Glucose-galactose malabsorption is a condition in which the cells lining the intestine cannot take in the sugars glucose and galactose, which prevents proper digestion of these molecules and larger molecules made from them.
Glucose and galactose are called simple sugars, or monosaccharides. Sucrose and lactose are called disaccharides because they are made from two simple sugars, and are broken down into these simple sugars during digestion. Sucrose is broken down into glucose and another simple sugar called fructose, and lactose is broken down into glucose and galactose. As a result, lactose, sucrose and other compounds made from carbohydrates cannot be digested by individuals with glucose-galactose malabsorption.