DIETARY CARBOHYDRATES - CLASSIFICATION BY CHEMISTRY AND PHYSIOLOGY

Food carbohydrates consist of mono-, di-, oligo- and polysaccharides, the latter composed of starch and non-starch polysaccharides (NSP). Th e glycaemic response to both sugars and starches is dependent on the t ypes of sugars present and the form of the starches, and 'complex carb ohydrates' do not necessarily produce slower or lower glycaemic respon ses than the sugars. Carbohydrates not absorbed in the small intestine are fermented more or less extensively by the large intestinal microf lora. There is a fundamental difference nutritionally between digestib le and undigestible ('unavailable') carbohydrates. NSP, resistant star ch (RS) and oligosaccharides are the main forms of undigestible carboh ydrates. Dietary fibre is generally conceived as more or less synonymo us with 'unavaiiable' carbohydrates. The nutritional effects of dietar y fibre are related to its undigestibility in the small intestine, and to the physical and chemical properties of its constituent polysaccha rides. Food structures built of dietary fibre as plant cell-walls, and also of other food components, are increasingly recognized as nutriti onally important. Food databases should include as much specific and d etailed information as possible on food carbohydrates. For food labell ing, carbohydrates have to be divided into a number of nutritionally m eaningful classes. A first classification should then aim at different iating the digestible and undigestible carbohydrates, i.e. dietary fib re. Copyright (C) 1996 Elsevier Science Ltd