Fibre is the part of our food that does its most important work by not being digested at all. For decades it was dismissed as mere “roughage”, a worthy but dull addition to the diet. Today we understand it as one of the most valuable components of a whole-food diet, central to digestion, to the health of the gut, and to the steady release of energy. This guide takes a naturopathic look at dietary fibre: what it is, what it does, and where to find it.
This article is educational and is not a substitute for professional medical advice.
What Is Dietary Fibre?
Dietary fibre is the group of plant carbohydrates that the human gut cannot break down and absorb. Because it passes through largely intact, it was long thought to be nutritionally inert. In fact its journey through the digestive tract is exactly where its value lies. Fibre is usually divided into two broad types:
- Soluble fibre dissolves in water to form a gel. It is found in oats, pulses, apples and many vegetables.
- Insoluble fibre does not dissolve; it adds bulk and helps material move through the gut. It is found in wholegrains and in the skins, seeds and structural parts of plants.
Most whole plant foods contain a mixture of both, which is one more argument for eating them whole.
Fibre and Elimination
The naturopathic tradition has always placed great value on good elimination, and fibre is central to it. Insoluble fibre adds bulk to the material in the bowel and helps it move through smoothly and regularly. This supports the body’s ongoing clearance of waste, a theme that runs through our article on food and detoxification. Certain fibres are recognised as contributing to normal bowel function and to an increase in faecal bulk, which is the modern, measured way of describing what naturopaths have long observed.
Feeding the Gut Flora
Perhaps the most exciting modern understanding of fibre is that much of it is not wasted at all: it nourishes us indirectly, by feeding the trillions of beneficial bacteria in the gut. Soluble and so-called prebiotic fibres are fermented by these bacteria, which in turn produce short-chain fatty acids that nourish the cells lining the colon. This is the mechanism behind much of fibre’s value, and it is explored in detail in our guide to gut health and the microbiome. The practical lesson is simple: a diet rich and varied in plant fibre is a diet that feeds a healthy inner ecosystem.
Fibre, Blood Sugar and Fullness
Fibre also changes how we experience a meal. One soluble fibre in particular, the beta-glucan found in oats and barley, is recognised as helping to reduce the rise in blood sugar that follows a meal. Fibre also adds bulk and slows eating, which many people find supports a natural sense of fullness. These qualities are part of why a high-fibre, whole-food diet is such a naturopathic staple for steady, everyday energy.
Whole Foods Versus Refined
Here the naturopathic emphasis on unrefined food is decisive. Refining strips fibre away: milling wholegrain into white flour removes the fibre-rich bran, along with much of the mineral wealth that travels with it. A diet built on refined flour, sugar and heavily processed foods is, almost by definition, a low-fibre diet. Choosing foods close to their natural state, wholegrains rather than white and whole fruit rather than juice, is the single most reliable way to raise your fibre intake, and it brings the accompanying vitamins and minerals along for free. Our article on vitamins in context explores this whole-food principle further.
The Best Whole-Food Sources of Fibre
There is no need for special “added-fibre” products when whole foods supply it so generously:
- Pulses: lentils, beans and chickpeas are among the richest sources
- Wholegrains: oats, brown rice and wholemeal grains
- Vegetables, especially eaten with their skins
- Fruit, particularly with edible skins and seeds
- Nuts and seeds
As with the gut flora it feeds, the watchword is diversity: a wide range of different plant foods across the week supplies a wide range of fibres, and with them the broadest benefit.
Key Takeaways
- Fibre is the indigestible part of plant foods, and its value lies precisely in passing through the gut.
- Insoluble fibre supports regular elimination; soluble fibre forms a gel and feeds the gut flora.
- Fermentation of fibre by gut bacteria produces short-chain fatty acids that nourish the gut lining.
- Beta-glucan (in oats and barley) helps reduce the blood sugar rise after a meal; fibre generally supports a natural sense of fullness.
- Refining removes fibre; whole, unprocessed foods are the reliable source.
- Aim for diversity: many different plant foods, eaten whole.
Fibre is a quiet example of a recurring naturopathic truth: that foods in their whole, natural state tend to serve the body far better than their refined and fragmented substitutes.
To understand digestion, the gut and the role of whole foods at this level is central to our Certificate in Nutrition and Health and the Professional Diploma in Nutritional Therapy.
References
- Plaskett, L., Plaskett College Nutritional Therapy course material
- European Food Safety Authority, Scientific Opinions on dietary fibre and normal bowel function
- Murray, M. and Pizzorno, J., Encyclopaedia of Natural Medicine, Simon and Schuster (2012)