The lactose -free milk He is chosen by lactose intolerant people for his digestibility. The lactose It is the most abundant sugar in milk and consists of two simpler sugars, the glucose and the galactoselinked together. Normally, to digest it, an enzyme, said lactaseswho “breaks” lactose in its component sugars. People lactose intolerant (only in Italy do we talk about 40-50% of the population) have a deficit of this enzyme and for this reason they can have problems of malabsorption of lactose, with inconvenience to intestinal level. So more and more people are looking for the wording “lactose“On the product they buy at the supermarket, whether it is cheese, yogurt or even a simple cardboard of milk. But are the lactose -free products truly lactose without all? do not guarantee total elimination of this sugar: according to the Ministry of Health, to define itself as “lactose without lactose” or “with a reduced lactose content”, the milk must contain respectively less than 0.1% And Less than 0.5 % of lactose. We must not worry, however: these are really minimal percentages, which have no repercussions on the health of intolerants.
What does lactose -free milk mean and how it is obtained
From an industrial point of view, lactose -free milk is produced through two main procedures: Adding lactases And filtration.
The simplest method consists in adding enzyme lactase directly in milk and let it act for a few hours. At the end of the process, Almost All lactose will have been “decomposed” in the two simple sugars that make it up, glucose and galactose. On the packs you can read it as “the product contains glucose and galactose“In fact, derive from the enzymatic split of lactose. For this reason, to think that the milk subjected to this procedure is sugar -free And totally incorrect: from a type of sugar you move on to two simpler sugars that are more easily absorbed by our intestine.
Among the filters, the most used in this area is the nanofiltration: the milk is passed through membranes with pores that have size between 0.5 and 2 nanometers (1 nanometer is one millionth of a millimeter), which are able to retain lactose and separate it from the milk.
Both the enzymatic demerger and nanophiltration are industrial processes that lead behind a Margin of error: in both cases, the finished product may contain traces of lactose. The split of all Lattose molecules by lactase, while filtering membranes may have usure or imperfections.
So how to know how much lactose contains the milk we are drinking? The Ministry of Health has provided indications in this regard:
- Label “Lactose“: When the lactose content is less than 0.1% (there must be less than 0.1 g of lactose in 100 grams or milliliters of milk).
- Label “With reduced lactose content“: lactose must not exceed 0.5% (100 grams or milliliters of product must contain no more than 0.5 grams of lactose).
Lactose intolerance
What happens in case of absence or reduction of the enzyme lactase? Lactose cannot be split and consequently absorbed, therefore it remains at the level of the intestine where it is metabolized by intestinal microbiota: bacteria metabolize lactose first ad lactic acidand then transform it into a series of by -products, including carbon dioxide (CO2). These chemical reactions have various intestinal inconveniences that include diarrhea, abdominal swelling And aerophagiah.
This condition is known as lactose intolerance (or, in a little more technical language, hypolattasia). At birth, the levels of lactase in the intestine are maximum (being breast milk the main source of nourishment); From weaning onwards they tend to reduce themselves gradually, causing lactose malabsorption. That is It does not happen in all peoplebut only in some: this because lactase is an enzyme, therefore a protein, and like all proteins synthesized within our body its production depends on the “instructions” contained in DNA. Normally, the production of lactases yes physiologically reduces with time: in some genetically predisposed people, lactase is also present in adulthood (phenomenon called “persistence of lactase“); those who do not have genes to summarize it even after weaning, will have problems digesting lactose.
According to the National Library of MedicineThe 65% of the world population is lactose intolerant, with a prevalence in South American, African and Asian ethnic groups, while it is estimated that in Italy the average is affected on average 40-50% of the population. It is important to underline how lactose intolerance is very often self -diagnosed in people, without a medical consultation. To ascertain that you are intolerant to this sugar, it is necessary to undergo specific diagnostic tests, such as the breath test.
