Why do we need fibre?
We only became interested in the role of dietary fibre in humans towards the end of the twentieth century. Building on the work of other scientists, a surgeon called Denis Burkitt proposed what is now known as ‘The Dietary Fibre Hypothesis’ in 1972.
At the time, this somewhat radical view identified that diets low in fibre increased the risk of many degenerative disorders such as cardiovascular disease, obesity, diabetes, cancer and bowel conditions, to name a few. So, public interest in fibre was put firmly on the map and the food industry went on an all-out fibre assault. Cereals were an obvious win for food manufacturers and subsequently ‘high fibre’ claims were established.
Fast forward to now and it’s not in dispute that fibre is beneficial, in fact research into fibre and digestive health particularly has evolved considerably (more on that later). There is a big market for products rich in fibre and a trend to find new sources. But what exactly is ‘high fibre’, where should we get it from and what does it do for us? I’ve written the fibre file to hopefully arm you with the facts, so that you can make an informed decision on your food choices.
What is fibre?
Its definition has been subject to a great deal of debate over the years. The most recent definition seems to be globally agreed as: ‘dietary ﬁbre is made up of carbohydrate polymers with three or more monomeric units (MU), which are neither digested nor absorbed in the human intestine’. (2) In simple terms, fibre is the indigestible portion of food derived from plants. It is often described as soluble fibre (e.g. in oats and fruit) and insoluble fibre (e.g. in wholegrains and nuts), simply meaning that can or can’t be dissolved in water.
Within the polysaccharide category, there are some types that are not digested or absorbed in the stomach or small intestine and therefore can’t be broken down into single sugar molecules. Cellulose is just one example, however there are now around 16 different types, as identified by a 2017 review of dietary fibre in Europe. (2) It’s way too confusing to talk about them all, however the following table gives a good summary of some of the main types along with their sources and health benefits. (4) Note that the fibre used to give Troo Granola & Porridge its sweet taste is inulin, derived from the chicory root and has benefits for both gut and immune function.