Dietitians speak of lactose intolerance, when eating milk, dairy products, and many other foods that contain milk in a hidden way causes complaints.

The disease is based on one of the types of food intolerance.


The reason for the complaints is the lack of the lactase enzyme. The lactase enzyme is responsible for breaking down the milk sugar, lactase, in the small intestine. Only after the breakdown of lactase can the components of milk sugar be absorbed by the body. Lack of the enzyme lactase means that the body produces insufficient amounts of the enzyme or it is not produced at all. As a result, milk sugar may be partially digested or not digested at all.


Dietitians' recommendations focus primarily on avoiding or reducing the consumption of milk, dairy products, and other products containing milk sugar, as they are the cause of the complaints described above.


Typical complaints of milk sugar intolerance are: abdominal pain, nausea, vomiting, diarrhea and flatulence (bloating).

In addition, there are a number of atypical complaints, the intensity and manifestations of which are different in different patients. These include, for example, headaches, fatigue, lethargy, sleep disturbances and skin problems.


There are a number of different tests that can be used to determine the presence of milk sugar intolerance.

H2 - breath test
The H2 breath test is one of the simplest and most reliable methods for diagnosing lactose intolerance. The patient drinks a solution of milk sugar, after which the level of hydrogen content in the air exhaled by the patient is measured. If milk sugar is not broken down by the enzyme lactase, then it will be converted by intestinal bacteria, including into hydrogen gas (H2), which is then emitted in a larger volume through breathing. The lower the patient's ability to tolerate milk sugar, the higher the level of hydrogen in the air will be.

Lactose intolerance test
The lactose intolerance test is usually combined with an H2 breath test. After the patient drinks the milk sugar solution, blood is taken for analysis and examined for a suspected increase in blood sugar levels. Usually, after the consumption of milk sugar, enzymatic release of glucose occurs, which through the walls of the intestine enters the circulatory system, into the blood, where it is detected in the laboratory. In the absence of the lactase enzyme, less glucose enters the blood, respectively. If the concentration of glucose in the blood is less than 20 milligrams per deciliter, nutritionists have reason to talk about a possible lactose intolerance.

Gentest is still a relatively new diagnostic method. He provides an explanation regarding the genetic predisposition to lactose intolerance. This method is not currently standard research, as it requires a very large investment of time and money compared to other methods.


In general, foods low in milk sugar, eaten in small amounts, are well tolerated. Complaints arise mainly at doses of milk sugar consumption of more than 10 g.

To find out the amount of milk sugar tolerable, it is suggested to endure from 4 to 6 weeks without this component in the diet.
As soon as a state free from complaints of intolerance is reached, various dairy products can be eaten, at first in small quantities. At this stage, fermented foods are recommended, such as yogurt, curdled milk, kefir or hard cheeses. They are generally very well tolerated. Gradually, you can begin to "experiment" with other products and increase their volume in the diet.

In addition, you can take (according to indications, in some exceptional cases) an enzyme in the form of tablets (for example, lactase).

Professor, Doctor of Medical Sciences
Head of the Clinic of Gastroenterology and Internal Diseases
Doctor of Medical Sciences
Head of the Gastroenterology Clinic
Professor, Doctor of Medical Sciences
Руководитель клиники гастроэнтерологии и гепатологии, университетская клиника Эссена