Final answer:
Milk is a significant source of the disaccharide lactose, which is made up of glucose and galactose and is essential for nutrition, though some may require lactose-free alternatives due to intolerance.
Step-by-step explanation:
Milk and other dairy products are major food sources of lactose, which is a disaccharide. Lactose is comprised of two monosaccharides, glucose and galactose, and is found naturally in milk. In individuals with lactose intolerance, lactose is not well digested in the small intestine, leading to symptoms such as bloating and cramps.
For good nutrition, especially for growing children, milk provides essential vitamins and minerals, but those with lactose intolerance may need to seek lactose-free options or supplements to aid digestion.