems. Annals of Gastroenterology : Quarterly Publication of the Hellenic Society of Gastroenterology [Internet]. 2015;28(2):203. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC4367209/
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