Featured ingredient part one: Fibre
Featured ingredient Fibre
The health benefits of whole wheat compared with refined wheat have been known for hundreds of years. The first recorded account of the health benefits of whole wheat compared with refined wheat was in 430 BC, when Hippocrates noted that course wheat was rather a good laxative. Then in 1920, Kellogg, the man behind the cereal brand, publicised the virtues of bran in its ability to increase the size and weight of daily stools, thereby preventing discomfort and diseases associated with constipation. After that, fibre was largely forgotten about. Then, on the 13th December 1975, a short letter appeared in the prestigious British Medical Journal titled ‘Dietary fibre hypothesis’.
The letter was written by Hugh Trowell, a medical doctor who had spent some time with his colleague Denis Burkitt studying the diets of people in Uganda. What Trowell and Burkitt noticed was that the Ugandan diet consisted of a high proportion of plant foodstuffs such as green vegetables, root vegetables, maize and potatoes. In addition, they observed that far fewer Ugandans suffered from diseases such as bowel cancer, diabetes and atherosclerosis than their British counterparts. Following the end of austerity and the rationing of food imposed during the second world war, wholefood-based diets went out of fashion in favour of more refined foodstuffs where the fibre content had been largely removed. Trowell and Burkitt’s big idea, laid out in this letter, lead the way for tens of thousands of studies that firmly established the role of fibre as an important dietary nutrient.
So, what exactly is fibre?
Fibre is a kind of carbohydrate, but it’s a bit more complicated than that. Carbohydrates are a group of nutrients found in a diverse range of plants such as fruits, vegetables, cereals, beans and peas. There are essentially 2 types of carbohydrate, the simple sugars (for example, glucose, sucrose fructose, etc.) and the complex carbohydrates (for example, starch and fibre). Complex carbohydrates are further divided into those parts of a plant that are stored in the cells as a source of energy for the plant - the starches. And those parts of a plant that make up its structural components, for example the cell walls, seed casings, or husks and so on - the fibre.
What makes fibre different from other kinds of carbohydrate is its resistance to digestion in the gastrointestinal tract of cats, dogs and people. Note that some starches are also resistant to digestion so they are also classified as fibre. Also note that ruminants like cows, goats and sheep have more complex gastrointestinal tracts and they are able to digest some of these fibres more effectively.
The indigestibility of fibre gives it 2 valuable properties as a nutrient, depending on its degree of ferment-ability by the billions of bacteria that live normally in the large intestine, generally referred to as the normal intestinal flora. Thus, there are 2 types of fibre, fermentable fibre, also called soluble fibre, and non-fermentable fibre, also called insoluble fibre. On many pet food labels, the fibre content of the food is expressed as ‘crude fibre’. Crude fibre consists mainly of non-fermentable fibre and very little fermentable fibre. The term ‘dietary fibre’ is more encompassing and includes both fermentable and non-fermentable fibre types.