What is lactose?

Lactose is indeed a natural sugar primarily found in milk and dairy products. It is classified as a disaccharide, composed of two simpler sugars, glucose and galactose. When people consume lactose, it is broken down in the small intestine by an enzyme called lactase. For individuals who produce sufficient lactase, lactose can be digested without issue. However, those who are lactose intolerant may experience discomfort because they lack enough lactase to effectively break down lactose.

The other options refer to different substances. The first option incorrectly suggests that lactose is associated with fruits and vegetables, while they contain different types of sugars like glucose and fructose rather than lactose. The third option mistakenly categorizes lactose as a type of protein found in eggs; however, proteins and sugars have distinct chemical structures and functions in the body. Lastly, the fourth option incorrectly identifies lactose as a carbohydrate found in grains when, in fact, grains typically contain starches and fibers rather than lactose. This context highlights the specificity of lactose as a sugar unique to dairy sources.