Your Second Brain

Gut-Brain Axis Guide

This guide is developed by the gut-brain axis scientists at APC Microbiome Ireland, a world-leading SFI Centre, in partnership with Yakult.

Gut Microbiota in numbers

Did you know that the surface area of your gut can cover the floor of a small studio flat? Or that there are more bacteria in your gut than stars in the milky way? You have more bacterial cells than human ones! Extraordinary, but the work that these bacteria do is even more amazing.

A Window into your Gut

It all began in the 1800s, with a gunshot to the stomach that never fully healed, leaving Alexis St. Martin with a permanent “window” into his gut. His doctor had thus a unique view of the human gut and noticed that whenever St. Martin became stressed, angry or annoyed, his digestion changed too. This paved the way for the study of how mood affects gut function or what we now call the gut-brain axis.

Gut Feelings

Have you ever felt butterflies in your tummy before a big interview or have followed your gut feeling when making a tough decision? These are first-hand experiences of the gut-brain-axis in action and our new scientific understanding of this relationship helps explain these centuries old sayings. Trusting our gut could bring exciting new opportunities to control how we think and feel.

Gut-Brain Talk

Your brain and gut communicate in different ways. Sometimes the conversations are direct chats between bacteria and the brain using the gut-brain axis, other times your immune cells need to act as ‘translators’. But there is also the vagus nerve and the bloodstream to link your gut and your brain. Discover more below!


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Here are some ways to keep your gut-brain-axis in tip top condition

You are what your bacteria eat

Your gut-brain axis works best when you have a rich diversity of bacteria in your gut. Think again about having an assembly team in your gut factory, with each member of the team performing a key task for you. Gut bacteria thrive on healthy, whole foods that are rich in fibre. So, give them what they need to perform well by eating a varied diet. Your daily menu should include a mix of fruits, vegetables, legumes, beans, nuts and seeds. Fermented foods like some dairy products, kimchi, kombucha and sauerkraut are good sources of live bacteria, so including these in your diet can add extra diversity.

Sleep Soundly

Everyone loves that “conquer the world” feeling after a restful night’s sleep. Having a rich diversity of bacteria in our gut helps support quality, restorative sleep. But if our gut bacteria take a hit (for example due to antibiotic use), this is communicated along the gut-brain axis and our sleep can suffer. Given that we spend a third of our lives asleep, focusing on the quality of your sleep is one of the best things you can do for your overall well-being.

Move more

Your whole body thrives when you exercise. Your bacteria love a good workout too, because it helps make the gut a better place for them to live in. Exercise can thus enrich the diversity of your gut bacteria. Elite athletes have noticeably more diverse gut bacteria compared to the average person. But you don’t need to be ‘elite’, the good news is that even moderate amounts of exercise can make a difference. So, choose activities you enjoy – walking, cycling, swimming, rollerblading, playing frisbee, dancing – and you’ll help your gut bacteria to work at their best for you.

Get a Pet

If there was ever an excuse to get a puppy, here it is: people who live with pets have more gut bacteria diversity than those living in pet-free homes. Because humans have lived in close contact with animals and livestock, our gut bacteria have evolved alongside theirs. The best time to get a furry friend is in childhood while the eco-system of gut bacteria is still developing.

Gut Diversity is a walk in the park

It’s not just owning a pet that can boost your gut bacteria, interacting with the natural environment can do that as well. Spending some time in urban green spaces is a good example. So, go on you city slickers, take a walk in the park – your gut bacteria will thank you!

Reduce stress levels

Research shows that how we react to stress depends on our gut bacteria although we still need to pinpoint exactly which bacteria are most important. Having a rich diversity is a good starting point and thought to keep your stress response in tip-top shape. But high levels of stress can change the composition and function of your gut bacteria. We told you the gut-brain axis is a two-way street! So, take good care of our gut bacteria so that they are ready to support you every day

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