The gut–brain connection: why fibre isn’t one-size-fits-all

By Lara Mills

My first memory of fibre has got to be the classic fruit ‘n fibre cereals—what I thought were unappetising, bland and cardboard-tasting options marketed to previous generations to make sure that they were getting enough “roughage” in their diet. 

Today, I don’t have to go to a specialist health shop to find more appealing fibre-boosting foods. Supermarkets now boast a multitude of on-the-go snacks boasting their high-fibre content on colourful packaging, but fibre isn’t anything new. A quick walk through the fruit and vegetable aisle reminds us that some of the best sources have always been there: whole, unprocessed and seasonally rich in additional nutritional value. 

What has changed, however, is our understanding of fibre, its universal appeal, and how we use it. Instead of focusing purely on “adding bulk”, many of us are now aware of fibre’s role in promoting a healthy gut microbiome, which in turn influences digestion, gut immunity, and even aspects of hormonal and skin health. 

I was delighted to see that the once-unsexy nutrient even found its way into a TikTok trend dubbed “fibremaxxing”, where adding powders like inulin or psyllium husk to drinks or sprinkling seeds onto meals throughout the day is encouraged in pursuit of better gut health. Although I’m always in favour of simple ways to improve how I feel day-to-day, for many people—especially those with sensitive digestion—suddenly increasing fibre intake can lead to bloating, gas and discomfort. ¹ 

As it’s both IBS Awareness Month and Stress Awareness Month this April, it feels like an apt time to reconsider how we approach fibre—and how we might personalise it. Stress Awareness Month, which aims to raise awareness of the impact of stress on both mental and physical health, is a useful reminder that our digestive system doesn’t operate in isolation. 

An overview of dietary fibre 

Often referred to simply as fibre, dietary fibre is a type of carbohydrate found in plant-based foods—such as fruits, vegetables, grains, and pulses—that the human body can’t digest. While much of nutrition focuses on what we absorb, this lack of absorption is actually what makes fibre so beneficial. They travel through the digestive system to the colon, where they help regulate bowel movements, support cholesterol balance, moderate blood sugar, and feed beneficial gut bacteria.² 

An often-overlooked form of non-digestible carbohydrate is resistant starch. Unlike most starches, resistant starch escapes digestion in the small intestine and instead ferments in the large intestine, where it exerts prebiotic effects. Common sources include green (unripe) bananas, cooked and cooled potatoes or rice, and legumes. Emerging evidence suggests resistant starch may support blood glucose regulation by improving insulin sensitivity and the body’s blood sugar response after eating. ³ 

Dietary fibre is found in two main forms: 

Both types play an important role, but not all fibres are tolerated equally. Some ferment more rapidly in the gut, which can lead to gas and bloating in sensitive individuals, while others are broken down more gradually and are often easier to incorporate. ⁷ 

Although it’s recommended that the average adult consumes around 30g of fibre per day, it’s estimated that up to a whopping 96% of us fall short.⁸ But incorporating more fibre doesn’t need to be complicated—aiming for a variety of up to 30 different plants per week in combination, including grains, pulses, fruit, vegetables, seeds, nuts, herbs and spices, provide rich sources of both soluble and insoluble fibre. The most important thing to remember is that fibre works together with hydration, so if you’re increasing your intake, keeping well hydrated is key. 

It’s also worth bearing in mind that 30g per day is a general guideline, not a one-size-fits-all rule. Our individual needs can vary depending on overall diet, lifestyle, and energy intake. ⁹ When we also consider stress, lifestyle and the gut–brain connection, it becomes clear that a blanket approach to fibre doesn’t work. 

The gut–brain connection explained