Up your fibre game by eating several different kinds of the nutrient from numerous food sources
Forget fibremaxxing – the latest food fashion is fibre layering and dietitians and doctors approve.
Fibre layering has no strict medical definition, but most people use it to mean consuming several different types of fibre, spread over the day – rather than just one bean-heavy meal, for instance.
“We may think of fibre as being this homogenous roughage, but really, it’s lots of different compounds that do quite distinct things,” said Bridget Benelam, a scientist at the British Nutrition Foundation.
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Fibre, a type of carbohydrate found in plant foods, has several health benefits, with perhaps the best-known being its ability to keep bowels moving and so preventing constipation. It is also thought to lower harmful forms of cholesterol and so helps prevent heart disease.
But most of us are not getting enough fibre in our diet. We are advised to aim for at least 30g of fibre every day – but this can be tough to hit.
For instance, the average slice of wholemeal bread has about 2g, while a banana has 3g. The average Brit consumes only 18g a day.
If simply boosting our fibre intake isn’t challenging enough, some experts now say we should also be trying to eat all the different kinds of fibre – and spread it more or less evenly through the day too.
“If you hit your 30g of fibre in one meal, that can overload your capacity to break it down,” said Anna Mapson, a nutritional therapist with Goodness Me Nutrition.
“It’s quite a lot for your body to process. So ideally, splitting it between your three meals a day is helpful.”
Using fibre to lower cholesterol
Ella Rauen-Prestes has been practising fibre layering for three years, before the term came into use.
She began the dietary change because her father died from heart disease, as had her grandfather. Then a blood test showed her own levels of “bad cholesterol” were too high.
Rauen-Prestes is not a fan of porridge – oats are high in fibre – so instead has a breakfast smoothie with oat bran, chia seeds and frozen berries. “Buying fresh fruit is expensive and it goes bad, so I buy those packs of frozen fruit and throw it in.”
For lunch and dinner, she has a mixture of vegetables, including beans and lentils, as well as whole grains. Her tips include having lentils instead of a carb-heavy food such as white rice or potatoes, loading up on beans and adding scoops of oat bran to dishes where possible.
Ella Rauen-Prestes layers her fibre (Photo: Greta Staknyte)
The strategy seems to have worked. As well as her gut health improving, her bad cholesterol has lowered from 3.3 to 2.7 millimoles per litre, and is now in the healthy range.
“There was this overwhelming sense of relief,” she said. “For a long time, the health history of my father and grandfather felt like a pre-written ending. Now I know my DNA doesn’t have to be my destiny.”
The different kinds of fibre
There are several main kinds of fibre. The type that may first come to mind is insoluble fibre, which cannot be digested in the gut at all, and so passes through the bowels unchanged.
Insoluble fibre adds bulk to poo and also encourages it to bind water, both of which help in making bowel movements easier.
It is found in the tough structural parts of plant foods, like nuts, seeds, skins of vegetables and whole grains, so it is in wholemeal bread and brown rice and pasta.
Another type is called fermentable fibre. This can’t be digested by our gut enzymes, but can be broken down and used as food by bacteria in the lower bowel.
This process means the bacteria release beneficial compounds called short-chain fatty acids which are thought to reduce inflammation in the gut.
Fermentable fibre is sometimes called prebiotics – as opposed to probiotics, which are the gut bacteria themselves, often sold as capsules or in the form of yoghurts or drinks.
Fermentable fibre is found in fruit and vegetables, such as onions, garlic, asparagus and bananas.
Another subtype of fermentable fibre is called resistant starch. This is found naturally in some plants like unripe bananas, but you can also manufacture it by pre-cooking some starchy foods like potatoes and pasta and letting them sit in the fridge for up to a day. These can then be eaten cold or reheated.
As well as feeding gut bacteria, resistant starch also causes blood sugar levels to rise more slowly after meals.
“If you’re only relying on breads and cereals, then you’re missing out on other types of fibres from, say, fruit, vegetables, nuts, seeds,” said Bahee Van de Bor, a spokesperson for the British Dietetic Association.
“You want to mix it up, because that appeals to a broader range of the beneficial bacteria, and it helps grow a diverse microbial community in your gut.”
Viscous fibre cuts cholesterol
A third category of fibre is viscous fibre, including a form called beta-glucans, which bind to water and form a sticky gel. This has the benefit of reducing cholesterol levels in the blood.
That’s because the viscous gel then binds with bile salts in the gut and means they are ultimately excreted. Bile salts are made by the liver using the building block of cholesterol. If bile salts are excreted, this forces the body to make more bile salts, using up cholesterol in the process.
This may be why some trials have suggested oats, which are high in beta-glucan, can reduce cholesterol levels.
And they may be the secret to Ella Rauen-Prestes’s fibre-layering diet. She said: “Seeing those numbers drop through nutrition alone at 51 was a moment of immense pride: proof that ‘you are what you eat’ isn’t just a cliché.”
