Lactase is an enzyme capable of breaking down lactose, the main sugar present in milk. Lactose is a disaccharide composed of two simple sugars: glucose and galactose.
Although the human body produces lactase, its biosynthesis naturally tends to decrease with age, which significantly reduces the assimilation of lactose provided by the diet. This is known as lactose intolerance. In fact, due to the lack of sufficient lactase, the lactose is not completely digested and ends up in the colon, where it is fermented by bacteria, which leads to the production of gas that causes bloating.