Why "Just Eat More Fibre" Isn't Good Enough Gut Health Advice

I do cringe a little when someone experiencing gut issues is given very general advice to "eat more fibre" or "take a fibre supplement."

There's a lot more to it than that. Getting dietary advice to simply increase fibre to manage your gut issues misses the timing, pace and volume of any fibre introduction or increase — and the various *properties* of fibre — all of which need consideration to get the best outcome.

Fibre 101: the two main types

Soluble fibre dissolves in water and can create a gel-like, softer stool. Ideally, it softens stools that are too hard and thickens stools that are too loose. Examples include psyllium husk, oats, oranges, carrots, sweet potato, avocado and black beans.

Insoluble fibre doesn't dissolve in water. It adds bulk to the stool, increasing mechanical irritation of the bowel to stimulate water and mucous secretion (if the particles are large enough), and supports the propulsion of stool via the bowel's existing waves of movement. Examples include bran, fruit and veg skins, nuts, seeds and wholegrains.

A more advanced look: fermentability and viscosity

For anyone affected by IBS, it's also important to consider a fibre's **fermentability**. Fermentability affects the production of beneficial short-chain fatty acids (SCFAs), which influence immune, metabolic and hormone signalling from the gut. It also impacts gas and fluid levels in the colon, and — depending on how quickly a fibre ferments — how far it actually travels through the colon to have an effect. Highly fermentable fibres like inulin, for example, may cause more pain, flatulence and bloating in some people, and may not be as effective at improving stool consistency along the entire length of the bowel.

Soluble doesn't automatically mean gel-forming, either. Gel-forming properties depend on a fibre's water-holding capacity and viscosity when hydrated — think a thick, sticky fluid versus a thin, runny one. This is what separates different soluble fibres in terms of likely effectiveness. Psyllium husk (found in products like Metamucil), for instance, has a higher water-holding capacity and viscosity, giving it good gel-forming properties. Benefibre, by contrast, has a lower w

ater-holding capacity and viscosity with poorer gel-forming properties — which is exactly why it dissolves into a thin, easily drinkable liquid.

The takeaway

It's not as simple as "eat more fibre," "get 25–30g a day," "eat more fruit and veg," "try fibre gummies," or "buy high-fibre products." Your dietary fibre prescription should be as unique as your gut is.