Lactose:Lactose is the substrate that lactase acts upon. It is a sugar found in milk and dairy products.
Glucose:Glucose is one of the two sugars produced when lactase breaks down lactose. It is a simple sugar that serves as an important source of energy for cells.
Galactose: Galactose is the other sugar produced when lactase breaks down lactose. It can be converted into glucose by further metabolic processes.