lactoses

Lactose is a disaccharide sugar composed of glucose and galactose linked by a beta-1,4-glycosidic bond. It is the principal carbohydrate in the milk of most mammals, produced in mammary glands by lactose synthase from UDP-galactose and glucose-1-phosphate. In cow milk lactose is about 4.8–5% by weight, while human milk contains around 7%.

Lactose occurs in the milk of dairy animals such as cows, goats, and sheep, and remains in many dairy products. In cheese and yogurt, lactose declines as bacteria ferment it to lactic acid. Lactose-free products are made by enzymatically hydrolyzing lactose with lactase.

Digestion: Lactose is broken down in the small intestine by lactase into glucose and galactose, which are absorbed. Lactase deficiency causes lactose intolerance, with symptoms such as bloating, gas, and diarrhea after consuming lactose-containing foods. Prevalence of lactase non-persistence varies by population.

Industrial uses: Lactose is less sweet than sucrose and is used as a filler and bulking agent in foods, pharmaceuticals, and some baked goods. It can be fermented to lactic acid. Lactose-free dairy products are common and produced by adding lactase.

Nutrition and health: Lactose provides about 4 kcal per gram. For those with intact lactase, it is digested normally; others may need dietary alternatives. It is generally considered safe when consumed within dietary guidelines.