How are carbohydrates digested?
Digestion of carbohydrates begins in the mouth. Amylase is an enzyme that helps break down the long chains of sugars into smaller chains. Amylase is also secreted by the pancreas into the small intestines. Once broken into 2-sugar units, enzymes called disaccharidases in the intestinal wall break the sugars into single units (i.e. – glucose, galactose, and fructose). These “simple” sugars can be absorbed through the intestinal walls into the bloodstream.
Starch digestion begins in the mouth. As food does not remain long in the mouth, only a little starch is digested by salivary amylase to maltose. No digestion of carbohydrates occurs in the stomach; only proteins are digested in the stomach. In the small intestine, starch is digested by pancreatic amylase into maltose, which is digested by maltase into glucose. Lactose is digested by lactase into glucose and galactose. Sucrose is digested by sucrase into glucose and fructose.The end products of carbohydrate digestion are simple sugars (glucose, fructose, and galactose) which can be absorbed. Cellulose is not digested in the humans’ gut.
