Milk sugar lactose is made up of

Milk sugar lactose is made up of Glucose + Galactose.
Milk sugar is composed of glucose and galactose. Galactose is less suitable as an energy source than glucose. Thus, it has been a puzzle as to why mammals utilize galactose as a major component of milk sugar.
This is one of the types of sugar molecules that make up lactose, the main type of sugar in milk and all products that contain milk. Galactose is found in milk and all milk products such as cottage cheese, yogurt, ice cream, buttermilk and cheese.