Food and Agriculture Organization (FAO), Roma, Italia
Fibre can be defined and measured in many different ways, each of which captures various constituents in varying amounts, resulting in significant different amounts. The chosen fibre method thus affects not just the fiber value, but also the value of total carbohydrate by summation, available carbohydrate by difference, and the final energy calculation of the foods. Fibre was first analysed as ‘crude fibre’ and than several methods evolved such as the methods of Englyst, Southgate, the acid or neutral detergent methods and the AOAC 985.29, Prosky, Asp, McCleary and others. Many food composition tables provide dietary fibre data determined by the Prosky method while older ones still list crude fibre values even though they are considered obsolete. Still others provide Englyst values alone or in combination with lignin. Because Prosky fibre values are widely available, many studies on nutrition and health relationships have used the Prosky values and many nutrition labelling regulations also prescribe this method, even though also other methods may be permitted. In the early days, fibre per se had no energy value assigned, and since 1998 the FAO/ WHO Expert Consultation Carbohydrates in Human Nutrition recommended an energy value of 8 kJ/g (2 kcal/g) which is increasingly used in food composition tables and labelling. In 2009, after several years of discussion, the Codex Alimentarius Commission adopted a dietary fibre definition and a list of accepted methods, but left it to national authorities to decide if monomeric units of 3-9 are included or excluded. While being a step forward, the new definition leaves room for national or regional differences, especially for labelling. During the presentation some impacts of the different fibre definitions and energy values will be presented. Conclusion: It is hoped that in the future, more analytical data on dietary fibre using a robust analytical method will be generated worldwide and that these data will be included in national and regional food composition databases and be used in a harmonized way for food labelling. This will harmonize nutritional research and programmes using nutrient intakes, including those of dietary fibre. Keywords: dietary fibre, definition, health, nutrition, food composition, Codex Alimentarius.