The Function of Disaccharides

Disaccharides play important functions in the human diet. Also called double sugars, disaccharides are a type of carbohydrate that contains two sugar molecules called monosaccharides that are linked together in a compound. Your body digests disaccharides in foods and breaks them into the two individual sugar molecules that are then absorbed through your small intestine. Disaccharides differ by chemical structure and function. Consult your doctor about the function of disaccharides in your diet.

A baby drinking from a bottle, which contains lactose. (Image: Christopher Robbins/Digital Vision/Getty Images)


Three disaccharides exist in the human diet. Lactose is naturally found in the milk of mammals and contains glucose and galactose. Sucrose is found in beets and sugar cane. Sucrose, also called table sugar, contains glucose and fructose. Maltose is a disaccharide that contains two molecules of glucose. Maltose forms during the breakdown of certain starches, such as barley, during food manufacturing. Glucose is the simple sugar cell that your body uses for energy. Your body normally converts galactose and fructose, also called fruit sugar, into glucose.


Lactose, also called milk sugar, is the nutritional source of energy for infants during nursing. Lactose makes milk tastes sweet and is an ingredient in many processed foods that contain dairy. Manufacturers add whey, a byproduct of dairy production that contains lactose, to certain food products, such as breads, cookies, cakes, doughnuts, breakfast bars and ice cream. Lactose requires you have an enzyme called lactase to digest the disaccharide. Many people are lactose intolerant and do not produce sufficient amounts of lactase to digest lactose, causing such symptoms as nausea, diarrhea, gas, abdominal cramps and bloating. You can take a lactase supplement to help you digest lactose and ameliorate the symptoms.


Sucrose is the disaccharide present most in the human diet. The function of sucrose is to sweeten foods for more taste appeal. Manufacturers add sucrose as a sweetener to candies, ice cream, cookies, cakes, breads, sauces, ketchup and canned goods. An advantage of using sucrose as a sweetener is that it is stable in both liquid and crystallized solid states.

Manufacturers replaced sucrose as a sweetener in many food and beverage products with high-fructose corn syrup, a sweetener that contains a mixture of glucose and high concentrations of fructose and is less costly than sucrose. However, high-fructose corn syrup increases abdominal fat and weight more than sucrose does, according to research by scientists at Princeton University that was published in "Pharmacology, Biochemistry and Behavior" in November 2010.


Maltose does not have a specific function in the body. Manufacturers convert maltose to a disaccharide sugar alcohol called maltilol for use as a bulk sweetener in powder and syrup and added to many sucrose-free and diabetic foods, including chocolates, chewing gum, bakery goods, candies, ice cream and jam. Your body slowly absorbs only 50 to 60 percent of maltilol, with the remainder excreted or fermented in the large intestine.

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