After digestion, disaccharides provide energy to muscles, fuel the central nervous system, metabolize fat and keep tissues from consuming protein for energy. A disaccharide is a type of carbohydrate made when two monosaccharides join and a molecule of water leaves the framework.
One example of a disaccharide is lactose, which is made from the juncture of glucose and galactose and is found in milk. When glucose and fructose join together, they form the disaccharide sucrose, or table sugar. After people eat foods containing disaccharides, the stomach and small intestine break them apart. The small intestine absorbs the resulting monosaccharides, sending them into the bloodstream and ultimately to the liver, which converts them all to glucose.
Whether it is absorbed directly or released by the liver, glucose in the bloodstream triggers the release of insulin, which allows the monosaccharide to enter cells. The bloodstream transports insulin and glucose to organs and tissues, such as the muscles and the brain, which use it for energy. When tissues have more glucose than they need, the excess goes to the liver and skeletal muscles for storage as glycogen. If these organs already have enough glycogen, the glucose is stored in the form of fat.