Gut feelings: the surprising connection between fibre and your mental well-being

You’ve probably heard that fibre is good for digestion. Keeps things moving, helps you feel full… nothing new there. But what if this humble nutrient could also play a role in how you feel emotionally? In how you manage stress? Even in how clearly you think?

The gut-brain connection

There’s a reason we talk about “gut feelings.” Your brain and gut are in constant conversation. They’re connected by a long nerve called the vagus nerve, which works a bit like a two-way radio. Your brain sends signals to your gut, and your gut sends signals right back.¹

Inside your digestive system lives a bustling community of microbes: bacteria, fungi, and other tiny organisms. Together, they make up your gut microbiome. These microbes help break down the food you eat, support your immune system and, crucially, produce many of the same chemicals your brain uses to regulate mood.²

One of these chemicals is serotonin, often linked to feelings of calm, focus, and emotional stability. And here’s the surprising part: around 90% of the body’s serotonin is made in the gut. But it’s not quite as simple as “gut serotonin = happy brain.” The serotonin produced in the gut doesn’t actually reach the brain, as it can’t cross the blood-brain barrier—instead, it helps regulate digestion, like nutrient absorption and gut motility.

Still, the gut plays a key role in supporting the brain’s production of serotonin and other mood-related chemicals. For example, gut microbes help break down nutrients from food that serve as building blocks for brain neurotransmitters. They also interact with the vagus nerve and the body’s stress-response system, and can influence inflammation and brain signalling. So while gut serotonin doesn’t directly make you feel good, a healthy gut environment can support better mental wellbeing in many indirect but powerful ways.^2 3

What does fibre have to do with it?

Fibre is fuel for your gut microbes. Your body can’t digest fibre, but the microbes in your gut can. When you eat plenty of fibre, you’re feeding the helpful bacteria that support your physical health and may foster a better sense of emotional well-being.^{4 5}

These microbes turn fibre into compounds called short-chain fatty acids. Think of them as chemical messengers that help lower inflammation, protect the gut lining and may even support the production of serotonin.³

In other words, eating fibre helps your gut microbes do their jobs: and that, in turn, supports brain function, energy levels, and a healthier response to stress.

What happens when you don’t get enough?

Low-fibre diets are common, especially when life gets busy. When there are a hundred places we need to be, it’s easy to start relying on low-fibre prepackaged meals. But when you’re not getting enough fibre in your diet, your gut microbes don’t have much to feed on. Some beneficial bacteria begin to shrink in number, while others that thrive on sugar or processed foods start to take over. This imbalance, known as dysbiosis, has been linked to anxiety, depression, and other mood disorders.³

And it’s not just about mood. A fibre-poor gut can also affect how well you sleep, how reactive you feel, and how clearly you can think, potentially impacting your judgment.

So what kind of fibre should you eat?

There are two types of fibre, and both are important.⁶

Soluble fibre dissolves in water and forms a gel-like texture in the gut. It helps slow digestion, balance blood sugar, and feed friendly bacteria. You’ll find it in foods including oats, lentils, flaxseeds, fruits and beans.⁷

Insoluble fibre adds bulk to your stool (poo) and keeps things moving through your system. It’s found in whole grains, root vegetables, nuts, fruit skins, and seeds.

Together, they create the variety your gut thrives on. And a healthy, well-fed gut tends to send calmer, more stable signals back to the brain.

Easy ways to eat more fibre (without overthinking it)

You don’t need to transform your diet overnight. Start where you are, and build from there. Here are a few gentle ways to add more fibre to your meals:

• Add a spoonful of chia or flaxseed to your breakfast
• Swap white rice or pasta for whole grain versions a few times a week
• Keep canned lentils or chickpeas on hand, they go with almost everything
• Eat the skins: apples, potatoes, carrots, all packed with fibre
• Try roasted veggies on toast or in wraps for an easy lunch
• Make porridge, muesli or overnight oats part of your morning routine

If fibre is new for you, increase it gradually and drink plenty of water to help your body adjust.

If you’re just getting started

Adding more fibre is simple, but go gently. Start with one or two swaps: maybe whole grain pasta instead of white, or roasted chickpeas instead of crisps. Drink more water than you normally would—both types of fibre need water to work properly. Insoluble fibre soaks up water to help keep things moving, while soluble fibre forms a gel that can slow digestion; without enough water, that gel can thicken too much and actually slow things down.⁸

Your microbiome is like a garden. It responds to what you feed it. And with the right nourishment, it can help you bloom, inside and out.

In summary

Fibre isn’t just about digestion. It supports the bacteria that help make mood-balancing chemicals. It reduces inflammation. It strengthens the lines of communication between your belly and your brain. And most of us aren’t getting enough.

The good news is, every little bit helps. A handful of lentils. A spoonful of seeds. A piece of fruit with the skin on. It doesn’t take much to start feeling the difference.

Gut feelings, it turns out, are real. And fibre might be the most underrated way to listen to them.