Sources, Chemical Composition and Analysis of Dietary Fibre

Abstract

As we have seen, the term ‘dietary fibre’ was originally used as a shorthand term for the constituents of the plant cell wall. Furthermore, in the case of the protective diets postulated by Burkitt and Trowell, the distinguishing feature that was considered most important was the consumption of plant foods that contained their cell walls in a relatively natural state. These are, principally, high-extraction (unrefined) cereal foods, vegetables and fruits. Conversely, the low-fibre diets were characterized by a high proportion of plant foods that had had their content of cell wall material reduced by processing and refining. This implies that the most appropriate primary definition for ‘dietary fibre’ is ‘the plant cell wall material in foods and the diet’. In discussing the sources and chemistry of dietary fibre, therefore, the starting point must be a consideration of the plant cell walls in foods. When we move to considering the analytical measurement of dietary fibre we have to consider how this primary definition can best be interpreted in practical terms.