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Lactose intolerance, where does it come from?

Another word for lactose is milk sugar. This is mainly found in dairy. There are people who cannot tolerate lactose. But how can this be? And what is lactose  exactly? Interesting studies have been done on this.

What is Lactose?

Lactose is a sugar that is mainly found in dairy and is also called milk sugar. Most people know someone in their environment who can consume a limited amount of dairy because of an allergy. This is often because people cannot tolerate lactose; lactose intolerance. As a baby we can (usually) tolerate lactose and we mainly need milk. As one gets older, it is often the case that people are less able to tolerate lactose and more and more often get complaints such as stomach pain or nausea.  research showed that adult humans originally cannot tolerate lactose because it cannot be broken down turn into.

Breaking down lactose

There is a certain enzyme that is produced that ensures that lactose is broken down. The name of this enzyme is lactase-phlorizin, also called lactase. Usually adults no longer make this enzyme, so they have a lactose intolerance; the lactose cannot be broken down. Especially in the European population groups, the number of adults who still produce the enzyme is high and so the number of people with lactose intolerance is low.

Lactose intolerance can be hereditary

Having lactose intolerance is genetically transmissible, i.e. it is indicated in the genes whether or not you make the enzyme in the adult years. This can then be passed on to the next generation.

Which genes help?

Positive selection in European populations ensures that this group can digest lactose, so that a lot of dairy can still be seen in the diet. Because there are so many people (especially in Europe) who are not lactose intolerant, the question arises whether it is only one gene that regulates it, or whether several genes work together to ensure that the lactose is broken down.


European populations are about the only group that can often break down lactose as adults through natural selection. In Asian countries, for example, lactose intolerance is very common, there is only a small percentage of adults who can break down lactose.

What does lactose contain?

Lactose is in many more products than just milk/dairy. In some medicines, lactose is used as a filler. These are such small amounts that someone with a lactose intolerance usually does not notice this, according to the Voedingscentrum. In addition, it is also in many foods that contain milk or milk powder. This is always stated on the label.

Good advice is essential

It is best for someone with a lactose intolerance to go to a dietician to get good advice on how much lactose can still be consumed and which types of products are best avoided. It is often not necessary to completely avoid lactose. The reactions usually only occur with a certain amount of lactose that is consumed. A good answer to  what is too much lactose for you, is essential here.