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Health

We're finally uncovering fibre's remarkable benefits for body and mind

From dampening inflammation to boosting mental health, the many types of dietary fibre have a surprisingly large impact throughout the body. Here's how to get your fill

By Graham Lawton

7 April 2025

New Scientist. Science news and long reads from expert journalists, covering developments in science, technology, health and the environment on the website and the magazine.

Lisa Sheehan

Deep inside your lower intestine is a 24/7 dinner party. The trillions of microorganisms that live in your colon are feasting on foodstuffs you ate but failed to digest. Their motives are selfish but they are still doing you a favour, tending to the health of your gut, brain, heart and immune system.

Meanwhile, in the background, even-more-indigestible food is quietly drifting past. Even the microbes won’t touch it, but it, too, has a positive effect on your health.

The name of all this undigested food? Fibre. Perhaps the most unglamorous of nutrients, it has so many things going for it that it deserves to be lauded as a superfood. But while the health benefits of a fibre-rich diet have been recognised since the 1950s, only in recent years have we gotten a firmer handle on the full complexity of this diverse substance and how to maximise these positive effects.

New research is uncovering the power of different types of fibre to dampen inflammation, improve our immune function and mental health – and even act as “nature’s Ozempic” by dialing down our appetite. These studies are also revealing why the fibre often added to processed food won’t do the same trick.

Dietary fibre

Dietary fibre – also known as roughage – is defined as the portion of ingested food that cannot be broken down by our own digestive enzymes. You could be forgiven for thinking that all fibre is basically the same, just humdrum rough stuff that goes in at one end and ultimately comes out at the other. After…

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