Letzte Aktualisierung am 7. December 2023 von Dr. Michael Zechmann-Khreis
The milk of mammals consists to a large extent of a sugar known as lactose. Milk sugar is also called lactose. There are different types of sugars in nature. They always consist of carbon atoms, which usually join together in a ring shape to form a unit. These units can occur alone (monosaccharides) or consist of two (disaccharides) or more units (polysaccharides). Lactose is such a disaccharide. It consists of the two individual sugars galactose (mucilage sugar) and glucose (grape sugar)1.
Where does the term “lactose” come from?
The name “lactose” is derived from the Latin word for milk (“lac, lactis”). In nature, lactose is found exclusively in the milk of mammals, including human breast milk. All types of milk that we consume today, whether cow’s milk, goat’s milk or sheep’s milk, contain roughly the same amount of lactose. The same applies to products made from these types of milk, such as sheep’s or goat’s cheese. Only very few animals such as kangaroos and sea lions have almost lactose-free mother’s milk2,3.
Lactose is broken down in the intestine
Lactose is broken down into the two individual sugars in our intestines by the enzyme lactase , because only these individual sugars can be absorbed into our bloodstream via the small intestinal wall. If this lactase enzyme is not present in sufficient quantities, this is known as lactose intolerance . But it’s not just our intestines that can break down lactose, bacteria can do it too. This happens, for example, during cheese production or during the maturing of yogurt. This is why many cheeses that have been matured for a long time are lactose-free.
Lactose in the industry
Lactose is a waste product of the dairy industry. It is obtained from whey left over from cheese production. Lactose is correspondingly cheap and has only 20% of the sweetening power of household sugar sucrose. Lactose is therefore well suited as a filler and carrier for medicines or doughs. It has many other properties that are often used by the food industry. For example, lactose creates a pleasant creamy feeling in the mouth or a nice tan when heated. This is why lactose is often found in products where you would not normally expect to find it. It is found in bread, snacks, sausages and chips. So if you have a lactose intolerance, you should always check the “lactose-free” label or read the list of ingredients – even if the product should not contain any lactose according to common sense. Lactose (or milk) must be labeled in the EU. The amount of lactose in medicines is usually too low to cause problems in the case of lactose intolerance. Caution is nevertheless advisable. It is best to talk to your pharmacist.
1) Stryer, L., Biochemistry, Specktrum Akademischer Verlag, 4th edition
2) King J.E., 1983:“Seals of the world”, Oxford Universitv Press
3) Weiss, Eugen; “Grundriss der speziellen pathologischen Anatomie der Haustiere”, 6th edition; Verlag Enke; 2007; p.324