Summary: Lactose is a disaccharide made of glucose and galactose. Lactose is broken down by lactase present in the brush border of enterocytes, in the greatest amount in "old" enterocytes located at the top of the villi, hence in the atrophy of the villi (regardless of the cause), in excessive exfoliation of enterocytes and in a very intense inflammatory reaction, e.g. in the course of allergies, especially to cow's milk proteins (CMA) transient lactose intolerance may occur. An additional activity of lactase is the breakdown of food glycolipids. Lactose is an important source of energy and galactose for the synthesis of galactolipids in the CNS (central nervous system), it also acts as a prebiotic, at least in infants, and improves the absorption of calcium. Although by its nature (a component of human food and modified milk) it seems to be indispensable, in disease situations you can completely do without it. The source of energy may be other carbohydrates (polysaccharides), galactose is very efficiently synthesized from glucose and the more important prebiotics in food are HMO (human milk oligosaccharides) or in mixtures of GOS (galactooligosaccharides), FOS (fructooligosaccharides) and synthetic HMO. Sufficient absorption of calcium can be achieved by increasing the supply of this element in infant formulas. Since the industrial source of lactose and lactose in the hydrolysates containing it is milk, it is safer not to include it in the hydrolysates, and research shows that lactose-free formulas do not disturb the physical and mental development of infants, and do not adversely affect bone mineralization.