It's all about lactose. Lactose is a lactic carbohydrate found in dairy products. In order for it to be digested, a healthy person's intestines produce a special enzyme called lactase. There are various abnormalities that occur when less of this enzyme is produced than necessary. For example, with age or after an intestinal infection. In such cases, it is not recommended to drink milk, as it causes unpleasant phenomena - nausea, increased gas, diarrhea. It is also known to have a genetically conditioned pathology, when little or no synthesis of this enzyme occurs. This is true lactase deficiency. For these people, the alternative to milk is dairy products, in particular yoghurt, where the lactose is already partially broken down. Because the lactose in yogurt is better digested (3-8 times better) than the lactose in milk.