compound

Lactose

Lactose is the disaccharide sugar naturally present in mammalian milk.

It is made from glucose and galactose and is broken down by lactase in the small intestine in people who produce enough of that enzyme.

Milk sugar

Lactose is a disaccharide, so digestion separates it into monosaccharides before absorption. Its amount and tolerance depend on the food and on lactase activity; those are distinct questions from lactose’s chemical identity.

Related topics

  • Lactose is digested to release Glucose

    Lactose digestion releases glucose and galactose as separate monosaccharides.

Worth knowing

  • It is not sucrose. Lactose contains glucose and galactose, whereas sucrose contains glucose and fructose.

A closer look

Digestion depends on lactase

Lactose content and lactose digestion are separate measurements: lactase activity in the small intestine determines how much is broken down before absorption.

References

Source-checked local draft.
Human editorial review pending.

  1. European Food Safety AuthorityScientific Opinion on Dietary Reference Values for carbohydrates and dietary fibreChecked 2026-09-05