You may not be able to tell by inspecting a granule of table sugar, but sucrose is actually made of two parts. Because sucrose is a disaccharide -- composed of simple sugars or monosaccharides called glucose and fructose -- it has to be digested by special proteins called enzymes. Once digested, the constituent parts of sucrose are absorbed into the bloodstream and transported to cells around the body.
Crunchings and Munchings
Take a bite of a sugary doughnut and immediately your teeth begin the process of digestion by grinding and mashing the food into smaller pieces. An enzyme called amylase, found in the saliva, starts the breakdown of sucrose. You swallow and the food travels through the esophagus to the stomach, where the food is mixed with hydrochloric acid, but very little digestion of sugars occurs. The primary site of sucrose digestion is next stop in the digestive tract -- the small intestine.
Small Intestine Action
A group of enzymes called brush border hydrolases digest all dietary polysaccharides and disaccharides, including sucrose. The small intestine is lined with fingerlike projections called villi that are composed of epithelial cells. When dietary sucrose comes in contact with the villi, a hydrolase called sucrase breaks the sucrose molecule into glucose and fructose, which are then absorbed into the bloodstream and used by the body.