Lactose is a natural sugar found in the milk of mammals, including cow's milk, goat's milk, and human breast milk. It is a disaccharide, meaning it is made up of two simpler sugar molecules—glucose and galactose—linked together. To digest lactose, the body uses an enzyme called lactase, which breaks lactose down into these two sugars so they can be absorbed into the bloodstream. Lactose is present in all dairy products and foods that contain milk such as yogurt, ice cream, and milk chocolate. However, some people have lactose intolerance, a condition where their bodies do not produce enough lactase to properly digest lactose, which can cause digestive discomfort. In terms of its characteristics, lactose is a white, water-soluble solid with a mildly sweet taste. It makes up about 2-8% of milk by mass and is sometimes referred to as "milk sugar." In summary, lactose is the sugar naturally found in milk, composed of glucose and galactose, and requires lactase enzyme for digestion in the small intestine.
