The problem of lactose intolerance has been with man since milk appeared in the human diet, but it was not until the 20th century that specialised research was carried out into the background of this phenomenon. Intolerance is the result of a deficiency of the enzyme lactase, responsible for digesting the lactose contained in milk and dairy products. The range of symptoms of intolerance is wide and, unfortunately, often confused with a food allergy, but, as numerous studies have shown, the basis of these two pathological processes is completely different.