Explain Classification Based on Digestive Fate of Carbohydrates?
The digestive fate of carbohydrates depends on their inherent chemical nature (monosaccharide composition and type of linkage between sugars) and on the supramolecular structures within foods of which they are a part. Mc Cance and Lawrence in 1929 were first to classify carbohydrates as 'available' and 'unavailable'. According to them, carbohydrates that are digested to constituent monosaccharides and absorbed fell under the category of 'available' carbohydrates. carbohydrates that are not digested by the endogenous enzymes of the human intestinal tract and therefore not absorbed were classified as 'unavailable' carbohydrates. However, these undigested carbohydrates enter the colon and are fermented by microflora.
It is realized now that it is misleading to use the term 'unavailable' carbohydrates because some indigestible carbohydrates can provide body with energy through fermentation in the colon. Therefore, 'unavailable' carbohydrates are not really 'unavailable' and the term 'Non Glyceinic Carbohydrates' is suggested for these by FA0 (Food and Agriculture Organization) and WHO (World Health Organization). Non glycemic carbohydrates include the raffinose series of oligosaccharides, non-starch polysaccharides (NSP), some disaccharides such as lactulose and resistant starch (RS). Here, we will get to know more about RS and the other non-glycemic carbohydrates. Similarly, carbohydrates that are digested to monosaccharides and absorbed as such in the small bowel are termed as 'Glycemic' carbohydrates. They include disaccharides, starch, maltodextrin and glycogen.